Short-toed Eagle, Circaetus gallicus

Short-toed Eagle

Short-toed Eagle, Spain, May 2009, © Markus Jais

Names

English: Short-toed Eagle, Short-toed Snake-eagle
Scientific: Circaetus gallicus
German: Schlangenadler
Spanish: Culebrera europea
French: Circaète Jean-le-Blanc

Taxonomy and Subspecies

No subspecies.
The genus Circaetus is probably closely related to the Old World Vultures Aegypiinae [GRIN 2009]. Closest relatives of the Short-toed Eagle are the Beaudouin's Snake Eagle Circaetus beaudouini and the Black-breasted Snake Eagle Circaetus pectoralis, both African species. Those three species form a superspecies [GRIN 2009]. The last two were also treated as subspecies of the Short-toed Eagle, but are now considered different species.

Size

Length: 62-68 cm
Wingspan: 170-190 cm
Weight: Males 1,200-2,000 g, Females 1,300-2,300 g

Maximum Age

30 years in the wild. [Bernard Joubert, pers. comm.]

Habitat

Suitable habitat for the Short-toed Eagle must also be suitable habitat for Snakes and other reptiles, the eagle's most important prey. That means, the short-toed Eagle often is found in warm climate where plenty of snakes are available. In southern Europe, this often means dry habitat, but also found in wet areas like moors and meadows, especially in eastern Europe. Also, suitable nest sites with large trees or cliffs must be available. Nests often in forests but hunts in open places, including agricultural areas. In eastern Europe, the Short-toed Eagle also nests in steppes [Mebs & Schmidt 2006].

Distribution

Depends on snakes. Therefore it does not occur in northern latitudes where there are no or only few snakes. In Europa restricted to southern and eastern regions. Largest populations in France and Spain. But also occurs in other countries along the Mediterranean like Italy, Greece or Turkey. In eastern Europe also further north like Belarus and very rarely in the Baltic States. Outside of Europe eastwards to Kazakhstan and south to Iran. Sedentary population on the Indian Subcontinent.

Migration

Migratory species. Most spend the winter in Africa south of the Sahara. A small number of individuals remains in southern Spain [Mebs & Schmidt 2006]. Autumn migration in Europe starts in the end of August and in September. They return again in Spring from March to May.
In a study in north-east Greece done from 1996-1998 the birds arrived between 18 March and 15 April and left between 8 September and 2 October [Bakaluides et al 2005]. Like most migrating raptors, the short-toed Eagle does cross the Mediterranean at it's narrowest points like Gibraltar or the Bosporus.

Breeding and Reproduction

Nests on trees or - very rarely - on cliffs. Only lays one egg which is incubated for 45-47 days [Mebs & Schmidt 2006]. This is rather long, even a few days more than with larger species like the Golden Eagle or the White-tailed Eagle. After hatching, the young eagle stays in the nest for 60-80 days. Similar to most raptors, after fledging, the adults will provide food for the juvenile bird for a few weeks. This will stop when the adults leave for migration [Bernard Joubert, pers. comm.].
In north-east Greece of 58 monitored pairs 52 laid eggs (always only one egg). Mean annual productivity was 0.69 young per breeding pair. The eagles had the worst breeding success when spring weather conditions were bad. If an egg was lost no replacement clutch was laid. The population density was 16.9 km²/pair. Nests were evenly spaced with a mean distance of 2.7 km between the nests [Bakaluides et al 2005].

Food and hunting

The most important prey are snakes. Mostly hunts nonpoisonous snakes from the family Colubridae, for example the Grass Snake Natrix natrix , but is also capable of killing venomous snakes from the family Viperidae [Mebs & Schmidt 2006].
Contrary to popular belief, the Short-toed Eagle is not immune against poison.
Other prey includes lizards and frogs. Sometimes small mammals or birds are taken.
Hunts either from a perch or from flight. Hovers regularly. Attacks prey with fast stoops. Sometimes it is a longer strugle until the snake is dead.

Population

Has declined or gone extinct in some places in Europe. For example, the species bred in Germany about 100 years ago (although probably only in small numbers), but today it is only a rare summer visitor there [Mebs & Schmidt 2006]. In some places like the Murnauer Moos (southern Bavaria), up to three (immature) birds have been seen and some stayed for several month. There seems to be enough food there and the birds where seen eating snakes (pers. observation). Maybe they will breed there in the future.
The European population is estimated to be between 8,200 and 10,350 pairs [Mebs & Schmidt 2006]. The largest populations live in Russia, Spain and France.
In Spain (between 2,000 and 3,000 pairs in 2003) the population is thought be stable or slightly increasing [GRIN 2009]. The population in France is estimated at 2,750 pairs [Mebs & Schmidt 2006]. According to [Joubert 2010], 2,400 pairs is a better estimate.

Threats

Habitat loss (mostly due to intensive agricultural practices) and a reduction in the availability of snakes have caused a decline in some areas.
Given it's high specialization in snakes, the Short-toed Eagle cannot live in places where snakes are gone. Many snake species have declined in Europe, due to persecution and habitat destruction.
Illegal hunting is also a problem in some places, especially during migration [Mebs & Schmidt 2006].

Conservation

Illegal hunting must be stopped.
The conservation of suitable habitat with enough snakes is important. Snakes themselves must be protected from (illegal) killing and habitat destruction. A healthy population of snakes is important for the conservation of the Short-toed Eagle in Europe.

Status IUCN/BirdLife

Least Concern (LC)

Status Global Raptor Information Network

Lower risk

Interviews about the Short-toed Eagle

Interview with Gregorio Moreno-Rueda about the Short-toed Eagle in Spain and it's impact on snake biodiversity

Interview with Francesco Petretti about the Short-toed Eagle in Italy

Interview with Bernard Joubert about the Short-toed Eagle in France

Interview with Konstantin Pismennyi about the Short-toed Eagles and the website short-toed-eagle.net

References

[Bakaluides et al 2005] Bakaloudis D., Vlachos C. and Holloway G. 2005. Nest spacing and breeding performance in Short-toed Eagle Circaetus gallicus in northeast Greece. Bird Study 52 P. 330–338.

[GRIN 2009] Global Raptor Information Network. 2009. Species account: Short-toed Eagle Circaetus gallicus. Downloaded from http://www.globalraptors.org on 18 Apr. 2009

[Joubert 2010] Joubert, Bernard. Interview on europeanraptors.org: Interview with Bernard Joubert about the Short-toed Eagle in France.

[Mebs & Schmidt 2006] Mebs, Theodor & Schmidt, Daniel (2006). Die Greifvögel Europas, Nordafrikas und Vorderasiens. Kosmos Verlag.

Books

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

Mebs, Theodor & Schmidt, Daniel (2006). Die Greifvögel Europas, Nordafrikas und Vorderasiens. Kosmos Verlag.

Websites