Homing in on herons

Biologists will survey great blue heron rookery sites in Southern Oregon and statewide to see how species is doing
Great blue herons build their spring nests in a tree near TouVelle State Park on the Rogue River. Federal biologists, along with groups like Klamath Bird Observatory, are conducting a census of colony-nesting birds such as herons, egrets and pelicans.Mail Tribune / Bob Pennell

River-runners who come upon a great blue heron along the banks invariably end up playing an accidental game of hide-and-seek with the majestic yet awkward bird.

After standing motionless as a boater floats nearby, the nervous heron will bolt skyward and fly downstream, afraid it's being stalked. Moments later, as the boat again approaches, the heron will consider its fears validated and fly farther downstream, only to repeat this paranoid hop-scotching again and again until it finally figures out it should fly upstream to apparent safety.

"You'd think they'd fly behind you, but they always fly in front of you," says Karen Hussey, research and monitoring program manager of the Klamath Bird Observatory.

Though the heron's suspicious mind-set is well known in the bird world, no one knows just how many of these anxious avians are out there. But field biologists across the West are now trying to find out.

With the help of organizations such as KBO, they are fanning out across Oregon and 10 other states to quantify known nesting sites, called rookeries, of herons and a cache of other colony-nesting birds that until now have had no real census.

Biologists will survey about 200 specific areas statewide for various species of herons, egrets, white pelicans, cormorants, Caspian terns and two species of gulls in what will be the U.S. Fish and Wildlife Service's first attempt to gauge the relative health of these colony-nesting birds.

Counting known breeding pairs during the spring nesting season will provide baseline data which, when compared to historical data and future surveys at these same sites, will offer insights into whether these birds are trending up or down over time.

"This is a snapshot in time," says Jenny Hoskins, a Fish and Wildlife Service biologist overseeing the Oregon part of the survey. "It gives us a starting point, baseline data, of what's out there."

The data will help federal biologists make management decisions about these birds and help resolve potential conflicts between birds and people, Hoskins says.

It can even quantify such things as how expanding populations of bald eagles are affecting herons, which eagles tend to chase away from their nesting grounds, she says.

"We've done surveys in bits and pieces, here and there," Hoskins says. "This is the first real comprehensive survey on them."

Over time, biologists hope to estimate the minimum regional population size of the various breeding waterbirds in the 11 Western states and produce an atlas of these breeding colonies in 2012, Hoskins says.


This is the third year of the surveys, which cost a little more than $1 million and include some in-kind services and staff time from various state wildlife agencies and conservation organizations, Hoskins says.

"There are some large-scale information gaps, and we're all filling them in together on a local level," Hussey says.

KBO has a $109,000 contract for its efforts here, which will include surveys at seven Jackson County sites.

They include two well-known heron rookeries — one on the Rogue River across from TouVelle State Park and another in the Kelly Slough area drained by last fall's removal of Gold Ray Dam from the Rogue.

Great blue herons are largely solitary creatures until spring, when they nest and breed in rookeries that consist of numerous nests, often in oak stands high above rivers or streams.

Herons are now in their nest-building, courtship and breeding phase, which typically lasts through April.

Birds fly in and out of the rookeries regularly, with others perched on thin branches that sway in the spring breeze.

The TouVelle-area birds are easily spotted and viewed with binoculars, especially in early spring before leaves camouflage the nests, Hussey says.

KBO teams will survey the various sites through June, Hussey says.

Reach reporter Mark Freeman at 541-776-4470, or email at mfreeman@mailtribune.com.



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