Diet of Circaetus gallicus in Valais, Switzerland

The place for new fieldguides and discussions on books on field herpetology, description and discussion on new (sub)species, etc.

Diet of Circaetus gallicus in Valais, Switzerland

Postby Stéphane Aubry » Thu Mar 21, 2013 4:47 pm

Some very interesting observations on the diet of the first nesting pair of Short-toed Eagle in Switzerland :

Maumary, L., H. Duperrex, J. Cloutier & L. Vallotton – First nesting of a pair of Short-toed Eagles Circaetus gallicus in Switzerland. Observations of reproductive biology in particular their diet. Between 1st April and 1st October 2012 a pair of Short-toed Eagles successfully fledged a chick in the Haut-Valais (Swiss Alps). This event had been long awaited and was the first proven reproduction in the country following increases in the number of sightings in the 1990’s. Following a rapid period of nest building incubation lasted 47 days from 13 April and the chick hatched on 29 May. The chick remained 79 days in the nest and fledged on 17 August. From the moment of fledging at least 42 days remained before total emancipation. The breeding success was certainly dependent on the availability of the Asp Viper Vipera aspis and made up 83% of prey items. The Asp Viper is the most common ophidian in Switzerland and covers a wide range of altitudes ; this species is locally abundant in the Valais. This choice is rare amongst Short-toed Eagles which normally tend to prefer the large grass snakes of which only the Aesculapian Snake Elaphe longissima is present in the Valais. The Asp Viper rarely exceeds much over 70 cm in length which resulted in this pair having to compensate by twice as many feedings compared with pairs in the South of France. As many as 8 daily feedings were observed towards the end of the period that the chick was in the nest, often until late in the evening, compared with 5 in the South of France. Reptiles, (Slow-worm Anguis fragilis, Grass Snake Natrix natrix, Aesculapian Snake, Smooth Snake Coronella austriaca, and Asp Viper) made up 97 % of 112 prey items, the remaining 3 % being made up of a Common Frog Rana temporaria, a Rock Ptarmigan chick Lagopus muta, and a Hazel Grouse chick Bonasa bonasia, it is the first time that these last two species have been reported as prey items of the Short-toed Eagle. The outstanding quality of the male played an essential part in the reproductive success (high participation in the incubation, feeding the female on the nest while two thirds of all the feedings of the chick at the nest were carried out by the male who also continued to feed it for another 42 days after fledging). This male had also been reported in the area every summer since at least 2008 and possibly already in 2007 where it had been seen hunting in the burnt Bannwald forest above Loèche that had burnt in 2003. The male’s very pale plumage tended to give the impression of an immature in spite of being at least 5 years old in 2012. The female had already been photographed in 2010. The Short-toed Eagle is the 218th wild species to have bred in Switzerland since 1800. (Translation : M. Bowman)

http://www.nosoiseaux.ch/issue.php?m_id=13&id=67&langu=en&highligh=
User avatar
Stéphane Aubry
 
Posts: 235
Joined: Mon Mar 26, 2012 9:21 am
Hometown: Neuchatel
country: Switzerland


Re: Diet of Circaetus gallicus in Valais, Switzerland

Postby Gerald Ochsenhofer » Fri Mar 22, 2013 1:34 pm

Very interesting article & pictures!
The Asp Viper is the most common ophidian in Switzerland

I had no idea of that.
Gerald Ochsenhofer
Moderator
 
Posts: 181
Joined: Mon Aug 17, 2009 7:08 pm
Hometown: Vienna
country: Austria

Re: Diet of Circaetus gallicus in Valais, Switzerland

Postby Thomas Reich » Fri Mar 22, 2013 3:47 pm

Gerald Ochsenhofer wrote:
The Asp Viper is the most common ophidian in Switzerland

I had no idea of that.

This is very probably true for the southern and southwestern parts of the country, especially the mountainous areas, but with regard to the entire country I would say it should be Natrix natrix. Of course it depends on the definition of "common". For example, the range of Natrix natrix and Coronella austriaca is undoubtedly larger than the one of Vipera aspis, that is missing in at least half of Switzerland.
User avatar
Thomas Reich
 
Posts: 143
Joined: Sun Dec 05, 2010 3:30 pm
Hometown: Switzerland
country: Switzerland

Re: Diet of Circaetus gallicus in Valais, Switzerland

Postby Gerald Ochsenhofer » Fri Mar 22, 2013 4:03 pm

Thanks for this clarification.
Gerald Ochsenhofer
Moderator
 
Posts: 181
Joined: Mon Aug 17, 2009 7:08 pm
Hometown: Vienna
country: Austria

Re: Diet of Circaetus gallicus in Valais, Switzerland

Postby Stéphane Aubry » Fri Mar 22, 2013 4:48 pm

Thank you, Thomas, for the additional informations :P
User avatar
Stéphane Aubry
 
Posts: 235
Joined: Mon Mar 26, 2012 9:21 am
Hometown: Neuchatel
country: Switzerland


Return to Reading Room

Who is online

Users browsing this forum: No registered users and 2 guests