Public Help Sought in Reporting Colonies
AUGUSTA – This spring, the Maine Department of Inland Fisheries and Wildlife will conduct a nearly statewide census for nesting great blue herons and other colonial wading birds. This large-scale effort will be conducted primarily by state biologists, but there are a couple of opportunities for the public to become involved.
Information regarding the location of active heron or other wading bird colonies is needed. In addition, a new volunteer-based adopt-a-colony program called the Heron Observation Network (HERON) will begin this spring – and members of the public are encouraged to join. These efforts have been prompted by recent concern over the status of Maine’s breeding population of great blue herons.
The great blue heron (Ardea herodias) is often touted as one of the most widespread and adaptable wading birds in North America. It certainly is no stranger to Maine. The birds can be seen foraging in tidal marshes, along riverbanks, and even in open grasslands. In flight, their form is reminiscent of a prehistoric creature: large body, long snake-like neck with a sharp dagger for a bill, all carried about by those ever so graceful wings that when wide open may stretch two meters across. Upon liftoff, their squawk further confirms their prehistoric essence.
Though they tend to forage alone, their nesting habits are the complete opposite. 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.
Recent observations have indicated that colonies in Maine may be declining. 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 is there a true decline in the number of breeding “great blues”? North American Breeding Bird Survey data for Maine indicate a significant declining trend in the number of birds detected between 1980 and 2007. Although most would still argue the great blue heron is a common sighting in Maine, this declining trend is somewhat alarming.
Consideration of this decline, evidence of fewer active nests in recent years, and observations of predation by an increasing eagle population prompted MDIF&W to list the great blue heron as a state Species of Special Concern in 2007. Unlike Endangered or Threatened status, Special Concern is an administrative category established by policy, rather than by regulation, and is used for planning and informational purposes only. Basically, it’s a way of saying, “let’s keep an eye on this species and make sure it’s not really in peril.”
MDIF&W conducts periodic breeding censuses of heron colonies, primarily along the coast. The last thorough census was done in 1996. Observations and reports of numbers of nests for most colonies have filtered in over the past 13 years, but have primarily been incidental and opportunistic in nature and therefore haven’t shed enough light on the situation. A thorough nest count is long overdue.
In late April through early May, MDIF&W will fly over the state in search of nesting colonies of great blue herons and other colonial wading birds such as 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 nesting great blue herons, will be checked for use in 2009. Suitable habitat en route to these locations also will be surveyed.
The formal census will be performed by state biologists, but reports of active colonies from the public are extremely helpful. As mentioned earlier, many of the larger colonies documented in past censuses have since broken up into smaller colonies and moved to other locations. Herons nest in a wide variety of habitats including coastal and freshwater islands, beaver flowages, small and large wetland complexes, as well as upland sites that may be fairly close to good foraging areas. Maine has no shortage of these habitat types, so finding colonies may be like looking for a needle in a haystack.
In order to maximize the efficiency of the aerial census and minimize flying time, information is needed from on-the-ground observers regarding the locations of active colonies. In addition, more detailed information regarding the use of these colonies over time will aid in assessing the population’s trend and planning future surveys and management activities.
During their 2009 springtime adventures, members of the public are encouraged to take note of active breeding great blue heron colonies and share their findings with MDIF&W. Nesting herons can be extremely sensitive to human disturbance, and may even abandon a colony as a result of human intrusion. From the onset of courtship behavior through fledging, it is extremely important to keep a distance of 300 meters (984 feet) from the colony. Without causing any disturbance to the birds, record the location on a DeLorme atlas, the approximate number of active nests (if visible from less than 300 meters), and the date(s) of your observation(s).
To take an even more active role in this project, the public may sign up to be part of the Heron Observation Network. HERON volunteers observe known active colonies one or more times between May and July to determine the number of nesting adults and the vegetative structure and health of the colony. Aerial censuses are expensive and time consuming; therefore they cannot be done on an annual basis. The information collected by HERON volunteers will assist with assessing the breeding population over time. An added benefit of this volunteer-based program is that the time contributed by volunteers can help to leverage federal dollars to perform future aerial censuses.
To help state biologists better understand the status of the great blue heron in Maine by reporting active colonies or becoming a HERON volunteer, please contact Danielle D’Auria at danielle.dauria@maine.gov or 941-4478.
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