New nest platforms benefitting endangered hawks
If you have visited southeast Washington, you know that it boasts some spectacular views of the arid shrubsteppe ecosystem bisected by the Columbia, Walla Walla, and Touchet rivers. Most of us have seen the tall poles supporting large raptors nests along these waterways providing nesting opportunities for ospreys that fish for a living. Less often, biologists have used a shorter version of the same nest platform in remote shrubsteppe habitats for another species: the ferruginous hawk. This species is often hindered from nesting where old homestead trees have been lost or small cliffsides have fallen.
In recent years, thirty of these nest platforms were mounted on poles that were installed about 15 feet off the ground, and an additional 26 have been fabricated and are awaiting installation. These platforms are funded, with support from the Washington State Department of Transportation, with mitigation funds from the Highway 12 realignment that is routed through existing ferruginous hawk territories.
These platforms don’t just provide a home for some big bird species, they allow biologists a rare opportunity to learn more about raptors. Washington Department of Fish and Wildlife (WDFW) research scientist Jim Watson, who specializes in raptor studies, and Mark Vekasy, WDFW assistant district wildlife biologist in southeast Washington, have been tracking birds in the area for many years for research purposes. They capture and equip them with tiny monitoring transmitters and immediately release them back into the wild.
“This allows biologists a look into the life of a raptor that we wouldn’t get otherwise,” said Vekasy. “You can only gather so much information from watching a bird from the ground.”
In June, the two tagged a ferruginous hawk fledgling (a young bird that has recently learned to fly but is still dependent upon its’ parents) at one of the new platform nest sites near Wallula Gap and a second fledgling from a natural cliff nest site near Starbuck, Washington. Ferruginous hawks are listed as endangered in Washington due to their populations being impacted by the loss of shrubsteppe and grassland habitat from development and agriculture, and declines in numbers of its’ primary prey, jackrabbits and ground squirrels. Illegal shooting, electrocution from powerlines, and collisions with wind turbines have also decreased this hawk’s population.
Tagging these big birds usually takes some effort to access a cliff or spindly tree nest, but the platforms make for relatively easy access using a step ladder. Corralling a bunch of young birds that are just about ready to fly is the hardest part. It involves climbing up to the platform, about 15 feet in the air, when the parents are out of the nest, measuring each young bird, applying a uniquely numbered band, and taking note of remains in the nest that show what kind of prey the birds have been eating. In the case of the Wallula Gap nest, the number of young birds in the nest was somewhat surprising.
“I haven’t seen five young in a nest in a long time and all were very healthy,” said Watson. “This is an exceptional number of young for this species. It’s also interesting that we’ve had several nests with four chicks this year as well.”
The largest female chicks from both broods had a band placed around one leg and were fitted with transmitters that were donated by a biologist at a cooperating agency. Both were immediately placed back into the nest with the rest of their banded siblings.
The transmitters are so small that they don’t interfere with a bird’s function.
“They are extremely small and light and don’t impede a bird’s movements. They are used around the world in studies on birds of all kinds and many falconers use them to keep track of their birds while hunting,” said Vekasy.
The transmitters will help biologists learn about long-term range use and how fledged juvenile birds use the landscape, both in Washington and at dispersal and wintering areas across the western United States. Identifying these use areas is important for protection of the species, particularly in light of wind power and other potential development.
The parents of the banded Wallula Gap fledgling have occupied this platform since it was built; this is their fourth breeding season there. They originally nested in a lone tree in the middle of plowed agricultural fields. Since “their” platform was erected, they have been successful in raising chicks every year.
There are four other new platforms occupied at this time. In addition to the first pair, four other pairs of ferruginous hawks have occupied the new platforms; two that were formally in what would be considered marginal territories (have extensive active agricultural operations around the nest sites) and two brand new pairs with no historical nest sites in the area. The platforms appear to be a success as they have increased resilience of hawk pairs in less-than-ideal territories and increased the population by providing nest sites in an area where suitable nest sites were absent. Historically, ferruginous hawks would even nest on the ground, at the tops of steep slopes or buttes, but in most areas these sites are no longer safe from ground predators that can easily find nesting birds in what is now limited foraging habitat.
“These platforms have been a benefit in that they provide the hawks a safe and suitable place to nest away from ground predators and human disturbance,” said Vekasy.
