Thursday, December 13, 2007

Shrikes, killer songbirds

Most songbirds we encounter are mild-mannered little birds that eat seeds or small insects. Members of the shrike family (Laniidae) are exceptions to that rule. Shrikes prefer open habitat where they survey their surroundings from a high perch for passing prey items. Top of the menu are large insects, like grasshoppers, and often other vertebrates like lizards, mice or small birds. To kill vertebrate prey shrikes have a special adaptation, the tomial tooth, an extension of the upper mandible that shrikes use to dislocate the neck vertebrae of their prey. Falcons have evolved a very similar structure independently of shrikes and use it in much the same way to dispatch their prey. Shrikes are also famous for keeping larders of their prey for later. A shrike's larder consists of large insects and vertebrate prey impaled on thorny bushes and trees or in some areas on barbed wire fences.

We've seen many shrikes during this latest trip to Taiwan with two species making up all the sightings, the Brown Shrike (Lanius cristatus, see photo above taken at the Aogou wetlands on Dec 10) and the Long-tailed Shrike (Lanius schach, see photo right taken near Yuanshan on Dec 8). There are only two species of shrike in all the Americas and neither of American species are found on the island of Taiwan. Eurasia and Africa are the strongholds for shrike diversity with most of of the 28 species in the genus Lanius occurring on these continents. Brown Shrikes are winter migrants but Long-tailed Shrikes can be seen all year on Taiwan. Lanius shrikes are common but still great birds to see on any trip to Taiwan.

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