The purple martin, the largest member of the swallow family in North America, has a range that stretches from the east coast of the United States and the Maritime Provinces of Canada, west to the Rocky Mountains, with isolated pockets in the western United States. Overall, the purple martin population is considered to be stable. However, based on Breeding Bird Survey data, purple martins have been showing range-wide declines in eastern North America and have been declining over most of their range in New England for the last 20 years. Early accounts from the 1920s suggested that purple martins were once widespread and abundant in New England. In Connecticut, the purple martin has declined to the point where it is listed as a threatened species.
 |
| Purple martins migrate from their winter range in South America through Central America and the Caribbean islands to their North American breeding colonies. http://www.natureserve.org/infonatura/ |
The recovery of this species in Connecticut and throughout New England is potentially straightforward because martins in this region rely exclusively on human provided nest structures. While adult martins show great site fidelity, returning to the same nesting location year after year, sub-adult martins (or returning juveniles) are much more likely to move to new locations. In theory, if housing is provided, sub-adult martins should find it, use it, and increase the population. However, this is not the case. Many housing locations in Connecticut, including some adjacent to active colonies, are available yet remain unoccupied. The reasons for this lack of occupancy and use are not clear. The criteria these birds use for selecting nesting sites in Connecticut are not understood. A lack of knowledge about dispersal patterns of young birds and the optimal conditions for establishing new colonies threatens to hamper recovery efforts. Where active colonies do exist, martins are often slow ·to colonize new locations.
 |
| Wildlife biologists from the DEEP band a purple martin chick with silver USGS and colored DEEP bands. |
To close this knowledge gap, a color banding project was initiated in early July, 2011, at six known martin colonies. Four coastal colonies in Clinton, Westport, and Madison (2 sites) and two inland colonies (both in Kent) were selected to see if coastal and inland colonies exhibit similar or different dispersion patterns. [Birds from the Hammonasset colonies were included in the banding program.] From those six sites, a total of 540 juvenile purple martins were fitted with both a standard silver United States Geological Survey (USGS) band and a color band. Each colony was assigned a different color (red, blue, green, purple, orange, or yellow) to facilitate the identification of the natal colony during future sightings of these birds. Additionally, each of the color bands has a unique alphanumeric code (CT###) so that individual birds can be identified. Other data collected by DEEP staff and volunteers included the weight and approximate age of each bird to assess its overall health.
The project will be repeated this year at the same locations with the same band colors to increase the number of banded birds, resulting in a greater likelihood of future sightings. The success of this study will be directly dependent upon the number of reported sightings of banded martins. You can help by keeping an eye out for banded birds starting this spring. If you see a color-banded purple martin, please report the sighting to the DEEP WIldlife Division by e-mail (geoffrey.krukar@ct.gov) or phone (860·675·8130). Be sure to provide the following information: location of the bird, date, color of the band.
No comments:
Post a Comment