Saturday, December 11, 2010

More than a glimpse...

Bird banders generally expect the rewards from band returns to be few, far between and more "vignette" than "mini-series", but within months of receiving a band on South Padre Island (SPI) in Fall of 2009, Joe's Hag began sharing more of her story than could be told from that first encounter.

That day, her weight and size told us she was a "she"; her plumage indicated that she was at minimum in her third year of life...and the long history of banding peregrines on SPI suggested strongly that she was a tundra peregrine. But from where exactly had she come? And where was she going? Had she bred successfully the previous summer? Would she survive the remainder of her migration, that winter and the subsequent return trip to the breeding grounds.

She did survive, produced 4 young, and we confirmed our suspicion that she is a tundra peregrine. In July 2010, she was captured again - this time in the Canadian High Arctic on the Melville Peninsular. She was fitted with a GPS satellite transmitter, and we "watched" as she foraged up to 40 miles from her eyrie, and on occasion remained more than 20 miles away from her nestlings for as many as 36 hours, except for brief visits presumably to deliver prey.

The male paired with Joe's Hag feeds a Lapland Longspur to 4 nestlings

In the latter half of September, we watched further as she left her breeding territory traversing Southampton Island and much of the Hudson Bay, presumably intent on reaching the Texas Gulf Coast where she'd been captured 11 months earlier. But Joe's Hag, it seems, had other ideas in mind...bearing SE from the Churchill shelf, she made decisively for Florida never coming closer than 1000 miles from Padre resulting in 2 entirely different migratory routes south in as many years.

Via Florida rather than Texas

Five weeks and over 5100 miles after leaving her breeding territory, Joe's Hag arrived on her wintering territory in northern Colombia. With a little luck, we'll watch her fly north and see her once again at the cliff on which she breeds.

Alastair


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.

Alastair