{ 2008 03 16 }

SH*T on YOU!

Do not be mistaken! This is NOT a blog attack! Instead, Fieldfares (Turdus pilaris) literally use faeces as a form of attack against predators. This form of “defensive defaecation” (Meilvang, Moksnes, Reskaft) is an effective weapon against predators, as shown in this video: Attenborough: Life of Birds: Fieldfares and Raven


A study on nest predation in Fieldfares was conducted and results showed that seventeen percent of the Fieldfares nests suffered predation and that this figure is significantly lower when Fieldfares live in colonies (Meilvang, Moksnes, Reskaft). Colonial-nesting in Fieldfares helps in early predator detection, allowing them enough time to assemble a defence force and drive the intruder away. Their actions are defensive rather than aggressive, as their aim is to distract and drive the predator away from the nest (Hogstad).

 IMG_8544

Fieldfares have a systematic way in carrying out their defence. They first raise an alarm call when a predator is detected, followed by diving and clawing at the predator and finally, defaecating on the predator. As in the case of the video, the young raven’s feathers risk getting waterlogged if it is continually defaecated upon by the Fieldfares. Once the feathers are waterlogged, the raven is unable to fly and risk being attacked by the Fieldfares. However, a point to note, the ejecting of faces on the predators by Fieldfares only works well with avian nest predators, and has little effect on mammalian predators as Hogstad has shown in his study.

 f-fare-mJPG

Usually, animals defaecate to mark their territories rather than use it as a form of defence against predators, which is why I find the employment of such a technique in Fieldfares interesting and unique. I ran a search through the Internet and it seems like only Fieldfares eject faeces on predators. In addition, the cooperative hunting in Harris hawks (Parabuteo unicinctus) also roused my interest to blog about animals living in groups [Bednarz, J. C., 1988. Coopoerative Hunting Hawks (Parabuteo unicinctus). Science, 239(4847: 1525 - 1527.] .

Citations:
D. Meilvang, A. Moksnes and E. Reskaft. Copenhagen 1997. Nest predation, nesting characteristics and nest defence behaviour of Fieldfares and Redwings. Journal of Avian Biology 28: 331-337.

Hogstad, Olav. Nest Defence Strategies in the Fieldfare Turdus pilaris: The responses on an avian and a mammalian predator.

References:
Slagsvold, Tore. Egg predation in woodland in relation to the presence and density of breeding Fieldfares Turdus pilaris. Ornis scandinavica 11; 92-98 Copenhagen 1980.

http://www.birdsofbritain.co.uk/bird-guide/fieldfare.asp

http://www.birdguides.com/html/vidlib/species/Turdus_pilaris.htm

Image Source:
http://telbirding10.blogspot.com/2007/11/fieldfares.html




by CHENG WENZHANG on 16-Mar-08 11:26 PM
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