Archive for June 25th, 2011

Well, now that the excitement and anticipation for the first tern chicks has subsided, we thought it was time for a little landbird interlude.  Below are some of the featured species captured during our spring migration monitoring on Metinic this year.

The second year (SY) male Rose-breasted Grosbeak pictured below, aged by the contrasting black and brown feathers on the wing, was just one of a few of its species banded this season (SY means it hatched out last summer).  Unlike most other passerines where it is strictly the female that incubates the eggs, male Grosbeaks often help with this aspect of parental care.  Among passerines, males are typically the song-makers, however, female Grosbeaks will also sing their robin-like song quietly when changing places with the male on the nest.

While every bander hopes to have a bird they banded captured elsewhere, that is not the main purpose of most modern day banding efforts.  It is the data collected during the banding process that provides details about each individual that is especially valuable.  This kind of information cannot be obtained through other methods.  For example, identifying age and sex ratios enables us to structure demographics of populations, and body mass and fat measurements provide information about the condition of each bird at the time of capture.

Our first foreign recap! This SY male Common Yellowthroat shows off his band.

With that said, every bander still hopes to find that needle-in-a-haystack, and on May 31st , WE DID!  It was not surprising to walk up to a net on Metinic and see a Common Yellowthroat, it was not surprising to find it had already been banded (there is actually quite the population of breeding Yellowthroats on the island), but it was surprising, and I recognized instantly, that we had not banded it!

This foreign recapture (i.e. a bird captured more than 90 miles away from the location of its original banding) was originally banded on Plum Island, Massachusetts (a station run by Parker River NWR) on May 21st.  Ten days and 110 miles later, he found his way into one of our nets on Metinic Island.  Only future recaptures would tell us for sure, but it appears as though he may have been setting up a breeding territory on Metinic.  I noted a developing cloacal protuberance, which indicates that a male is in breeding condition, and he had dropped from 11.0g at original capture to 9.7g, suggesting he was no longer in a migratory state.

A handsome shot of “George”, affectionately named by his original captors.

Because of their prevalence on the island, we would expect Common Yellowthroats to be the number one species banded, but they were surpassed this year by Magnolia Warbler(93 to 90).  While Magnolia Warblers breed in Maine and at higher elevation sites throughout New England, more than 50% of their global breeding population is dependent upon the boreal forests to our north.  Because these habitats are especially sensitive to changes in climate and are increasingly threatened by timbering practices and oil and natural gas development, it is important that we closely monitor boreal dependent species.  With their populations largely occurring in remote, inaccessible areas, it is important that monitoring efforts continue where concentrations of these birds occur during migration.  Through the partnership between the Refuge and the University of Maine and a number of other network collaborators, we are doing our part to study and conserve these species throughout the Gulf of Maine.

The Magnolia Warbler (SY male pictured above) was once called the Black-and-Yellow Warbler. Interestingly, the current name came from an observation made of this species in a magnolia tree during migration. Other than now sharing a name, there is no connection with this species’ life history and its namesake.

Finally, when we caught the male and female Blackburnian Warblers pictured below together in the net, we just couldn’t pass up on this great opportunity for comparison, and photo taking!  The male’s flame orange throat is probably this species most striking and unique feature.  It is actually the only North American warbler with an orange throat.  As with many of the other migrants banded this spring, Blackburnian Warblers are considered neo-tropical migrants, meaning they breed in Canada or the U.S. during our summers and winter in Mexico, Central, or South America.  Months prior to being captured on Metinic, these two birds departed from South America, and possibly from as far south as Peru or Bolivia.

A male (left) and female (right) Blackburnian Warbler. As with most dimorphic bird species, the males are more brightly colored and conspicuous than females.

Authored by Adrienne J. Leppold with Courtney Viall (and special guests Charlie Walsh and Jennie Wiacek).  All photos by Adrienne J. Leppold.


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