2014
EAC – Ecological Evaluation Pty Ltd
June 2014
Bird Island Biodiversity Action Plan
Document Information Client Adelaide & Mt Lofty Ranges Natural
Resources Management Board
Issue Date 12/9/2014
Version 2.3
Author Tim Milne
Title Director
Signature Verified by Sarah Telfer
Title Director
Signature
Document History Version Issue Date
1.0 20/6/2014
2.0 4/7/2014
2.1 21/7/14
2.2 24/7/14
2.3 12/9/14
EAC – Ecological Evaluation Pty Ltd have prepared this report for the sole purposes of the Client for the specific purpose only for which it is supplied. We accept no liability for any direct or consequential loss arising from the transmission of this information to third parties. This report is current at the date of writing only and EAC – Ecological Evaluation Pty Ltd will not be responsible for informing of any future changes in circumstances which may affect the accuracy of the information contained in this report. EAC – Ecological Evaluation Pty Ltd does not offer or hold itself out as offering any advice relating to legal or regulatory implications. Certain assumptions have been made in the preparation of this report. We have assumed that all information and documents provided to us by the Client or as a result of a specific request or enquiry were complete, accurate and up-to-date. Where we have obtained information from a government register or database, we have assumed that the information is accurate. Where an assumption has been made, we have not made any independent investigations with respect to the matters the subject of that assumption. We are not aware of any reason why any of the assumptions are incorrect.
EAC- Ecological Evaluation Pty Ltd 5/26 Hack St Mount Barker, South Australia 5251 Telephone: (08) 8185 3225 [email protected]
E c o l o g i c a l E v a l u a t i o n
mailto:[email protected]
Contents Executive Summary............................................................................................................................... 4
1. INTRODUCTION ............................................................................................................................. 1
2. STUDY AREA .................................................................................................................................. 2
2.1 Current land management .................................................................................................... 3
2.2 Brief History of Bird Island .................................................................................................... 3
2.3 Biodiversity significance ........................................................................................................ 9
3. AIM AND OBJECTIVES OF THE PLAN ............................................................................................ 10
4. ENVIRONMENTAL ASSETS ........................................................................................................... 10
4.1 Landform and soils .............................................................................................................. 10
4.2 Native vegetation communities .......................................................................................... 10
4.2.1 Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland .................... 10
4.2.2 Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia
marina ssp. marina ..................................................................................................................... 13
4.2.3 Atriplex cinerea / Nitraria billardierei Open Shrubland ............................................... 14
4.2.4 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland .................... 16
4.3 Significant Flora Species ...................................................................................................... 17
4.4 Native Fauna ....................................................................................................................... 18
4.4.1 Birds ............................................................................................................................ 18
4.4.2 Reptiles and Frogs ....................................................................................................... 20
4.4.3 Mammals .................................................................................................................... 20
4.4.4 Fish .............................................................................................................................. 20
4.4.5 Intertidal Invertebrates ............................................................................................... 21
5. THREATS (MANAGEMENT ISSUES) .............................................................................................. 21
5.1 Predation of birds and their nests by pest animals ............................................................. 21
5.2 Recreational activities ......................................................................................................... 22
5.3 Invasive weeds .................................................................................................................... 23
5.4 Over-proliferation of Silver Gulls ......................................................................................... 24
5.6 Marine pollution ................................................................................................................. 24
5.6 Lack of cadastral status ....................................................................................................... 26
5.7 Dredge spoil deposition from dredging of the Outer Harbor Channel ................................ 26
5.8 Climate change.................................................................................................................... 26
6. MANAGEMENT OBJECTIVES AND ACTIONS ................................................................................ 27
6.1 Biodiversity management objectives .................................................................................. 27
6.2 Biodiversity management actions ....................................................................................... 27
6.2.1 Managing pest animals ................................................................................................... 27
6.2.2 Managing recreational impacts ....................................................................................... 27
6.2.3 Managing weeds ............................................................................................................. 29
6.2.3.1 Samphire Shrubland Communities .............................................................................. 30
6.2.3.2 Atriplex cinerea / Nitraria billardierei Open Shrubland ............................................... 30
6.2.3.3 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland .................... 30
6.2.4 Rubbish/debris removal .................................................................................................. 30
6.2.5 Dredge spoil deposition from dredging of the Outer Harbor Channel ............................ 30
6.2.6 Maintaining open habitat areas ...................................................................................... 31
6.2.7 Revegetation ................................................................................................................... 31
7. COMMUNITY INVOLVEMENT ...................................................................................................... 32
8. MONITORING .............................................................................................................................. 33
8.1 Monitoring Pest Animals ..................................................................................................... 33
8.2 Monitoring of Native Vegetation Extent and Condition ...................................................... 33
8.3 Monitoring Seabird and Wader Populations ....................................................................... 33
8.4 Plan implementation – progress reporting ......................................................................... 34
9. BIODIVERSITY ACTION PLAN ....................................................................................................... 35
Appendix 1: BushRAT monitoring data ............................................................................................... 39
Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland ....................................... 41
Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp.
marina ............................................................................................................................................ 43
Atriplex cinerea / Nitraria billardierei Open Shrubland ................................................................... 45
Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland ........................................ 48
Appendix 2: Notes on birds in the Outer Harbor Area (adapted from Telfer 2013) ............................ 51
Appendix 3: Weed control methods ................................................................................................... 66
Appendix 4: Works record sheets ....................................................................................................... 74
Executive Summary Bird Island (also known as Section Banks) is situated at the northern end of the Outer Harbor
breakwater. It is an exposed artificial island made of coarse shell-grit, clay and sand that extends for
approximately 1600m. It has been created by a combination of anthropogenic and natural
processes.
Bird Island provides significant habitat values for many bird species, including seabirds and waders of
state, national and international conservation significance. Ten native bird species have been
observed to breed on the island, with another three species considered to possibly breed there. Of
this total of 13 native breeding species, three are considered to be Rare at a state level - Kelp Gull,
Pied Oystercatcher and Sooty Oystercatcher, and the fourth species, the Fairy Tern, is Endangered at
State level and Vulnerable at a national level. The tidal flats around Bird Island are rich in
invertebrates, adding to the value for the area for seabirds.
The vegetation of the island is composed of both native and introduced weed species. The
vegetation varies from areas dominated by introduced species, to areas where native species
predominate. Time series photography indicates that samphire and mangrove vegetation has
colonised the eastern side of the Island in the last ten years.
The Island, and particularly its significant vagrant, resident and breeding bird species, is exposed to a
number of threats. Key threats include:
the impact of introduced pests, such as black rats and foxes;
unmanaged human visitation, particularly when associated with uncontrolled pet dogs
invasive weeds
overproliferation of native Silver Gulls and their impacts on other bird species
marine pollution
possible future dredging and spoil deposition
loss of open habitat areas favorable for nesting for some bird species
A series of management actions are proposed to maintain or improve the biodiversity values on the
Island. These include:
controlling pest animals
managing recreational impacts
restricting access of pet dogs
treating priority weeds, whilst recognising the roosting values provided by some species
replacing weedy shrub species with native shrubs
monitoring growth of vegetation with removal (if required) to ensure some open habitat
areas remain
removing rubbish and debris
increasing community awareness of the significance of Bird Island
A Biodiversity Action Plan table has been developed which summarises the actions required,
provides specific targets, and links to an ongoing monitoring program that can document success.
1. INTRODUCTION
Bird Island (also known as the Northern Breakwater/Revetment or Section Banks) is situated at the
northern end of the Outer Harbor breakwater. It is an exposed artificial island made of coarse shell-
grit, clay and sand that extends for approximately 1600m. It has been colonised by indigenous local
plant species and introduced weedy species. The island also forms a significant roost and feeding
site for both migratory and non-migratory shorebirds, and is a breeding rookery for seabirds,
including Australian Pelican and the endangered Fairy Tern. As such, it has high inherent biodiversity
values, and provides habitat for bird species of national and international significance.
