Secretarybirds and Citizen Science in South Africa
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Transcript of Secretarybirds and Citizen Science in South Africa
Secretarybirds in South Africa:
what citizen sciencecan tell us
Sally Hofmeyr & Les UnderhillAnimal Demography Unit
University of Cape Town
Craig SymesUniversity of the Witwatersrand
Dawie de Swardt
Sally Hofmeyr
Secretarybird (Sagittarius serpentarius)
• Eats insects, reptiles, mammals, birds, eggs• Disturbs prey by stamping on ground; kills prey with bill
or by stamping on it• Large territories: 50–60 km2 around nest• Breeds in pairs in trees; usually seen in pairs, walking
around, hunting• Mainly grassland and open savanna habitats
Beverly Joubert
• Vulnerable (2011 IUCN Red List), declining throughout rest of Africa – but how is it doing here in SA?
We used data from:
CAR project (Coordinated Avifaunal
Roadcounts)
SABAP1 & SABAP2(Southern African Bird Atlas Projects 1 and 2)
Bird lists collected throughout southern Africa, which is divided up into grid cells based on latitude and longitude.
Comparing the two projects:
Southern African Bird Atlas Projects (SABAP)
SABAP2:• 2007 – ongoing• Pentads (5 × 5)• 5-day recording period
SABAP1: • 1987 – 1992• Quarter degree grid cells
(15 × 15)• 30-day recording period
SABAP data analysis
• Compared reporting rates between SABAP1 and SABAP2. (Reporting rate = % of checklists for each grid cell that report the species you’re looking at)
• Used a statistical method to test how likely the differences are to be real
• Made a map with grid cells colour-coded according to how sure we are that the difference is real
SABAP data – changes in Secretarybird reporting rates from SABAP1 to SABAP2
22 May 2014
Johann du Preez
Red, orange, yellow = DECLINESBlue, green, green = INCREASESThe darker the colour, the more sure we are that the change is real, and reflects a change in abundance.
SABAP data – changes in Secretarybird reporting rates from SABAP1 to SABAP2
22 May 2014
Johann du Preez
Red, orange, yellow = DECLINESBlue, green, green = INCREASESThe darker the colour, the more sure we are that the change is real, and reflects a change in abundance.
Note that we needed ALL the checklists for each grid cell to be able
to use this method.
Thus every checklist submitted was used – not just those that reported
Secretarybirds!
Kruger National Park
Northern Cape
Eastern Cape
Free State
Western Cape
North West
Gauteng
Mpumalanga
KwaZulu-Natal
Limpopo
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
SABAP data – counts of each type of grid cell in each province and in Kruger National Park
The CAR project
• Counts of large terrestrial birds in agricultural habitats
• Fixed routes, mostly about 60 km long; strict protocol
• Two counts per year – summer and winter – same day countrywide
• Project started in 1993, spread across south-eastern half of SA
• We used the habitat data to look at Secretarybirds’ habitat selection and habitat use
340 routes;~ 19 000 km
CAR route map – a huge chunk of the country is sampled!
S W S W S W S W S W S W S W
Eastern Cape Free State Gauteng KwaZulu-Na-tal
Mpumalanga Northern Cape
Western Cape
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8Tr
ansf
orm
ed |
N
atur
alCAR data – habitat selection
Dawie de Swardt
S = summer, W = winter
E Cape F State Gauteng KZN Mpum. N Cape W Cape
This shows that except in Northern Cape in winter, Secretarybirds prefer natural habitats to transformed. “Transformed” includes
everything from cultivated land to cities and mines. “Natural” includes natural veld that is used as grazing land, however, so it does
not necessarily mean “pristine”.
CAR data – habitat use
The majority of Secretarybirds were seen in natural habitats, except in W Cape, where more than half werein transformed areas.
In W Cape, cultivation has converted fynbos shrublands into open habitats, more suitable for Secretarybirds.
Despite this, these long-legged marching birds still actually prefer natural W Cape habitats – it’s just that there’s so little of those left now.
Helen and Dicky Badenhorst
• SA population seems to be declining overall• Main causes in SA are probably habitat loss and bush
encroachment
Most importantly, we could not have known this without the hugely valuable contributions of thousands of
citizen scientists! Read the full paper:Hofmeyr SD, Symes CT, Underhill LG (2014) Secretarybird Sagittarius serpentarius Population Trends and Ecology: Insights from South African Citizen Science Data. PLoS ONE 9(5): e96772. doi:10.1371/journal.pone.0096772 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0096772
To concludeNico Myburg Dawie de Swardt