Nycticorax nycticorax -- (Linnaeus, 1758)ANIMALIA -- CHORDATA -- AVES -- PELECANIFORMES -- ARDEIDAECommon names: Black-crowned Night-heron; Black-crowned Night Heron; Black-crowned Night-Heron.; Héron bihoreau; Night Heron

European Red List AssessmentEuropean Red List Status

LC -- Least Concern, (IUCN version 3.1)

Assessment InformationYear published: 2015Date assessed: 2015-03-31Assessor(s): BirdLife InternationalReviewer(s): Symes, A.Compiler(s): Ashpole, J., Burfield, I., Ieronymidou, C., Pople, R., Van den Bossche, W., Wheatley, H. &

Wright, L.Assessment RationaleEuropean regional assessment: Least Concern (LC)EU27 regional assessment: Least Concern (LC)

At both European and EU27 scales this species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence 10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (30% decline over ten years or three generations).

For these reasons the species is evaluated as Least Concern within both Europe and the EU27.

OccurrenceCountries/Territories of OccurrenceNative:Albania; Armenia; Austria; Azerbaijan; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; Czech Republic; France; Georgia; Germany; Greece; Hungary; Italy; Macedonia, the former Yugoslav Republic of; Malta; Moldova; Montenegro; Netherlands; Poland; Portugal; Romania; Russian Federation; Serbia; Slovakia; Slovenia; Spain; Canary Is. (to ES); Switzerland; Turkey; UkraineVagrant:Denmark; Faroe Islands (to DK); Greenland (to DK); Finland; Iceland; Ireland, Rep. of; Liechtenstein; Luxembourg; Norway; Sweden; United Kingdom; Gibraltar (to UK)

PopulationThe European population is estimated at 60,000-86,100 pairs, which equates to 120,000-172,000 mature individuals. The population in the EU27 is estimated at 26,300-33,900 pairs, which equates to 52,600-67,700 mature individuals. For details of national estimates, see Supplementary PDF.

TrendIn Europe and the EU27 the population size is estimated to be decreasing by less than 25% in 26.4 years (three generations). For details of national estimates, see Supplementary PDF.

Habitats and EcologyNorthern populations of this species are migratory, with those breeding in the western Palearctic travelling on a broad front across the Sahara (Martínez-Vilalta et al. 2014). Post-breeding southward movements occur from September to October and return northward movements occur from March to May (Kushlan and Hancock 2005). In temperate regions breeding occurs in the local spring (Kushlan and Hancock 2005). The species usually nests in small numbers (Snow and Perrins 1998) in single- or mixed-species colonies, although sometimes groups may reach several thousand pairs (Martínez-Vilalta et al. 2014). When nesting within mixed-species colonies the species tends to form monospecific clusters (Kushlan and Hancock 2005).

The species inhabits fresh, brackish or saline waters with aquatic vegetation and trees (e.g. pine, oak) for roosting and nesting in (Martínez-Vilalta et al. 2014), showing a preference for islands or predator-free areas for nesting sites (Kushlan and Hancock 2005). It occupies the forested margins of shallow rivers, streams, lagoons, pools, ponds, lakes and marshes and may feed on pastures, reservoirs, canals, aquaculture ponds (Martínez-Vilalta et al. 2014) and rice-fields (Kushlan and Hancock 2005). On migration the species may also frequent dry grasslands or marine coasts (Martínez-Vilalta et al. 2014) and estuaries (Hockey et al. 2005). It is common at elevations of up to c. 2,000 m (Snow and Perrins 1998). It is an opportunistic feeder taking fish, frogs, tadpoles, turtles, snakes, lizards, adult and larval insects (Martínez-Vilalta et al. 2014) (e.g. beetles, bugs, grasshoppers, crickets, flies and dragonflies) (Kushlan and Hancock 2005), spiders, crustaceans, molluscs, leeches, small rodents, bats and the eggs and chicks of other bird species (Martínez-Vilalta et al. 2014). The nest is a platform constructed of sticks and vegetation (del Hoyo et al. 1992, Kushlan and Hancock 2005) placed 2–50 m above water or on dry ground near water (Snow and Perrins 1998) in trees, bushes, reedbeds, on cliff ledges and on the ground (Martínez-Vilalta et al. 2014) in protected sites (Kushlan and Hancock 2005).Habitats & Altitude

Habitat (level 1 - level 2) Importance OccurrenceMarine Intertidal - Salt Marshes (Emergent Grasses) suitable breedingWetlands (inland) - Bogs, Marshes, Swamps, Fens, Peatlands suitable breedingWetlands (inland) - Permanent Freshwater Lakes (over ha) suitable breedingWetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls) suitable breedingAltitude max. 4800 m Occasional altitudinal limits

