By Gustave Axelson
On a pleasant summer day in Chippewa National Forest, I was strolling down a woodsy trail -- until I crossed a boundary where I was unwelcome. A screaming goshawk hurtled out of the forest shadows.
Kee-kee-kee-kee-kee! Its high-pitched, incessant alarm call pulsated like a siren. The hawk fluttered from perch to perch amid the leafy treetops, then settled atop a dead aspen to assume an aggressive posture. Its undertail feathers flared, a snow-white, fluffy plume befitting this bird's Latin name: Accipiter gentilis, a raptor of gentility.
Kee-kee-kee-kee-kee! The strident refrain continued. The goshawk protested with agitated bobs of its head. Its red eyes burned like hot, glowing coals embedded in its dark-gray facial stripes.
Kee-kee-kee-kee-kee! The message was clear: Leave.
"She must have nestlings," said Department of Natural Resources Nongame Wildlife biologist Maya Hamady, indicating that the goshawk's young must have already hatched. "The female doesn't leave the nest when she's sitting on eggs."
Hamady had agreed to guide me to one of the 109 goshawk nest sites in northern Minnesota that the DNR and other agencies have been monitoring since 1991. As she records goshawk nesting activity, Hamady is filling a void in Minnesota's avian annals. No one has ever conducted a comprehensive survey of goshawk populations in Minnesota, so biologists don't really know how many goshawks live in our north woods -- or how they are faring.
But this lack of a historical baseline for evaluating the goshawk's conservation status doesn't stop Hamady from looking into the future of Minnesota forests to see if goshawks will have enough closed-canopy habitat for nesting. Habitat fragmentation and declining stands of mature aspens could pose challenges for goshawks as they seek nesting territories over the next two decades and beyond.
Goshawk Encounters:Go in search of goshawks
The northern goshawk is the largest Minnesota accipiter, a genus of forest-dwelling, fast-flying hawks that includes Cooper's and sharp-shinned hawks. The goshawk's ferocity is legendary. It has been known to attack other hawks, people, even black bears. Attila the Hun rode into battle wearing a helmet that bore an emblem of this most truculent bird of prey.
Hamady has experienced the accipiter's aggressiveness firsthand on several nest-site checks, when goshawks swooped at her. On one visit, a goshawk flew overhead for most of her quarter-mile retreat to her car.
She also witnessed a prime example of the goshawk's territorial tendencies. "I once got a call from a landowner about a goshawk nest, but when I went out to confirm it I only saw a sharp-shinned hawk. So I thought the landowner was mistaken," Hamady said. Later another raptor researcher visited the nest and found two fledgling goshawks, and the skeleton of a sharp-shinned hawk on the ground below.
Goshawks hunt by executing surgical strikes in thick woods -- weaving among tree boles, flying at speeds up to 55 mph. Relentless in pursuit of prey, a goshawk will crash through brush at top speed and even drop to the ground to run down its quarry on foot.
The goshawk's choice of prey has tarnished its reputation among some hunters, who worry the "grouse hawk" could depress local game bird populations. But a 2003 research study of northern goshawk food habits in Minnesota revealed a broad diet. Over 45 days, a pair of breeding goshawks averaged two daily deliveries of prey, including 29 red squirrels, 14 eastern chipmunks, six crows, five snowshoe hares, five ruffed grouse, two diving ducks, one cottontail rabbit, one blue jay, and 31 miscellaneous forest creatures (including pileated woodpeckers, a weasel, and a veery).
The prime hunting grounds for goshawks is dense forest, where their jet-fighter flight tactics provide an advantage that keeps out other raptors better suited to open spaces. Goshawks prefer habitat with a closed tree canopy, shrubby cover on the forest floor to give prey a false sense of security, and a midway fly zone free of branches. One Minnesota goshawk study showed they preferred nest trees that averaged 72 feet tall and forests with 60 percent to 90 percent canopy closure.
This mature-woods preference has landed the goshawk in a few spotted owl-type timber harvest controversies. In Arizona and New Mexico, lawsuits were filed in the early 1990s against the U.S. Forest Service to add the goshawk to the endangered species list as a means of halting old-growth logging projects, though the attempts failed due to a lack of evidence that goshawk populations were declining.
