Tuesday, March 9, 2010

Rusty Blackbird Road Trip

The Rusty Blackbird is declining for reasons which are poorly understood. Given the robust populations of many blackbird species in North America this is surprising to many birders. Sadly it is real. The Rusty Blackbird Working Group was formed in 2005 to discover and understand the cause(s) of the decline. http://nationalzoo.si.edu/ConservationAndScience/MigratoryBirds/Research/Rusty_Blackbird/default.cfm
At present there are research projects in progress throughout the range of the Rusty Blackbird.

One of the projects is taking place on study sites in the Carolinas by a University of Georgia/Smithsonian graduate student. Her efforts are directed to understanding aspects of the wintering ecology of the Rusty. During the 2008-09 winter she was able to trap good numbers of Rusties using mist nets. This winter capture rates were discouraging to the point that use of a new method was in order.

Whoosh nets in the back of my truck and the prospect of poor banding conditions in Virginia Beach for a few days, I drove to a study site near Greenville, South Carolina and back between March 3-5. The whoosh net is a modern, bungee-powered net which throws a folded net over birds within the capture area when triggered. The net gains elevation by the use of launch poles. The net is very fast, safe when used properly and can be made in many sizes. The nets used in Greenville were ~38 feet by ~15 feet in coverage. The whoosh pictured above is 19 feet by 14 feet. The net is set and ready to fire.

I have been building and using whoosh nets (usually in concert with my drop nets) for six years. Over that time I have whooshed many targeted species of shorebirds (including many of The Bahamas plovers, see Feb 2010 blogs), Virginia Rails, lure birds for the CVWO Kiptopeke raptor station (Starling and Rock Dove), and some passerines, including 100s of Red-winged Blackbirds. Thus, notwithstanding the almost "mythological" wariness of the Rusty, I had confidence that they could be whooshed if there was a location at which the birds regularly fed AND at which a whoosh could be set.[note: whoosh and drop nets are active nets which only capture birds which the researcher intends to capture, i.e. target species; the mist net is a passive net which catches most birds which encounter the net, target or not.]

By 0630 on the morning of March 5th in a gravel driveway in a surburban neighborhood outside Greenville, we had the whoosh in place. The birds arrived just before 0700, as they had the previous morning when we were still setting the whoosh. Five minutes and one pull of the trigger line later we had eight Rusties to process and release.

No comments: