Friday, December 10, 2010

A summary for Scott

Few would likely argue that a band fixed to the leg of a bird is a cause for worry by those who band birds...but attaching a satellite transmitter to a bird is a different matter. Yes, guidelines exist that help to resolve the conundrum, and good arguments can be made that do or don't tip the balance in favor of securing a tracking device to a bird that migrates several thousands of kilometers twice annually.

Banded Peregrine (Todd Kemper)

Most reasoning rests on the trade-off between risks that accrue for the individual and the benefits that can applied to the population...but the "recipe" that ultimately governs our insights into both obligates the use of a sufficient number of individuals - i.e. go big or go home.

Peregrine with PTT (V. L'Herault)

Some time ago a colleague interested in what effect the Deepwater Horizon oil spill may have on Peregrine Falcons that migrate through the Gulf of Mexico with millions of songbirds, shorebirds and waterfowl asked me for a summary of the tracks for peregrines that we've followed.

The following southern migration tracks of 12 individuals hint that the Gulf Coast of Louisiana, Mississippi and Alabama receives a high proportion of the tundra peregrine population migrating to wintering areas further south, and the coast serves as a "decision point" with some birds simply choosing to overfly the Gulf, while others choose an eastward route through Florida or a westward one through Texas. While most (7/12) opted for a route that took them directly into the Florida peninsular, the remaining 5 spent 1-3 days along a 400 mile section of the Louisiana, Mississippi and Alabama coastlines.

Southern migration tracks of 12 tundra peregrines

Any effect of Deepwater Horizon on Peregrine Falcons remains unknown, but two organizations (the Peregrine Fund and Earthspan) have partnered to study the issue.