Phylogenetic Analysis of the Socioecology of Neotomine-Peromyscine Rodents

This chapter focuses on the breeding systems of Neotomine-Peromyscine rodents. There are three specific objectives to this chapter. First, we describe the patterns for major Neotomine-Peromyscine clades using data collected from the literature (table 6.1). Second, we examine data from the literature on the following breeding behaviors: male spacing, female spacing, relative intersexual home range/territory size, paternal care, and juvenile dispersal patterns. We examine breeding behavior data in a phylogenetic framework to test if any phylogenetic patterns emerge in the observed variation in these breeding behaviors and if relationships occur among these behaviors. Third, we examine in a phylogenetic framework whether dietary, physiological, or life-history characteristics of the taxa are able to explain the observed variation in these breeding behaviors

Peromyscus boylii (Rodentia: Cricetidae)

Peromyscus boylii (Baird, 1855), the brush deermouse, is a common cricetid rodent in the southwestern United States and Mexico. It is a member of the Peromyscus boylii species group and has had a complicated taxonomic history because many former subspecies have been elevated to species. It is a medium-sized Peromyscus with small ears and a long, slightly bicolored and slightly haired tail that ends in a tuft of long hairs. It prefers brushy habitat, showing an affinity for oak–scrub oak and canyon–creek bottoms. It is not of special conservation concern

Altered Understory Characteristics Affect Spatial and Foraging Behaviors and Reproduction Patterns

Understanding how changes to habitat characteristics affect behaviors is necessary to integrate biodiversity goals with land management. Managed forests are a significant landscape component in the southern United States and provide opportunities for conservation alongside production of wood products. We investigated behavioral responses of rodents to differences in understory habitat characteristics from intercropping switchgrass (Panicum virgatum), a native biofuel feedstock, in intensively managed loblolly pine (Pinus taeda) stands. Previous research indicated that planting switchgrass increased rodent population abundance but reduced recruitment and community diversity. To understand potential mechanisms underlying our previous results, we measured behaviors of individual cotton rats (Sigmodon hispidus), a grassland specialist, to planted switchgrass. We hypothesized that female territory size, foraging activity, overlap with other adult females, and reproduction indices would differ among treatments (switchgrass monocrop, intercropped switchgrass, and control plots) due to variation in grass abundance and vertical vegetation cover. We conducted live-trapping, radio telemetry, and foraging activity surveys on cotton rats during summers of 2013–2015. We found no treatment effect on territory size, but foraging activity was 2 times higher in monocrop than control plots. We also found a positive relationship between female spatial overlap and percentage of grass in control plots and evidence for higher reproductive indices in control than monocrop plots. Our results suggest that cotton rats in monocrop plots exhibited unexpected behaviors, and monocrop plots may serve as population sinks with low rodent diversity. Overall, results from this replicated experiment suggested that intercropping provides adequate food and cover to maintain rodent populations and produce forest products

Impact of predation risk on emergence by little brown bats, Myotis lucifugus (Chiroptera: Vespertilionidae), from a maternity colony.

When bats emerge from their roosts in the evening to forage and drink, it appears as though their departure involves brief periods when many individuals emerge interspersed with periods during which few individuals emerge. Clustering is seen in many species of animals and probably has an anti-predator or information-transfer function. Regardless of its function, clustering in the emergence of bats may intensify as a result of large numbers of individuals trying to pass through a small exit hole in a short period of time. A total of 31 observations of emergence were made from May to Aug. 1992 and 1993 at a maternity colony of little brown bats (Myotis lucifugus), in Cypress Hills, Saskatchewan, Canada. To determine the effects of a predator on clustering in the emergence, a plastic great horned owl (Bubo virginianus) was used as a predator model and mounted close to roost exits on 8 nights. Recorded calls of a great horned owl were played back towards the roost. The predator model and associated calls did not affect the number of bats that emerged, the median time of emergence, or the degree of clustering in the emergence. There was a significant positive relationship between the extent of clustering in the emergence and the number of bats that emerged. Emergences of more than 25 bats were clustered. Thus, we found no evidence to support clustering during emergence as being an anti-predator response. However, clustering may be intensified with increased numbers of individuals trying to pass through a narrow space in a short period of time

Female and male adult brush mice (Peromyscus boylii) use ultrasonic vocalizations in the wild

We examined the individual context of ultrasonic vocalizations (USVs) produced by free-living wild male and female adult brush mice (Peromyscus boylii). We tested the hypothesis that USV production is dependent on behavioral context, and is important during both adult male and female interactions. Our methods included a 12-channel microphone array, radio-telemetry and thermal imaging that allowed us to determine: (1) who produced USVs, (2) characteristics of USVs, (3) type of USVs, (4) behavioral context of USVs and (5) the identity of the second mouse if an individual was not alone when a USV was produced. Females vocalized as much as males and produced the same types of USVs as males. There were no differences between spectral characteristics of male and female USVs. Females and males vocalized in the presence of one another. Importantly, when females were together they vocalized more than expected based on the proportion of time they spent together. Our results suggest that, in addition to facilitating courtship and mating, USVs are general territorial calls for neighbors because females vocalized in the presence of their neighbors. Despite a large literature on laboratory mouse (Mus musculus) USVs, studies are heavily biased towards males. Our results on brush mice, a species with a similar breeding system to the lab mouse and other rodents, suggest that female-female communication is an important and underappreciated component of the evolution and maintenance of mouse USVs

