Osprey, Pandion haliaetus

Osprey

Osprey, December 2008, Oman, © Jochen Fünfstück

Names

English: Osprey
Scientific: Pandion haliaetus
German: Fischadler
Spanish: Águila pescadora
French: Balbuzard pêcheur

Taxonomy and Subspecies

Sometimes placed inside it's own monotypic family, the Pandionidae. Others place it in the subfamily Pandioninae within the Accipitridae.
Wordwide, four supspecies are recognized. In Europe, only P. h. haliaetus occurs. Some authors treat the subspecies as full species, but this is not yet fully accepted. [GRIN 2009]

Size

Length: 55-60 cm
Wingspan: 150-170 cm
Weight: Males 1,250-1,600 g, Females 1,600-2,100 g

Maximum Age

32 years in the wild [Mebs & Schmidt 2014].

Habitat

Bound to water with a regular supply of fish. Ospreys can live at the coast, along large rivers and at lakes. Reservoirs and fish ponds are also used if enough prey is available.
During the breeding season, a suitable tree (Scots Pine Pinus sylvestris is preferred) is necessary, or an alternative like a pylon. Artificial nests are used regularly in my places.

Distribution

Worldwide distribution. Does not breed in South America (only wintering or non breeding birds). In Africa, most birds are winter guests from Europe.
In Europe Ospreys breed in Great Britain (most pairs in Scotland), Scandinavia, and from Germany on eastwards in Poland, Belarus, the Baltic States, Russia and Ukraine. A few pairs (0-5) breed in Bulgaria.
A small population breeds in central France, on Corsica and in Spain (Canary Islands, Balearic Islands). [Mebs & Schmidt 2014]

Migration

Most European birds spend the winter in western Africa south of the Sahara. In recent years, there have been more observations of Osprey spending the winter in Spain [Mebs & Schmidt 2014, Dennis 2008].
In Central Europa, the first Ospreys leave already in August with the majority in September and some late birds in October and even November [Mebs & Schmidt 2014].
In Scotland, adult females and nonbreeding birds leave Scotland throughout August. The young and the breeding males leave from mid-August onwards. All Ospreys will be gone from Scotland by the end of September [Dennis 2008].
In Germany most birds return by the end of March to their breeding territories [Mebs & Schmidt 2014].

Breeding and Reproduction

Ospreys can start breeding with three years. Males often settle close to their the location where they were born (on average within 20 km). For females, the distance is a lot longer with on average 120 km. This helps to avoid inbreeding [Mebs & Schmidt 2014].
Nest will either be built on trees (preferably old pine trees) or on power poles. Cliffs are used on some islands in the Mediterranean.
Normally 2 or 3 eggs are laid, rarely 4. Incubation lasts between 38 and 41 days and the young stay in the nest for 50-54 (sometimes up to 60) days [Mebs & Schmidt 2014].

Food and hunting

Feeds almost entirely on fish. There are a few records of Ospreys catching small mammals and water birds, but even Osprey expert Roy Dennis writes in his book A life with Ospreys that he has never seen an Osprey eating anything else but fish [Dennis 2008]. So an Osprey taking something different than fish is really a very rare event.
The species of fish caught depends on what is locally available. The most common fish species is normally the one most often caught. Fish with a weight of 150-300 g are preferred, but everything from 50-500 g and sometimes up to 1.200 g is taken [Dennis 2008]. The length of a caught fish in eastern Germany varied from 7-57 cm [Mebs & Schmidt 2014]. Ospreys need 300-400 g of fish every day [Dennis 2008]. Mebs & Schmidt [2014] give 300-800 g as a the daily requirement. The amount eaten each day also depends on the calorific value of the caught species.

In Scotland pike and brown trout are popular prey species. The introduced rainbow trout also is important now.

