I just attended a very interesting and informative program on purple martins at Wild Birds Unlimited in Ames. I have enjoyed watching and listening to purple martins since I was a little boy growing up in the Story City area. There were a number of active colonies in town in big old wood multi-apartment boxes that were the standard back then. We had a big martin house at our place out in the country, too. We always had a few martin nests, but never the numbers our friends in town did.
We didn’t do much to maintain the box since it was high up on an old concrete street light pole. It couldn’t be lowered and we didn’t have a ladder that would reach it safely. My trusty Daisy BB gun kept competing starlings and English sparrows somewhat thinned out, but that was about the only help our martins received.
Purple martins are North America’s largest swallow with a wing span that can approach 11 inches. They once nested in old woodpecker holes high up on dead trees. They readily took to hollowed out dried gourds hung on poles at Indian encampments and seem to prefer being near people. Perhaps the Indians enjoyed their happy chatter and graceful flight, but it’s more likely they appreciated the help the martins provided in keeping down the number of flies and other bugs around the camp. They prefer larger insects like beetles and dragonflies, and normally feed only on the wing. Unfortunately, they’d just as soon not waste time on small game like mosquitoes. Although they’ll eat an occasional mosquito, they’re not the supper mosquito eaters that some folks seem to think they are.
A couple of lonely old posts remain that used to hold martin houses in Story City, but none of the colonies I knew as a kid are there anymore. Martins are now almost totally dependent on humans to provide safe housing. Thankfully, a few thriving colonies still remain, and those are mostly in towns. If you see an active colony, know that there is a human (or group of humans) serving as an active caretaker and landlord. Competition from English sparrows and starlings for nest space is still intense, but cities frown on kids with BB guns popping the determined little pests off. Their nests are easy to tell from martin nests, and can repeatedly be removed. It’s still hard to discourage these unwanted guests. I have often written about how these introduced pests harass and compete with bluebirds, too.
I learned that owls can be a major problem for martins. Owls readily learn that a martin colony is an easy place to snag a meal. New martin nest boxes have owl guards engineered over the entries to keep owls from having a place to land. Some may even have the whole colony enclosed in a welded wire fence with openings big enough for the martins, but not owls or hawks. Squirrels and coons love to snack on martin eggs and nestlings, so squirrel guards are needed on the poles to keep them from climbing. Some snakes can even climb high enough to grab nestlings and eggs. Bird mites, though very tiny, can rapidly multiply into thousands if a colony becomes infested. They can weaken and even kill young martins as they feed on blood. Products are available to control them, but require human vigilance and a good deal of work to apply to each nest compartment in a colony. A thorough annual cleaning of each nest compartment helps remove mites that could overwinter.
I have maintained a couple of martin houses next to Nevada’s Parks and Rec. shop for several years. A small colony has established there, but I now know there’s much more I should be doing to help them multiply and be successful. Some remodeling is in order to better meet their needs. The first martins could be back within three weeks unless winter is particularly stubborn. I’d better get busy so my “rental properties” are ready for them.
Steve Lewka is a former director of Story County Conservation.