Natural Resource Ecology & Management
Non Technical Summary
Black bears (Ursus americanus) disappeared from Oklahoma in the early 1900's, but began moving back into the eastern part of the state from Arkansas in the 1990's. Eastern Oklahoma now has two black bear populations; one in the Ouachita Mountains of southeastern Oklahoma and one in the Ozarks region of east-central Oklahoma. The Ouachita Mountain population has been in existence the longest and supports an annual bear harvest in the counties of Latimer, LeFlore, McCurtain, and Pushmataha. The Ozark population is more recent, smaller, and more sparsely distributed, and is not currently hunted. As a top consumer with a highly varied diet, black bears likely played important roles in the forests of Oklahoma prior to their disappearance. However, the species is moving back into a landscape that is now heavily dominated by humans and different land uses.To manage the black bear populations in Oklahoma, it will be necessary to understand their population growth rates, population responses to hunting, habitat relationships, and factors that promote or discourage conflicts between bears and humans. Capture-mark-recapture methods will be used to estimate population size in the Ouachita Mountains, but because of their smaller numbers and sparser distribution, we will use genetic methods, based on hair samples obtained from a grid of hair snares, to estimate population size of the Oklahoma Ozark population. Mortality rates of 1-20 year old bears will be determined by remotely tracking animals fitted with GPS collars. GPS-collared females will be tracked to their dens during hibernation, when cubs are born, to assess reproductive rates. Den visits in subsequent years will reveal cub survival because yearlings hibernate with their mothers one last time. We will use scat analysis to assess foods eaten by the bears in different months, and stable isotope methods with hair samples to determine the proportion of an individual bear's diet comes from human-associated foods (primarily corn-based) vs. native foods. We will also design an apparatus (which will be tested with bears in the Tulsa zoo) to conduct a field experiment of food preferences, native vs. human-associated food, of wild black bears. Finally, detailed studies of food production (fruits, berries, grasses, insects, acorns and nuts) in burned and/or thinned areas of different ages in the Ouachita National Forest will be conducted, and compared to seasonal habitat use and movements of black bears.The results of our study will inform management of Oklahoma's black bear populations, as well as neighboring states, and begin to develop practices that will help to reduce bear-human conflict while maintaining healthy populations of black bears in eastern Oklahoma. In particular, our results will help the Oklahoma Department of Wildlife Conservation set regulations for current and future black bear hunting seasons. The research also provides numerous opportunities for outreach to public schools, landowners, and other groups in Oklahoma.
Animal Health Component
Research Effort Categories
Goals / Objectives
The overall objective of this research is to provide information on the recently re-established black bear populations in Oklahoma that will provide a scientific basis for their management and contribute to a broader understanding of the ecological and anthropogenic effects on black bear populations. Specific objectives are: 1) to estimate demographic parameters of the southeast Oklahoma black bear population 6+ years after initiation of an annual hunt and collect baseline demographic data for the newly colonizing bear population in the Ozark region of Oklahoma; 2) to assess impacts over time of prescribed burning and thinning for forest management on production of foods, movements and home range shifts of bears in southeast Oklahoma; and 3) to investigate use and importance of anthropogenic food sources by black bears in relation to native food sources.
Population Size and Demography: In the Ouachita Mountains, we will use a capture-recapture method to estimate size of the black bear population, using the same traplines used in the initial black bear study (Bales et al. 2005) for comparison to population demographics prior to hunting. In addition, traplines outside the Ouachita National Forest will be established to provide a population estimate. Bucket snares will be used to capture bears, with occasional use of barrel or culvert traps. Age structure and sex ratio will be determined based on captured bears. A proportion of the bears captured will be given G2110E Iridium/GPS Location Collars programmed to take fixes every 7 hours. The collars will also contain a VHF beacon for tracking to den sites, a mortality sensor, and a remote break-off mechanism. Bears will be tagged with a standard livestock ear tag, & ear tissue, a blood sample, & hair will be collected for genetic, disease, and stable isotope studies.At the Ozark study area, the bear population is smaller & less dense. Therefore, in addition to capturing and marking the bears as above (but using primarily barrel and culvert traps), we will also use genetic methods for capture-recapture estimation of population size.DNA from bear hair follicles, will be extracted & individual bears identified using ~15 microsatellites developed and used previously with black bears from the Ozark and Ouachita regions. New statistical methods allow the use of the Lincoln-Petersen estimator with modification for multiple sources of data. The ability to increase the number of captures and recaptures by using multiple data sources will increase the reliability of population estimates.GPS-collared bears will be tracked to their hibernacula during winter to check, assess reproduction, & check survival of previous year's cubs. Females with cubs will be chemically