Feeding Habits of Purple Martins

Purple martins east of the Rocky Mountains rely on humans for survival. History shows that these birds have been living in close proximity with man for centuries. Native Americans are believed to have provided early housing for martins which, in turn, kept crows away from the Indians' corn. Today, martins still look to humans for housing, preferring to be within 120 feet of a dwelling. Since martins feed solely on insects while in flight, occasional weather patterns cause minimal insect activity, resulting in colony starvation.

  1. Flight Pattern

    • Martins require a minimum of 40 feet around their housing for flight clearance. They fly and feed over water, open fields, marshes and above treetops, at heights ranging from a few inches to 500 or more feet in the air. Feeding usually takes place 200 to 300 feet above ground during daylight hours. Martins are most active from early dawn until just before dusk. They will fly a 2-mile radius in search of water for drinking and bathing.

    Foods

    • Martins belong to the swallow family. They naturally eat only winged insects, which they catch in flight. Their diet includes dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leaf-hoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants and ballooning spiders. Contrary to belief, martins consume few, if any, mosquitoes. An intensive 7-year diet study conducted by the Purple Martin Conservation Association found a zero mosquito population among the 500 diet samples collected from parent martins feeding their young, even in mosquito-infested regions. Since Purple Martins feed at high altitudes and freshwater mosquitoes live in lowlands, they rarely cross paths.

    Adverse Weather Shortages

    • Since martins feed solely on flying insects, they are extremely vulnerable to weather conditions that affect insect availability. Prolonged bad weather, such as rain, snow, cool temperatures and heavy winds, all reduce or eliminate insect flight. If poor weather continues for more than 2 or 3 days, martins begin to die of starvation. Threatening weather can occur anytime in spring after the martins' arrival or even during migration. Heat waves and droughts are also a problem in summer. Extended drought negatively affects insect numbers.

    Supplemental Feeding

    • Supplemental feeding is controversial, since some argue that it is against the laws of nature. Landlords or stewards must make their own decisions. Two basic methods provide supplement for feeding distressed martins. Active feeding requires tossing food into the air and stationary feeding means to offer food on a platform or inside the nest. Martins need training to recognize crickets, meal worms and cooked eggs as food when weather does not allow natural foraging.

      Tossing food items into the air tempts martins to go after them, so this is a more natural supplemental feeding unless the bird is already too weak. Toss meal worms and crickets, with their legs removed, into the air around the martin housing by hand, or with a slingshot or plastic spoon. Patience is required before the birds identify the worms as food.

      Stationary feeding on a platform is easier and more effective once the martins have learned to accept tossed food. As with active feeding, it can take martins some time to catch on. Start stationary feeding at the beginning of poor weather, by providing some items in a feeder while also tossing food. Conversion from tossed to stationary feeding saves energy for the martins.

      Purchase crickets and meal worms alive and then store in the freezer. Thaw before feeding to the martins.

      Introduce small egg pieces once the martins have accepted insects. Eggs are readily available and inexpensive compared to insects, but they still provide necessary protein.