Abstract True metabolizable energy (TME) assays were first developed to refine poultry diets but have since been adapted by wildlife biologists and conservation planners to determine the assimilable energy within natural wetland foods (i.e., seeds, invertebrates, vegetation) for waterfowl. Bioenergetic models incorporate TME values to quantify the energetic carrying capacity of wetlands. Prior TME research focused on the food items commonly found in mallard ( Anas platyrhynchos ) diets, leaving uncertainty in bioenergetics modeling as to the carrying capacity of other dabbling duck species in combination with a wider range of moist‐soil plant seeds consumed by waterfowl. We collected 287 TME N (nitrogen corrected TME) feeding trial samples between August and March 2020–2022 to quantify TME N for 8 moist‐soil plant seed species ( Cyperus erythrorhizos , Cyperus iria , Leptochloa panicoides, Panicum rigidulum , Polygonum hydropiperoides, Polygonum lapathifolium , Sesbania herbacea, Sida spinosa ) among 3 species of dabbling duck (mallard, northern pintail [ Anas acuta ], and green‐winged teal [ A. crecca ]). We found TME N values varied among duck and seed species (min–max = −0.29–2.58 kcal/g), with northern pintail values generally being 1–2 kcal/g lower than mallard and green‐winged teal. Our results indicate that bioenergetics models could be improved by incorporating species‐specific energy supply estimates, customized by species composition for the region or area comprising the planning unit. Moreover, management practices can be focused on providing plant species most beneficial to target species or groups of ducks representing the expected species composition in a management unit using this new information that illustrates the variability in assimilable energy across plant species and for dabbling duck species other than the generalist mallard.
Assessments of small mammal (e.g., rodents) relative abundance provide important information to safely manage airfields, as small mammals attract larger mammals and raptors that are involved in collisions with aircraft. Snap-trapping is the standard method for assessing small mammal relative abundance at U.S. airports, yet thermal scopes/optics or tracking tunnels may be efficient alternative methods. Thermal optics (used at night) convert objects' far-infrared energy (3-14 & micro;m) into visible images. Tracking tunnels are baited ink cards placed inside plastic tunnels that allow the footprints of visiting animals to be identified. After suspecting thick and tall grass interfered with spotting mammals smaller than striped skunks (Mephitis mephitis, similar to 1.8-2.7 kg) when using thermal optics, we assessed detectability by placing carcasses of heated mice (Mus musculus) of 2 sizes ( = 19.8 g and 33 g) within varying heights of grass (0-20.3 cm) and distances from observers (4-30 m; n = 144 trials) when thermal units were held by an observer (1.7 m above ground) or when fastened to the roof of a truck (2.1 m above ground). Also, within airfields, we compared small mammal relative abundances using tracking tunnels to those using snap-traps. We found that grass >= 10 cm tall consistently obscured thermal detections of both mouse carcass sizes, yet mouse carcasses were detected in similar to 50% of attempts in 8.9 cm tall grass and 78% of attempts in 7.6 cm tall grass. Most airports do not maintain grass to heights <10 cm. Detectability decreased with distance from the observer. There was no significant difference in detections between roof-mounted and hand-held thermal optics, nor did mouse carcass size significantly affect detectability. Small mammal detections using tracking tunnels significantly correlated with snap-trap captures (best fits [R = 0.51-0.73] with 1 or 2 nights of tracking tunnels active). We concluded that the use of ground-based thermal optics would not be a viable survey tool for mouse-sized mammals (19-41 g) at airfields and other grassy habitats with thick grass unless grass height was maintained <= 7.6 cm tall. Tracking tunnels may be a viable alternative method to snap-traps for assessing small-mammal relative abundances and potentially saving one day of snap-trapping labor.
Abstract Eastern spotted skunks ( Spilogale putorius ) have experienced a range‐wide decline since the 1940s and are classified as vulnerable by the International Union for the Conservation of Nature Red List. To address research priorities for the species, effective monitoring methods are crucial. In this study, we used traditional tree‐mounted camera traps and 2 novel detection methods for spotted skunks: enclosed camera traps and a detection dog. We also tested 2 previously untried scent lures to attract spotted skunks: weasel gland paste and rabbit urine. Camera surveys were conducted at 16 sites and detection dog surveys were conducted at 20 sites (21 total sites) in the Ocala National Forest in Marion County, Florida, USA, between October 2020 and October 2022. We detected spotted skunks at 5 sites during camera surveys and 2 sites during detection dog surveys. No significant difference in detection probability was observed between tree‐mounted and enclosed cameras or between camera surveys and detection dog surveys. Detection probability was low for all survey methods (min–max = 0.20–0.22), but similar probabilities indicated that the methods could be used interchangeably to best fit a particular site or study design. However, there were notable differences between lures; weasel paste and rabbit urine had a similar initial detection probability, but detection probability for weasel paste declined quickly after application, while detection probability for rabbit urine remained relatively stable throughout the survey period. In general, detection probability decreased over time after camera setup and during summer months. We provide recommendations for spotted skunk surveys, including how a combination of methods can be used for a more comprehensive approach to detecting the species.
