No flood effect on recruitment in a Louisiana black bear population

Abstract

A flood event in 2011 had minor impacts on apparent survival and movement probabilities of a small, isolated population of Louisiana black bears (Ursus americanus luteolus) in the Upper Atchafalaya River Basin, Louisiana, USA. However, the potential effects of the flood on recruitment of juveniles into the population, then listed as threatened under the United States Endangered Species Act, were not evaluated. We used hair trapping data collected from 2007 to 2015 and Pradel temporal symmetry models in a robust‐design framework to investigate changes in per capita recruitment that could have resulted from the flood. We detected 91 bears (37 M:54 F) within the flooded area during our study period, ranging from 21 to 44 individuals/year. Models that tested for reduced recruitment resulting from the flood were not supported more than models with constant recruitment, and the population growth rate did not decline. Although we documented marginally lower recruitment following the 2011 flood, lag effects and detectability biases complicated our analysis. We suggest that wildlife managers continue monitoring recruitment and survival in this recently delisted black bear population given the potential for heightened flood frequency and severity in the future. © 2017 The Wildlife Society.

Seasonal flooding effects on deer in the Mississippi river batture

“…Reproductive failures are commonly associated with flooding when young are immobile and cannot escape their circumstances. Cub mortality has been observed for black bear ( Ursus americanus ) from flooding of natal dens (Alt , White et al ), but flooding after den emergence reportedly does not affect recruitment (Clark et al ). Reptiles and ground‐nesting birds may suffer reproductive failures when nests are inundated (Kushlan and Jacobsen , Janzen , Sanders and Maloney ).…”

“…Reproductive failures are commonly associated with flooding when young are immobile and cannot escape their circumstances. Cub mortality has been observed for black bear (Ursus americanus) from flooding of natal dens (Alt 1984, White et al 2001), but flooding after den emergence reportedly does not affect recruitment (Clark et al 2017).…”

Extension of Pradel capture–recapture survival‐recruitment model accounting for transients

“…This simple decomposition is possible using the well‐known Pradel (1996) temporal symmetry model, which can estimate survival, recruitment and population growth. This model has become a ‘classic’ for demographic studies and has been used on wide range of taxa, including birds (Ancona et al., 2017; Saracco et al., 2008, 2020), rodents (Nichols et al., 2000; Polyakov et al., 2021; Schorr, 2012), bears (Clark et al., 2018; Sawaya et al., 2012), leguans (Rodrigues et al., 2021), turtles (Sasso et al., 2006) and toads (Lambert et al., 2016; Muths et al., 2011). The Jolly–Seber model is also capable of this analysis (Kéry & Schaub, 2012), but the Pradel model is more straightforward, as it circumvents the estimation of absolute population sizes.…”