The intent of this project is to develop a Biodiversity Action Plan which documents the significant
biodiversity assets of the Island, threats to these assets, and develops practical and pragmatic
actions to ameliorate these threats. An ongoing monitoring program to evaluate success of
proposed actions will also be devised.
The Biodiversity Action Plan includes:
mapping of different vegetation associations
inventory of plant species present
inventory of actual and potential habitat for native species, with a focus on species of conservation significance at state, national and international level
mapping pest plant distribution and density
prioritising weeds for control
an assessment of the presence of pest animals
identification of priority issues relating to human activity/usage
identification of actions necessary to improve the conservation, management and protection of the Island
baseline monitoring and a description of an ongoing monitoring methodology to measure success of management actions
The Bird Island Biodiversity Action Plan is intended to align with, and contribute to, the objectives of
the following strategies and plans:
The Adelaide and Mount Lofty Ranges Natural Resources Management Plan (2013) which
outlines the Adelaide and Mt Lofty Ranges NRM Board's investment priorities over a three-
year period. This includes the establishment of long-term goals and clearly defined targets.
The Metropolitan Adelaide and Northern Coastal Action Plan 2009. The goal of this Plan is to
understand and facilitate the conservation, protection and maintenance of the region’s
natural coastal resources and to establish conservation priorities for places and areas within
the Region. The Plan includes a regional recommendation on Conserving Valuable Areas,
with an objective: To raise the conservation status and management investment in selected
significant areas within the region. A specific action is identified: To facilitate management of
the Section Banks through clarification of its status.
The Regional Recovery Plan for Threatened Species and Ecological Communities of Adelaide
and the Mount Lofty Ranges 2009-2014.
Page 2
Adelaide Dolphin Sanctuary Management Plan Objectives
Wildlife Conservation Plan for Migratory Shorebirds (2006)
Proposal for the Adelaide International Bird Sanctuary. Surveys indicate the importance of
the island as a roost site for migratory shorebirds and adjacent tidal flats of Section Bank
have high species richness of shorebird food species.
2. STUDY AREA Bird Island is located in the Port River, approximately 15km northwest of Adelaide. It is at the
northern end of the Northern Revetment mound (a rock breakwater) about 700 m offshore from
Outer Harbor. This Biodiversity Action Plan also incorporates the area known as the Northern
Revetment, which is the northernmost section of the north Outer Harbor breakwater (Figure 2.0).
Figure 2.0: Bird Island Study Area
Page 3
2.1 Current land management The Island and the surrounding seabed and intertidal area are owned freehold by the Minister for
Transport and Infrastructure by virtue of the Harbors and Navigation Act 1993. The southern portion
of this island is under the long term control of Flinders Ports by way of a Port Operating Agreement
that expires in 2100. The northern portion of the island is not covered by the Port Operating
Agreement and management responsibility is with the Minister for Transport and Infrastructure.
2.2 Brief History of Bird Island Outer Harbor was constructed in the early 1900s and opened to shipping in 19081. The northern
breakwater, consisting of jarrah piles and huge stone blocks, was completed in 19132, although was
increased in height by two metres in 19623. Bird Island was created from sediment dredged from
the Port River and deposited to the north of the northern revetment in about 19764. At that time the
Section Bank was separated from the northern revetment by about 160 m, but the two are now
joined.
Cooe (2008)5 noted “The loss of extensive areas of seagrass along the Adelaide metropolitan coast
has caused the mobilisation of exposed sediment. Resuspended sediment moves northwards and is
deposited on sand banks (such as Section Bank [Bird Island]) off Outer Harbor and the northern
beaches”. As such Bird Island is slowly growing to the north-east as this sediment accumulates.
Vincent (1988) noted the Island was only 900m long in 1987, but its current length is approximately
1.6 km from the northern revetment to the north east, with a vegetated width of up to 200 metres.
This near doubling in length of Section Banks in the last 30 years has resulted both from channel
dredging and dumping, as well as accumulation of sediments driven north along the coast by wave
energy and the northerly littoral or longshore current.
Bird Island has been colonised by coastal plants, particularly Nitre-bush Nitraria billardierei and
Coast Saltbush Atriplex cinerea on higher ground, with Australian seablite Suaeda australis and
samphire Sarcocornia quinqueflora (and seedling mangroves Avicennia marina) on finer sediments
on the eastern side6.
Figures 2.2.1 to 2.2.5 show the historical changes that have occurred to the site from the late 1960’s
1 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 2 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 3 Vincent, D. 1988. Nesting of the Kelp Gull and other new breeding records from Outer Harbor. South Australian Ornithologist 30: 122-24. 4 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 5 Cooe. 2008. Marine and Coastal Environment and Potential Impact Assessment. Report prepared for Walker Corporation. 6 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008.
Figure 2.2.1: Aerial photography 9/1/1969. There is some sand accumulation at the end of the
breakwater, but Bird Island does not exist in its current location. The northern revetment does
not exist.
Figure 2.2.2: Aerial photography 19/3/1979. There appears to have been deposition of
materials to create a wall from the northern end of the breakwater. There appears to be
some vegetation present. Nitre Bush (Nitraria billardieri) was planted around this time (Greg
Johnston pers. comm.).
Page 5
Figure 2.2.3: Aerial photography 28/9/1989. The wall of deposited material appears to have
been washed away. Bird Island is isolated from the northern breakwater. Vegetation is
evident.
Figure 2.2.4: Aerial photography 6/10/1999. The northern revetment has been created which
joins Bird Island to the northern breakwater. The Island is increasing in size to the north, with
vegetation developing in this newly formed area.
Page 6
Figure 2.2.5: Aerial photography 24/1/2005. There is continued development of vegetation on
the northern end of Bird Island, as well as expansion north eastwards.
Figure 2.2.6: Aerial photography 2013. Note samphire vegetation developing on the eastern
side (brown-red in colour) and continued expansion north eastwards.
Page 9
2.3 Biodiversity significance Populations of shorebirds (also known as ‘waders’) appear to be declining throughout the world.
Section Banks / Bird Island has been identified as a significant area for several shorebird species and
also supports regular breeding populations of 4 resident shorebirds as well as several waterbird and
tern species7. It is one of seven priority habitats on the eastern Gulf St Vincent with one or more
species in internationally or nationally significant numbers7. Carpenter (2008) noted: “The Section
Bank and adjoining revetment have significant value as a habitat for waterbirds, particularly:
1. as a nesting site for ground nesting colonial species (Australian Pelicans, Black-faced Cormorants,
Australian White Ibis, Royal Spoonbill, Fairy, Crested and Caspian Terns), and;
2. as a safe high tide roost for migratory and non-migratory waders. Its value as a roost reflects the
productivity of the adjacent tidal flats of Barker Inlet as a feeding habitat for these birds. Numbers
of migratory waders are greatest in summer, although significant numbers (mostly immature birds)
may remain over winter. Numbers of non-migratory waders fluctuate according to conditions
elsewhere, particularly inland floods. “
The large open mudflats on Section Bank provide some protection from raptors, contributing to
favourable habitat conditions for shorebirds8. Based on invertebrate surveys, Section Bank also has
some of the most species-rich tidal flats in the northern region. About 90 taxa found in total, being
highest on Section Bank and in particular zones of single sites. Molluscs, Annelida and Crustacea
accounted for the majority of the species9.
In addition, Johnston and Wiebkin10 note the northern revetment at Outer Harbor has “the largest
breeding colony of the endemic Black-faced cormorant, with up to 6000 nests recorded during the
winter breeding season”. The nesting colonies for Black-faced Cormorant, Royal Spoonbill, Fairy
Tern and Australian Pelican are significant at State level11.
Purnell et al (2013) recommend “The significant refuge habitat on Section Banks should be secured
and optimised by increasing pest control and reducing recreational visitation12.”
