I had exactly the same reaction as Peter Shute to the BBC report of the Cardiff Universty study on Peregrine and Saker beaks. The beaks are not designed for impact as suggested, the feet are – and in the case of the Peregrine with a built in killing spike. I reached for J.A. Baker’s classic (1967) monograph on “The Peregrine” – the result of a 10 year study of the bird in and over the woods, marshes and coast of East Anglia in the UK. I quote from page 26:”Killing is simple once the peregrine has the advantage of his prey. Small, light birds are seized in his outstretched foot; larger heavier birds are stooped at from above, at any angle from ten to ninety degrees, and are often struck to the ground.” The strike is described later: “The peregrine swoops down towards his prey. As he descends, his legs are extended forward till the feet are underneath the breast.The toes are clenched, with the long hind toe projecting below the three front ones, which are bent up out of the way.He passes close to the bird, almost touching it with his body, and still moving very fast. his extended hind toe (or toes- sometimes one, sometimes both) gashes into the back or breast of the bird, like a knife. At the moment of impact the hawk raises his wings above his back. If the prey is clean hit- it is usually hit hard or missed altogether-it dies at once, either from shock or from the perforation of some vital organ. A peregrin e weights between 1 1/2 and 2 1/2 lbs: such a weight, falling from a hundred feet will kill all but the largest birds. Shelduck, pheasants, or great black-backed gulls, usually succumb to a stoop of five hundred feet or more.” (Baker goes on to describe the use of the beak for tearing open the choice parts of the prey and for eating.) Baker conducted all his ornithology in the field, not the laboratory. It is usually the best starting point. Angus Innes.
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To be fair to the research team, there is no reference in the original scientific paper to Peregrines striking their prey in the air with their beaks. The paper can be downloaded online and the details are provided below. The paper was examining evolutionary divergence of the Peregrine and Saker Falcons and investigated genes involved in beak development, olfaction and arid environment-related homeostasis (osmoregulation and thermoreguation). So it’s possible that reference to Peregrines using their beak to strike prey was artistic licence by the BBC journalist reporting the story.
Stephen Ambrose Ryde NSW
Xiangjiang Zhan, Shengkai Pan, Junyi Wang, Andrew Dixon, Jing He, Margit G Muller, Peixiang Ni, Li Hu, Yuan Liu, Haolong Hou, Yuanping Chen, Jinquan Xia, Qiong Luo, Pengwei Xu, Ying Chen, Shengguang Liao, Changchang Cao, Shukun Gao, Zhaobao Wang, Zhen Yue, Guoqing Li, Ye Yin, Nick C Fox, Jun Wang & Michael W Bruford.
Peregrine and saker falcon genome sequences provide insights into evolution of a predatory lifestyle.
Nature Genetics (2013) doi:10.1038/ng.2588
Received 13 April 2012 Accepted 28 February 2013 Published online 24 March 2013
Abstract
As top predators, falcons possess unique morphological, physiological and behavioral adaptations that allow them to be successful hunters: for example, the peregrine is renowned as the world’s fastest animal. To examine the evolutionary basis of predatory adaptations, we sequenced the genomes of both the peregrine (Falco peregrinus) and saker falcon (Falco cherrug), and we present parallel, genome-wide evidence for evolutionary innovation and selection for a predatory lifestyle. The genomes, assembled using Illumina deep sequencing with greater than 100-fold coverage, are both approximately 1.2 Gb in length, with transcriptome-assisted prediction of approximately 16,200 genes for both species. Analysis of 8,424 orthologs in both falcons, chicken, zebra finch and turkey identified consistent evidence for genome-wide rapid evolution in these raptors. SNP-based inference showed contrasting recent demographic trajectories for the two falcons, and gene-based analysis highlighted falcon-specific evolutionary novelties for beak development and olfaction and specifically for homeostasis-related genes in the arid environment-adapted saker.
This suggests that the prey is killed by a combination of hitting and gashing. I didn’t know about the gashing. Perhaps the article was mistaken, and they really meant that the hind toe had evolved to withstand this kind of treatment, not the beak.
Peter Shute
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