immobilized & cubs will be weighed and measured, and sex will be determined. Because they are too small to apply eartags, each cub will have a microchip inserted under the skin above the shoulders. Number and identity of yearlings denning with their mother will be recorded to assess survival of cubs born the previous year. Survival of all radio-collared bears will be monitored throughout the year as an estimate of age-specific survival.Prescribed Burning, Food Production, and Habitat Use by Black Bears: We will establish four 200-m transects in each of 12 different patches in the Ouachita National Forest representing different burn ages. For this study, burns > 5 years are lumped together as most food-producing species important to bears will peak in productivity within 5 years of the burn. Starting points for transects were randomly generated, but were constrained to be >100 m from roads, trails, and other human structures. Five permanent plots, at 50-m intervals, will be marked on each transect with rebar. Soft mast surveys will be conducted monthly from May-August 2014-2016 within a 3-m radius circular plot centered on the rebar, recording soft mass species and percent cover, and estimating the number of buds, flowers, and/or berries/fruits in the plot. Percent cover of herbaceous vegetation will be estimated within a 1-m2 plot with one corner placed at each rebar post.Sticky traps will be placed on the ground, tied to the rebar post, to investigate type and relative abundance of ants. The traps will be collected and replaced each month. Rocks and logs within 0.5 m on each side of the transect will be lifted to check for ant nests and grubs, replacing the rocks and logs after being checked. Perpendicular distance of ant nests to the transect will be recorded and a small number of ants will be collected in vials to identify species.Hard mast production will be assessed August-December 2014-2016 using our own design for acorn traps that will be hung beneath trees. The traps will be hung from trees and placed high enough off the ground and far enough from the trunk of the tree that a bear cannot reach them. In each burn unit, one seed trap per tree will be placed under five trees in the white oak group, five trees in the red/black oak group, and 5 hickory trees. We will record the canopy area for each tree & hard mast will be collected monthly.Seasonal home ranges & resource selection will be calculated for individual bears. Habitat selection parameters will be investigated. If the forage production analysis with respect to prescribed burns produces an adequately-predictive model, predicted forage production at different locations can also be included as a variable. Seasonal home range shifts will be investigated.Use of Anthropogenic Foods by Black Bears: Black bear scat will be collected on both study areas & analyzed to identify food items. Percent of total weight of scat made up by each food type will be calculated and corrected using biomass correction factors developed for grizzly bears (Hewitt and Robbins 1996).We will assess proportion of the diet composed of anthropogenic foods by individual bears using stable isotope analysis. Hair shafts from captured bears and from hair snare samples will be analyzed. We are interested in the proportion of the bears' diet made up of corn from deer feeders. We will also collect different types of native foods from the Ozark study area & process them for stable isotope analysis for comparison to hair samples.We are developing & testing a novel apparatus to investigate black bear preferences for anthropogenic vs. native foods in a field experiment. Giving up density methods have been used to assess perceived risk in different foraging conditions/habitats and more recently to assess food preferences. These studies have primarily involved small mammals and this technique has not yet been applied to large omnivores. Giving up density (GUD) methods set up a foraging situation with diminishing returns, resulting in the animal leaving the feeding apparatus before depleting all the food it contains (Brown 1988). The amount of food left when the animal departs is the GUD. Higher GUDs suggest the animal perceived higher risk in remaining to forage longer at the feeder. To investigate forage preferences, we will present pairs of feeders, one containing deer corn and the other containing a native food type. The feeder with the lowest GUD suggests that the bear was willing to work longer to extract more of the type of food it contained, exhibiting a preference for that food type. We are collaborating with the Tulsa Zoo to find a durable feeder and develop methodology with zoo bears before beginning the field experimental study with wild black bears. We have had great success in creating a situation of diminishing returns that the zoo bears have not destroyed. Our apparatus consists of a horse treat-dispensing toy. We drilled five 4-cm holes in the 'cap' end of the plastic container. To standardize the amount of food reward, the food is placed in large gelatin capsules. Larger, empty gel capsules that cannot fit through the drilled holes are placed in the feeder with the food-containing capsules to increase the difficulty of obtaining a food reward & ensure diminishing returns. Field trials with wild black bears will consist of hanging two feeders by cables or chains from sturdy tree branches or metal poles in areas of high use by individual GPS-collared black bears. The two feeders will be within 4 m of each other, one containing deer corn, the other containing acorns or dehydrated berries/fruit in the smaller gel capsules. Wildlife cameras will be set to record activity. Following visitation by a bear, the number of remaining food capsules in each feeder will be counted. Trials will be conducted in different seasons to investigate seasonal changes in preference.