The Great Blue Heron Essay
The Great Blue Heron
The blue heron belongs to the order of Ciconiiformes, birds that are characterized by long, thin legs and spear-like bills. Ciconiiformes walk or wade in water in order to find food. Aside from herons, other birds in the Ciconiiformes order are storks, ibises, and spoonbills. The Great Blue Heron belongs to the family Ardeidae which also include egrets, bitterns, and herons. Great herons specifically belong to the genus Ardea. Ardea is distinguished from similar-looking great birds in that they flex or curve their necks in flight. Finally, the species is Ardea Herodias, or the Great Blue Heron.
(Schreiber & Burger, 2001, 618) Kingdom: Animalia, Phylum: Chordata, Subphylum: Vertebrata, Class: Aves, Order: Ciconiiformes, Family: Ardeidae, Subfamily: Ardeinae, Genus: Ardea, Species: Ardea herodias Physical Description http://www. fnal. gov/ecology/wildlife/pics/Great_Blue_Heron. jpg The Great Blue Heron is the biggest of the American herons. With wings that span some six feet and standing tall at four feet, the blue heron is majestic both while soaring in the air and standing on land. It weighs from three to four kilograms.
The Great Blue Heron is deusually are blue-gray in color, with black plumage in its back and belly. As can be seen in the picture, the Great Blue Heron curves its neck in an S-shape when in flight. This S-shape is the normal posture of the bird even when standing. (Eastman, 1999, 191) The Great Blue Heron’s long, piercing bill is yellow-orange in color. It has a small white head, with a horizontal black stripe that runs from above its eyes to the back of its head. Similarly, the ventral neck is white with a black stripe that runs in the vertical axis. Its eyes are golden yellow.
The neck is a dull gray with several short black lines down the front of it. Like its bill, the blue heron’s legs and feet are yellow-orange. There is no marked difference between the male and female in terms of physical characteristics. (Eastman, 1999, 95) The young of the blue heron are born small, disproportionately smaller compared with their grown-up size. The eggs measure roughly two inches long and one inch wide. The young blue heron has a dull, brownish coloring, with a black, cap-like plumage in the head. The young blue heron does not have plumes used by adults during the mating season.
(Audubon, 1843, 135) Chicks are hatched atop branches of trees, but spend most of their adult life wading in shallow water to forage for food. Distribution The Great Blue Heron is present across the continental United State, as well as in areas of Central and Southern America. They occur in large numbers in Illinois, where they are considered permanent residents. They are commonly found in wetland areas, where they feed on abundant marine life. They are also abundant in Michigan. The birds that live in the northern region migrate in winter to the warmer south.
Great Blue Herons may migrate alone or with a flock of up to 30 birds. (Nellis, 2001, 116) http://www. birding. com/topbirds/3672gbh. asp Diet and Habitat The Great Blue Heron mainly feeds on fish. But it will also feed on other small creatures such as small amphibians, reptiles, and small mammals found in their feeding area. As with all animals, the Great Blue Heron can be found where its source of food can be found as well. As Thompson once said, the social habits of animals are directly related to the nesting and feeding needs of a species.
(2001, 3) The Great Blue Heron are mostly found in wetland environments such as river beds, coastal areas, mangroves swamps, and other similar ecosystems. They eat by patiently standing in still waters until an unsuspecting prey passes, and then with quick, jerking motion, the Great Blue Heron will stab or swallow its prey. Reproduction The Great Blue Heron mates once a year and they stay with one mate for the entire breeding season, until the chicks hatch and are ready to live on their own. Their mating habits vary depending on their location.
Nellis mentioned that in Florida, mating may start as early as the early fall or as late as the middle of summer. (2001, 114-115) The courtship involves a display of plumage and neck stretches Nesting takes place in colonies and are shared among other herons and egrets. Where predators abound, the nests are perched in branches of high trees, but in areas where there are no predators, some nests have been found on shrubs. If proven to provide a safe haven for chicks, these nesting colonies are used again and again by new mates.
(Nellis, 2001, 114-115) Population The Great Blue Heron is one of the few remaining wildlife that exists in healthy populations. However, that is not to say that they are safe. The increasing encroachment upon their habitats threatens their existence along with countless other animals and plants that are being sacrificed in the altar of human progress. Management Strategies Conservationists are resolved to protect the wetland ecosystem, not just for the Great Blue Heron but for the diversity of animals living in this environment.
The trend is to declare areas as protected sanctuaries in order to prevent humans from destroying further the Great Blue Heron’s natural habitat. Alternative housing and crop farming systems should be explored so that natural lands will be left as they are. As inheritors of earth, it is incumbent upon us to protect the land and the wildlife even as we live off of its abundance and graces. And that includes the Great Blue Heron and other animals and plants. Review of Scientific Journal Article Cheng, K. M. , Henshel, D. S. , Martin, J. W. , Norstrom, R. , Steeves, J. D. , Whitehead, P. (1995).
Morphometric abnormalities in brains of great blue heron hatchlings exposed in the wild to PCDDs. Environ Health Perspect. 1995 May; 103(Suppl 4): 61–66. This paper is study of the possible exposure of Canadian Great Blue Heron hatchlings to environmental contaminants coming from the effluents of a nearby paper mill. Aside from levels of exposure, the paper also looked at the possible adverse side effects of such an exposure. Specifically, the contaminants are polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).
The study was conducted in the late 1980’s until early 1990’s. Results from the study show that exposure to said chemicals effect gross morphological abnormalities in the hatchlings brain, indicating that the contaminants are possible neurotoxins. The brains were markedly malformed in areas where exposure has been documented as very high. Over the years, as the presence of the toxins decreased, so did the morphologic abnormalities in the Great Blue Heron’s hatchlings brain. The methods used in this research were direct measurement and gross observation of dissected hatchlings brains.
To ensure consistency, the study made sure that only one person handled the measurement and weighing of the brains. The results were not that difficult to see, as abnormalities can be seen easily by the naked eye. Avian brains are very symmetrical, and slight morphological changes can be easily detected, even to an untrained eye. The results of this study have proven what we all know already. That chemicals from factories can cause irreversible damage to living creatures. But what is surprising is the ability of organisms to recover from a contaminant as shown by the improvement of the brain when exposure decreased.
This remarkable healing ability is is testament to the resiliency of life. Literature Cited: Audubon, J. J. (1843). The Birds of America. J. B. Chevalier. 135. Eastman, J. (1999). Birds of Lake, Pond, and Marsh: Water and Wetland Birds of Eastern North America. Stackpole Books. 191. Nellis, D. W. (2001). Common Coastal Birds of Florida and the Caribbean. Pineapple Press. 114-116. Schreiber, E. A. , Burger, J. (2001). Biology of Marine Birds. CRC Press. 618. Thompson, C. F. (2001). Current Ornithology, Volume 16. Springer. 3.