Black-Crowned Night Heron - Research Paper Example

Black-crowned Night Heron The organism I have chosen for my Endangered Species Focal Point research paper and presentation is the Black-crowned Night Heron, commonly referred to as just Night Heron. Nycticorax nycticorax is the scientific name of Black-crowned Night Heron. This bird is found across major parts of the world except Australia and some other cold regions. Historically, Black-crowned Night Heron is a common breeding species. By the end of the 19th century, this species was widely killed by men for its plumes as food. Once the plume sales were banned in New York in 1910, Night Heron populations quickly recovered. The species was very common along the Atlantic Coast by the 1930s “with colonies in excess of 300 pairs” (Stolz). As Stolz reports, during 1940s and 1950s, coastal maritime dune forests were largely destroyed to meet the land needs for summer cottages; and this situation caused the Night Herons to lose their habitat, and which in turn contributed to their population decline in this period. Contaminants such as DDT and PCBs also affected the population growth of this species. As Stolz states, this species again began to grow in number since the DDT ban in the United States in 1972. Breeding Bird Surveys showed that Night Herons’ population noticeably declined from 1980 to 1999. There were only 196 Night Heron nests in 2010 although the number was better than that of the previous year where it was only 143 (“San Francisco Bay..”). Habitat This species of birds mainly live in fresh and saltwater marshes, swamps, rivers, mud flats, and wooded streams. Mosquito breeding sites are considered to be the most preferred habitats for Black Crowned Night Herons and they are not much found near human homes. Although most of these birds live in wetland vegetation, it is also observed that some Night Herons live in riparian trees and shrubs. This species of birds tend to live in more open areas. According to the findings of Fischer, this species is also found in lowland areas dominated by cottonwood, mesquite, and willow and in tamarisk dominated drainages; and referring to the observations made in different regions, the author points that a notable percent of these adaptable herons live in urban settings including golf courses, canals at parks, and waste water facilities (114). Birds including Dotterels, Eastern Swamp Hen, Egrets, Coots, Cormorants, and Swans also share the habitat of Black Crowned Night Herons. Reproductive Characteristics Black crowned night herons are believed to be monogamous. “Pair formations are signaled by males becoming aggressive and performing Snap Displays, in which they walk around in a crouched position, head lowered, snapping their mandibles together or grasping a twig” (Ivory). The Advertisement Display or Stretch Display, occurring after the Snap Display is the central feature of male Night Herons in attracting females. In the Advertisement Display, a male bobs his head to the level of his feet so as to give a snap-hiss vocalization. Preening and twig shaking are the most notable characteristics of their songs. According to Ivory, these displays pass a social stimulus, which plays a crucial role in ensuring successful reproduction in colonial species. Although the female attracted towards a displaying male is rejected at first, she is gradually allowed to enter his territory. Then, this newly formed pair engages in mutual billing. It is observed that the legs of both male and female Night Heron turn pink at the time of pair formation. Generally, Night Herons engage in copulation on the very next day the pair is formed and it may take place on or near the nest. As Ivory points out, Black Crowned Night Herons build nests on a colony basis and the males initiate nest building. Eggs (a clutch size of 3-5 eggs) are laid four to five days after the pair formation and it happens at two day intervals. The incubation period lasts 24-26 days and this process is carried out by both adults. On the first day, the eggs are green and it will eventually turn to pale blue (Ivory). Research based observations indicate that Night Herons wet their feathers on hot days to provide sufficient cooling facilities to the egg. The young leave the nest nearly after two weeks of birth even though they do not go far from the nest. The young Night Herons may be clustered at the tops of trees after three weeks. However, the young will be able to fly better within 6-7 weeks and therefore they may go far away from the nest for feeding grounds. Studies show that the parent Black Crowned Night Herons cannot recognize their own brood during this time and hence they may accept other young brood. In short, Black Crowned Night Herons have more distinct reproductive characteristics than other Herons. Special Adaptations Researchers indicate that the long breeding season is a special adaptation of Black Crowned Night Herons and the feature assists this species to take advantages of habitats over much of its range. In addition, this species has extreme patience that makes it suited to live