7 Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts 8 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 9 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 10 Johnston, G. and Wiebkin, A. (2008). Birds of Gulf St Vincent. In “Natural history of Gulf St Vincent”. S. A. Shepherd, S. Bryars, I. Kirkegaard, P. Harbison and J. T. Jennings (eds). Royal Society of South Australia, Adelaide. pp. 324-338. 11 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 12
Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts
Page 10
3. AIM AND OBJECTIVES OF THE PLAN The aim of the Biodiversity Action Plan for Bird Island is to document the significant biodiversity
assets of the Island, threats to these assets, and to develop practical and pragmatic actions to
ameliorate these threats, based on an understanding of resources available. An ongoing monitoring
program to evaluate success of proposed actions is also included.
4. ENVIRONMENTAL ASSETS
4.1 Landform and soils Bird Island has been created by two processes – deposition of silty material in the late 1970’s from
material dredged from the Outer Harbor channel, and accumulation of sediments driven north along
the coast by wave energy and the northerly littoral or longshore current. As such, the soils present
are silt, particularly in the southern and landward sides of the Island, and sands which are present on
the seaward and northern sides and overlie the silt in some places.
4.2 Native vegetation communities The vegetation of Bird Island is defined by soil types, exposure to the sea, and time since deposition.
It can be broadly categorised into coastal dune, samphire and mangrove communities. The
following section describes the vegetation types found on site, which are also shown in Figure 4.2.
Note that plant species lists are based upon a once-off visit only. A comprehensive list would require
visiting the site on multiple occasions to take into account seasonal and rainfall related variability.
Each vegetation community was also assessed using the Department for Environment Water and
Natural Resources “BushRAT” methodology, with results summarised in Appendix 1.
4.2.1 Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland
This low closed samphire shrubland occurs in the eastern, sheltered side of Bird Island (Figure 4.2).
It is essentially weed free, with a high cover of native samphire species. Identification to species
level was not possible for all samphires due to the timing of the one-off visit on which this plant
species list was based.
Table 4.2.1.1: Plant species present in the Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland
Species Name Common Name Conservation Status
Comment
AUS SA SL
Sarcocornia quinqueflora Beaded Glasswort
Suaeda australis Austral Seablite
Tecticornia sp.
Page 11
Figure 4.2.1.1: Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland
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Figure 4.2: Vegetation Communities of Bird Island
4.2.1: Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland
4.2.2: Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina
4.2.3: Atriplex cinerea / Nitraria billardierei Open Shrubland
4.2.4: Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
Page 13
4.2.2 Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia
marina ssp. marina
This vegetation type borders much of the sheltered eastern side of Bird Island (Figure 4.2), generally
on the boundary between samphire communities of 4.1.1 and marine environments. It is essentially
weed free, with a high cover of native samphire species, and emergent young Mangroves (Avicennia
marina ssp. marina). Identification to species level was not possible for all samphires due to the
timing of the one-off visit on which this plant species list was based. The first permanent mangroves
were noted in this area in 2005 (Greg Johnston pers. obs.). Whilst not extensive at this stage,
ongoing expansion of this mangrove may be a management issue. This is because expansion may
pose a threat to shorebird habitat in Gulf St Vincent, with incursion by mangroves occurring in many
coastal areas. The expansion of mangroves can limit the availability of the open spaces that
shorebirds use for roosting and feeding. Shorebirds prefer the security of open spaces with high
visibility for the easy detection of approaching predators13.
Figure 4.2.2.1: Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp. marina
13
Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts.
Page 14
Table 4.2.2.1: Plant species present in the Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp. marina
Species Name Common Name Conservation Status
Comment
AUS SA SL
Avicennia marina ssp. marina Mangrove
Sarcocornia quinqueflora Beaded Glasswort
Tecticornia sp.
4.2.3 Atriplex cinerea / Nitraria billardierei Open Shrubland
This open shrubland occurs in northern, sand-based soils of Bird Island. In some parts the shrubland
is very open. Woody weeds are relatively sparse, and there is a moderate to good diversity of
native plant species.
Figure 4.2.3.1: Atriplex cinerea / Nitraria billardierei Open Shrubland
Table 4.2.3.1: Plant species present in the Atriplex cinerea / Nitraria billardierei Open Shrubland
Species Name Common Name Conservation Status
Comment
AUS SA SL
Atriplex cinerea Grey Saltbush
Atriplex semibaccata Creeping Saltbush
Page 15
Species Name Common Name Conservation Status
Comment
AUS SA SL
Austrostipa sp. Speargrass
Carpobrotus rossii Karkalla
Enchylaena tomentosa var.
tomentosa Barrier Saltbush
Myoporum insulare Native Juniper
Nitraria billardierei Dillon Bush
Sarcocornia quinqueflora Beaded Glasswort
Senecio pinnatifolius var.
pinnatifolius
Senecio quadridentatus Cotton Fireweed
Suaeda australis Austral Seablite
Threlkeldia diffusa Coast Bonefruit
Table 4.2.3.2: Weed species present in the Atriplex cinerea / Nitraria billardierei Open Shrubland
Species Name Common Name Cover Comment
Ammophila arenaria Marram Grass 1
Arctotheca calendula Cape Dandelion 1a
Cakile maritima ssp. maritima Beach Rocket 3
Conyza bonariensis Tall Fleabane 1
Euphorbia paralias Sea Spurge 1
Galenia pubescens var.
pubescens Galenia 1
Lycium ferocissimum African Boxthorn 1a Mostly at southern end
Mesembryanthemum
crystallinum Iceplant 1a
Solanum nigrum Black-berry Nightshade 1
Sonchus oleraceus Milk Thistle 1a
Cover Rating
not many, cover
Page 16
4.2.4 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
This shrubland is found in the southern portions of Bird Island. It is principally on silty soils, or sand
over silt. Boxthorns (Lycium ferocissimum) are prevalent, and the understorey is heavily weed
invaded by species such as Beach Rocket (Cakile maritima ssp. maritima), Galenia (Galenia
pubescens var. pubescens), Marshmallow (Malva parviflora) and Stinging Nettle (Urtica urens).
Figure 4.2.4.1: Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
Table 4.2.4.1: Plant species present in the Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
Species Name Common Name Conservation Status
Comment
AUS SA SL
Atriplex cinerea Grey Saltbush
Carpobrotus rossii Karkalla
Enchylaena tomentosa var.
tomentosa Barrier Saltbush
Ficinia nodosa Knobby Club-sedge
Myoporum insulare Native Juniper
Page 17
Species Name Common Name Conservation Status
Comment
AUS SA SL
Nitraria billardierei Dillon Bush
Sarcocornia quinqueflora Beaded Glasswort
Senecio pinnatifolius var.
pinnatifolius
Table 4.2.4.2: Weed species present in the Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
Species Name Common Name Cover Comment
Ammophila arenaria Marram Grass 1a
Arctotheca calendula Cape Dandelion 1a
Atriplex prostrata Creeping Saltbush 2
Cakile maritima ssp. maritima Beach Rocket 2
Chenopodium murale Sowbane 1a
Euphorbia paralias Sea Spurge 1a
Galenia pubescens var.
pubescens Galenia 4
Lycium ferocissimum African Boxthorn 3
Malva parviflora Marshmallow 2
Mesembryanthemum
crystallinum Iceplant 3
Oxalis pes-caprae Soursop 1
Reichardia tingitana Reichardia 1a
Urtica urens Stinging Nettle 1a
Cover Rating
not many, cover
Page 18
4.4 Native Fauna
4.4.1 Birds
Bird Island provides a safe haven for numerous local and migratory bird species, due to restricted
access to the Island. Table 5, adapted from Carpenter (2008) and Johnston et al (2010), summarises
birds known from the Island, along with their conservation status and breeding and visitation status.
Ten native bird species have been observed to breed on the island, with another three species
considered to possibly breed there. Of this total of 13 native breeding species, three are considered
to be Rare at a state level - Kelp Gull, Pied Oystercatcher and Sooty Oystercatcher, and the fourth
species, the Fairy Tern, is Endangered at State level and Vulnerable at a national level. In addition to
these breeding species, a further 61 species have been noted using the island or adjoining tidal flats
and waterways as habitat, including thirteen species of state conservation significance, and the
Southern Giant-Petrel (Macronectes giganteus) which is considered to be nationally Endangered and
Vulnerable at a state level.
