DEEP, Connecticut Audubon to study travel of purple martins
As purple martin bird parents did their aerial acrobatics above the marshes Monday, July 9 to hunt for flying insects to feed to their young, the little ones were being gently leg-banded so biologists can study how the species travels.
The organized bird-banding operation was done at Connecticut Audubon’s coastal center by state Department of Energy and Environmental Protection staff on the observation platform next to the marsh, only feet from where some of the 70 man-made gourds hold the nests of the purple martin colony, named as such because the adult males have a purple sheen. There are 46 “active” gourds at the coastal center, meaning they contain nests.
After retrieving the approximately 100 baby birds from their nests — keeping families together in numbered empty whipped topping containers — they were banded and returned to the same nest.
Purple martins were removed from the state’s threatened species list a couple of years ago because of conservation efforts at places such as the coastal center, but they’re still rare and listed as being of “special concern,” bird experts said Monday.
Patrick Comins, executive director of Connecticut Audubon Society, who was there for the excitement, said there are colonies of purple martins along the East Coast — making their nests in man-made structures that look like gourds and other natural cavities and in bird houses. The colony in Milford is the second-largest in the state next to Hammonasset Beach State Park and not counting a colony on private property.
“These have a long history of co-existing with humans,” Comins said.
Comins said purple martins are aerial insectivores and catch insects on the wing while flying, which makes them fun to watch because it looks like they’re doing all kinds of tricks. They do not eat mosquitoes, but they do dine on some other non-popular pests such as Japanese beetles and gypsy moths, the experts said.
They are colonial nesters, meaning they nest in big groups, and they fly to Brazil for the winter every year, although little is known about what they do there, Comins said.
Brian Hess, a wildlife biologist with DEEP, led the banding operation that involved several others from DEEP.
Hess said each young bird was getting two bands: one bearing a nine-digit individual number for a U.S. geological survey so that if it’s found or caught, its age will be known. The other band has a color to identify the colony from which the birds come.
Hess said they are trying to find out how the birds disperse or move locally and after they fly to South America and return. This means trying to answer, for example, whether they return to the colony they came from or whether birds from Milford end up in Clinton, Stratford or somewhere else.
Hess said the bands don’t bother their tiny legs at all and their legs are already full grown.
Comins said the birds, which nest near water, were abundant decades ago, and made their ideal homes in gourds used by the Native Americans and sometimes cavities of big trees.
The purple martin population declined for decades, along with that of other aerial insectivores, Comins said. One theory is that aerial insects declined because of more widespread use of insecticide, he said. There also was a decline in their ideal nesting habitats.
Jim Arrigoni, a conservation biologist with Connecticut Audubon, said development and time have taken down some of those old, huge trees where birds such as the chimney swift and purple martins like to build their nests, and those environments take years to grow.
The man-made gourds at the coastal center are located on the edge of the marsh in the high tide bush, where those involved with the banding gently retrieved and returned the tiny birds after banding.