OCCURRENCE OF MANGE IN AMERICAN BLACK BEARS (URSUS AMERICANUS) IN NEW YORK STATE, USA.

Mange, a parasitic skin disease caused by various species of mites, is found in free-ranging wildlife populations and has been increasingly reported in American black bears (Ursus americanus) over the last decade in New York State (NYS), USA. Our goal was to describe the geographic, seasonal, and demographic factors associated with mange in this species in NYS. Our retrospective study used historic, opportunistic data from diagnostic necropsy records and visual sighting reports collected by the NYS Wildlife Health Program from 2009 to 2018. We used chi-square tests for independence and odds ratios to examine whether geographic location, year, season, sex, age, and reason for laboratory submission were associated with mange in bears. We used maps and seasonal analysis to investigate emerging patterns. We confirmed increased black bear mange reports in recent years. Necropsy data revealed more bears submitted to the laboratory because of mange, mainly caused by Sarcoptes scabiei; females were more likely than males to present with sarcoptic mange. We found that cases of mange in the Northern Zone were widely disseminated throughout the region, whereas cases in the Southern Zone were concentrated in two areas along the Pennsylvania border. Seasonally, mange cases showed peaks occurring in late spring to early summer and in fall. Our results were on the basis of available data; a comprehensive statewide surveillance program would be useful to better understand the apparent increase in mange and its potential impact on both the welfare of individual animals and the population of black bears in NYS. Additional research on the timing of transmission dynamics associated with females in winter dens may be helpful to wildlife managers to identify strategies to mitigate deleterious spread of the disease in black bears.

Another look at the eigenvalues of a population matrix model.

Population matrix models are important tools in resource management, in part because they are used to calculate the finite rate of growth ("dominant eigenvalue"). But understanding how a population matrix model converts life history traits into the finite rate of growth can be tricky. We introduce interactive software ("IsoPOPd") that uses the characteristic equation to display how vital rates (survival and fertility) contribute to the finite rate of growth. Higher-order interactions among vital rates complicate the linkage between a management intervention and a population's growth rate. We illustrate the use of the software for investigating the consequences of three management interventions in a 3-stage model of white-tailed deer (Odocoileus virginianus). The software is applicable to any species with 2- or 3-stages, but the mathematical concepts underlying the software are applicable to a population matrix model of any size. The IsoPOPd software is available at: https://cwhl.vet.cornell.edu/tools/isopopd.

How can we augment the few that remain? Using stable population dynamics to aid reintroduction planning of an iteroparous species.

Restoration of depleted populations is an important method in biological conservation. Reintroduction strategies frequently aim to restore stable, increasing, self-sustaining populations. Knowledge of asymptotic system dynamics may provide advantage in selecting reintroduction strategies. We introduce interactive software that is designed to identify strategies for release of females that are immediately aligned with stable population dynamics from species represented by 2-, 3-, 4-, and 5-stage life history strategies. The software allows managers to input a matrix of interest, the desired number of breeding females, and the desired management timeline, and calls upon stable population theory to give release strategies that are in concert with both stable population status and the management goals. We demonstrate how the software can aid in assessing various strategies ahead of a hypothetical restoration. For the purpose of demonstration of the tool only, we use published vital rates of an ungulate species, but remark that the selection of species for demonstration is not central to the use of this tool. Adaption of this tool to real-life restorations of any 2-, 3-, 4-, or 5-stage iteroparous species may aid in understanding how to minimize undesirable recovery complications that may naturally arise from transient population dynamics. The software is freely available at: https//cwhl.vet.cornell.edu/tools/stapopd.