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Friday, July 8, 2011

The Martins of Glen Mills

On Tuesday, July 5, Doris assembled her volunteers to band what is probably the largest Purple Martin colony in Delaware County. The Glen Mills School has 32 boxes arranged in groups of 16 in a central quad. Three teams (Doris and Don, Lauren and Sheryl, Erika with several helpers during the final hour) worked their way from box to box banding more than 650 nestling purple martins over the course of four hours.

Apartments come in the traditional style or in synthetic gourd form (as seen here), as well as in castle complexes (see photo #4). There are perches and railings good for protecting the home base or enjoying the view. Adults returning with food for the young often sit for some time before entering a nest. We saw them carrying dragonflies and butterflies (definitely one red admiral), but the number of insects they eat must be incredible.

Once each house is lowered, the contents of each numbered compartment are recorded. The young are removed, banded and replaced in the same compartment. Here Doris and Don are working at one apartment complex. . .

. . while Lauren and Sheryl are working on a castle.

At this point in the summer, nests are at various stages. Nests may contain eggs, young hatchlings that are pink and featherless, or larger young, some nearer to fledging. The bellies of the birds this year were prominent, as you can see in the photos of both of these well-fed birds. Most quietly accept their jewelry without protest, but a few do squawk loudly. Interestingly, the stick and mud nests also contain green Ginkgo leaves, possibly as a pest deterrent.

Notice that the tail feathers on this purple martin youngster are still in sheath. The big fat baby bird lips are also apparent. If you look closely, you may even be able to locate the ear.

Many hands are useful in holding the birds since each nest may contain anywhere from 2 to 6 young. Here is a crew of happy helpers (namely, Erin, Ellie, Sarah and Kristen) holding birds. Most nests hold 4 or 5 young, though we did find one gourd with 8 eggs in it. Particularly in colonial nesters, females may lay eggs in other females' nests. If you can slip an egg in for someone else to incubate and feed, that's one extra set of your genes that you pass on. In purple martins, both parents incubate and feed the young.

Thanks to Dale Kendall for providing most of these photos, to Kristen for photo #2 and the video, and to Lauren and Karl for technical help with sizing the photos and video. Click on the play button below to see and hear the birds in action. (I hope it works. This is the first time I have tried incorporating a video clip.)


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