May 202015
 

On Monday the 18th May 2015, we received an email from Mark Shieldcastle of the Black Swamp Bird Observatory (http://www.bsbo.org/) in Ohio informing us that they had just captured and released a Gray-cheeked Thrush wearing a SELVA bird band. A quick check of our database revealed that the bird had been banded on the 21 April 2014 in the Hacienda La Victoria in the Sierra Nevada de Santa Marta in north-east Colombia. This represents the first recapture of a migratory bird banded in Colombia by SELVA in North America and is just one more piece in the puzzle of unraveling the migratory strategy of this species. In a paper published in 2013, we showed that Gray-cheeked Thrushes stored enough energy reserves in the Sierra Nevada to undertake a migratory flight of over 2,700 km and in many cases further still (over 4000 km in the heaviest birds). This enables birds to not only cross the Caribbean Sea without requiring additional fuelling stops but also to fly hundreds of kilometers inland on reaching North America.

Catharus minimus - Gray-cheeked Thrush contemplating the next meal

From the Victoria to the Black Swamp Bird Observatory is a straight line distance of 3500 km and therefore within the capacity of a bird leaving Colombia. Whether this individual made the entire journey without refueling will remain a mystery. The scant evidence that we have to date, suggests that birds may not take a direct route to North America but instead drift with the prevailing south-easterly winds towards Central America on leaving Colombia, thereby increasing the overall distance traveled. Indeed, last year we had an even more remarkable recapture of a Gray-cheeked Thrush that had been banded by SELVA researchers in Belize during the spring of 2008 and was recaptured by the same researchers in Colombia in April 2014. This suggests that some birds may take the route indicated by the black lines in the map shown here.

GCTH Recovery 2

During the spring migration of 2015, 36 Gray-cheeked Thrushes were fitted with tiny radiotransmitters in the Sierra Nevada de Santa Marta, as part of an exciting collaboration with Universidad de los Andes, Environment Canada, Bird Studies Canada, Acadia University, and the Canada Foundation for Innovation. These transmitters send a uniquely coded signal that can be detected by automated receiver stations which are now being deployed across North America as part of the Motus Wildlife Tracking System (http://motus-wts.org/). These individuals left Colombia over the last two weeks and the hope is that they will be detected by stations across north-eastern North America, thereby providing incredible information on journey times and routes……we hope to post an update on this soon!