Abundance, genetic diversity and conservation of Louisiana black bears (Ursus americanus luteolus) as detected through noninvasive sampling

Although the Louisiana black bear (Ursus americanus luteolus) is currently listed as threatened under the Endangered Species Act, there have been no attempts to estimate range-wide abundance. This subspecies was thought to occupy a near contiguous range across southern Mississippi, Louisiana and east Texas but is now restricted to three isolated areas in Louisiana. In 1964, Louisiana initiated a restocking program in which black bears from Minnesota were introduced into two of these areas. It is not clear how the additions affected population structure or if substantial breeding occurred between native and introduced bears. Using baited sites to snare hair samples, and microsatellite DNA analysis to distinguish individuals, we estimated abundance of two geographically isolated bear populations in south central Louisiana: Inland and Coastal. Additionally, we examined genetic variation both within and between the two populations. Mark recapture analysis of the distribution of individual captures during two primary sampling periods resulted in population estimates of 77 +/- 9 for Coastal and 41 +/- 6 for Inland. Genetic analysis revealed significant population differentiation (F-ST = 0.206) between the two populations. The apparently smaller Inland population exhibited more diversity than the Coastal, which suggests that the genetic structure of the Inland population has been influenced by the reintroduction. Both of these populations are isolated and face considerable demographic and genetic threats, thus conservation measures to protect both are warranted. However, the Coastal population is more representative of Louisiana black bears prior to reintroduction and special consideration should be given to insure its integrity.