Robin Parents Shield Nestlings from Mosquitoes
By Gregory Gough
Mosquitoes are not just a problem for humans. There are mosquitoes that bite birds, too. And some of these mosquitoes carry diseases, such as West Nile virus, that can be fatal.
So how do nestling birds, which can't fly away from mosquitoes and are not completely feathered, deal with them?
Scientists placed infrared cameras next to active robin nests in the Washington, D.C. area to find out. It turns out that a stationary nest is quite the target for ravenous mosquitoes. Adults that were brooding the nestlings were landed on an average of 123 times per night!
And by providing a protective cover for their chicks, the nestlings were only landed on 37 times a night. The cameras were unable to discern how often the mosquitoes actually bit the birds because of the low resolution. Since the adults would tuck their heads under their wings and their feet would be below them in the nest—there may not have been much exposed flesh.
However, other studies, see below, have shown that robins are important vectors for the transmission of West Nile virus.
This article summarizes the information in this publication:
Griffing, S. M., Kilpatrick, A. M., Clark, L. and Marra, Peter P. 2007. Mosquito landing rates on nesting American robins (Turdus migratorius). Vector-Borne and Zoonotic Diseases, 7: 437-443.
We measured mosquito landing rates on adult and nestling American robins at nests with infrared cameras in Washington, D.C., and Maryland, United States. Mosquitoes landed on nesting robins almost exclusively between dusk and dawn. The mean number of mosquito landings per night was higher for adults (123.3 ± SE 32.8) than nestlings (37.26 ± 14.8). The fraction of mosquitoes landing at a nest on nestlings increased with decreases in adult brooding. Oral swabs from nestlings at these and 13 other robin, gray catbird, and house finch nests were negative for West Nile virus (WNV). These results show that landing rates were higher on adults and that parental brooding reduces the landing rates of mosquitoes on nestlings.
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