Wildlife Feature Part I: Meet the Martins

Part I of a blog series by Troy Clark, CSWC Board Member

I don’t suppose very many people know that purple martins fly 5,000 miles in migration twice a year. Actually, I don’t suppose very many people know what a purple martin is. When one starts talking about these birds, some minds seem to be scrolling and landing on Steve Martin in a purple get-up. One must slowly introduce them to the largest of the swallows that visit and nest in North America (and in our Columbia Slough watershed) every year.

Male (left) and female (right) purple martins rest on a snag. Photo by Sam May.

The purple martin (Progne subis) is abbreviated in field nomenclature as PUMA. Where the other six swallow species that migrate to our region every year are six-inch birds, martins are eight inch birds—a very big swallow. Unlike most swallows, a martins’ gender is distinct in plumage. The male martin is a very dark blue that sometimes reflects light as a deep purple, hence the name. The females are dressed more in blue and gray tones.

Martins are colonial nesters whenever possible. They like to be with their kind. I am sure they have their own martin prejudices, but not such as we humans can easily discern. They seem to be amiable, chattery and rather into life. Martins have adapted well to human-supplied nest cavities, as natural cavities are lost to tree removal and competition with European starlings.

Currently purple martins have two distinct groups, yet remain one species. There is speculation that the western and eastern martins winter in different regions of the Amazonian rainforest, and do not mingle with their brethren in migration. This might mean that, in time, the two groups will become separate species, much like the western and eastern bluebird. The estimated population of martins that migrate east of the Rocky Mountains is 10 to 15 million birds. The western group is thought to be 10 to 15 thousand birds. This is a significant difference and has roots in human action, which we will discuss in a future post.

Purple martin on the hunt for flying insects!

All swallows are aerial feeders. They may snag a bug occasionally while picking up nest material on the ground, but their normal dining approach is on the wing—we’re talking very fast food. It has been speculated—but not verified—that martins can eat up to 2,000 mosquitoes a day. This is a very lovely thought, and stories are told of purple martins having remarkable impact on biting bugs. I’ve read that the town of Griggsville, Illinois, proclaimed itself the purple martin capital of the world because the whole town got into putting up martin houses. They said it made it possible for the citizens to enjoy being outside on a summer evening.

Purple martins usually have clutches of four to six eggs that hatch in about 18 days. The young fledge (leave the nest) in around 30 days. Both parents are active in feeding their young. Numerous times I have seen a parent come to the nest with a large dragonfly, choose one of its four nestlings bawling for food, and cram the whole dragonfly down the baby’s throat, saying, or so it seems, here’s your full meal deal sweetheart.

Prepping kids for long trips is a challenge. A few months after the young fledge, martin families return south for the Amazon. Imagine 5,000 miles with a pack of brats—sometimes in groups that can reach 100,000 birds in the eastern population. How do they do it?

Around 50 to 60% of birds are estimated to return the next year. There is a lot of mortality on the migration trip, both ways, and we know little about habitat loss on the wintering grounds. And there is always that wonder when the birds return here the first week of April: Are you here because it is imprinted that this is your summer home, the place of your birth, where you first opened your eyes and first took flight to join the family, that big and boisterous purple martin family?

Next time we’ll talk about becoming a gourd lord and the learning curve of working with purple martins.