Louisiana Black Bear Management and Research

Black bear management in Louisiana is focused on conservation and development of habitat required by black bears and the reduction of human/bear conflicts.   Research is directed at gathering of data to assess and monitor bear populations, productivity, population viability and public opinion regarding bears and bear management.

Habitat Management and Restoration

Habitat loss was one of the primary reasons black bears were listed as a threatened species in 1992.  Following the Mississippi River flood of 1927, a massive flood control effort was launched which resulted in much of the upper Mississippi River floodplain of Louisiana being protected from flooding by U.S. Army Corps of Engineers levees.  The resulting reduction in flooding, coupled with technology made the fertile soils of the upper Mississippi River floodplain desirable for agriculture.  In addition, high soybean prices accelerated conversion of forestland to agriculture in the 1960s and 1970s. Conservation provisions in the federal Farm Bill slowed forestland conversion by the mid-1980’s.  However, by then only about 20% of the landscape remained forested.

A number of programs and initiatives have resulted in the conservation and restoration of over 600,000 acres of forestland in the Mississippi River floodplain of Louisiana.  The Louisiana Department of Wildlife and Fisheries and the U.S. Fish and Wildlife Service have conserved land through acquisition of Wildlife Management Areas and National Wildlife Refuges.  Forestland on private property has been restored through U.S.D.A. programs such as the Wetlands Reserve Program and Conservation Reserve Program as well as through programs of private conservation organizations such as the Black Bear Conservation Coalition, The Nature Conservancy and Ducks Unlimited.

It is not enough to just restore forestland.  For maximum benefit to bears and other wildlife, it must also be managed properly.  Wildlife habitat management assistance is provided to landowners through a number of state, federal and private programs.  One such program is the Louisiana Department of Wildlife and Fisheries’ Technical Services Program.  Through this program, department biologists work with landowners to provide guidance to improve wildlife habitat on their property.

Conflict Management

An important component of bear management involves educational efforts to reduce bear – human conflicts.  Bears are intelligent and adaptable animals that will take advantage of sources of food that are made available to them as a result of human activity.   Unsecured garbage and wildlife feeders are two common causes of bear – human conflict.   The department works to educate and inform the public about living around bears  through brochures, public meetings, teacher workshops, outreach events, hunter education classes and technical assistance to individuals experiencing problems. 

Research

The department and its partners have been conducting extensive research on black bears for several years.  This research is being conducted to gather information on populations, productivity, and population viability to determine if the criteria for removing the LBB from the list of threatened species have been met and to gather information needed to properly manage LBB populations to ensure they remain a viable part of Louisiana’s wildlife community. 

“Estimating Population Parameters of the Louisiana Black Bear in the Tensas River Basin, Louisiana, Using Robust Design Capture-Mark-Recapture.”

 

                               ABSTRACT

The Louisiana black bear (Ursus americanus luteolus) is listed as a threatened species under the protection of the Endangered Species Act of 1973. The Louisiana Black Bear Recovery Plan calls for research regarding bear population viability and biology. From July 2006 to August 2008 I conducted a 3-year robust design capture-mark-recapture study of bears in the Tensas River Basin of northeast Louisiana. I used microsatellite genotypes from DNA extracted from hair samples to identify individual bears.

Robust design encounter histories of bears were analyzed using Huggins full heterogeneity models in Program MARK. I ranked models using Akaike’s Information Criterion (AIC). I used model averaging to account for model selection uncertainty.

Apparent survival rate, temporary emigration, the probability of an individual coming from 1 of 2 mixtures, and the probability of capture and recapture were estimated from encounter histories. Population abundance was a derived parameter.

I used abundance estimates to calculate density, and population growth. Apparent survival did not differ by gender or year and was 0.91 (95% CI = 0.62–0.98). There was no temporary emigration. Models in which capture probabilities varied by mixtures were favored over models lacking mixtures. For both genders and across all years, >80% of individuals were in a mixture with capture probabilities ranging from 0.02 to 0.03 for males and 0.07 to 0.08 for females.

Estimates for recapture were higher than capture indicating a positive behavioral response to being captured for females. Model-averaged estimates of abundance for females were 143 (95% CI = 113–204), 106 (95% CI = 83–151), and 133 (95% CI = 100–195) and for males were 198 (95% CI = 117–360), 116 (95% CI = 69–209), and 185 (95% CI = 112–323) during 2006, 2007 and 2008, respectively.

