Comparing incubation behavior of nesting cranes during black fly parasitism

Blood-feeding black flies (family Simuliidae) serve as vectors for parasites, bacteria, and viruses in wild and domestic birds. Approximately 37% of black fly species that occur in North America are ornithophilic, and can... [ view full abstract ]

Blood-feeding black flies (family Simuliidae) serve as vectors for parasites, bacteria, and viruses in wild and domestic birds. Approximately 37% of black fly species that occur in North America are ornithophilic, and can serve as stressors at nests of common loons, great-horned owls, and purple martins, among others. Black flies may be contributing to low nest success of the reintroduced Eastern Migratory Population of federally endangered whooping cranes (Grus americana) nesting at Necedah National Wildlife Refuge in central Wisconsin because emergence of black flies at NNWR coincides with whooping crane incubation. Whooping cranes exposed to black flies exhibit head rubs and bill flicks, behaviors indicative of black fly parasitism. Nest desertion coincides with black fly emergence as well. The Eastern Population (EP) of sandhill cranes (Grus canadensis) are ecologically similar to whooping cranes and nest in close proximity to whooping cranes on and around NNWR. Sandhill cranes in the EP experience an annual population growth of 3.9% and appear to be successful despite black fly parasitism at NNWR. Our objective was to compare incubation behavior between sandhill cranes and whooping cranes during incubation by installing camera traps at active nests. Cameras took a photo every 5 minutes and remained at nests until nests failed or were successful (defined as one egg hatching in a nest). We quantified the percent time nesting cranes spent exhibiting various incubation and black fly avoidance behaviors and ran a discriminant function analysis to compare incubation behaviors by species and fate of nest. Our data suggest that behavior indicative of black fly emergence was more prevalent at failed whooping crane nests. Possible management strategies to reduce black fly harassment during incubation and potentially increase nest success will be discussed.