In the mid-1990s, the Minnesota offices of the Sierra Club and Audubon filed appeals on timber harvest proposals in Chippewa National Forest, charging that the USFS hadn't properly considered goshawk habitat needs. Harvest levels in the forest were high in the late 1980s and early 1990s, says Chippewa wildlife biologist Jim Gallagher, and the harvests were guided by a 1986 forest plan that didn't contain specifics about goshawk management. Gallagher says that the USFS didn't know much about goshawks back then. He says the USFS was only aware of one or two goshawk nests in the entire 1.6 million-acre Chippewa National Forest.
As a result of the Sierra Club and Audubon appeals, the USFS got to work finding out more about goshawks in Chippewa National Forest -- and soon discovered the forest's goshawk population was more abundant than previously thought.
"Researchers at other national forests told me they searched all summer and couldn't find any goshawk nests," recalled Gallagher. But he found a couple of nests just by visiting some proposed timber harvest sites and being attacked by goshawks. Several more nests were reported to him as eagle or osprey nests but turned out to be goshawk nests. And as Gallagher gained experience, he got better at finding goshawks. After a few field seasons, Gallagher had located 21 goshawk nests.
Maya Hamady's second goshawk nest visit of the day took us to a different nook of Chippewa National Forest. In her DNR truck, we bumped down an active logging road past 15-foot-tall stacks of logs, which looked like Paul Bunyan's firewood. We stopped at the edge of a pine plantation, where we immediately saw an ominous sign: a red-tailed hawk perched in a tree.
Red-tailed hawks and great horned owls are the archrivals of goshawks; the presence of redtails and great horned owls often results in nest and territory abandonment by goshawks. Redtails and owls are prime predators of goshawks (which lose their acrobatic flight advantage beyond the forest's edge) and their nestlings. More important, they are harbingers of forest fragmentation, which renders goshawk habitat unsuitable.
We walked a trail until red pines mixed with aspens, where sunlight filtered through an enclosed tree canopy and dappled the forest floor. In the fork of an aspen, about 50 feet high, sat a nest of kindling-sized twigs, patched together with mosses and duff. A goshawk emerged from the nest, circled silently overhead, then flew off into the forest, leaving the echo of a fading call, KEE-kee-kee. Hamady said this goshawk might have been a male attempting to draw us away from the nest.
Of the 15 goshawk territories closely monitored by the DNR Nongame Wildlife Program for habitat requirements, this site has had the most logging -- with 35 percent of the upland mature habitat harvested between 1995 and 2005. Yet, this nest has also been one of the most productive, with hatchlings most years since 2003.
Gallagher says the USFS and DNR are smarter about balancing timber harvests with goshawk habitat needs now, compared with the 1990s when logging activity in federal forests used to take all trees except the actual nest tree. In 2003 the DNR issued a set of state forest management considerations that are sensitive to goshawk breeding territories, including nest areas.
In 2004 the revised Chippewa National Forest plan introduced new rules for timber harvests near goshawk nests on federal land: no logging allowed during the nesting season; no logging allowed in an area of 50 acres around the nest; and only selective logging within a 500-acre area around the nest, such that 60 percent of that area remains in suitable habitat condition (tall trees, partially closed canopy). Since the national forest rules were implemented, Gallagher says timber harvests have not harmed monitored goshawk nests in Chippewa National Forest. And there have been no further appeals from the Sierra Club and Audubon.
"Audubon has been watching to see that [the rules] work," said Mark Martell, director of bird conservation for Audubon Minnesota. "We want to give the system a chance to work. It's premature to call it a success after only a few years. But it seems to be working so far."
During 2008 the Minnesota DNR Nongame Wildlife Program joined the Wisconsin DNR and U.S. Forest Service in a survey of goshawks across the western Great Lakes region, including Wisconsin and Michigan.
"Goshawks are an indicator species in many national forests in the western Great Lakes. There have been lawsuits in other national forests. And we truly don't know how many goshawks there are out in the woods," said Mary Shedd, a Superior National Forest wildlife biologist who is helping to guide the effort. "This is a standardized, randomized, scientifically sound effort to finally get a handle on our regional goshawk population."
In the future, regional surveys will be repeated and findings will be used to develop a long-term monitoring plan for goshawks across the western Great Lakes area. The surveys will also help managers better understand how to maintain goshawk populations across the landscape.