The tidal flats adjacent to Bird Island provide significant habitat for wading birds covered under the
‘Japan- Australia Migratory Bird Agreement’ (JAMBA) and ‘China Australia Migratory Bird
Agreement’ (CAMBA). Species covered by these agreements are noted in Table 5.
Table 5: List of Birds known from Bird Island and surrounding flats (adapted from Carpenter 2008 and Johnston et al 2010
14)
COMMON NAME SCIENTIFIC NAME EPBC NPW Status in study area
Arctic Jaeger Stercorarius parasiticus Vagrant
Australasian Gannet Morus serrator Irregular non-breeding visitor
Australian Hobby Falco longipennis Regular non-breeding visitor
Australian Pelican Pelecanus conspicillatus Breeding resident
Australian White Ibis Threskiornis molucca Breeding resident
Australian Shelduck Tadorna tadornoides Irregular non-breeding visitor
Banded Stilt Cladorhynchus leucocephalus
V Irregular non-breeding visitor
Bar-tailed Godwit Limosa lapponica R Regular non-breeding visitor
Black-faced Cormorant Phalacrocorax fuscescens
Breeding resident
Black-shouldered Kite Elanus axillaris Irregular non-breeding visitor
(one bird observed in 2003)
Black-winged Stilt Himantopus himantopus Irregular non-breeding visitor
Black Swan Cygnus atratus Regular non-breeding visitor
Brown Falcon Falco berigora Irregular non-breeding visitor
(one observed in 2006)
Cape Barren Goose Cereopsis novaehollandiae R
Irregular non-breeding visitor (seen once in 2011)
Caspian Tern Sterna caspia Breeding resident
14 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished.
Page 19
Crested Tern Sterna bergii Breeding resident
Chestnut Teal Anas castanea Regular non-breeding visitor
Common Greenshank Tringa nebularia Regular non-breeding visitor
*Common Starling *Sturnus vulgaris Breeding resident
Curlew Sandpiper Calidris ferruginea Regular non-breeding visitor
Double-banded Plover Charadrius bicinctus Regular non-breeding visitor
Eastern Curlew Numenius madagascariensis
V Regular non-breeding visitor
Eastern Great Egret Ardea modesta Resident (breeds nearby)
*Eurasian Skylark *Alauda arvensis Irregular non-breeding visitor
Fairy Tern Sterna nereis V E Breeds and disperses
Fluttering Shearwater Puffinus gavia Vagrant
Galah Cacatua rosiecapilla Irregular non-breeding visitor
Great Cormorant Phalacrocorax carbo Regular non-breeding visitor
Great Egret Ardea alba Regular non-breeding visitor
Grey Plover Pluvialis squatarola Regular non-breeding visitor
Grey Teal Anas gracilis Regular non-breeding visitor
Hoary-headed Grebe Poliocephalus poliocephalus
Regular non-breeding visitor
Hooded Plover Thinornis rubricollis V Vagrant
Kelp Gull Larus dominicanus R Irregular breeding resident
Little Black Cormorant Phalacrocorax sulcirostris
Regular non-breeding visitor
Little Egret Egretta garzetta R Resident (breeds nearby)
Little Grassbird Megalurus gramineus Irregular non-breeding visitor
Little Penguin Eudyptula minor Irregular non-breeding visitor
Little Pied Cormorant Phalacrocorax melanoleucos
Resident (breeds nearby)
Little Raven Corvus mellori Regular non-breeding visitor
Magpie-lark Grallina cyanoleuca Irregular non-breeding visitor
Marsh Sandpiper Tringa stagnatilis Irregular non-breeding visitor
Masked Lapwing Vanellus miles Breeding resident
Nankeen Night Heron Nycticorax caledonicus Resident (breeds nearby)
Osprey Pandion haliaetus E Irregular non-breeding visitor - observed once in 2001
Pacific Gull Larus pacificus Possible breeding resident
Pied Cormorant Phalacrocorax varius Resident (breeds nearby)
Pied Oystercatcher Haematopus longirostris R Breeding resident
Red-capped Plover Charadrius ruficapillus Breeding resident
Red-necked Avocet Revurvirostra novaehollandiae
Irregular non-breeding visitor
Red-necked Stint Calidris ruficollis Regular non-breeding visitor
Rock Parrot15 Neophema petrophila R Irregular non-breeding visitor
Royal Spoonbill Platalea regia Breeds and disperses
Ruddy Turnstone Arenaria interpres M R Vagrant. One observed in 2010.
Salvin’s Prion Pachyptila salvini Vagrant
Sharp-tailed Sandpiper Calidris acuminata Regular non-breeding visitor
15 Noted on site as part of this study 9/5/14
Page 20
Short-tailed Shearwater Puffinus tenuirostris Vagrant
Silvereye Zosterops lateralis Irregular non-breeding visitor
Silver Gull Larus novaehollandiae Breeding resident
Singing Honeyeater Lichenostomus virescens Regular non-breeding visitor
Sooty Oystercatcher Haematopus fuliginosus R Possible breeding resident
Southern Giant-Petrel Macronectes giganteus E V Vagrant
Straw-necked Ibis Threskiornis spinicollis Breeding resident
Swamp Harrier Circus approximans Irregular non-breeding visitor
(observed once in 2007)
Terek Sandpiper Xenus cinereus R Irregular non-breeding visitor
Welcome Swallow Hirundo neoxena Resident (breeds nearby)
Whimbrel Numenius phaeopus R Regular non-breeding visitor
Whiskered Tern Chlidonias hybridus Regular non-breeding visitor
Whistling Kite Haliastur sphenurus Irregular non-breeding visitor
White-bellied Sea-eagle Haliaeetus leucogaster E Resident (breeds nearby)
White-faced Heron Egretta novaehollandiae Resident (breeds nearby)
White-fronted Chat Epthinaura albifrons Breeding resident
Willie Wagtail Rhipidura leucophrys Irregular non-breeding visitor
Yellow-billed Spoonbill Platalea flavipes Irregular non-breeding visitor
EPBC: Environment Protection and Biodiversity Conservation Act, NPW = Schedules of the National Parks and Wildlife Act 2008
4.4.2 Reptiles and Frogs
No reptiles were noted at the time of inspection, although it is possible that small lizards, such as the
Marbled Gecko Christinus marmoratus may have colonised the area as this species has been
observed on small offshore Islands such as Wright Island near Victor Harbor (pers. obs). Due to the
very exposed, saline nature of the environment at the site it is considered highly unlikely that frogs
will be present.
4.4.3 Mammals
There are no native terrestrial mammal present on Bird Island. Bats may possibly fly over the area,
but there are currently no suitable niches for shelter (such as tree hollows). The waters around Bird
Island provide important Dolphin habitat, which has led to the creation of the Adelaide Dolphin
Sanctuary. Introduced mammal species for management include the fox, cat, rat and domestic dog.
4.4.4 Fish
Bird Island is part of a larger ecosystem unit which includes the Port River, Barker Inlet and Torrens
Island, Mutton Cove to the west on the LeFevre Peninsula and the St Kilda Mangroves to the north.
Whilst the focus of this Management Plan is the area of Bird Island above the high tide mark, it
should be noted that the Port River estuary contains the largest area of mangrove forest, shallow
seagrasses and mudflats in Gulf St Vincent. Sheltered conditions and good light penetration create
very high levels of plant and animal production making these prime contributors to the ecology of
the gulf and major nursery habitats for juvenile species of commercial fish and crustaceans,
particularly juvenile Western King Prawns and King George Whiting16.
16 Adelaide and Mount Lofty Ranges Natural Resources Management Board, 2008.
Page 21
4.4.5 Intertidal Invertebrates
Section Bank has some of the most species rich tidal flats in the northern region. About 90 taxa have
been found in total, being highest on Section Bank and in particular zones of single sites. Molluscs,
Annelida and Crustacea accounted for the majority of the species17.
