Purple Martins have become urban dwellers over the past century. These birds find their food in open areas like beaver ponds, meadows, and fields that are scattered over the terrain. In the past, they built their nests along the edges of streams and wooded areas, but now prefer the nest boxes that humans supply them in the eastern part of the US. Out west, they still use the holes left by woodpeckers in the forests of the Pacific lowlands and mountainous regions or move into holes left in cacti in the drier regions of the Southwest.
The menu of this extraordinary bird species is diverse. They feed on insect types as diverse as mayflies, grasshoppers, beetles, and leafhoppers. An insectivore with a big appetite, Purple Martins have been seen hunting their prey at elevations 500 or more feet above the ground. Skilled hunters, they turn rapidly high in the sky when they spot their prey during the long daylight hours of summer. They are solitary hunters, although occasionally they do go out in pairs.
A conventional purple martin bird house is best described as “apartment style”. Purple martin gourds are the other preferred nesting site. These are primarily provided by humans at this points. A nesting pair will visit several cubby holes before selecting the one in which they will rear their young. Some people choose to put up only a single birdhouse with eight to ten compartments for their avian guests, which leaves individual pairs with more territory. However, when many large houses are placed in a single area, the birds naturally reduce the size of the territory that they will defend once they lay their eggs. By the time the eggs are laid, most martins will only defend their own compartment.
While most Purple Martins are paired with one male and one female per nest, it is not unusual for two or more females to share the same male mate. Each female does have her own compartment within the nesting boxes. However, females do mate with other males besides the one with which they are paired. During the mating seasons, there are occasional physical fights between competing birds.
The vast majority of this bird species breeds within the United States. They do migrate to South America during the winter months. While the species is not in danger, their numbers are declining at a relatively low rate. This decline has been counteracted by the nesting sites built in suburban and urban areas. In fact, almost all nesting is now done within these homes provided by humans in the eastern part of the country.
The single greatest cause of death is cold weather. Because insect activity drops off precipitously as the temperatures plummet, the timing for migration is vital for their survival. Cold snaps lasting longer than four or five days during the warm weather months significantly impact the population. They are rarely seen on the ground when the insect population is dense.
In the west, the removal of dead trees by the logging industry has had a direct and negative impact on their ability to breed. In addition, species such as the House Sparrow and the introduced European Starlings will move into Purple Martin breeding nests, destroy the eggs or kill the nestlings, and take over the compartments for their own use. A movement by Brazil’s government to reduce the use of insecticides is aiding conservation efforts.
Consider placing a martin house in your backyard to help this species thrive. You’ll get a chance to watch them as they compete for mates and territory. Best of all, you’ll help the next generation to get their start in the world.