RUMFORD – Declining populations of great blue herons across Maine have prompted a census-minded state wildlife biologist to seek help from the public to identify nesting locations.

“Instead of looking for a needle in the haystack, we want to concentrate our efforts,” biology specialist Danielle E. D’Auria of the Maine Department of Inland Fisheries and Wildlife said Wednesday.

D’Auria plans to conduct a census next year along the coast, mainly from fixed-wing planes, unless more funding is found. Then the survey will go statewide.

That’s why she wants to know where the 46-inch-tall wading birds with five-foot wingspans are nesting. Great blue herons traditionally return to the same sites year after year unless food and water sources dwindle or their site is disturbed.

“I was going through the species listing process looking at great blue herons and noticed in a breeding bird survey that it’s showing an annual decline,” D’Auria said.

Although the last Inland Fisheries and Wildlife great blue heron census was conducted in 1996, D’Auria said she believes the decline started about 1980 and continued through 2006.

“I’m curious to know why. Colonial nesting wading birds are a great resource in Maine, but I’ve noticed that a lot of colonies I knew of in the past have broken up or shrunk in size.

“Are they simply distributing themselves across the landscape or is there really a decline going on? We will not get to any causes through the survey, but at least we’ll get a feel for the population,” she said.

Possible reasons behind population declines could involve loss of habitat from increased development, competition for food, or nest thievery from recovering populations of bald eagles and ospreys.

Great blue herons eat crustaceans and small mammals, but primarily feed on fish and amphibians.

“I used to work in Washington state and watched immature bald eagles hop from nest to nest to get fresh-from-the-eggs (heron) young,” D’Auria said.

Normally, great blue heron colonies contain from 40 to 60 nests, but in some places, D’Auria said rookeries will have from 150 to 200 nests.

She initially sought help from birders on Monday through a post on the Internet site Mainebirding.net. That site provides information about birding in Maine. Since then, she’s opened it up to the public, providing they don’t get too close and disturb nesting sites for North America’s largest heron.

“We mainly want to hear from anyone who has information on currently active (rookeries), which are the best source for what’s going on this year because they will still be going on next year.

“But (the herons) are very vulnerable to human disturbances, so we don’t want people to cause any flushing from the nests. A good spotting scope will do wonders,” D’Auria said.

To report colony sightings or for more information, D’Auria can be contacted at 941-4478 or danielle.dauria@maine.gov.

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