Liberty Wildlife saves a troublesome Harris' hawk

The Sonoran pronghorn population in Arizona and Mexico has reached dangerously low numbers. Although these swift and graceful animals once roamed across the West in numbers equal to the buffalo, habitat loss, fencing and disease have decimated the population. At the Cabeza Prieta Wildlife Refuge, the pregnant females are kept in a protective pen while they birth and raise their fawns. It is hoped this breeding program can help renew the wild populations in both Arizona and Mexico. Pronghorns can run 55 mph, and easily outrun their predators. But in the wild as many as 50 percent of the newborns fall prey to coyotes while they are still too young to run with the herd. The mothers hide their well-camouflaged babies and only visit them once every five hours for a quick feeding before moving away again so as to not draw attention to the fawn. A newborn pronghorn weighs just about six pounds, a nearly identical weight to the adult jackrabbit.

In the Cabeza Prieta desert, jackrabbits are the favored diet of the Harris’ hawk. And it was probably the jackrabbits that also live in the refuge’s rearing pens that originally attracted the family of hawks. Arizona’s Harris’ hawks are unique among raptors because they live together in a family unit that is led by a dominant member of the family, often a female. Youngsters stick around and help raise subsequent broods, and the hawks boost their prey intake by hunting cooperatively, much like a pack of wolves.

One day late in March a refuge biologist watched while two Harris’ hawks flew low over the pronghorn pens, startling the fawns, who struggled to their feet. As the first fawn stood up, a Harris’ hawk swooped into an ocotillo immediately above the fawn, while a second hawk landed a short distance away. As the fawn began to slowly walk away, one of the hawks dove at it. At this point, the baby turned to face the hawk and kicked its front feet at the bird. The birds continued to attack until the mother pronghorn arrived and both hawks moved on.

After observing several of these attacks, and fearing for the safety of the endangered pronghorns, the refuge managers contacted both US Fish and Wildlife Services and Arizona Game and Fish. When Jamey Driscoll of Game and Fish heard that the birds might have to be killed, he contacted Liberty Wildlife. Jan Miller took the call. Her knowledge of Harris’ hawks led her to believe that if the alpha bird of this family group could be trapped, that the rest of the hawks would return to hunting rabbits. She immediately rounded up three volunteers to go down to the Cabeza Prieta Refuge.

Ron and Greg Martin are Liberty Wildlife medical services volunteers and are also falconers. Greg Kendall is a biologist and a Liberty rescue and transport volunteer. The three set out that evening for Ajo. They were put up in a nice cabin at the refuge and, during their visits with the group there, learned of a hawk nest that had been observed in the area. The nest held three eggs.

At first light, a Bal-Char trap was baited with several rats. The trap soon held a large female Harris’ hawk. Another juvenile was briefly trapped but it escaped. The hawk nest was monitored throughout the day and no female was seen to visit it. It was decided that the trapped female was the mother of the eggs. Fish and Wildlife Services pulled the eggs and handed them over to the Liberty Wildlife volunteers. The eggs and the female were brought back to Liberty Wildlife on Sunday.

Since then, there have been no further attacks on the pronghorn fawns. The alpha female is doing fine at the rehabilitation center, and the managers of Cabeza Prieta Refuge would like to see her come home to her territory as soon as the fawns are big enough to be safe from attacks. The eggs are currently incubating at Liberty Wildlife. This fascinating instance of animal behavior is also about dedicated people. In this case, highly trained biologists worked with eager and experienced volunteers as well as government officials, to find a solution that saved both a breeding program and an incredible family of hawks.