Monday, November 01, 2010

A Peregrine's (Nocturnal?) Diet

Naturalists in the U.K. have been collecting feathers and other bird parts from a Peregrine Falcon nest box to monitor what sorts of prey items they catch. One of the biologists described some surprising finds to the BBC:
By studying the diet of the Bath peregrines I have discovered that they not only feed on the ubiquitous feral pigeon and common garden birds - they also consume more unusual birds that you wouldn't see in the city.

There was evidence of our smallest, dainty duck - a teal - and the lapwing, more associated with ploughed fields.

I then began to find prey remains of birds that are very difficult to spot in the Bath region or don't normally occur here.

Secretive water birds such as water rails, spotted crakes, little grebes and shy woodland wading birds such as woodcock were all appearing in the diet.

The one thing they all had in common was that they migrate at night, travelling hundreds of miles west from mainland Europe.

I was able to confirm the peregrines were behaving like owls, catching birds as they flew over Bath at night.

The street lamps in Bath light up the migrating birds as they fly overhead.
I have watched a Peregrine hunting things in floodlights, so I am not all that surprised that others would do it. At the time, though, I assumed that it was catching bats or nighthawks. Nocturnal migratory birds had not occurred to me, but it makes a lot of sense. One thing I wonder if whether this behavior is something that Peregrines do naturally (e.g., hunting by moonlight or the sounds of flight calls) or whether it is something they learned over the past century.

Or maybe Peregrines are just better at finding rare birds than birders. That pair must have quite a life list!