Monday, February 17, 2020

Northbound progress, but all Kites still in South America

ARCI will be reporting on the 14 Swallow-tailed Kites we are tracking with GPS-equipped transmitters as they return from their wintering grounds in South America. These kites were tagged during the summer on their breeding range in the southeastern US from 2015 to 2019. They are named after the area where they were tagged.  

Please get to know our Swallow-tailed Kites. Each has its own story, continuing to unfold, and wonderful sponsorship and support teams that have made this tracking project possible.

Eleven tracked kites have begun their northbound migration. As of 17 February, 2020, in the State of Mato Grosso, Brazil, Pritchard and JAX are the farthest south, and Suwannee has not shown signs of migrating just yet. Many kites are in the State of Rondônia, Brazil where Wilson and Sanibel take the lead and the other four; Apopka, Sawgrass, Sarasota and PBC-ERM Male not far behind. Our two Louisiana kites, Lacombe and Ponchitolawa are cruising through the Brazilian Amazon State. The biggest surprise was Babcock, now at the Colombia/Panama border. We had not heard from her since mid-December and now she’s the farthest north.

All of these kites are carrying solar-powered GSM/GPS transmitters that communicate through the cell phone network. When birds are beyond cell-tower range, they are unable to upload their GPS data. When this happens, the data are stored until the birds move within range of a cell tower. Therefore, we may go for long periods not “hearing” from birds as they migrate through and/or winter in remote areas. If something goes wrong during these times, we have no way of knowing what might have happened. Some of the Swallow-tailed Kites we have tagged remain beyond tracking range for their entire wintering period, and we must wait in anticipation for their radios to resume transmission once they have begun migrating again. When this happens, we receive all of the GPS fixes that have been received and stored while the transmitter has been silent. Not displayed on the map are OK and PBC-ERM Female, both last heard in Colombia in August 2019 on their southbound route. We are still hoping that they have only been beyond cell-tower range and may soon begin uploading their stored GPS locations. 

The other type of tracking unit contributing to this study are solar-powered satellite/GPS transmitters, for which the GPS data are uploaded every other day from anywhere in the world. These are being carried by two birds tagged in Louisiana by our colleague Dr. Jennifer Coulson of the Orleans Audubon Society. When we do not receive data from this type of tracking unit, we know that something is wrong with either the transmitter or the bird. The solar-powered transmitter may be damaged or otherwise unable to charge its batteries. This may occur when the bird has been in dense vegetation, or if it has shed the transmitter or died is in a location where the radio cannot recharge or transmit. This has been the case with Bayou Vincent in Bolivia this winter, and now with Hobolochitto in the State of Amazonas, Brazil, which had already begun moving northward. We remain uncertain as to the fates of these birds.