Jeremy A. White

The Problem of Low Agreement among Automated Identification Programs for Acoustical Surveys of Bats

Abstract. We compared 4 programs designed to identify species of bats from their echolocation calls (Bat Call ID, EchoClass, Kaleidoscope Pro, and SonoBat) using field data collected in Nebraska, USA (29,782 files). Although we did not know the true identity of these bats, we could still compare the pairwise agreement between software packages when identifying the same call sequences. If accuracy is high in these software packages, there should be high agreement in identification. Agreement in identification by species averaged approximately 40% and varied by software package, species, and data set. Our results are not consistent with the high accuracy often claimed by some software packages and may be a warning about the importance of understanding accuracy of acoustical identification in designing ecological experiments and interpreting results.

Summer Burrows of Ord's Kangaroo Rats (Dipodomys ordii) in Western Nebraska: Food Content and Structure

ABSTRACT. Extent of larder hoarding differs among species of kangaroo rats, and limited information is available for food stored in burrows by Ords kangaroo rat (Dipodomys ordii)—the most widespread species of Dipodomys. I excavated 9 burrows recently used by adult D. ordii during summer in the Sandhill Region of Nebraska. I observed only small quantities of food stored in burrows. Eight of 9 burrows contained segments of sand dropseed (Sporobolus cryptandrus) in limited quantities. These segments consisted of upper leaves with fruits (containing seeds) housed in sheaths. My observations represent the first documentation of D. ordii storing food in burrows under natural conditions. Compared to the burrows of other species of kangaroo rat, burrows of D. ordii were simple in structure with 1 main tunnel and 1–3 entrances. In summer, Ords kangaroo rats commonly harvest seeds from plants in the Sandhill Region of Nebraska, but individuals apparently do not store large quantities of food in burrows, which suggests they store food in scatter hoards during this season.

Seasonal Differences in Onset of Surface Activity of Ord's Kangaroo Rat (Dipodomys ordii)

Abstract Activity patterns of many nocturnal mammals are synchronized to daily cycles of light and dark. Light intensity is an important cue for nocturnal mammals because of the interplay between illumination and risk from visual predators. Studies suggest that nocturnal rodents are at greater risk from visually oriented predators before full darkness than after full darkness. We examined onset of surface activity of Ords kangaroo rat (Dipodomys ordii) over 3 seasons in central Nebraska. To determine surface activity, we used a nonobtrusive procedure—buried timers near burrows. Although initiation of aboveground activity was significantly correlated with sunset from season to season, mean onset of surface activity differed among seasons: 1 min before the start of full darkness in summer, 4 min before full darkness in autumn, and 15 min after full darkness in winter. Despite apparent costs of emerging before darkness, 61% of kangaroo rats in summer and 63% in autumn emerged before full darkness. In winter, however, only 19% of kangaroo rats began surface activity before full darkness. We suggest that emergence behaviors of nocturnal rodents from daytime shelters are plastic and probably linked to seasonal trade-offs between costs of predation and benefits of reproduction and food abundance.

Acoustic Detection Reveals Fine-Scale Distributions of Myotis lucifugus, Myotis septentrionalis, and Perimyotis subflavus in Eastern Nebraska

Abstract. Before white-nose syndrome arrives in Nebraska, it is important to document the preexposure distributions of cave bats in the state. We examined the distributions of Myotis lucifugus (little brown myotis), Myotis septentrionalis (northern long-eared myotis), and Perimyotis subflavus (tri-colored bat) in eastern Nebraska by setting acoustic detectors for a single night at 105 sites in wooded habitats during summers of 2012 and 2014. We compared 2 methods of determining presence at each site. Results of our analyses are fine-scale distributional maps for these bats and some range extensions from published records. Results for M. septentrionalis and P. subflavus are largely consistent with previous reports. Results for M. lucifugus vary depending on the method of determining presence; however, our preferred method creates a pattern consistent with the known vouchered distribution of this species. The differences between published distributions of these species and distributions based on acoustic detection from our study might result from a lack of extensive netting in many areas of eastern Nebraska, underrepresentation of P. subflavus from mist net surveys in Nebraska, and a recent westward range expansion of P. subflavus and M. septentrionalis in southern Nebraska.