Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over 10 years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in 10 years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The European population is estimated at 8,400-12,300 pairs, which equates to 16,700-24,600 mature individuals (BirdLife International 2015). Europe forms approximately 14% of the global range, so a very preliminary estimate of the global population size is 119,000-176,000 mature individuals, although further validation of this estimate is needed. Partners in Flight Science Committee (2013) estimate the global population as 500,000 individuals which equates to 333,000 mature individuals. The population is placed in the band 100,000-499,999 mature individuals.
This species has undergone a large and statistically significant increase over the last 40 years in North America (1,100% increase over 40 years, equating to a 84.2% increase per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). Note, however, that these surveys cover less than 50% of the species's range in North America. In Europe the population size is estimated to be increasing (BirdLife International 2015).
Behaviour Individuals in the tropics and subtropics are resident, but others migrate to the lower latitudes of the Amazon Basin, South America’s northern coast, or West Africa in the non-breeding season (del Hoyo et al. 1994). Migrants begin moving to lower latitudes in August and arrive by October, returning in March and April (Ferguson-Lees and Christie 2001). Birds are generally solitary and usually migrate alone, but may congregate in small groups at roosts or plentiful food sources (del Hoyo et al. 1994, Ferguson-Lees and Christie 2001). The species migrates on broad fronts and is not dependent on land bridges during migration (Snow and Perrins 1998, Ferguson-Lees and Christie 2001); birds readily cross bodies of water using flapping flight, but can soar easily over land. It is entirely diurnal (Brown et al. 1982). Habitat It inhabits the areas around shallow waters, being sufficiently tolerant of human settlement to persist in suburban and sometimes urban environments (del Hoyo et al. 1994). Diet Almost its entire diet consists of live fish (del Hoyo et al. 1994). Breeding site Birds usually build large nests high in exposed trees (del Hoyo et al. 1994). Management information Reintroduction has helped populations to recover across parts of its range (del Hoyo et al. 1994).
Human persecution was the main historical threat, prevalent from the 18th-20th centuries (Ferguson-Lees and Christie 2001). A combination of deforestation and the collection of eggs and live birds drove the species extinct in Azerbaijan (del Hoyo et al. 1994). In the U.S.A. (and to a lesser extent elsewhere), numbers fell significantly from 1950-1970 as a result of pesticide use, although they are now recovering, as they are in Scotland where the species had been extirpated by collection and hunting (del Hoyo et al. 1994, Ferguson-Lees and Christie 2001). Pesticide use has now been reduced to a minor threat. However shooting still affects many birds on migration in the Mediterranean, notably in Malta, as well as wintering birds in tropical regions including Latin America and the West Indies (Global Raptor Information Network 2015). A few Australian birds are apparently impacted by local human disturbance (del Hoyo et al. 1994). It is very highly vulnerable to the effects of potential wind energy development (Strix 2012).
Text account compilers
Butchart, S., Ekstrom, J., Khwaja, N. & Ashpole, J
BirdLife International (2019) Species factsheet: Pandion haliaetus. Downloaded from http://www.birdlife.org on 18/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/09/2019.