5. THREATS (MANAGEMENT ISSUES) For Bird Island the management issues of particular concern in terms of biodiversity conservation
include:
Predation of nests and birds by pest animals (foxes, cats, rats);
Recreational activities disturbing nesting species and impacting on habitats;
Disturbance and impacts from domestic dogs
Weed invasion;
Over-proliferation of native Silver Gulls limiting nesting success of less abundant bird
species;
Marine pollution;
Lack of cadastral status;
Dredge spoil deposition from dredging of the Outer Harbor Channel;
Climate change
These are discussed in detail below.
5.1 Predation of birds and their nests by pest animals Many waterbirds nest or roost on the ground where they are vulnerable to introduced predators.
Small numbers of foxes travel to and possible live on the Island, and large numbers of black rats
(Rattus rattus) inhabit Bird Island. The Metropolitan Adelaide and Northern Coastal Action Plan
notes that the nesting birds on the Section Bank are at risk from fox predation18. Foxes were first
noted on Bird Island in 2002/3 (Greg Johnston pers. comm.). Following these initial sightings, a
number of roosting waders ceased to roost on Bird Island (Greg Johnston pers. comm.), providing
evidence of the significant impacts of this feral species.
It is likely that more foxes will access the Section Bank as sand deposition provides a low tide link to
Torrens Island19. Foxes have been sighted crossing the mudflats and sandbanks between Torrens
and Bird Island (Greg Johnston pers. comm.). Unwanted domestic cats are regularly dumped on
Torrens Island and are a problem around the Quarantine Station and the Torrens Island Power
Station20. These cats may also access Bird Island as linkage between Bird and Torrens Island
increases. Foxes also spread weeds amongst native vegetation, increasing the risk of introducing
weeds not currently present on Bird Island. The use of poisoned baits to control foxes and cats is
17 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 18 Caton B., Fotheringham D., Krahnert E., Pearson J., Royal M. and Sandercock R. (2009). Metropolitan Adelaide and Northern Coastal Action Plan. Prepared for the Adelaide and Mount Lofty Ranges NRM Board and Department for Environment and Heritage 19
Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 20 Aaron Machado, AMWRO, pers. comm., July 2013
Page 22
problematic, as domestic pets are at times let loose on Bird Island, and may ingest the poison.
However domestic dogs themselves are also a significant cause of disturbance and appear to have
resulted in nest failures of pelicans on the island.
Black Rats (Rattus rattus) feed on refuse around nesting colonies, and may also prey on the eggs of
smaller waterbirds, and so are likely to be affecting the breeding of terns on Bird Island21. Rat
populations undergo an annual flux related to the timing of bird breeding on the Island – with peak
numbers following the principal bird breeding time during winter, and with a population crash in the
summer months (Greg Johnston pers. comm.). At the time of writing there is a baiting program
underway to control Rats on the Island, with poisoned bait rodent stations being established from
the northern end of the Northern Revetment.
5.2 Recreational activities As Bird Island has increased in size and the vegetation present has become more structurally
complex, visitation rates have increased. Humans are accessing the island for a number of reasons,
including out of interest, to allow pets to get exercise and defecate, for toileting, and even as a short
cut for kayakers to carry their craft across the island and hence reach the open sea faster (J. Hayes
pers. comm.). Whilst most are day visits, camping may also occur. The collection of bird eggs from
breeding colonies (for human consumption) has impacted the black-faced cormorant colony on the
Northern Revetment Mound and pelican, ibis, gull and tern colonies on Bird Island in some years22.
Collection of intertidal invertebrates (for bait and a commercial cockle fishery on Section Bank) has
the potential to directly affect the amount of prey available to birds23. Both humans and animals
may cause incubating birds to flush from their nests, leaving them vulnerable to predation by Silver
Gulls24. Domestic dogs may also attack or maim juvenile or adult birds. Carpenter (1998) noted that
larger bird species (such as egrets and herons) typically flush from about 100 metres and smaller
species (eg plovers) from 20-50 metres. In the process of flushing, there may also be stampedes of
adults or young, and trampling of eggs and nests25. Disturbance of the adult birds when they are
departing from or returning to the colony may possibly lead to regurgitation of food carried for
chicks26.
Whilst direct impacts on birds and their nesting success are the key recreational impacts, other
impacts include:
21 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 22 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 23 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 24 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 25 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics
Australia and Gordon Claridge for the Great Barrier Reef Marine Park Authority and Environment Australia-
Biodiversity Group. 26 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics
Australia and Gordon Claridge for the Great Barrier Reef Marine Park Authority and Environment Australia-
Biodiversity Group.
Page 23
trampling or crushing vegetation when walking through dune areas;
compaction of soil which limits natural regeneration;
disturbance of soil and erosion which encourages weeds;
introduction of new weed species; and
the illegal dumping of rubbish and debris which may cause entanglement;
littering with food scraps which may attract unwanted Silver Gulls.
5.3 Invasive weeds Weeds threaten the diversity and structure of native vegetation communities, and can have
concomitant effects on native fauna. However, in sand dune systems it is important to be careful
with treatment and removal as the weeds may be playing a role in binding the sand and thus
preventing sand drift and loss. Table 5.1 lists the priority weeds for control, based upon the
Metropolitan and Northern Coastal Action Plan (MANCAP). Ongoing weed management strategies
need to address both removal of priority weed species, as well as revegetation with native species at
appropriate densities.
Table 5.1: List of Priority Weeds for control
Species Common Name 27Declared 28WONS 29MANCAP Threat Level
30Red Alert Weed Rating
*Ammophila arenaria Marram Grass 3 3
*Euphorbia paralias Sea Spurge 2 3
*Euphorbia terracina False Caper Y 2 3
*Galenia pubescens var.
pubescens
Coastal Galenia 2 -
*Lycium ferocissium African Boxthorn Y Y 2 3
*Mesembryanthemum
crystallinum
Common Iceplant 2 -
*Oxalis pes-caprae Soursob Y 2 3
Carpenter (2008) 31 also notes that more open sites are favoured for nesting by terns, whereas areas
where weedy ground cover is high favour Silver Gulls. Tree Mallow has caused significant problems
in coastal habitats in South Australia, and has blanketed bare sites favoured by nesting terns on
Section Banks32 (although note that Mallow (Malva parviflora) was the dominant plant noted in the
27
Biosecurity SA Weeds and Pest Animals. Declared plants in South Australia, October 2012 http://www.pir.sa.gov.au/biosecuritysa/nrm_biosecurity/weeds/declared_plants_in_south_australia,_october_2012 28
Australian Weeds Committee (2012), Weeds of National Significance 2012. Department of Agriculture, Fisheries and Forestry, Canberra, ACT http://www.weeds.org.au/WoNS/ 29 Caton B., Fotheringham D., Krahnert E., Pearson J., Royal M. and Sandercock R. 2009. Metropolitan Adelaide and Northern Coastal Action Plan. Prepared for the Adelaide and Mount Lofty Ranges NRM Board and Department for Environment and Heritage 30
Refer to Croft, S.J., J.A. Pedler & T.I. Milne (2005 – 2008) Bushland Condition Monitoring Manual. Nature Conservation Society of SA Inc. 31 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 32
Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts
http://www.pir.sa.gov.au/biosecuritysa/nrm_biosecurity/weeds/declared_plants_in_south_australia,_october_2012http://www.weeds.org.au/WoNS/
Page 24
assessment undertaken as part of this project, not Tree Mallow (Malva arborea)). As such, weed
management needs to aim for a reduction in weed ground cover to a more natural state.
5.4 Over-proliferation of Silver Gulls Silver Gulls have increased in numbers enormously over the last half century33. Carpenter (2008)
notes:
“Silver Gulls began nesting on the Northern Revetment as early as 1955 (Cleland 1956), and about
400 birds nested there in 1970, prior to the construction of the Section Bank (Vincent 1988). Silver
Gulls began nesting at the Section Bank as soon as December 1979, when 20,000 nests were
recorded. By October 1987 over 50,000 birds were nesting over all of the vegetated parts of the
island (Vincent 1988). The Wingfield Dump provided a ready source of food for breeding gulls until
operations at the dump changed in late 2005 (G. Johnston pers. comm.). Breeding birds were then
reduced to about one third of former numbers, and only about 150 nests were attempted in 2007.