Despite the success in Chippewa National Forest, there have still been logging- goshawk conflicts in Minnesota. Federal and state guidelines only apply to national and state forests, which hold 60 percent and 15 percent of known goshawk nests, respectively. About 15 percent of known goshawk nests are on private land, and 10 percent are on county forestland. From 2003 to 2007, DNR goshawk nest surveyors found three instances in which nest stands were logged, twice on private land and once on county land. In two of those cases, the goshawks abandoned their territory.
But individual timber harvest-goshawk nest conflicts don't concern Hamady nearly as much as the forecasts for a changing northern forest composition, which could result in less goshawk nesting and foraging habitat over the next two decades.
Goshawks are very particular in choosing nesting areas, seeking mature forest structure with a closed canopy and trees about 50 feet to 100 feet tall. In the Black Hills and Arizona, those nesting areas are in stands of ponderosa pine. In British Columbia, goshawks choose Douglas fir or lodgepole pine. And in Minnesota, that prime goshawk nesting habitat tends to consist of the most dominant trees on the northern forest landscape: aspen.
Aspens aren't inherently suited to goshawk nests, but their abundance here makes aspens the most likely trees to provide suitable nesting structure, at least for now. Red and white pines can also provide that structure, but Minnesota currently has far fewer mature pines on the landscape.
Hamady worries that over the next few decades there will not be enough mature aspen forests, or mature upland forests in general, for goshawks. The Chippewa National Forest plan estimates that mature and old forest will decrease from 49 percent of total upland forest to 43 percent within the next 10 to 20 years. In state forests, currently over 30 percent of aspen forests are mature, but long-term goals aim for about 10 to 15 percent of aspen stands in a mature or old forest condition. County forests have more early successional forests and could see a steeper decline in mature forest habitat. All federal, state, and county forestlands have a lack of middle-aged aspens (30 to 50 years old), which would age over the next two decades into mature forest habitat.
"Whether through harvest or natural processes like wind, decay, or diseases, the old aspen trees that currently exist won't last very long," says DNR Forestry policy and planning supervisor Jon Nelson. He notes that aspen is a short-lived species with a life expectancy of about 80 years. "We can't create middle-aged aspen stands out of thin air to replace them," he says.
Hamady says she sees that conifers will replace old aspens in the 50- to 60-year forest plans for the Chippewa and Superior national forests. "But old aspens will [be less abundant] in the next 20 years," Hamady says. "What then?" she asks.
To conserve goshawk habitat, the DNR is identifying contiguous, mature forest complexes in the north woods. DNR biologists are working with foresters to coordinate and maintain that habitat on the landscape through extended-rotation forests -- timber stands left to grow longer than their typical harvest age.
"Coordination among land management agencies to conserve goshawk habitat is a crucial part of goshawk conservation," says Hamady. "It's not about stopping logging, but managing forests so there's a dynamic patchwork of mature forest habitat available. That doesn't just benefit goshawks, but fishers, spruce grouse, boreal owls, and many species of warblers, including ovenbirds, black-throated blue warblers, and blackburnian warblers."
The Superior and Chippewa national forest plans now contain guidance to manage for larger patches of mature forest. "The goshawk was one of the driving species for this large-patch management," says Gallagher.
Likewise, the DNR's forest management planning process is working to maintain and restore larger patches of older forest, such as long-lived conifers, to provide more mature forest habitat.
Months after my summer nest visits, I was still mesmerized by the goshawk -- its fearless spirit, its regal form. So in the autumn, I went to Hawk Ridge in Duluth to perchance see a goshawk again. Hundreds of goshawks from Minnesota, Canada, and Alaska migrate by Hawk Ridge every fall.
I was in luck. On the October morning of my visit, the biologists at the bird banding station had captured a goshawk. They handed the bird to me so I could admire it for a few moments before its release. A juvenile with a brown-streaked body, this goshawk shifted within my grip -- a bundle of intense power. The eyes were yellow, not yet red, but every bit aflame. The goshawk glared at me like an alpha predator does its prey, like a timber wolf wrapped in feathers.
Upon release, the gos swooped to take a swipe at a bystander -- one last act of pugnacity before winging to wintering grounds somewhere farther south.
Much of the DNR's goshawk research has been federally funded by the State Wildlife Grant Program, which focuses on protection and management of species in greatest conservation need. See Minnesota's State Wildlife Action Plan Tomorrow's Habitat for the Wild and Rare.