A visit to the bird banding research station on Plum Island

A red-eyed vireo is removed from the mist net at the bird banding station.

I recently had the opportunity to visit the bird banding research station at the Parker River National Wildlife Refuge on Plum Island. This was my first opportunity to observe mist nets in use and to observe wild birds being tagged. It was a wonderful learning experience and a chance to see wild birds closer than you would in any other circumstance that I can imagine.

The bird banding research station at Plum Island is run by the Mass Audubon's Joppa Flats Education Center and is closed to the public except by prior arrangement. In our case, arrangements were made by Sue McGrath of Newburyport Birders who has a very good working relationship with the group. The research station is hidden in a restricted area within the Parker River National Wildlife Refuge on Plum Island. The station itself consists of a small work cabin surrounded by a spider web like network of narrow paths extending out from the cabin to the mist nets.

• Pictures of the bird banding operation at Plum Island

The mist nets themselves are set up in narrow clearings carved from the island’s thickets. Because of the very fine string used to construct the nets, they are virtually invisible to the birds, which fly directly into the nets and become entangled. The birds generally realize they are inextricably tangled and do not waste energy on struggle. Highly trained volunteers come and gently untangled them and place them in a small collection bag. When the net is cleared of birds, the bags are brought back to the research station where they are marked with the location and collection time, and then hung to await processing.

On our morning visit, the majority of birds caught were yellow-rumped warblers (Dendroica coronata) which breed in the northern United States and throughout Canada in the summers and then return to Central America and the Caribbean for the winter. Also caught was a red-eyed vireo (Vireo olivaceus), a ruby-crowned kinglet (Regulus calendula), and several swamp sparrows (Melospiza Georgiana). Many of the warblers were first year hatchlings preparing for their first migration.

Each bird was carefully removed from the collection bag in which they were individually contained by the gentle and confident hands of the trained researchers in the bird banding station. Each bird was measured, sexed, and observed by researchers who called out the data to an assistant who recorded the data. The bird’s sex was determined primarily by the length of the wing chord (the distance between the tip of the wing feather and the first joint (wrist) of the wing. The males have a distinctly longer chord length than females of this species. However, some birds with intermediate length chords had to be sexed by other means. The age of the birds, first year or not first year, was determined by the skull growth. Prior to migration, birds should be establishing fat stores that will get them through the journey to their winter grounds, so the level of subcutaneous fat of each bird was also recorded, as were any signs of molting. The birds where then weighed, banded and released, completely unharmed.

Although the banding process is no doubt stressful for the birds, the data collected can be very important for the continued survival of bird species. The aggregate data allows researchers to note any long term trends among the bird populations in terms of population numbers, overall health, lifespan, and average weight (possibly indicating the quality and quantity of feeding habitat available). Banding also helps scientists track the movements of birds during their migration. By identifying key stopover points on the migration route, conservationists can help ensure that suitable habitat is preserved to allow the birds a safe and healthy trip.

New England, and New Hampshire in particular, is the summer breeding ground of many birds that are actually native to South and Central America. As such, we have a responsibility to these birds that goes beyond our own region. Poor stewardship of our region’s Important Bird Areas could result in great harm to, or even eventual extinction of, many tropical songbirds and other migrants.

Our support of the research being done by the Mass Audubon's Joppa Flats Education Center and the bird banding research station at Plum Island demonstrate our acceptance of this responsibility and our concern for the survival of the many species of songbirds that we share with the tropics. Even more important are efforts to set aside and maintain wilderness areas of various types that provide grounds for breeding and feeding of these colorful guests during their annual summer stays in New Hampshire and the rest of New England.

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