Silver Gulls also probably affect breeding of terns by predating eggs and young, particularly when
ready sources of other food are not available.”
As noted in Section 5.3, open nesting habitat areas need to be maintained to favour less prevalent
species (such as Fairy Terns) over Silver Gulls.
5.6 Marine pollution Carpenter (2008) provided a succinct summary of the issues with marine pollution:
“Being located at the entrance of a busy city port, there is greater potential for marine pollution to
impact on waterbirds at the Section Bank. The Port River has been used to discard various industrial
and human waste for many years. Oil spills have the potential to affect seabirds anywhere in marine
environments. High levels of heavy metals in the marine environment have also been found in South
Australia (Long et al. 1997), although their impacts on birds (especially nesting species) are
unknown. Entanglement with fishing gear is also an important issue. It is likely that many birds
would die or are preyed upon as a result of entangling with fishing-line. Copley (1996) also
considered entanglements in fishing nets a potential threat to Black-faced Cormorants, although
total mortalities are likely to be low. Ingestion of plastic debris by surface feeding seabirds may also
result in increased mortality (Copley 1996).”
Preliminary studies (Fernandes et al 200834, 201035) highlighted possible concern about the
contamination of Barker Inlet with anti-bacterial and endocrine disrupting chemicals present in
33 Johnston, G. and Wiebkin, A. (2008). Birds of Gulf St Vincent. In “Natural history of Gulf St Vincent”. S. A. Shepherd, S. Bryars, I. Kirkegaard, P. Harbison and J. T. Jennings (eds). Royal Society of South Australia, Adelaide. pp. 324-338. 34 Fernandes, M., Shareef, A., Karkkainen, M. and Kookana, R. (2008) The occurrence of endocrine disrupting chemicals and triclosan in sediments of Barker Inlet, South Australia. A report prepared for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. SARDI Publication No. F2008/001026-1. South Australian Research & Development Institute (Aquatic Sciences), Adelaide, 11 pp. 35
Fernandes, M., Shareef, A., Kookana, R., Gaylard, S., Hoare, S. & Kildea, T. (2010) Estrogens, triclosan and derivatives in sediments of Barker Inlet, South Australia. A report prepared for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the South Australian Environment Protection Authority.
Page 25
pharmaceuticals and personal care products. The authors note “The implications for shorebird prey
species is unclear. Very little information is available on the toxicological response of marine
organisms to these compounds. Triclosan has been identified as toxic to freshwater algae at trace
levels. The need for further research has been identified to determine the risks associated with
accumulation in Barker Inlet, particularly to photosynthetic organisms at the base of the food chain,
from phytoplankton to mangroves. These compounds also have the potential for bioaccumulation,
and to cause hormonal disruption, and the effects to the local fauna, including its resident
population of Indo-Pacific bottlenose dolphins and seasonal populations of migratory shorebirds,
requires further research in the future.”
With the increase in the size of the island and its increased significance for sea and shorebirds, there
is a need to ensure that the importance of the island is noted on oil spill response atlas. Much
rubbish/debris is washed up on Bird Island. This includes items such as fishing line, rope, plastic
drink containers, plastic bags, old shoes, hats, timber, etc. The build-up of rubbish poses a threat to
the biodiversity assets of the area by inhibiting the growth of native flora species as well as
entanglement or ingestion by birds as discussed above. An example of debris accumulation is shown
in Figure 5.4.1.
Appendix 3 includes an example Marine Debris Monitoring Strategy datasheet provided by AMWRO
who regularly undertake the systematic collection and sorting of marine and other debris.
South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 20 pp. SARDI Publication No. F2010/000385-1. SARDI Research Report Series No 448. 20p..
Page 26
Figure 5.3.1: Debris accumulation in seaweed on the north eastern edge of Bird Island
5.6 Lack of cadastral status Due to its recent development, Bird Island has no formal cadastral status. This has been identified as
a significant issue in the Metropolitan Adelaide and Northern Coastal Action Plan. Without formal
land tenure, ongoing responsibility for management is unclear.
5.7 Dredge spoil deposition from dredging of the Outer Harbor Channel Whilst Bird Island has been created from a combination of anthropogenic (spoil deposition) and
natural (sand accumulation) processes, any future deposition of dredge spoil as a result of dredging
the Outer Harbor Channel needs to consider the substantial biodiversity values of the Island as it
currently exists.
5.8 Climate change It is expected that the current mean sea level rise of 3mm/year in the region will accelerate over the
next 50-100 years. Bird Island is likely to be inundated, unless the rise is offset by sedimentation
and/or possible mangrove expansion.
Page 27
6. MANAGEMENT OBJECTIVES AND ACTIONS
6.1 Biodiversity management objectives It is recognised that the key biodiversity asset of the Island is the habitat value it provides for
waterbirds. As such, the key biodiversity management objectives are to:
remove or reduce threats to waterbirds, especially significant nesting species
improve habitat values of remnant vegetation
6.2 Biodiversity management actions These management objectives will be achieved by the following broad actions:
managing pest animals
managing recreational impacts
managing weeds
rubbish/debris removal
managing potential dredge spoil deposition
maintaining the open nature of the habitats of the Island
revegetating appropriately
Each is discussed below.
6.2.1 Managing pest animals Implementation of a fox control program is seen as a high priority, however as discussed previously
this is problematic due to ongoing visitation to the Island by people and their domestic animals.
Control programs in Torrens Island Conservation Park may reduce numbers that traverse sand banks
to reach Bird Island. The Adelaide Pelican Research and Bird Monitoring Group is a group of
volunteers that regularly access the Island to gather data on bird species and to assist in
management. It is recommended that this group remain vigilant for the signs of foxes and when
signs are noted and reported to DEWNR so that a short term baiting program can be implemented.
This would help to minimise potential impacts on native fauna and pets that may access the island
(as there would be less risk when baits are only present for a short time) whilst still retaining
effectiveness in reducing fox numbers. Signage is also recommended (refer Section 6.2.2).
Ongoing control and monitoring of Black Rats is recommended. The optimal time for poisoning
would be in autumn/early winter, prior to the annual peak of rat numbers as noted previously. At
the time of writing there is a baiting program underway to control Rats on the Island, with poisoned
bait rodent stations being established from the northern end of the Northern Revetment across the
Island. Current rat control is being monitored, as one risk identified is that it may result in increased
silver gull numbers which themselves have potential to predate other native seabird and shorebird
eggs and chicks.
6.2.2 Managing recreational impacts To protect the nesting habitats of bird species that are important at national and international
levels, unmanaged human visitation to Bird Island needs to be minimised. The Great Barrier Reef
Page 28
Marine Park Authority has produced a series of guidelines to reduce the impact of daytrip visitors to
seabird breeding islands36. These guidelines include the following actions:
establishment of activity zones located to limit the movement of visitors to the least
sensitive parts of seabird breeding islands and designation of these with fences, markers,
signs etc.;
erection of screen fences to avoid disturbance of birds;
construction of appropriate viewing facilities to reduce random access to the breeding area;
restriction of human presence to the beach so that this is not visible to the nesting birds;
restriction of daytrip visits so that people do not arrive less than two hours after sunrise and
do depart at least two hours before sunset;
brochures, videos, talks and other awareness tools to make visitors aware of the potential
for disturbance;
restriction of access to the breeding island to only those daytrip operators who are
marketing the breeding seabirds as a major attraction; and
provision of appropriate waste bins and education about the dangers of carelessly disposing
of waste such as cigarette butts.
Not all of these actions are relevant or required for Bird Island at this stage, but may be reflected
upon in the future if circumstances change. The following are the key activities recommended at
this point in time to manage recreational impacts:
Signage: It is recommended that interpretive and regulatory signage is installed to inform visitors of
the significant values present, and to keep people and their animals away from these nesting areas.
