Purple martin banding project aimed at learning more about these entertaining birds
WILLMAR -- Every year, Dick Doll hosts visitors from Brazil.
They take over the apartments he provides them, raise their young and leave.
Now, he's going to find out a little bit about them.
For three years now, Michael North, a senior natural resource specialist with the Minnesota Department of Natural Resources has been banding the purple martins that set up housekeeping in Doll's back yard.
He and Doll kept up a hectic pace on July 10 banding birds in Doll's colony.
It's a long-term project, one that should continue for at least 20 years, according to North.
North is banding purple martins at colonies maintained by others across the state as well. The Mille Lacs Band of the Ojibwe is participating in the project, too, and banding colonies at sites on its tribal lands.
The birds should be banded when they're 13-21 days of age, giving North a very short time frame in which to visit the colonies that are part of the project.
It's all aimed at learning more about the colorful and entertaining birds. Their numbers in Minnesota have declined by 70 percent since 1966, said North.
He believes their numbers could be on the rebound right now, but the fact is we don't know a lot about them.
We do know the birds depend on humans in Minnesota to provide their housing. We've learned to make larger and better insulated houses to improve the survival rates for the young, said North.
More of the bird's hosts are also aware of the importance of cleaning out the bird houses every year to prevent debilitating mite infestations that are believed to have contributed greatly to their population losses.
Doll hosts the purple martin colony in apartments he built and maintains at his home south of King Lake and Long Lake near Willmar. This year, his 50 units are host to 47 different families in the colony.
If last year is any indication, Doll expects 200 new purple martins to take wing when the colony leaves for its roosting site later this summer.
Three will be leaving with miniature radio transmitters. It will help shed light on their route south to their wintering grounds in Brazil, believed to be mainly in the Amazon basin.
A couple of years ago, Doll and birding enthusiast Randy Frederickson, also a Willmar science teacher, tracked the birds as they left their local apartments to roost and start their journey south. To their surprise, they discovered a purple martin roosting site not far from Willmar in the midst of a corn field.
In most cases, purple martins will roost on islands located in marshes and other wetlands. Was the corn field a wetland drained for farming, or was something else going on here?
Other known roosting sites in the state -- and some are large enough to hold 20,000 to 40,000 birds -- are true-to-form and located on islands, said North.
There are lots of questions to answer when it comes to purple martins, and North said he is hoping the banding project will help answer them.
But it will almost certainly require the 20 years or more to gather meaningful data, he said. Less than one percent of the purple martin bands are ever recovered, he explained.
Bands placed on larger predators, such as hawks and eagles, have an eight-percent return rate. Bands on birds sought by hunters, such as waterfowl, have a 33-50 percent return rate, he said.
Some of the bands placed on Doll's birds in the last two years have been returned, including from sites near West Union and Darwin.
Each banded bird carries a silver-colored, U.S. Fish and Wildlife Service band with a nine-digit identification number and a matching, red band that has the last three digits in a large size. That makes it possible to read the bands on living birds with a telescope and learn some things about them without their having to sacrifice their lives for science first.
Doll said he started hosting purple martins for the enjoyment of it, and that is still why he tends to the colonies. He enjoys the activity, song and color of the birds as they perform their aerobatics in his backyard while snapping up dragon flies and other insects to feed their young.