November 23, 2024
ON THE WING

Great blue herons tolerate activity near feeding areas Too-close approach will still send birds to quieter spot

Someone asked me the other day about a great blue heron he had observed at a small pond beside a road. The bird routinely hunted there, despite the close proximity of traffic, and he was surprised to see it hanging around so late in the season.

In fact, these herons may winter in Maine, and have even been seen in Canada during Christmas bird counts. They are a widespread and very adaptable bird, taking a variety of prey including amphibians, fish, small birds and mammals, and reptiles.

They may utilize both freshwater and saltwater habitats for foraging, as well as grassland areas. During the cold season they will remain near open-water margins of rivers and coastal marine environments.

Juveniles are easily distinguished from adults by the absence of a white crown, body plumes, and a black shoulder patch. They will not acquire full adult breeding plumage until their third year, and there is no way to tell males and females apart in this way. However, there is one behavioral clue during the breeding season: the female will do most of the nest building.

Nests are built in tall trees in aggregations known as colonies. Most of these are located on an island or isolated trees in the middle of swamps to deter ground predators. These locations generally have the added advantage of being far from human activity and disturbance, which will interfere with courtship, breeding, and nesting success.

These birds seem to tolerate human activity in their foraging habitat more readily. A friend and I managed to get within several yards of one during a walk along the coast in Bar Harbor. However, we crossed a certain point that put us into what the bird considered its safety zone, and off it flew. Our too-close-for-comfort approach probably denied the bird a good hunting area, made it expend needless energy in flying to another spot, and prevented us from observing its hunting strategy. I had to wonder how many times it had been forced to move on in this way over the course of the day.

It is always better, when approaching on foot, to not push your luck in these situations.

The birds seem to ignore moving car traffic, and will tolerate a vehicle stopping close by – again, only if you don’t approach too closely. Otherwise, you can use your car as a bird blind, getting great views without disturbing them.

I had the opportunity to observe a hunting heron in this way earlier in the season, and it was a delight to watch its slow, fluid motions as it stalked its prey among the lily pads.

Chris Corio’s column on birds is published each Saturday. Corio, a volunteer at Fields Pond Nature Center in Holden, can be reached at fieldspond@juno.com


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