and reproduce in wetlands. For instance, Black Crowned Night Herons can stay perfectly still in a small pool or backwater for long period, until their prey arrives. The long and flexible toes help the Night Herons to maintain their balance even on a slippery or unsteady surface. As Kaufman points out, its stout beak is another special adaptation that assists the bird to feed hard shelled crustaceans (60). This species has another special adaption called automatic locking that prevents Night Herons from losing their grip while sleeping. Hence, this bird can securely perch on a branch. These special adaptations greatly assist this species to overcome the survival threats to a great extent despite the human disturbances. Threats to Survival In the opinion of Niles, habitat destruction, human made disturbances, increasing environmental issues, contaminants, and predations are identified to be the major threats to the survival of Black Crowned Night Herons. The author continues that the quick growth of New Jersey’s barrier islands have considerably reduced habitat facilities available for this species. Niles adds that foraging habitats have also been damaged by contamination of wetlands (39). Data indicate that nearly 31 percent of the coastal wetlands have been lost over the last 110 years. Increasing levels of human recreational activities also threaten the survival of this species since they cannot live in close association with humans. When humans continue to disturb their rookeries repetitively, they may give up nesting activities and often abandon the nest. This situation in turn would increase the predation levels. It happens as Night Herons are heavily prone to disturbances, especially during nest building and incubation. Crows, foxes, dogs, cats, and raccoons are the main predators to Night Heron eggs and young brood. In addition to these predators, non-native invasive plants including water hyacinth, mangrove, and pickleweed adversely affect the survival of Night Herons. Pesticides may continue to impact Black Crowned Night Herons that acquire contaminants on their wintering, breeding, or migratory grounds.” (Niles, 39). Although pesticides such as DDT have been banned in the United States, they are used in other countries where Night Herons live during the winter. Avian disease has been discovered to be the most important disease affecting Night Herons while fuel and oil spills become major other contaminant threat to this species of birds. International environmental organizations strongly believe that Black Crowned Night Herons may completely disappear from the earth if the current level of threats continues to exist. Conservation Action Plans Different countries have planned different conservation action plans and programs for Black Crowned Night Herons. Conservation actions intent to develop new Night Heron populations and thereby lessen the risk of extinction in addition to ensuring the preservation of existing populations and the key breeding habitats. To illustrate, the state of Hawaii and USFWS have mutually designed policies for protecting 23 percent of the State’s coastal wetlands which still remain undamaged. In addition, the Ducks Unlimited structured a comprehensive plan in 1997 to ensure the sustainability of existing wetlands that are used by water birds. Even though there are no conservation actions specifically aimed at the preservation of Night Herons, this species is benefited from the policies that are formed towards wetland protection and predator controls. As discussed earlier, DDT was banned by the Federal government in 1972 with intent to protect birds including Night Herons. Similarly, the US government banned the use of Night Herons for food purposes. In 1996, the Indiana Department of Natural Resources designed Indian Wetlands Conservation Plan (IWCP) mainly to preserve wetlands and to reduce the extinction risk of waterbirds. Similarly, many other environmental organizations and NPOs educate people regarding the extinction risk associated with this species and thereby significance of wetland preservation. Such awareness programs have been greatly beneficial to protect the existing Night Heron populations. In addition, the US government and other national governments have made budgetary provisions for the preservation of wetland vegetations and Night Heron populations. Works Cited Fischer, Dan L. “A brief history of Arizona ornithology.” In Corman, Troy E & Wise-Gervais, Cathryn (Eds). Arizona Breeding Bird Atlas. Mexico: University of New Mexico, 2005. Print. Ivory, Alicia. “Nycticorax nycticorax: black-crowned night heron.” Animal Diversity Web. (n.d). Web. 03 February 2012. Kaufman, Kenn. Lives of North American Birds. New York: Houghton Mifflin Harcourt, 2001. Print. Niles, Larry. Endangered and Threatened Wildlife of New Jersey. USA: Rutgers University Press, 2003. Print. Stolz, Garv M. “Black-crowned Night-heron, Nycticorax nycticorax.” (n.d). Web. 03 February 2012. “San Francisco Bay Area National Parks Science and Learning.” Sfnps.org. (2012). Web. 04 February 2012. < http://sfnps.org/> Read More