Do Purple Martins help reduce mosquitoes?
It has been known for many years that bird species like purple martins consume large numbers of flying insects. Proponents of their use in mosquito control are quick to cite J. L. Wade, an amateur ornithologist, who reasoned that an average 4 oz. adult purple martin, due to its rapid metabolism, would have to consume its body weight (14,000 mosquitoes) per day in order to survive. Wade recognized that the purple martins diet includes many other types of insects, but this appears to have been lost on many individuals searching for a natural means of control. In fact, during daylight, purple martins often feed voraciously upon dragonflies, known predators of mosquitoes. At night, when mosquitoes are most active, purple martins tend to feed at treetop level, well above most mosquito flight paths. Ornithologist James Hill, founder of the Purple Martin Conservation Association (PMCA), writes, “The number of mosquitoes that martins eat is extremely insignificant, and they certainly don’t control them. In-depth studies have shown that mosquitoes comprise no more than 0 to 3 percent of the diet of martins”. They eat only flying insects, which they catch in flight. Their diet is diverse, including dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants, and ballooning spiders. Martins are not, however, prodigious consumers of mosquitoes as is so often claimed by companies that manufacture martin housing. An intensive 3-year diet study conducted at PMCA headquarters in Edinboro, PA, failed to find a single mosquito among the 350 diet samples collected from parent martins bringing beakfuls of insects to their young. The samples were collected from martins during all hours of the day, all season long, and in numerous habitats, including mosquito-infested ones. Purple Martins and freshwater mosquitoes rarely ever cross paths. Martins are daytime feeders, and feed high in the sky; mosquitoes, on the other hand, stay low in damp places during daylight hours, or only come out at night. Since Purple Martins feed only on flying insects, they are extremely vulnerable to starvation during extended periods of cool and/or rainy weather. Rather than erecting martin houses to specifically attract insect-eating birds for mosquito control, we should at least promote them for their aesthetic and educational value. AMCA
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