Tuesday, March 20, 2012

Black Swift - 165 years of winter mystery

165-Year-Old Mystery of Disappearing Black Swift Solved

Via the American Bird Conservancy


Where the high flying bird vanishes to after breeding and spending summers in many parts of western North America has puzzled ornithologists since the species was discovered in 1857. Now, thanks to a new study, we learn that at least some of them travel about 4,300 miles to a remote part of western Brazil in lowland rainforest.

The study, which was published in the March 2012 issue of Wilson Journal of Ornithology, involved attaching geolocators (tiny devices that record and store tracking information) to four adult Black Swifts from two nesting sites in Colorado, then recapturing the same birds at the same sites the next year to download the stored data. Three of the four tracking devices were recovered, and showed the birds departing for their fall southerly migration between September 10 and September 19, arriving in Brazil between September 28 and October 12, departing Brazil between May 9 and 20, and arriving back at their Colorado breeding sites between May 23 and June 18.

Further, satellite GPS devices, which transmit real time tracking of individuals, are not sufficiently small to place on a species the size of the seven-inch-long Black Swift. As a result, geolocators (which record data but do not transmit it) were used which meant that the study birds would need to be recaptured for the location data to be analyzed. That necessity was made easier on one hand by the fact that the birds typically are very committed to returning to their previous breeding colony, but made more challenging because they tend to nest in areas that are incredibly difficult to access – behind waterfalls in deeply shaded niches in steep and narrow canyons.

Curiously, the birds averaged about 211 miles per day during fall migration and about 244 miles per day during spring migration, about a 15 percent increase in average daily distance covered. They spent about 220 days in Brazil before migrating north again.

Tuesday, March 13, 2012

Look for banded Golden-cheeked Warblers!

From a Texbirds post, re: a banded Golden-cheeked Warbler photographed by Sean Paul Kelly (click here for the photos) "This bird is part of the Balcones Canyonlands Preserve Golden-cheeked Warbler study that is now going on. This bird was banded last year on April 20th at Emma Long Park."

Subject: banded Golden-cheeked Warblers

From: Bill Reiner (spizella/AT/SBCGLOBAL/./NET)
Date: Mon, 12 Mar 2012 20:45:18 -0700


I had a feeling I needed to send out this message pronto, and it seems I am one day late. But thanks to Mr. Kelley, for asking the question, and for posting those photos of the banded Golden-cheeked Warbler in Emma Long Park this morning! (And also thanks to the quick-responding TexBirders who alerted me to his post.)

The bird Mr. Kelley photographed is one of more than 350 Golden-cheeked Warblers that have been banded by biologists on study plots scattered across the Balcones Canyonlands Preserve, on the west side of Austin, over the past three years. The vast majority of the banded birds have been males, but a few females have also been banded. Biologists at Fort Hood have banded even more individuals of this species, over an even longer time. The goals of the studies in these two locations have included learning more about the survival rates, age ratios, and dispersal of these endangered birds.

Some of the plots where Golden-cheeks have been banded around Austin are in areas open to the public, such as Emma Long Park (Turkey Creek Trail), Barton Creek Greenbelt (Sculpture Falls area), Saint Edwards Park, and, for the first time last year, Wild Basin. However, the birds returning from their winter ranges could turn up anywhere (even South Padre Island!), so please look closely at the legs of any Golden-cheeked Warbler you spot. A banded warbler will have one numbered aluminum band (don’t even try to read it with binoculars) and two or three colored resin or plastic bands to allow for recognition of individuals in the field. If you do see a banded Golden-cheeked Warbler, I will be very happy to hear about it, and can direct the information to the biologists -- either at Fort Hood or here in Austin -- who banded it. The best place to contact me is: william.reiner AT austintexas.gov

Information to provide:
1) What color bands in what order. Banders read bands as: upper left leg/lower left leg : upper right leg/lower right leg. So, for example, Mr. Kelley's bird is red/orange : white/silver. Colors are not always what they appear at first glance, so a photograph is always welcome, if it's possible. Colors can often be misread. Legs can be mixed up -- it's the bird's left and right legs, not which is right or left as you are looking at it. Even upper and lower can be confused depending upon your vantage point. Because of the potential for confusion, it is also very important to give us...

2) The location of the bird. A GPS position would be very helpful to pinpoint its location, but if this is not possible, landmarks along a trail or road or other feature can greatly help us to relocate the individual and verify its identity.

If you want to help even more with this project, please come volunteer with us!

The BCP biologists cannot possibly watch all the suitable habitat on the Preserve, so we are seeking experienced birders willing to devote at least 3 field days this spring to searching for banded warblers. Volunteers will have the opportunity to explore a part of the Balcones Canyonlands Preserve that is not normally open to the public. Several birders are already trained and ready to go this spring, but, because we banded birds on new plots last year, we still need people to look for returning birds on the outskirts of those plots. If you have the time and the interest, please contact me at the e-mail address above.

Thank you,
Bill Reiner, field biologist
Balcones Canyonlands Preserve
City of Austin
(512) 972-1676