Population Dynamics of the Louisiana Black Bear in the Upper Atchafalaya River Basin

The Louisiana black bear (Ursus americanus luteolus) is listed as Threatened under the Endangered Species Act as a result of habitat loss and human-related mortality. Two of the 3 sub-populations must be viable for delisting to occur. I collected hair samples from 2010 to 2012 in a DNA mark-recapture study to augment data collected from 2007 to 2009 in the Upper Atchafalaya River Basin (UARB) to estimate abundance (N), growth rate (λ), and apparent survival rates (φ) to ultimately be used in a population viability analysis. In addition, I evaluated the effects of the opening of the Morganza Spillway in 2011 which flooded >50% of the UARB study area. I used a Multi-state model to estimate changes in transition rates (ψ) from the flooded area to non-flooded area before (2007–2010), during (2011), and after (2012) the flooding event. Finally, I evaluated a 2-wire hair sampling system that was implemented in 2010 to increase capture probabilities (p) for males. Average N from 2010 to 2012 was 62.1 (SE = 3.6) and averaged across all years of study (2007–2012) N was 57.6 (SE = 2.2), excluding the year of the flooding event. Population growth rate indicated an increasing population, averaging λ = 1.11 across all 6 years of the study and mean φ was 0.83 (SE = 0.01). Estimates of ψ from the flooded to non-flooded areas increased slightly during the flood year indicating that some bears left the floodway but most did not. Apparent survival did not change for flooded or non-flooded areas during the period of flooding. Finally, p for males increased and decreased for females as predicted for a wire effect, but models with constant p were more parsimonious. The 2-wire system increased capture probabilities but the effect was not significant.