ThreatsThe species is threatened by wetland drainage and destruction (Kushlan and Hancock 2005, Martínez-Vilalta et al. 2014) and by drought in wintering areas (Hafner and Kushlan 2002). It is highly susceptible to pesticides (Kwon et al. 2004, Kushlan and Hancock 2005, Martínez-Vilalta et al. 2014) such as organophosphates, carbamates (Kwon et al. 2004) and DDE (a breakdown product of DDT) which negatively affect hatching success (Kushlan and Hancock 2005). There are also cases of genetic damage to chicks as a result of petroleum contamination (Custer 2000). The species is susceptible to avian influenza (Melville and Shortridge 2006) and Newcastle disease so may be threatened by future outbreaks (Kuiken et al. 2006). It is also persecuted (anti-predation killing) at aquaculture facilities due to its depredation on fish stocks (Kushlan and Hancock 2005), and has suffered declines due to the exploitation of chicks from nesting colonies in the past (Martínez-Vilalta et al. 2014). Chicks of the species are still taken for food in some areas (Hafner 2000, Kushlan and Hancock 2005).Threats & Impacts

Threat (level 1) Threat (level 2) Impact and StressesBiological resource use

Fishing & harvesting aquatic resources (motivation unknown/unrecorded)

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesEcosystem degradation

Climate change & severe weather

Droughts Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesEcosystem degradation

Human intrusions & disturbance

Recreational activities

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesSpecies disturbance

Natural system modifications

Abstraction of surface water (unknown use)

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesEcosystem degradation

Threats & ImpactsThreat (level 1) Threat (level 2) Impact and Stresses

Natural system modifications

Other ecosystem modifications

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesEcosystem degradation

Pollution Domestic & urban waste water (type unknown/unrecorded)

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesEcosystem degradation

Pollution Herbicides and pesticides

Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesReduced reproductive success

Pollution Oil spills Timing Scope Severity ImpactOngoing Minority (<50%) Slow, Significant

DeclinesLow Impact

StressesReduced reproductive success

ConservationConservation Actions UnderwayThe species is listed on Annex I of the EU Birds Directive, Annex II of the Bern Convention and Annex II of the Convention on Migratory Species, under which it is covered by the African-Eurasian Waterbird Agreement (AEWA).

Conservation Actions ProposedA study carried out in north-west Italy suggests that existing nesting sites should be protected and that breeding habitats should be actively managed in order to maintain suitable habitat characteristics (Fasola and Alieri 1992). The creation of a network of new nesting sites spaced at 4–10 km in relation to available foraging habitats in zones currently without suitable nesting sites is also recommended (Fasola and Alieri 1992). Measures should: Sustainably manage river valleys and reed marshes, including the reduction of water pollution and fish overexploitation and minimize disturbance from recreation at the breeding sites.

BibliographyBrown, C.R., Brown, M.B. and Ives, A.R. 1992. Nest placement relative to food and its influence on the evolution of avian coloniality. American Naturalist 139(1): 205-217.Custer, T. W. 2000. Environmental contaminants. In: Kushlan, J. A., Hafner, H. (ed.), Heron conservation, pp. 251-267. Academic Press, San Diego.Fasola, M. and Alieri, R. 1992. Conservation of heronry Ardeidae sites in North Italian agricultural landscapes. Biological Conservation 62: 219-228.Hafner, H. 2000. Heron nest site conservation. In: Kushlan, J. A.; Hafner, H. (ed.), Heron conservation, pp. 201-217. Academic Press, San Diego.Hafner, H. and Kushlan, J.A. 2002. Action plan for conservation of the Herons of the world. Heron Specialist Group, Gland, Cambridge and Arles.Hockey, P.A.R., Dean, W.R.J. and Ryan, P.G. 2005. Roberts birds of southern Africa. Trustees of the John Voelcker Bird Book Fund, Cape Town, South Africa.Kuiken, T., Fouchier, R.A.M., Rimmelzwaan, G.F. and Osterhaus, A.D.M.E. 2006. Emerging viral diseases in waterbirds. In: Boere, G., Galbraith, C. and Stroud, D. (ed.), Waterbirds around the world, pp. 418-421. The Stationary Office, Edinburgh, UK.Kushlan, J.A. and Hancock, J.A. 2005. The herons. Oxford University Press, Oxford, U.K.Kwon, Y.K., Wee, S.H., Kim, J.H. 2004. Pesticide Poisoning Events in Wild Birds in Korea from 1998 to 2002. Journal of Wildlife Diseases 40(4): 737-740.

BibliographyMartínez-Vilalta, A., Motis, A. and Kirwan, G.M. 2014. Black-crowned Night-heron (Nycticorax nycticorax). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds.) 2014. Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/52707 on 15 April 2015).Melville, D.S. and Shortridge, K.F. 2006. Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G., Galbraith, C. and Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.Snow, D.W. and Perrins, C.M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Map (see overleaf)