Mean population size for both genders averaged across years was 294 (SE = 31) and density was 0.66 bears/km2 (SE = 0.07). Video and photographic evidence suggested that adult males were less likely to be sampled while visiting hair snares. I offer suggestions to reduce this heterogeneity bias.

“Estimating Population Parameters of the Louisiana Black Bear in the Upper Atchafalaya River Basin.”

Abstract

In 1992, the Louisiana black bear (Ursus americanus luteolus) was granted threatened status under the Endangered Species Act primarily because of extensive habitat loss and fragmentation.

Currently, the Louisiana black bear is restricted to 3 relatively small, disjunct breeding subpopulations located in the Tensas River Basin of northeast Louisiana, the upper Atchafalaya River Basin (ARB) of south-central Louisiana, and coastal Louisiana. The 1995 Recovery Plan mandates research to determine the viability of the remaining subpopulations.

I conducted a capture-mark-recapture study during 2007–2009 to estimate population parameters for the ARB bear subpopulation by collecting hair samples (n = 2,977) from 115 barbed-wire hair traps during 8 1-week periods each summer. DNA was extracted from those hair samples and microsatellite genotypes were used to identify individuals. I analyzed encounter histories using the Huggins full heterogeneity estimator in a robust design framework in Program MARK.

I compared candidate models incorporating heterogeneity, behavior, and time effects on capture using information-theoretic methods. I directly estimated apparent survival, temporary emigration, probability of capture and recapture, and probability of belonging to 1 of 2 mixtures; population abundance was a derived parameter. Apparent survival was 0.91 (SE = 0.06) and did not vary by gender or year.

There was some evidence of temporary emigration for males only (0.10, 95% CI = 0.001–0.900). I modeled capture probabilities with a 2-mixture distribution for both male and females. Overall mean weekly capture probability was 0.12 (SE = 0.03) and 0.25 (SE = 0.04) for males and females, respectively. Recapture rates indicated a positive behavioral response to capture.

Model-averaged mean annual abundance was 56 (SE = 4.5, 95% CI = 49–68). I calculated population density using spatially-explicit maximum-likelihood methods; model averaged density was 0.15 bears/km2 (SE = 0.03). My results updated previous abundance estimates for the ARB bear subpopulation and will be used in a population viability analysis to determine if recovery criteria for the Louisiana black bear have been met.

POPULATION DEMOGRAPHICS AND GENETIC STRUCTURE OF BLACK BEARS IN COASTAL LOUISIANA”

ABSTRACT

The range and abundance of the Louisiana black bear (Ursus americanus luteolus) were greatly diminished during the 20th century. This subspecies was reduced to 3 small, isolated subpopulations in Louisiana as bottomland hardwood habitat was converted to agriculture. These bears were listed as threatened by the U.S. Fish and Wildlife Service in 1992 and a recovery plan was published in 1995. Recovery requires estimates of population parameters to evaluate current population status and future viability. I conducted a mark-recapture study from 2010 to 2012 to estimate demographic parameters of the coastal population of Louisiana black bears. Because inbreeding is a concern for small, isolated populations, I analyzed 23 microsatellite loci to investigate genetic structure and migration rates within the coastal population and between the coastal and other regional populations. Using non-invasive methods, I collected 3,698 hair samples during 3 summers and used DNA to identify 190 individuals. I analyzed encounter histories using Robust Design, a combination of open and closed mark-recapture models, with the full closed captures with heterogeneity model in Program MARK. I estimated density using spatially explicit capture-recapture. I used Akaike’s Information Criterion (AIC) to rank models and averaged across years according to AIC weight. The model-averaged abundance estimate for females was 77 (95% CI = 66–89) and for males was 61 (95% CI = 53–69). Population growth rate was negative from 2010 to 2011, positive from 2011 to 2012, and averaged 1.08. Apparent survival ranged from 0.83 to 0.89 depending on sex and year. Population density was 0.35 bears/km2 (95% CI = 0.30–0.41). Principal Coordinate Analysis and assignment tests revealed 2 genetic clusters within the population. Migration rates were male biased and higher than expected based on genetic structure. The population appears to be recovering from past fragmentation but evidence for a bottleneck was inconclusive. I conclude that genetic isolation and inbreeding within the coastal population pose less danger than isolation and demographic threats. My results will ultimately be used as part of a population viability analysis to estimate the sustainability of the Louisiana black bear population.