College of Forestry, Wildlife and Environment

Second Guessing the Maximum Likelihood Estimator Values for Bat Surveys

2026-06-09T21:15:58Z

Second Guessing the Maximum Likelihood Estimator Values for Bat Surveys The U.S. Fish and Wildlife Service allows acoustical surveys and automated identification software to determine the presence of the endangered northern long-eared bat (Myotis septentrionalis) and Indiana bat (Myotis sodalis). Analytical software is required to assess presence probability on a site-night basis using a maximum likelihood estimator (MLE) that accounts for interspecific bat misclassification rates. The current standard for occupancy is a returned MLE P-value < 0.05 at the nightly level irrespective of the number of files identified as either northern long-eared bats or Indiana bats. These MLE P-values can vary based on presence of other bat species with similar calls and the relative proportions of all species recorded. Accordingly, there is concern that with few nightly northern long-eared bat or Indiana bat recordings or the presence of large numbers of high-frequency bats, false-negative findings from a swamping effect could result. Using data collected in 2020–2021 by the U.S. Fish and Wildlife Service to set nationwide acoustic monitoring guidelines, we examined the relationship of returned software MLE P-values from 4873 site-nights of acoustic detector data relative to nightly counts of northern long-eared bats and Indiana bats, overall counts of other high-frequency bats, and habitat cover type. For both northern long-eared bats and Indiana bats, nights with one or more echolocation pass files identified as either species but above the MLE P-value threshold largely occurred where nightly counts of the target species was <15 and their proportion to the count of high-frequency bat species was low. We followed this analysis with a simulation using a known call library and observed similar patterns. Accordingly, with few nightly cholocation passes, post-hoc visual assessment following automated software identification easily could be undertaken. Evidence of swamping by other high-frequency species causing positive file identification creating false-negative or false-positives of northern long-eared bats and Indiana bats was not apparent at nightly counts of either species > 10.

Status of Historical Translocations of Gopher Tortoises Outside of Their Geographic Range in Central Alabama

2026-06-09T21:11:53Z

Status of Historical Translocations of Gopher Tortoises Outside of Their Geographic Range in Central Alabama The gopher tortoise (Gopherus polyphemus) is a species of concern in the southeastern United States, and its distribution is within the range of the longleaf pine (Pinus palustris). One conservation strategy within the state of Alabama has been translocation of adult tortoises to other areas with longleaf pine and sandy soils, including areas outside the current accepted species’ range. Prior examples of such tortoise translocations occurred in two counties in central Alabama: one in the 1960s in Macon County and another in the 1980s in Autauga County. Both introductions occurred near the Coastal Plain fall-line, which is deemed the northernmost landmark designation that tortoises were historically presumed to reside. The status of these translocated tortoise populations had not been recently assessed. Therefore, we surveyed the two locations, captured individuals, and qualitatively examined the minimum known number of alive adult tortoises. We found populations of tortoises at both translocation sites, including evidence of reproduction and recruitment. Notably, we found two marked tortoises (one at each of the two relocation sites) from the original translocations, indicating that translocated tortoises survived in these new areas for 30 and 49–56 years, respectively. Although inference about translocation success is limited by overall low tortoise projected densities, our results suggest tortoise populations can persist in areas of Alabama outside their mapped geographic range, including on soil types not documented previously.

Effects of Trap Door Width on Wild Pig Entrance into Corral Traps

2026-06-09T21:07:32Z

Effects of Trap Door Width on Wild Pig Entrance into Corral Traps Wild pigs (Sus scrofa) are arguably one of the greatest wildlife management challenges facing natural resource professionals and landowners in the U.S., and lethal removal by trapping is often the most cost- and time-effective means for managing populations. Whereas numerous studies have examined the effects of trap type, trap activation designs, and baits on trapping effectiveness, no studies utilizing a conditioning period and accounting for unique individuals/sounders and wild pig social structure have examined the effects of trap door width on wild pig entrance into corral-style traps. Modifying trap door width may impact wild pig entrance rates into corral-style traps with wider doors better facilitating entrance. Our objective was to examine wild pig entry times into standard three-panel corral traps with wooden guillotine trap doors of either 0.8-m or 1.2-m widths. We placed these doors on 12 traps at a study site in east-central Alabama from June–September 2014 and 2015. We positioned a motion-sensitive game camera on each trap to record wild pig visitation behavior and then began baiting each trap. We recorded the time when wild pigs initially visited the trap site, time until the first wild pig entered the trap, and the time until 50% and 100% of the sounder had entered the trap. We used camera imagery data collected from 27 solitary individuals and 47 sounders to evaluate the effect of door width on the length of time that wild pigs took to enter traps. First entry time for sounders did not differ between 0.8-m and 1.2-m widths, nor did time until entry by 50% and 100% of sounders. However, first entry time was similar among solitary individuals. Our results suggest trap door width may not have as large of an impact on entrance rates into traps as previously thought.

No Corn, No Problem: A Test for the Best Non-Grain Attractant for Wild Pigs

2026-06-09T20:56:22Z

No Corn, No Problem: A Test for the Best Non-Grain Attractant for Wild Pigs Grain-based attractants (e.g., corn) are standard among most wild pig (Sus scrofa) trapping and non-invasive sampling efforts (e.g., genetic spatial capture/recapture, camera trapping), but their use is not always feasible due to cost, deployment restrictions (e.g., difficulty of transporting grain into remote areas, property rules), and potential disease concerns associated with concentrating non-target species at bait sites. Attractant deployment and efficacy should be considered by biologists, private landowners, and researchers given the ultimate need to use attractants to attract wild pigs. To examine the efficacy of potential non-grain attractants, we used remote camera grids to identify attractant(s) that maximized wild pig visitation while minimizing non-target species visitation in a forested landscape in the southeastern United States. Further, we only considered non-grain attractants easy to carry (i.e., <0.5 kg and compact) and deploy (i.e., painted on tree trunks or activated scent wicks). Comparing eight non-grain attractants among food, non-food, and control (i.e., no attractant; n = 11 visitations) treatments, we found used cooking oil (i.e., fish fryer grease; n = 38 visitations), orange marmalade (n = 36 visitations), and caramel syrup (n = 29 visitations) were most attractive to wild pigs. Although also attractive to opossums (Didelphis virginiana; n = 50 visitations), used cooking oil was not a significant attractant among other non-target species. In contrast, orange marmalade was attractive to raccoons (Procyon lotor), opossums, and eastern gray squirrels (Sciurus carolinensis; n = 188 combined visitations), and caramel syrup was attractive to raccoons and opossums (n = 137 combined visitations). In our study, used cooking oil was the non-grain attractant most likely to maximize wild pig visitation while minimizing non-target species attraction, and increases the efficacy of sampling of remote areas considering its ease of distribution.