Snowy egrets perched in apple trees.
This past May, I had the unique opportunity to assist National Audubon Society (NAS) with a wading bird census on Stratton Island in Saco Bay. Part of NAS’s Phineas W. Sprague Memorial Sanctuary, this 23-acre island is located 1.5 miles south of Prout’s Neck and is home to an immense diversity of wading birds, waterfowl, seabirds, and songbirds, and is an important stopover for all the above during migration.
In fact, Stratton Island hosts the most diverse wading bird colony in Maine, and is the most northerly U.S. breeding location for a few of these species. On the north side of the island, great and snowy egrets, black-crowned night-herons, little blue herons, and glossy ibis layer their nests in among the branches of choke cherry and apple trees.
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Posted in Field Notes, Photos | Tagged black-crowned night-heron, eggs, glossy ibis, great egret, herons, little blue heron, Maine, National Audubon, nestlings, nests, snowy egret, spring, Stratton Island, wading bird colony, wildlife | 4 Comments »
We’ve had some hot sultry days this summer, and if you were smart you retreated to a shady spot or went for a swim at a nearby pond. But what about all those great blue heron nestlings that were sitting in their nests 20-100 feet up in a tree, often in full sun? Sure, their nest tree may be surrounded by water if it is a snag in a beaver flowage, but that water is completely inaccessible to a nestling who takes around 80 days to learn how to fly.
How do they keep cool on those 90+ degree days? Like humans, birds rely on evaporative cooling to release heat; however, birds do not have sweat glands like you and me. Instead, they lose heat through their respiratory tract. Some birds do this by panting, but others, including herons, do so by “gular flutter”. Gular flutter is a rapid vibration of the upper throat and thin floor of the mouth. By opening their mouths wide and rapidly flapping the thin gular membranes of the throat, they expose a large featherless area to moving air. To see what gular flutter looks like, click on the link below to a web album containing 2 short videos:
Gular Flutter Videos
Herons may also change their posture to keep cool. The “sunbathing” posture or “delta-wing” is sometimes assumed to aid in cooling the bird itself as well as to help shade its nest contents (eggs or nestlings). Often sunbathing is accompanied by gular flutter. The sunbathing posture I witnessed below was seen in mid-May on a day that was not noticeably hot (at least to me, but I was shaded by a blind). This adult most likely had eggs or newly hatched young in the nest, but it doesn’t appear that the sunbathing posture is serving to shade any nest contents here. The adult is actually facing into the sun. Perhaps this is one of many reasons that led to this nest’s failure? It was inactive only 1 week later.
Adult great blue heron “sunbathing”.
Posted in Field Notes, HERON, Photos, Species Specific | Tagged behavior, great blue heron, gular flutter, Maine, nestlings, thermoregulation, wildlife | 1 Comment »
Last Wednesday I took to the field to check out a great blue heron colony that I have only seen once during an aerial survey in 2009. Since then, a volunteer has been monitoring the colony on the ground. I finally made personal contact with the landowners this year and made a date to meet them and take a walk through the woods to the beaver flowage that housed the snags that held the heron nests.
As we approached the wetland, we quieted ourselves knowing that our presence could easily disturb the nesting herons. We ducked in and out of brush and young trees and snuck our way stealthily towards an opening at the water’s edge.
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Posted in Field Notes, Photos, Species Specific | Tagged great blue heron, great horned owl, heron colony, Maine | 3 Comments »
Molly Meserve is a graduate student at the University of New England.
Hello, my name is Molly Meserve and I am a graduate student at the University of New England in Biddeford, ME. Along with all of you I will be closely observing the fascinating behavior of Maine’s Great Blue Herons this summer. As a Maine native I am particularly interested in this work because the Great Blue Heron has been a constant in my life here in Maine. My master’s thesis focuses on the following question: Do prey delivery rates and total foraging times of Great Blue Herons in coastal and inland colonies differ and how may these factors affect chick survival? With the help of Danielle D’Auria and some wonderful HERON volunteers I have been able to visit a few of the Great Blue Heron colonies in the State. Two of those colonies have been chosen as the main focus of my study; the inland colony is located in Hollis, ME and the coastal colony is in Brunswick, ME. I will be out in the field from April 1st until about mid-August observing from ground blinds that I have set up in each of the sites mentioned above. While in the field I will be focusing on gathering accurate numbers of adults, chicks (their approximate ages), and nestlings along with prey delivery rates and time spent foraging for each nest observed.
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Posted in HERON, Research, Species Specific | Tagged behavior, feeding, food habits, great blue heron, HERON, heron colony, Heron Observation Network, Maine, monitor, nestlings, productivity, research, volunteer | 5 Comments »
Great blue herons started arriving back in Maine over two weeks ago. The first report I received was of two birds seen near a breeding colony in Brunswick on Monday, March 12th. Despite these early arrivals, most of the state’s birds don’t initiate nesting until mid-April, and some as late as mid-May. In New York, it appears the great blue heron nesting season begins a bit earlier. A live webcam on a nesting pair of great blue herons at the Cornell Lab of Ornithology just documented that the female laid her first egg last night!
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The following was written and shared by Diane Winn of Avian Haven, one of the largest bird rehabilitation practices in New England. Located in Freedom, Maine, they have treated over 12,000 birds comprising over 100 species.
Great Blue Heron found injured at Cobbosseecontee Lake. Photo by Steve Allarie
Warden Steve Allarie called on the afternoon of October 24th to give us a heads-up that he was about to attempt a rescue of a Great Blue Heron tangled in fishing line near the north end of Cobbosseecontee Lake. Responding to a call, Steve had found her standing up, half in and half out of the water, with a significant length of monofilament wrapped around the left wing and leg, and some tissue damage to the wing. Steve made a quick detour to grab a large kennel, and returned to the site with Warden Dan Christianson.
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Posted in Field Notes, Photos, Species Specific | Tagged Avian Haven, fishing line, great blue heron, herons, Maine, post-breeding, rehabilitation, volunteer, warden, wildlife rescue | 2 Comments »
Since 2007, the great blue heron (Ardea herodias) has been listed inMaine as a Species of Special Concern. While this status has no regulatory significance, is does signify possible decline and that more information is necessary to accurately determine the population trend. Thus, an effort was initiated in 2009 to better track great blue heron colonies and the number of nesting pairs in the state, both on coastal islands and at inland sites. Continue Reading »
Posted in HERON, Photos, Species Specific | Tagged adopt-a-colony, aerial surveys, great blue heron, HERON, heron colony, Heron Observation Network, herons, Maine, monitor, volunteer, wildlife | 2 Comments »