Do Purple Martins Eat Genetically Engineered Mosquitoes?
Perhaps the most frequently anecdotally cited bird as a consumer of mosquitoes is the Purple Martin (Progne subis). However, both the American Mosquito Control Association (AMCA) and the Purple Martin Conservation Association (PMCA) declare that this belief is not supported by scientific fact (AMCA, 2016; PMCA, 2017). In-depth studies have shown that mosquitoes comprise a negligible portion of the diet of purple martins. Studies that have been conducted on the purple martin diet reveal that it prefers larger, more energetically-rewarding insects such as dragonflies, damselflies, butterflies, moths, grasshoppers, katydids, mayflies, cicadas, beetles, flies, wasps, midges, bees, and flying ants (Brown, 2013; Helms, 2016; Johnston, 1967). The activity periods of diurnal purple martins and nocturnal mosquitoes do not overlap significantly. There is temporal and spatial isolation between the purple martin and the mosquito flight patterns, with the birds and mosquitoes not flying at the same times or altitudes (Johnston, 1967; Kale, 1968; Helms et al., 2016). Out of the approximately 930 minutes available to purple martins each day for foraging, there is only a 10-minute overlap with mosquito activity, which amounts to only 1% of their total foraging time (Hill, 2017).
Helms (2016), in a study of the diets of purple martin nestlings, reported that only 0.03% of the total diet consisted of mosquitoes. In a two-year study of purple martin nestlings, Walsh (1978) reported no consumption of mosquitoes. An intensive 7-year diet study conducted at PMCA headquarters in Edinboro, PA, failed to find a single mosquito among the 500 diet samples collected from purple martin nestlings (AMCA, 2016). Beal (1918) analyzed the stomach contents of 205 purple martins, collected from the U.S. and Canada, and found no evidence of consumption of mosquitoes. Beal (1918) reported that the most important insects in the diet of purple martins were flies (16%), beetles (13%), bees and wasps (19%), ants (4%), and moths and butterflies (9%).