Forest Guidelines For Goshawks May Not Help

Surprising study of rare raptor raises questions about forest thinning

The largest forest thinning contract in history could sharply reduce fire dangers, but officials long supportive of the concept still have doubts about the contractor chosen.


The largest forest thinning contract in history could sharply reduce fire dangers, but officials long supportive of the concept still have doubts about the contractor chosen.


No doubt about it: The federal government wants the Northern Goshawk to survive.

So every national forest in the West wrote into its forest plan detailed rules to protect critical habitat the bird- and rodent-hunting raptors need to survive.

Forest Service administrators apply those prescriptions to every thinning project, timber sale, off-road vehicle analysis and pipeline construction plan that comes along.

But what if goshawks don’t actually need the closed forest canopy, tree thickets and nearby underbrush full of scuttling rodents that biologists had assumed?


Turns out, the guidelines the U.S. Forest Service has applied to millions of acres in the West to protect the goshawk don’t help the beleaguered bird at all, according to a study by researchers from Northern Arizona University and published in the Journal of Applied Ecology.

In fact, a decade-long study of 13 goshawk nesting areas in the Apache Sitgreaves National Forest yielded the startling conclusion that the more closely the area resembled Forest Service guidelines for goshawk heaven, the fewer chicks the feathered pairs actually produced.

The researchers confessed themselves confounded by “these surprising results.”

Authors of the paper included Paul Beier, Erik Rogan, Michael Ingraldi and Steven Rosenstock, all with the NAU School of Forestry or the Arizona Department of Game and Fish.

“Contrary to expectation,” the researchers concluded, “goshawk breeding areas that resembled most closely the forest structure prescribed by the goshawk guidelines tended to have lower goshawk productivity.”

The research demonstrated the limits of common sense when it comes to predicting something as complicated as the relationship between an adaptable predator like the forest-dependent goshawk and either its habitat or its prey base. The goshawk guidelines now in effect on millions of acres start with the reasonable assumption that goshawks need clusters of big trees in which to build their nests close to the kinds of underbrush that harbor the rabbits, mice, squirrels and other creatures on which they prey.

Many biologists have assumed that goshawks have moved into forests in the Southwest as those forests have grown thicker in the past century, shifting from big trees separated by grassy swales to fire-prone tree thickets. Therefore, the Forest Service has struggled to shift back toward an open, fire-adapted forest without exterminating species that prefer a closed canopy with interlocking tree branches — like the goshawks and the Mexican Spotted Owl.

The NAU research now throws into question many key assumptions built in ponderous legal strictures of existing forest plans.

“The results raise questions about the decision to implement the goshawk guidelines on most Forest Service lands in Arizona and New Mexico,” the researchers concluded.

However, the Forest Service remains legally bound to the detailed guidelines now cast in the legal concrete of adopted forest plans.

That applies even to vital efforts like the 4-Forests Restoration Initiative, an ambitious plan intended to dramatically thin millions of acres of forest across central Arizona.

The U.S. Forest Service recently picked Pioneer Forest Products to thin an initial 300,000 acres over the next decade. The project relies on completing a single environmental assessment on nearly a million acres as a way to streamline the thinning process. The Forest Service would then train the Pioneer subcontractors to create with their chain saws a more healthy, diverse, fire-adapted forest. The prescription attempts to also protect critical habitat for a host of species, including goshawks.



Northern Goshawk

That means implementing the current goshawk guidelines, which will leave many dense patches of forest as nesting areas for goshawks and Mexican Spotted Owls.

4FRI Forest Service team leader Henry Provencio expressed surprise at the NAU findings, which cast doubt on the goshawk guidelines embedded in the current approach. But he said that once the guidelines get written into the forest plans, the Forest Service remains legally required to abide by them.

“Our forest plans require it,” he said. “But that would be a pain” if the existing guidelines don’t actually help the goshawks successfully rear more chicks. “We do have different prescriptions for the goshawk areas. In those breeding areas we know they typically have a higher (tree) density. So we have prescriptions for that. We’re trying to manage the future forest. One of the big concerns is whether we’re going to have adequate canopy cover — so we’re really managing groups of trees and also providing for those interspaces and managing for their prey.”

But the NAU study raises questions about whether biologists yet know enough to micro-manage the forest for the benefit of any individual species.

The goshawk and the Mexican Spotted Owl for years have fluttered about at the center of the legal and political fight about the future of the forest. The agile, crazy-orange-eyed goshawk is nearly as large as a red tailed hawk, but can maneuver deftly through the thick forest. In open areas, they tend to lose out to the red tails — which circle overhead looking for prey rather than perching on tree branches for a quick swoop to the ground.

The now nearly defunct timber industry in Arizona made most of its money on cutting the big, old growth trees associated with those species and others like the Kaibab squirrel and the Allen’s lappet-browed bat. With most of those trees reduced to two-by-fours, the timber industry had a hard time making money on the smaller trees that remained in dangerous profusion.

The Centers for Biological Diversity has repeatedly sued to prevent timber sales that included a large number of old growth pines greater than 16 inches in diameter at about chest height. For instance, earlier this year the Centers for Biological Diversity successfully blocked a timber sale on the North Rim of the Grand Canyon on the grounds that the 25,000-acre sale would include about 8,000 old-growth trees — even though such trees account for only about 3 percent of the trees.

The NAU study demonstrated that biologists still don’t really understand what species like goshawks need.

None of the sites studied very closely matched the guidelines, which call for clusters of giant, old-growth trees and nearby areas with underbrush likely to result in high populations of 14 different prey species.

Although little true old-growth ponderosa pine forest remains in Arizona, the researchers expected to find that the more closely the conditions around the nest area resembled that prescription — the more chicks the goshawks would produce. In fact, the more closely the forest matched the prescription the fewer chicks the hawks reared.

That doesn’t mean the goshawks don’t prefer nesting in big, old growth trees. But it does mean that they’re not as sensitive to the prey populations in the area or the nearby forest conditions as biologists had expected.

The study did find that goshawks produce more chicks in years when conditions produce a bumper crop of rodents, but that accounted for year-to-year variations — not a consistent difference between nesting areas.

The results “were remarkably consistent in documenting that goshawks use forest structures characterized by relatively dense canopy and many large trees, but do not use sites with higher prey abundance,” the researchers concluded.

The moral of the story would seem to support an approach that produces a diverse, healthy forest — without trying to micromanage the details.

Moreover, the researchers concluded that many seemingly common-sense assumptions must be challenged — and the impact of changes in management monitored.

That conclusion might also raise red flags when it comes to the current approach to the 4FRI effort, which many consider the last best hope to both avert catastrophic wildfires and restore forest health.

As it happens, the Forest Service rejected the bid of the 4FRI contractor that pledged to spend about $5 million monitoring the ecological effects of the massive thinning effort in favor of a contractor that included no money for monitoring in the bid.

However, the NAU researchers concluded, “our study suggests that goshawks did not respond as expected and the monitoring and adaptive management approach recommended in 1993 (when the goshawk guidelines were first adopted) is equally important today.”


Pat Randall 4 years, 5 months ago

Does the govt and do gooders want to save the birds and animals or the people and thier homes? Which will do the country the most good? Seems to be a no brainer to me.


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