ABQ’s urban raptors

A newly independent juvenile female Cooper’s hawk, complete with a band and radio-transmitter, is seen here in the Albuquerque study area. (Source Courtesy of NMSU)

A student in New Mexico State University’s Biology Department recently published a paper in “Condor – Ornithological Applications,” an international scientific journal, about the population ecology of Cooper’s hawks in urban Albuquerque.

Brian Millsap is a Ph.D. candidate who, since 1978, has worked for the U.S. Bureau of Land Management, the Florida Fish and Wildlife Conservation Commission, and the U.S. Fish and Wildlife Service.

After three years as the national raptor coordinator for the USFWS, the position he still holds today, Millsap decided he wanted to apply his professional knowledge to obtaining his Ph.D., and has been working with NMSU’s Department of Fish, Wildlife and Conservation Ecology’s professor Gary Roemer since 2013.

Focusing on New Mexico’s largest urban location, Albuquerque, Millsap and Roemer have been studying the ecology of a relatively new and expanding population of Cooper’s hawks.

“Urban wildlife populations can be ‘sources’ or ‘sinks,’ either reproducing and surviving so well that excess individuals … leave to settle in the surrounding natural areas, or doing so poorly that they need constant immigration from outside …,” Millsap said. “Our research has focused on the relationship between the urban Albuquerque Cooper’s hawk population and the surrounding natural populations in forests along the Rio Grande, and in the nearby conifer woodlands in the Sandia and Manzano mountains.”

Millsap has been engaged in this research since 2011, as a USFWS employee and a graduate student with NMSU. The publication details the results of his research from 2011-15 in a 28-square-mile area in northeast Albuquerque, where he monitored the fate of 320 Cooper’s hawk nests.

The study shows that another bird that colonized urban Albuquerque in the 1980s, the white-winged dove, is an important part of the puzzle, Millsap said. “Because of the proliferation of white-winged doves, the city-dwelling hawks have an abundant year-round food source,” he said. “This turns out to be extremely important, because it allows urban hawks to spend winters in Albuquerque, near their eventual breeding sites. Prey is less common outside the city in winter, and hawks from these areas leave their breeding areas in the fall and migrate south.”

Because the urban hawks do not leave, they have an advantage by settling on nesting territories before the migrants return, without having to compete with them. Urban hawks fill nesting slots in town first; those not able to settle in town move into the countryside.

Millsap’s research thus far has shown that the urban Cooper’s hawks are displacing their rural counterparts at nests.

Millsap’s article can be found at: http://americanornithologypubs.org/doi/full/10.1650/CONDOR-17-124.1.

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