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Other things Mike plays with . . . get you mind out of the gutter

Wednesday, July 23 2008 | Comments (1)

Blue Herons in the nest -
these are what Mike was scared of!?

It seems that many of the dirty jobs Mike picks up consist of inseminating or cleaning up after some sort of animal. As part of a continuing series on the critters he interacts with, this article will explore the blue heron and egret, another bird in the heron family.
On West Sister Island, nicknamed Vomit Island, Mike help tag heron and egrets. There are tens of thousands of birds from nine different species inhabiting the island, but for the puporse of this story we will use Wikipedia.com and Encyclopedia Brittanica Online to explore the two birds Mike dealt with directly.
Vomit Island earned its wonderful name because of a defense mechanism the birds share. When a predator approaches the tree a nest is in, the birds vomit or poo on the creature, in this case humans, in an attempt to scare it away.
Although the island was once used for artilary practice during WWI, it is now forbidden to humans, except once a year when the scientists Mike was shadowing go to the island to study the birds.
Heron
Herons are wading birds in the Ardeidae family. The classification of the individual heron species is fraught with difficulty, and there is still no clear consensus about the correct placement of many species into either of the two major genera, Ardea and Egretta.
Herons resemble birds in other families, like storks, ibises and spoonbills, but they differ from these because they fly with their necks retracted, rather than outstretched. They are also one of the bird groups that have powder down. Powder down is a special type of down, layer of fine feathers found under the tougher exterior feathers, that are exceptionally fine and produce a dust. The bird takes this dust and coats all its external feathers. It provides the bird with waterproofing for the main flight feathers so it can fly in the rain. It also conditions the flight feathers to provide good lift. It may also be useful in suffocating feather lice and other parasites.
Herons live mostly in wetlands, and prey on rabbits, fish, frogs and other aquatic species. Some, like the Cattle Egret and Black-headed Heron, also take large insects, and are less tied to watery environments.

In February 2005, Dr. Louis Lefebvre, a Canadian scientist, announced a method of measuring avian IQ, in terms of their innovation in feeding habits. Herons were named among the most intelligent birds based on this scale.

There are three major groups of herons, which are (from the most primitive to the most advanced): tiger herons and the boatbill, bitterns, day-herons and egrets, and night- herons.
The herons Mike picked on were great blue herons. The Great Blue Heron is a wading bird, common over most of North and Central America as well as the West Indies and the Galapagos Islands, except for the far north and deserts and high mountains where there is no water for it to feed in.
It is the largest North American heron, with a head-to-tail length of 36-54 inches, a wingspan of 71 inches, and a weight of 4.8-8 lbs. It is blue-gray overall, with black flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks. The neck is rusty-gray, with black and white streaking down the front. The head is paler, with a nearly white face, and a pair of black plumes running from just above the eye to the back of the head. The feathers on the lower neck are long and plume-like; it also has plumes on the lower back at the start of the breeding season. The bill is dull yellowish, becoming orange briefly at the start of the breeding season, and the lower legs gray, also becoming orangey at the start of the breeding season. Immature birds are duller in color, with a dull blackish-gray crown, and the flank pattern only weakly defined; they have no plumes, and the bill is dull gray-yellow.
This species usually breeds in trees close to lakes or other wetlands; often with other species of herons. The groups are called. The size of these colonies may be large, ranging between 5–500 nests per colony, with an average of about 160. Or, in the case of Vomit Island, several thousand.
Great Blue Herons build a bulky stick nest, which Mike insisted was held together by their poo. The female lays three to six pale blue eggs. One brood is raised each year, but if the nest is abandoned or destroyed, the female may lay a replacement bunch.
Both parents feed the young at the nest by regurgitating food, often in large chunks that fall on cameramen’s heads. Parent birds have been shown to consume up to four times as much food when they are feeding young chicks than when laying or incubating eggs.
Eggs are incubated for approximately 28 days and hatch over a period of several days. The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, and so often grows more quickly than the other chicks.

Snowy Egret searching for food.

Egrets

Egrets are not a biologically distinct group from the herons, but tend to be named differently because they are mainly white and/or have decorative plumes. And while they may have the same build as the larger herons, they tend to be smaller.

An egret is any of several, most of which are white, and several of which develop fine plumes (usually milky white) during the breeding season.

The distinction between a heron and an egret is rather vague, and depends more on appearance than biology. The word "egret" comes from the French word "aigrette,” referring to the long feathers that seem to cascade down an egret's back during the breeding season.

In the 19th and early part of the 20th century, some of the world's egret species were endangered by relentless hunting, since hat makers in Europe and the United States demanded massive numbers of egret plumes and breeding birds were killed in locations all around the world.

Mike’s egret was, the Snowy Egret, a small white heron. It is the American counterpart to the very similar Old World Little Egret, which has established a foothold in the Bahamas.

Adults are typically 24 inches long and weigh just under a pound. They have a slim black bill and long black legs with yellow feet. The area of the upper bill, in front of the eyes, is yellow but turns red during the breeding season, when the adults also gain recurved plumes on the back, making for a shaggy effect.

The juvenile looks similar to the adult, but the base of the bill is paler, and a green or yellow line runs down the back of the legs.
Their breeding habitat is large inland and coastal wetlands from the lower Great Lakes and southwestern United States to South America. The breeding range in eastern North America extends along the Atlantic and Gulf Coasts from Maine to Texas, and inland along major rivers and lakes.

They nest in colonies, often with other waders, usually on platforms of sticks in trees or shrubs. Three to four greenish-blue, oval eggs are incubated by both adults. The young leave the nest in 20 to 25 days and hop about on branches near the nest before finally departing. Or, if you’re Mike, they fall from the tree, too big to nest but still unable to fly.

The birds eat fish, crustaceans, and insects. They stalk prey in shallow water, often running or shuffling their feet, flushing prey into view, as well dip-fishing by flying with their feet just over the water. Snowy Egrets may also stand still and wait to ambush prey, or hunt for insects stirred up by domestic animals in open fields.

At one time, the beautiful plumes of the Snowy Egret were in great demand by market hunters as decorations for women's hats. This reduced the population of the species to dangerously low levels. Now it is protected by law and thanks in part to the Migratory Bird Treaty Act, this bird's population has rebounded.

Stayed tuned next week for more craziness with Mike, and maybe some more bugs.

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