Thursday, January 22, 2015

2015 northbound migration begins!

For new followers, this blog is the first in an annual series in which we will describe the northbound migration of seven satellite-tracked Swallow-tailed Kites: Palmetto, Bluff, Gulf Hammock, Pace, Day, MIA, and PearlMS. All of these birds made it safely to their South American winter range last fall.  Now we will watch as they make their way back to their nesting areas in the southeastern U. S. 

This magnificent odyssey takes them across the Andes Mountains and several hundred miles of open ocean, where the late-winter weather can quickly turn perilous. The most dangerous leg is when they fly northward over the Gulf of Mexico. Rather than jump from the Yucatan Peninsula to western Cuba or the southern tip of Florida, the reverse of their southbound track, they generally head northward from the tip of the Yucatan Peninsula on the first good tailwind. If all goes well, they will reach land somewhere along the Gulf coast and turn toward the place where they nested last year. 

Because Swallow-tailed Kites cannot maintain continuous flapping flight, they are unable to make way against headwinds. Instead, they circle over the water waiting for the winds to change and carry them to land anywhere from southern Florida to the east coast of Mexico. We have learned from our telemetry research that many Swallow-tailed Kites die during their northbound migration because they cannot remain aloft for more than four days. In 2013, three of the 11 kites we were tracking by satellite perished while crossing the Gulf when unusually large high-pressure systems spawned strong northerly winds that persisted for over a week.

From the expansive family-owned cattle ranches of the Brazilian Cerrado, two of our seven GPS/satellite-tagged Swallow-tailed Kites have started their 5,000-mile journey back to the southeastern U.S.
The Swallow-tailed Kite northbound migration begins. Tracking data from 1 Dec. 2014 to 20 Jan. 2015. 

As in the last two years, MIA has made the first move.  He wintered the farthest south of all of the tracked birds and started north from the state of Mato Grosso do Sul, Brazil, on 8 January.  He is already 200 miles past PearlMS, who wintered the farthest north in Rondonia, Brazil.

Day is also making her first moves towards the U.S., having departed her winter range on 16 January.  She shared the same roosts and foraging grounds with Palmetto and Pace, which are still within their 100 square mile winter range near Santa Rita do Pardo.

Palmetto’s mate, Bluff continued moving south during the winter months.  Don’t be fooled by the green track. This is a 600-mile southbound move he made in early December.  Currently, Bluff is 300 miles north of Palmetto.

Gulf Hammock still occupies the lush forests in the state of Santa Cruz, Bolivia.

Any guesses on which of the remaining Swallow-tailed Kites will start north next?