Use of modified water sources by bats in a managed pine landscape

In eastern North Carolina, USA, intensively managed pine (Pinus spp.) forests, a primary forest type in the Southeastern United States, often are established where water levels are maintained via ditching. In these landscapes, water occurs in numerous linear ditches and several small ponds (heliponds), used by helicopters for the suppression of forest fires. Changes to the physical structure of water sources may be important to bats that use these sources for drinking and foraging. Therefore, we examined bat activity in a managed pine landscape and an adjacent natural wetland in relation to water source type (heliponds, ditches, and natural wetland) and insect abundance. We sampled bat activity using remote acoustic detectors; we sampled insects using passive traps. Insect abundance did not differ among water source types. Bat activity was most concentrated at modified water sources within the managed pine landscape (heliponds and ditches). Feeding activity was highest at heliponds. Heliponds and ditches were important sources of open water and insect prey for bats in the managed pine forest landscape. We suggest management for bats in similar forest landscapes should include maintenance of open and accessible water sources such as heliponds

Anthropogenic noise decreases activity and calling behavior in wild mice

Background Animals rely on sound to mediate a myriad of daily activities, and anthropogenic noise is a pollutant that alters the natural soundscape within which they are active. As human infrastructure expands, broadband anthropogenic noise increases, which can affect behaviors of free-living nocturnal animals. Mice are nocturnal animals that produce ultrasonic calls as part of their behavioral repertoire. Methods We assessed effects of anthropogenic and natural noise on the behaviors of wild deer mice (Peromyscus maniculatus) and woodland jumping mice (Napaeozapus insignis), two species of mice that produce ultrasonic calls. We measured activity, foraging behavior at a foraging tray, and calling behavior to broadcasts of natural and anthropogenic noise, compared to a baseline with no broadcasting, at 25 focal areas in the Southern Appalachian Mountain Range of North Carolina, USA. Results Deer mice exposed to anthropogenic noise spent less time in focal areas with broadcasted anthropogenic noise. Mice took longer to begin foraging in the presence of anthropogenic noise, they spent less time at the foraging tray, and left fewer husks but consumed the same number of seeds as mice exposed to natural noise. Deer mice were less likely than woodland jumping mice to be the first to enter the focal area and approach food when in the presence of anthropogenic noise. Both species produced few ultrasonic calls in the presence of broadcasted natural and anthropogenic noise compared to their baseline level of calling. We present the first calls recorded from woodland jumping mice. Conclusion Anthropogenic noise affects activity, foraging behavior, and calling behavior of nocturnal mice. Natural noise also affects the calling behavior of mice. Mouse species respond differently to anthropogenic noise, with deer mice appearing more sensitive to anthropogenic noise than woodland jumping mice. Responses to noise could have important effects on the ecology of mice and these two species respond differently. Species differences should be considered when mitigating the effects of noise in conservation ecology

Bat Ecology [book review]

A broad review of bat ecology is timely because of advances over the past two decades in the technical approaches to the study of bats in an ecological and evolutionary framework. These advances include, but are not limited to, a range of ultrasonic detection methods, radio-telemetry, transponders, stable isotopes, bio-informatics, and molecular markers. Not surprisingly, since the publication of the Ecology of Bats (Kunz, 1982), our knowledge about the field of bat ecology has advanced. Bat Ecology attempts to summarize this advance through a mix of review and analytical chapters. Each chapter provides some historical perspective as well as highlights recent advances and suggests future directions. The editors divide the book into three main sections: Life History and Social Biology, Functional Ecology, and Macroecology. Within each of these sections are chapters written by authorities in the field

Can External Radiotransmitters be used to Assess Body Temperature and Torpor in Bats?

We tested externally applied, temperature-sensitive, radiotransmitters for determining the body temperature of big brown bats (Eptesicus fuscus) in various ambient temperatures (2- 260C). There was a slight, but significant, effect of ambient temperature on skin temperature (measured by the transmitters), but skin temperature accurately reflected rectal temperature in torpid and active bats, and it was never >3.30C below rectal temperature. External radiotransmitters are, thus, useful in studies of torpor in bats, even when only small decreases in body temperature occur

Secondary Use of Aspen Cavities by Tree-Roosting Big Brown Bats

To further explore natural roost-site selection by temperate bats, we examined the use of tree roost sites by big brown bats (Eptesicus fuscus) in the West Block of Cypress Hills Provincial Park, Saskatchewan, an area where the number of human structures is limited. In this area, we found big brown bats roosted exclusively in cavities of trembling aspen trees (Populus tremuloides), despite the availability of cavities in snags of conifer trees. Most cavities had been excavated and previously used by yellow-bellied sapsuckers (Sphyrapicus varius). The use of aspens by sapsuckers relates to the relatively soft wood and susceptibility to heart rot of these trees, which provide ideal conditions for nesting: decayed heartwood with a firm sapwood shell. Orientation of cavity entrances was close to due south. The width of bats and the width of cavity entrances differed, suggesting that bats are not using roosts for protection from predators or exclusion of competitors. Bats showed fidelity to a particular group of roost trees because, despite roost switching, bats reunited in subsequent roost sites. During the day, temperatures in aspen cavities were approximately 50C cooler than in cavities of conifer snags. Microclimate differences, including temperature, may be why aspen cavities are selected over available cavities in conifer snags. All of the randomly selected cavities in aspen that we searched showed evidence of use by bats, which suggests roost sites for big brown bats in southwestern Saskatchewan may be a limiting resource