I am always a fan of raptors, and have a special place in my heart for social and predation behaviour. Here is a story that combines all three! In the latest issue of Journal of Raptor Research, a remarkable observation of a large group of Golden Eagles harassing elk on a steep ridge is reported (but paywalled).
Matt O’Connell and Michael Kochert witnessed and filmed the astonishing sight of at least 8 eagles repeatedly stooping at a group of elk, either trying to drive them off a cliff, or perhaps just playing around.
Golden Eagles are known to prey on ungulates, sometimes by driving them off cliffs, but the authors are cautious at definitively stating the motivation of these birds. I would suggest that the hypothesis of play and that of predation are not mutually exclusive. I could certainly see a great selective advantage for these carnivorous birds to engage in “play” that sometimes results in the grisly death of a large ungulate.
If you would like to see the video, here it is below. What do you think?
Bergo, G. 1987. Eagles as predators on livestock and deer. Fauna Norvegica Series C, Cinclus10:95–102.
Deblinger, R.D. and A.W. Alldredge. 1996. Golden Eagle predation on pronghorns in Wyoming’s Great Divide Basin. Journal of Raptor Research 30:157–159.
Erwins, P.J. 1987. Golden Eagles attacking deer and sheep. Scottish Birds 14:209–210.
Zettergreen, B. 2006. Golden Eagle attacks and kills yearling mountain goat. Wildlife Afield3:27–28.