Migration In Black Bears Essay

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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 …show more content…

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 other females to mate with. Female mothers, on the other hand have a predilection to stay close to their den and care for their cubs. (Garneau, Boudreau, Keech, & Post, 2008) Female bears, or sows, usually breed between June and July around the average age of 4 and produce litter of one to six cubs in late January to early February. (North American Bear Center) However, no molecular data studies have been performed to substantiate previous studies. Since a strong male based dispersal system has been observed in black bear populations, I propose to study this sex biased dispersal using microsatellite markers on the X and Y …show more content…

Fruits or meat will placed about 6 ft high as bait to ensure that the bears reach up between the snares and hair is snagged in the wires. (Engle, 2013) RAPD analysis would be used initially for basic species specific identification from hair-root and scat samples in the field. ‘Minisatellite loci’ can then be used in DNA fingerprinting to identify individuals in the species for the study. If the DNA from a hunted bear matches a previously known individual from either a hair snare or scat sample, that bear will be categorized as a “recapture”. Mitochondrial DNA (mtDNA) would further be used to assign females. A combination of Y-based SNP (single nucleotide polymorphism)—SRY, AML, and ZF, three sex-specific genes, would further be used in distinguishing males from “non-male” bears. (Pagès, Maudet, Bellemain, Taberlet, Hughes, & Hänni, 2008) The genetic data collected and amplified by PCR will be used in assignment tests to determine dispersal and migration in black bears.
The study will take about 5 years (A year being calculated as a period of twelve consecutive months). Each year will be divided into 3 seasons to accommodate for hibernation, migration and mating, and finding new dens. For large mammals like black bears, natural barriers such as rivers do little to hamper migration. Therefore expected dispersal ranges can be over 50

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