A couple weeks ago, I accompanied eagle biologist Charlie Todd and warden pilot Dan Dufault on an aerial survey for nesting bald eagles. Starting in Waterville, we ventured down the Kennebec to the coast, in and out of coves, back and forth over peninsulas, and hopping from island to island. While early April is prime time for catching bald eagles in the incubation stage, it is not what we consider the peak of the great blue heron nesting season. In spite of this, it was still a good opportunity to fly by some known heron colony locations to see if anyone was home.
We spot-checked 11 heron colony sites and 9 were occupied to some degree. To our surprise, we even found one new colony site in Boothbay, and the herons were home here as well. This was truly an opportunistic find. We were just flying over the area from one known eagle territory to the next and spotted a wetland with snags that just had “that look” – the look of possibility! We veered over toward it and dropped lower to get a closer look. Sure enough it was a great blue heron colony and one that we hadn’t yet known about. This, combined with half a dozen colony sites that were reported this fall and winter, proves to me that there are probably a lot more colonies out there that we still don’t know about. This is why anyone who finds a heron colony or knows of one should contact me to make sure we know about it, too. I don’t mind getting several calls about the same site. I’d rather be sure that it is in our database and being tracked.
Besides great blue herons, we also need to know about nesting sites of other colonial wading birds such as black-crowned night-herons (a State Threatened species), snowy egrets, great egrets, and glossy ibis. There are a few other colonial waders that nest in Maine in much lower numbers: little blue herons, tricolored herons, and cattle egrets. We want to know about these as well.
All of the above species tend to nest in groups and build fairly large stick nests in trees or shrubs. Seeing a group of these birds feeding in shallow water does not imply a colony, although there may be one nearby. The colony site is the actual place where their nests are found, and should not be entered as this could cause great disturbance to the birds, and could even cause nest abandonment or the loss of eggs or young. It is best to observe from several hundred meters, watching birds enter and exit the colony as they venture off to find food and return with it for their young.
Thank you in advance for any info you have regarding wading bird colonies, and for respecting their sensitivity to disturbance.