AUGUSTA – Calling all big-bird watchers with binoculars: The Maine Department of Inland Fisheries and Wildlife is seeking public help to find active great blue heron colonies this spring for a long overdue census undertaking.

Additionally, members of the public are encouraged to join the department’s new volunteer-based adopt-a-colony program called the Heron Observation Network (HERON).

To help or join, contact wildlife biologist Danielle D’Auria at [email protected] or call 941-4478.

Between May and July, HERON volunteers will observe known active colonies one or more times to determine the number of nesting adults and the vegetative structure and health of a colony.

According to a Tuesday report by D’Auria, information collected by HERON volunteers will help biologists better assess breeding populations over time.

Concerns about declining heron colonies and witnessed predation by Maine’s increasing eagle population are driving the need to determine just how many are out there.

With their large bodies, long snake-like necks with sharp dagger bills, 6-foot-wide wingspan and deep squawk on liftoff, great blues have been described as prehistoric-looking creatures.

Of course, since Maine has no shortage of heron habitat – freshwater and coastal islands, beaver flowages, small, large and upland wetland complexes – finding colonies can be like looking for a needle in a haystack.

“Recent observations have indicated that colonies in Maine may be declining,” D’Auria said. “Colonies that once held scores of active nests have dwindled to a few pairs or have been abandoned altogether.”

Have the birds simply redistributed themselves across the landscape, occupying different sites that support fewer pairs, or are “great blue” populations in true decline?

“Colonies can contain anywhere from a few pairs to several hundred and often, multiple nests occupy the same tree. Location of a colony is somewhat predator driven, but is also determined by the proximity of quality foraging habitat. In addition, human disturbance can be a real threat to a colony’s continued occupancy,” D’Auria said.

According to the North American Breeding Bird Survey data for Maine, great blue heron numbers significantly declined from 1980 to 2007.

In 2007, the department listed great blues as a state Species of Special Concern.

“Basically, it’s a way of saying, ‘Let’s keep an eye on this species and make sure it’s not really in peril,'” D’Auria said.

The last thorough breeding census of heron colonies was done in 1996.

During breeding season in late April through early May, biologists will fly over the state searching for nesting colonies of great blue herons and other colonial wading birds like snowy, great and cattle egrets; little blue and tricolored herons; glossy ibis; and black-crowned night-herons.

All historical wading bird colonies – including more than 180 that have hosted great blue herons – will be checked for use in 2009.

To maximize aerial census efficiency and minimize flying time, information is being sought from on-the-ground observers about locations of active colonies, D’Auria said.

However, because great blues are very sensitive to human disturbance and can abandon colonies as a result, she said it’s extremely important for observers to stay 984 feet (300 meters) away, from the onset of courtship behavior through fledgling stages.

Without disturbing the birds, observers are asked to record the location on a DeLorme atlas, the approximate number of active nests, and observation dates.

Over time, more detailed information on colony usage will help biologists better assess population trends, and plan future surveys and management activities, D’Auria added.