Tuesday, September 3, 2019

Essays --

Sex- Based Migration in Black Bears (Ursus americanus) Introduction: Ursus americanus, the American black bear is the most common of the world’s bear species, about up to twelve times more abundant than grizzly or brown bears. They usually occupy forested areas but their habitats are highly variable— from the Louisiana Bayou to the Labrador Tundra, and the Northwestern rain forests in between. (Wilson & Ruff, 1999) American black bears are hunted legally seasonally due to their widespread population and distribution. However, with the increase in deforestation for industrialization in the Tri-State (New Jersey, New York, Pennsylvania) area, the habitat loss could have adverse effects on the black bear populations. An interference with their natural territory could lead to alteration in the dispersal patterns. (Dixon, Wooten, McCown, Oli, Eason, & Cunningham, 2007) Black bears are omnivorous and although a part of their diet consists of meat and insects, they primarily rely on fruits and nuts for their diet. Therefore, a plant’s annual cycle of fruiting is tied to a bear’s annual behavior and its physiological cycle. (Wilson & Ruff, 1999) Bears tend to congregate and gather in an area with an abundance of food and occasionally return time and again to areas with ease of access to foods- like dumpsters. (North American Bear Center) Despite this, black bear dispersal is not reliant on local food shortages in population densities that have been observed. (Rogers, 1987) There are other factors influencing the dispersal and migrations of black bears which have been studied. Urus americanus are not known to monogamous and mate promiscuously. (Rogers, 1987) Males mate with more than one female and disperse more, sometimes looking for oth... ... cubs will be expected to be found closer to or at their initial home range. If however, a larger number of female bear’s DNA is collected farther than their home ranges, it could imply that previous studies bases solely on observation or mark and recapture methods were inaccurate due to the limited populations that were sampled. An observation of this nature could imply that sows dispersed farther in search for new mates or safer dens for their cubs rather than males who were expected to wander away. More likely though, this observation could be an exception to the rule or just flawed collection and processing techniques. Providing that the study conducted is not faulty, it will supply important information regarding dispersal patters of the American black bear. Even the data gathered in the course of this study can be used for further research on Ursus americanus.

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