May 19, 2016
Thanks to student blogger, Jacyln Melvin, for explaining why hummingbirds might nest in close proximity to hawks.
For sale: One small nest. Camouflaged exterior. Tree branch provides an excellent view. Neighbors are aggressive raptors.
You might think this listing would turn away birds in the market for a new home, but this nest would be considered prime real estate for Black-chinned Hummingbirds. By living in close proximity to raptors, Black-chinned Hummingbirds acquire a winged defense system which reduces their risk of becoming victims of nest predation, a phenomenon called protective nesting association.
Nest predation affects both the nesting success and distribution of breeding bird species. When choosing where to make their homes, birds will select a location that offers protection from predators. For some, these spots lie within a raptor’s hunting ground. The presence of birds of prey reduces the number of other nest predators in the area. As a result, young chicks have higher chances of making it to adulthood. This relationship has been documented with a variety of birds, but it was not observed in hummingbirds until recently.
Researchers Harold Greeney and Susan Wethington noticed that Black-chinned Hummingbird populations were clustered around nests belonging to Northern Goshawks and Cooper’s Hawks. The researchers measured the distances between the hummingbird nests and the raptor nests and estimated fledging dates for the hummingbird chicks by the state of their plumage. Nests checks were preformed every couple days over a two-month period. A nest found to be empty before the estimated fledging date was an indication that nest predation had occurred.
The results showed there was a major advantage for Black-chinned Hummingbirds to make their homes close to the raptors’ nests. Hummingbird chicks in nests less than 300 meters from the raptors were much more likely than those farther away to successfully fledge.
Although the researchers did not record the numbers of other predators in the area, it is likely that the presence of the hawks kept the other predators to a minimum. Common hummingbird predators include cats, jays, and crows, which go after chicks and eggs. The aggressive raptors help drive away these animals. Because hummingbirds are small and difficult to catch, raptors prefer to hunt larger prey. At the end of the day, the Black-chinned Hummingbirds can settle safely into their nests knowing their taloned security guards are patrolling the neighborhood and keeping other predators in check.
Greeney, Harold F. and Susan M. Wethington. Proximity to Active Accipiter Nests Reduces Nest Predation of Black-Chinned Hummingbirds. The Wilson Journal of Ornithology 121.4 (2009): 809-812. Web. 3 Oct. 2014.
Hummingbird Predators. The Hummingbird Society. The Hummingbird Society, n.d. Web. 17 Oct. 2014.