It is recommended that this signage also reflect the risk posed to domestic animals through poisoned
baits that may be laid on the Island. As such the following key points should be noted:
Bird Island forms critical habitat for native seabird and wader species
Nesting birds that are frightened from their nests may lose their young
Foxes need to be controlled using poisoned baits, as they prey on the nesting birds
At some times, poisoned baits will be laid that are toxic and may be dug up and eaten if
domestic pets are allowed to roam freely
It is recommended that signs be established at the south eastern end of the Island (adjacent the
northern revetment), the south western seaward side (adjacent the northern revetment) and at the
northern end.
Prevention of dog access: Purnell et al. 37recommend that dogs are prohibited from Section Banks
during the migration/breeding season (September – March). These recommendations could
36 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics
Australia and Gordon Claridge for the Great Barrier Reef Marine Park Authority and Environment Australia-
Biodiversity Group. 37
Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts
Page 29
potentially be implemented, with signage supporting these restrictions, although implementation
and enforcement of restrictions would need to be negotiated between key stakeholders.
Fencing: Fencing could also be considered as a potential management intervention – for example,
key nesting areas for Fairy Terns could be fenced such that humans and dogs could not access the
area. However, there are risks in such an approach – for example, ringlock fence established around
Hooded Plover nests has led to nest abandonment38. Natural Resources Adelaide and Mount Lofty
Ranges staff undertake beach-nesting bird management in other areas, (for Hooded Plover) with
BirdLife Australia. It is recommended that fencing is considered as an intervention only in the
following circumstances:
that Fairy Tern colonies consistently nest in the same area
that other attempts to reduce disturbance by dogs and humans are not successful
Guidelines for nest site management and appropriate dimensions for fencing can be found in
Maguire (2008) 39.
Visitor and community awareness: Signage will help raise visitor awareness, but there would be
additional benefits to raising broader community awareness. These are discussed in Section 7.
6.2.3 Managing weeds Whilst weed infestation, particularly when leading to a reduction in open nesting spaces, is
considered likely to reduce nesting opportunities for terns40, it should be recognised that:
Vegetation community 4.4.2 is on silty soils that were deposited as a result of dredging,
rather than a more natural sandy base. There is ongoing nutrient addition as a result of bird
faecal deposition. This leads to conditions more suited to the weed species that are present
than coastal native species. Even if weeds were treated/removed, ongoing infestation is
likely to occur;
To treat weeds present in winter/spring (when most appropriate for control when green)
would result in significant disturbance to nesting birds;
Some introduced species, such as boxthorn, are providing roosting values for species of birds
such as Australian White Ibis (Threskiornis molucca) and Straw-necked Ibis (Threskiornis
spinicollis). Staged removal that incorporates replacement with medium sized native shrub
species such as Atriplex cinerea and Nitraria billardierei needs to be undertaken;
As a rule of thumb, weed control activities should focus on removal of priority weeds from
the least weedy areas first41.
The following weed control strategy has been prepared with reference to these key points.
38 Maguire, G.S. (2008). A practical guide for managing beach-nesting birds in Australia. Birds Australia, Melbourne. 39 Maguire, G.S. (2008). A practical guide for managing beach-nesting birds in Australia. Birds Australia, Melbourne. 40
Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 41 Robertson, M. (2005). Stop Bushland Weeds. Nature Conservation Society of South Australia Inc.
Page 30
6.2.3.1 Samphire Shrubland Communities
There are no current weed issues in the samphire shrubland communities (4.2.1 Sarcocornia sp. /
Tecticornia sp. / Sueda australis low closed shrubland and 4.2.2 Sarcocornia sp. / Tecticornia sp. low
closed shrubland with emergent Avicennia marina ssp. marina Figure 4.2). Ongoing monitoring of
this area for the presence of weeds should be undertaken, and weeds removed if detected.
6.2.3.2 Atriplex cinerea / Nitraria billardierei Open Shrubland
Weed control efforts should initially focus on the removal of Boxthorn and Galenia from the Atriplex
cinerea / Nitraria billardierei Open Shrubland in the northern sections of the Island (Figure 4.2). This
will maintain the open structure favoured by key nesting species. As these weeds are only at
relatively low levels currently, it is unlikely that their control and removal will cause sand movement
as a result of loss of stabilising roots, and native species present are in relatively high density and
thus can provide the habitat values required by roosting birds. There are also small patches of
Marram Grass on the low primary dunes on the western side of the Island. It is recommended that
this grass is removed.
6.2.3.3 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland
The southern end of Bird Island (vegetation community 4.4.2 Figure 4.2) has the greatest issue with
weeds. It is recommended that weed control focus on priority weeds and commence in a staged
fashion, working from the north, and replacing weedy species with native plants that can bind the
soil. Any boxthorn control needs to take into consideration the roosting values of the plant.
Therefore it is recommended that after poisoning, the plant skeleton be left in place until
replacement native species are established. In this area Mallow (Malva parviflora) is prominent, and
as indicated previously has been implicated in reduction of bare sites favoured by nesting terns.
Weed control activities at all times need to consider disturbance to nesting birds at the time control
is undertaken. As such, control programs should be limited to summer months, when there is little
breeding occurring, and impacts on roosting habitat considered as discussed above.
6.2.4 Rubbish/debris removal Ongoing removal of rubbish and debris will help to minimise impacts on seabirds. The Adelaide
Pelican Research and Bird Monitoring Group regularly remove rubbish from the Island, particularly
that rubbish which poses a threat to nesting birds, such as tangled fishing lines and nets. This action
may be maintained by community groups into the future. However, these should always be
targeted clean ups by small supervised groups, who are aware of bird disturbance issues, rather
than large community clean ups, unless undertaken outside of seabird breeding and shorebird
seasons.
6.2.5 Dredge spoil deposition from dredging of the Outer Harbor Channel No dredge spoil should be put on top of the existing vegetation on the Island. Any potential future
dumping of spoil needs to be done in such a manner that the biodiversity values of the Island as
detailed in this document are not compromised. This includes consideration of disturbance to
nesting birds. Any dredging or dumping activities proposed should be timed to minimise impact to
nesting seabirds and migratory shorebirds. The tidal flats have a high biodiversity and provide a
valuable shorebird resource. Any potential dredging or removal of sand may need referral under the
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Environment Protection and Biodiversity Conservation Act for potential impact to migratory
shorebirds listed under the Act.
6.2.6 Maintaining open habitat areas It is desirable to maintain significant areas of bare habitat on Bird Island. More open sites are
favoured for nesting by terns, whereas areas where weedy ground cover is high favour Silver Gulls42.
Shorebirds also prefer the security of open spaces with high visibility for the easy detection of
approaching predators43. The continued expansion of both shrub habitats and Grey Mangrove on
Bird Island may therefore have a negative impact on seabird and wader populations on the Island.
Whilst at this point in time there is no evidence that management intervention is required (aside
from those already discussed), it may be a requirement in the future to intentionally remove
vegetation (including native vegetation) to create appropriate bare areas for nesting, and retain the
required open spaces. As an example, Towra Spit Island near Sydney is a significant breeding site for
the endangered Little Tern. Areas of spinifex, Lomandra and Acacias have been removed from the
Island so there are areas of bare sand for little terns to build their nests. However, as chicks require
shelter once they begin to stray from the nest before fledging, vegetation on Towra Spit Island is
maintained in a perimeter around the cleared area44. Similar actions could be undertaken on Bird
Island if warranted. Consultation would need to be undertaken with the Native Vegetation Section,
Department for Environment, Water and Natural Resources if this clearance involved native species.
6.2.7 Revegetation Revegetation efforts should be undertaken in conjunction with weed control efforts. These efforts
should focus upon supplementing existing habitat, using appropriate species for the vegetation type
and planting at appropriate (natural) densities. The site has already demonstrated an ability for
native species to naturally colonise and regenerate, and as such, revegetation should specifically
focus on replacing structural weed species (eg Boxthorn) with native species. The revegetation
recommended is relatively limited, recognising the key biodiversity values of the Island (seabird and
wader species) may be disturbed by a broad scale revegetation program.