Ospreys hunt alone. Cooperative hunting as it is known from other raptors, for example White-tailed Eagles, does not occur. Sometimes they hunt from a perch, but mostly from flight above water or along the shore. When a suitable fish is found, the Ospreys hovers above it's prey and then dives down at the fish. Shortly before the wate surface, the Osprey thrusts it's powerful talons forward at the fish. Sometimes the bird disappears completely under the surface for a short moment. With powerful wing beats it lifts itself from the water and flies away with or without prey. Adult ospreys are successful in one out of four fishing attempts [Dennis 2008]. Inexperienced birds may take many more attempts.
Ospreys can reverse their outer toe which allows them to point two toes forward and two backwards which makes it easier to grasp and carry a fish. When transporting a fish, the Osprey holds the fish with both feet and the head of the fish points forward to reduce drag.

Population

Widespread decline in Europe in the 19th and also 20th century (about until the 1970's) thanks to shooting and egg-collecting [HBW Alive 2014]. In the last decade the Osprey population has increased in many places including Scotland, Germany, Scandinavia and also has recolonized places where the species was gone like England, Bavaria or France. A reintroduction Program is currently underway in Spain.
According to [Mebs & Schmidt 2014] the countries with the largest poplations are Sweden (4100 pairs), Russia (2000 - 4000), Norway (500), Finland (1300) and Germany which had 627 breeding pairs in 2013.

Threats

The Osprey in many countries suffered from problems with DDT during the 1960s and 1970s but with the banning of DDT, it does not seem to be a major problem at the moment (although DDT is still used in countries outside of Europe).
But in the future, other pollutants may cause similar problems.
Destruction of suitable wetlands and trees that Ospreys can use for building their nests is a concern, at least in some areas. The Osprey prefers old pine trees for nesting in many countries, but the intensification in forest management has lead to the removal of suitable trees.
Illegal hunting during migration is probable not a huge problem at the moment but can still occur in some countries (for example on Malta).
Disturbance during the incubation and chick rearing period by tourism or forest management can result in the failure of breeding attempts [Mebs & Schmidt 2014].
Egg theft was a huge problem, especially for the recovering population in Scotland (see [Dennis 2008] for details) in the 1970s and 1980s. Today it can still occur but is probably no longer a big problem (which does not mean it should be neglected).
Young Ospreys can get entangled in nylon fishing line or have hooks embedded in their throats [Dennis 2008].
In the future, overfishing along the African cost (mostly by European ships) could dramatically reduce fish stocks there. That would also affect wintering Osprey populations [Dennis 2008].

Conservation

In order to recognize problems with environmental pollutants as soon as possible, close and constant monitoring is necessary. Another disaster similar to that with DDT must never happen again.
Artifical nest platforms on trees, power poles or other suitable structures can have a very positive effect on Osprey populations and have been used with great success in many countries like Germany, Scotland or the United States.
Disturbance during the breeding season must be avoided (forest work should be avoided close to the nest).
Suitable habitat must be protected. It should also remain free of windfarms.
The fishery along the African coast must be managed in a sustainable way to ensure the protection of the fis stocks there - for the fish themselves, for the people who live in that area and for the wildlife that depends on those fish including Ospreys.

Status IUCN/BirdLife

Least Concern (LC)

Status Global Raptor Information Network

Lower risk

References

[Dennis 2008] Dennis, Roy (2008). A life of Ospreys. Whittles Publishing, Dunbeath (UK).

[GRIN 2009] Global Raptor Information Network. 2009. Species account: Osprey Pandion haliaetus. Downloaded from http://www.globalraptors.org on 3 Mar. 2009

[HBW Alive 2014] del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/ on 2 November 2014).

[Mebs & Schmidt 2014] Mebs, Theodor & Schmidt, Daniel (2014). Die Greifvögel Europas, Nordafrikas und Vorderasiens. Kosmos Verlag, Stuttgart

Books

Forsman, Dick (1999). The Raptors of Europe and the Middle East A Handbook of Field Identification. Poyser, London

Mebs, Theodor & Schmidt, Daniel (2014). Die Greifvögel Europas, Nordafrikas und Vorderasiens, 2. Auflage. Kosmos Verlag, Stuttgart

Dennis, Roy (2008). A life of Ospreys. Whittles Publishing, Dunbeath (UK).

Websites

BirdLife Species Factsheet for the Osprey

GRIN species account for the Osprey

Roy Dennis, Highland Foundation for Wildlife

Rutland Osprey Project

Reintroducción del águila pescadora en Andalucía (Reintroduction in Andalusia)