by Barbara Walvoord
First published in Lathrop Lamp Post, Dec. 8-14, 2017
Along Bassett Brook the other day, Sharon and I surprised a great blue heron. Though more northerly blue herons migrate, Massachusetts herons stay put. Their secret is flexibility.
Great blue herons eat mostly fish. They stand or stroll along the shore or in shallow water, watching for movement, and then spearing the fish with their beaks and swallowing it whole. They may choke on a too-big fish.
When shallow ponds freeze, a great blue will move to flowing water in Bassett Brook or Pine Brook, and if those freeze, then downstream to the Manhan or Connecticut River.
If fish are scarce, the great blue will eat toads, snakes, turtles, and insects. Or it will give up on water altogether and go to the fields for mice or voles. In one study in Idaho, up to 40% of the diet was voles.
Its adaptable hunting behaviors include “standing in one place, probing, pecking, walking at slow speeds, moving quickly, flying short distances and alighting, hovering over water and picking up prey, diving headfirst into the water, alighting on water feet-first, jumping from perches feet-first, and swimming or floating on the surface of the water.” (https://en.wikipedia.org/wiki/Great_blue_heron)
Great blues often hunt at dawn or dusk, but also by night or by day. Their nests, made from sticks, can be sited on the ground (on predator-free islands), in shrubs, or in trees anywhere from lower branches to 100 feet high.
People working to clean up the heavily polluted Onandaga Lake in New York were thrilled to see returning blue herons, which one expert called an “indicator species,” signaling the restored health of the lake. The greatest danger to our great blue herons at Lathrop is pollution of the wetlands from pesticides we use on our land, as well as toxins in the bodies of the fish and amphibians the herons eat. When we keep our land unpolluted, these flexible and beautiful birds can stay put on at Lathrop.