Table 6.2.7: Revegetation plant list
Scientific name Common name Notes
Atriplex cinerea Grey Saltbush Plant as replacement species for staged removal of Boxthorn
Enchylaena tomentosa var. tomentosa Barrier Saltbush
Nitraria billardierei Dillon Bush
42 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 43 Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts. 44
Department for Environment and Climate Change NSW (2008). Best practice guidelines. Managing threatened beach-nesting shorebirds. State of NSW and Department of Environment and Climate Change NSW.
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7. COMMUNITY INVOLVEMENT The Adelaide Pelican Research and Bird Monitoring Group and several key individuals such as Greg
Johnston and David Close have been involved in ongoing monitoring and management of Bird Island.
Aside from this group, there is little general awareness of the importance and sensitivity of the
Island. As noted previously, visitation rates to Section Banks and Bird Island are increasing, with
increasing impact on the biodiversity of the Island. Increasing community involvement and
understanding of the Island may be an approach to improving protection from key threats such as
pet dogs being allowed to run free on the Island and disturb nesting birds. Positive impacts that may
occur through increased community involvement include:
Increased understanding of the importance of Bird Island in the local community;
Increased media opportunities to build community awareness of threats to the Island;
Reduced impacts on the Island of inappropriate recreational use (including impacts of dogs)
through:
o avoidance of the Island by community members aware of the values of the Island;
o informal enforcement of restrictions (such as no free ranging dogs on the Island) by
community members aware of the need for such restrictions;
Ongoing involvement in management and monitoring activities;
Ongoing active community involvement ensures that conservation actions become
sustainable.
However increased community involvement would need to managed to be consistent with
maintaining the conservation values of the Island, and so would need to ensure perverse outcomes,
such as increased visitation (as a result of increased awareness) that causes disturbance to nesting
and roosting birds, does not occur. As such there needs to be ongoing broad oversight of
community involvement with the Island.
The South Australian Government has made a commitment to an International Bird Sanctuary over
the Dry Creek saltfields that also extends 60km along the Gulf Saint Vincent coast from the Barker
Inlet to the south to Port Parham in the north. It is recommended that as part of the process of the
development of this Sanctuary, consideration is given to the broader context of wader and seabird
dynamics within the Gulf, and that all components of this system are considered and managed
appropriately. With regard to community involvement, there will be a suite of community
engagement opportunities, as well as tourism opportunities, related to this new International
Sanctuary. There will also be significant opportunities to build community understanding of the
importance of the seabird and wader habitat in the Gulf, including Bird Island. As such this new
Sanctuary could contribute to the management of Bird Island by:
Improving community awareness of issues relating to wader and seabird conservation;
Improving understanding of the importance of Bird Island as a safe place for birds to breed
Providing opportunities for community to be involved with conservation, whilst also
ensuring that sensitive locations, such as Bird Island, do not become overexposed to threats
from excess visitation by sympathetic users;
Providing opportunities for birdwatchers/tourists to see waders and seabirds in situ at
locations other than Bird Island;
Providing broad oversight of community involvement with the Island.
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It is also recommended that the Adelaide Pelican Research and Bird Monitoring Group is consulted
and empowered in any ongoing management and decision making processes as part of ongoing
community involvement with the project.
8. MONITORING
8.1 Monitoring Pest Animals As discussed previously, it is recommended that ongoing surveillance is undertaken for the presence
of foxes, and responsive baiting undertaken if detected. Black Rats should also be monitored
through an annual baiting program in early winter, with the number of baits taken being an indicator
of the presence and number of rats present. Monitoring of Silver Gulls should be undertaken to
determine if rat control is leading to increased gull numbers. Additionally monitoring of nesting
seabirds should also be undertaken.
8.2 Monitoring of Native Vegetation Extent and Condition Baseline data has been collected as part of this report using the Department for Environment, Water
and Natural Resources “BushRAT” assessment methodology45. This technique is derived from the
Nature Conservation Society of South Australia’s ‘Bushland Condition Monitoring’ (BCM)
methodology, including a Rapid Assessment version (Croft et al, 2005), but uses an area of
vegetation of consistent condition rather than the 30m x 30m quadrats used in the BCM
methodology. Three ‘components’ of the biodiversity value of the site are measured and scored:
vegetation condition, conservation value and landscape context. For this project, only the
vegetation condition components have been scored. Example datasheets from the BushRAT method
are provided in Appendix 1.
A summary of the BushRAT method and the data collected for this project is provided in Appendix 1.
The baseline mapping of extent of vegetation types (Figure 4.2) can be used in conjunction with
weed cover estimates to track progress of weed control activities. GPS locations of site photographs
can be used for ongoing photopoint monitoring (refer Appendix 1)).
Figure 4.2, site photographs and BushRAT data can also be used as a baseline to evaluate changes to
the extent and type of vegetation on the Island. As discussed in Section 6.2.6, ongoing evaluation of
the extent of open nesting and feeding habitat needs to be undertaken to ensure optimal habitat
conditions for seabirds and waders.
8.3 Monitoring Seabird and Wader Populations Greg Johnston has conducted research into the Pelicans and other birds of Bird Island for over 15
years. This work has been carried on by the Adelaide Pelican Research and Bird Monitoring Group,
who visit the Island each week and conduct bird counts and gather observations. This group has also
begun to contribute data to shorebird counts in Gulf St Vincent through Birds South Australia and
BirdLife Australia’s Shorebirds 2020 Program, along with other volunteer contributors. The Adelaide
and Mount Lofty Ranges Natural Resources Management Board along with BirdLife Australia has
been undertaking shorebird population monitoring across Gulf St Vincent. This includes surveys of
45 DEWNR (2012) NVBMU BushRAT assessment and scoring Manual. Unpublished document, Department for Environment, Water and Natural Resources, Waite.
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Bird Island by shorebird researchers. These works should be continued, to help confirm the
significance of the Bird Island area, as well as to contribute to the broader understanding of wader
and seabird populations.
8.4 Plan implementation – progress reporting Progress reporting helps with the assessment of the effort put in to management actions. Some
efforts will be more successful than others. Various factors such as weather or control technique
may affect outcomes. Example Works Record sheets are included in Appendix 4.
9. BIODIVERSITY ACTION PLAN The table below lists the biodiversity management threats/issues for Bird Island, related objectives, actions already taken to address them, and further
actions being proposed.
ISSUE/THREAT 5-Yr Objective Actions to date – what/ who Proposed actions- what/ where/how Priority (H, M, L)
Expected yr completion
Pest animals
Foxes No foxes present and new incursions treated when detected
Undertake an opportune baiting program whenever signs of foxes are detected.
H
Ongoing
Feral Cats No cats present and new incursions treated if detected
Remain vigilant for presence of cats and control with baiting program as required. Inform Cat and Dog Management Board of issues and seek targeted awareness in the Port and Torrens Island area.
H
Ongoing
Rats Rat populations treated annually to reduce impacts
72 bait stations established in June/July 2014.
Continue to treat rats using bait stations in late autumn / early winter. Monitor potential effects on seabirds, particularly increases of Silver Gulls.
H Ongoing
Recreation – Negative impacts on biodiversity (trampling, disturbance to native fauna, erosion, rubbish dumping, etc)
Recreational activities (including pet dogs) disturbing nesting
All visitors to Bird Island are not negatively impacting on native flora and fauna.
On an ad-hoc basis when inappropriate activities have been noted.
Install appropriate interpretive/regulatory signage at strategic locations to inform/educate visitors about the values of Bird Island and the risks posed to pets by baiting programs. Consider closing Island at key nesting periods. Improve knowledge and understanding of the values of Bird Island through appropriate local media. Seek to incorporate the Bird Island area into patrols by Adelaide Dolphin Sanctuary staff. Ensure that planning for visitor management of the island is incorporated into management planning for the proposed Adelaide International Bird Sanctuary
H H
2017
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ISSUE/THREAT 5-Yr Objective Actions to date – what/ who Proposed actions- what/ where/how Priority (H, M, L)
Expected yr completion
Weeds
Boxthorn Eradicate from Bird Island once replacement structural plants have bee
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