web analytics

Remarkable Recapture

Posted by on Jun 29, 2017

Golden-winged Warblers are among the most imperiled birds in North America. Their numbers have plummeted nearly 70% in the past 50 years, and this species continues to decline at a staggering 2.5% each year. Outside of their core breeding range in the upper Great Lakes Region (mostly Minnesota and Wisconsin) they have just about disappeared altogether, and several northeastern states now no longer have viable populations of Golden-winged Warblers around. What causes these declines? Well, a number of factors play a role here. Golden-winged Warblers prefer to live in open, wet areas that are harder to come by now that forests are covering areas that were once prairie habitat; invasive reeds (Phragmites) replace the sedge tussocks that they like to nest in, and closely-related Blue-winged Warblers continue to expand their range into Golden-winged Warbler territory and both forms now hybridize at the expense of the rarer Golden-wings. Things are not looking great for these beautiful birds and scientists are working hard to reverse the declining trend in a variety of ways.

                        Golden-winged Warbler (Vermivora chrysoptera) – photo by Sean Graesser

While studying migratory birds on their Costa Rican wintering grounds this past March, we were able to add some important data to the understanding of Golden-wing Warbler biology. RTPI affiliate Sean Graesser, who was working in a remote rainforest reserve in northeastern Costa Rica with other RTPI staff on a tropical biology course for high school students, captured a gorgeous male Golden-winged Warbler. When he extracted it from the net to collect data and band it, he realized that this bird already had a uniquely numbered band on its leg – a band that Sean had put there himself a year ago! Since we last saw this bird in March of 2016, it had flown to North America – likely somewhere in that upper Great Lakes Region area, possibly nested and raised young against all odds, and returned to Costa Rica to overwinter. This bird looked healthy as could be and was getting ready to make the same trek again – possibly travelling as far as 6,000 miles each year between its breeding and wintering grounds. This exciting recapture gives us a strong indication of where these birds go when not breeding, helping to narrow down the core wintering habitat for Golden-winged Warblers that needs to be protected in order for the species to survive. Even though the odds seem steep, we’re going to try our best to help save the Golden-winged Warbler from disappearing altogether. Even though RTPI staff sees a lot of birds each year, some really stand out. You can share in the excitement of one of these truly amazing finds by watching this video created by Orbitist.