0000000000054628
AUTHOR
Jana A. Eccard
showing 18 related works from this author
Reducing Mortality of Shrews in Rodent Live Trapping — a Method Increasing Live-Trap Selectivity with Shrew Exits
2013
Shrews have very high metabolic rates and are often unintentionally starved in rodent live-traps during capture-mark-recapture (CMR) studies. Here, we suggest a shrew exit as a modification to rodent traps. To test whether this modification is (1) saving shrews and (2) not jeopardizing results of rodent captures, we compared captures in Ugglan traps with and without shrew exits, studying bank voles (Myodes glareolus) in a spruce forest in central Finland. Numbers of captured bank voles and body size of smallest juvenile bank voles were not affected by the shrew exit, while the number of captured common shrews (Sorex araneus) was reduced from 31 to 0 individuals per 100 trap nights. However,…
How livestock grazing affects vegetation structures and small mammal distribution in the semi-arid Karoo
2000
In this study we investigated vegetation changes superimposed by grazing and their effect on small mammals in the Karoo (South Africa) on grazed farmland and an adjacent, 10-year livestock enclosure. Plains and drainage line habitats were compared by monitoring vegetation height and cover, and small mammal species composition and abundance along transects. Animals were captured by live trapping. Vegetation cover was low on the grazed compared to the ungrazed study site, but vegetation height did not differ. The number of small mammal individuals and the number of species captured was higher at the ungrazed study site. Two species of climbing rodents captured in the ungrazed drainage line we…
Polyandrous females produce sons that are successful at post-copulatory competition.
2014
Some of the genetic benefit hypotheses put forward to explain multiple male mating (polyandry) predict that sons of polyandrous females will have an increased competitive ability under precopulatory or post-copulatory competition via paternally inherited traits, such as attractiveness or fertilization efficiency. Here, we tested these predictions by comparing the competitive ability of sons of experimentally monandrous and polyandrous female bank voles (Myodes glareolus), while controlling for potential material and maternal effects. In female choice experiments, we found no clear preference for sons of either monandrous or polyandrous mothers. Moreover, neither male type was dominant over …
WEASELS’ (MUSTELA NIVALIS NIVALIS) PREFERENCE FOR OLFACTORY CUES OF THE VOLE (CLETHRIONOMYS GLAREOLUS)
2003
Many studies on life history strategies of small mammals under predation risk are based on assumptions that mammalian predators use scent marking from prey in searching and hunting. This is especially true for small mustelids hunting in the tunnels and cavities of their prey. It is assumed that weasels use the estrous signs of female voles as hunting cues, which exposes such females to a more pronounced risk of predation. We studied the preferences of 57 least weasels (Mustela nivalis nivalis) toward odor cues from four different reproductive categories of the bank vole (Clethrionomys glareolus). In the first experiment, weasels selected clearly for vole odors over clean bedding in a Y-maze…
WHO BEARS THE COSTS OF INTERSPECIFIC COMPETITION IN AN AGE-STRUCTURED POPULATION?
2003
Social and density-dependent life history processes may differ according to age and the reproductive history of individuals. Arvicoline rodents have a typical, season-dependent, bimodal, age distribution of breeding individuals within a population. This distribution may influence population fluctuations. In this study, we measured effects of interspecific competition from field voles (Microtus agrestis) on various fitness components of female bank voles (Clethrionomys glareolus) in an age-structured breeding population in large (0.25 ha) outdoor enclosures. We monitored survival, reproduction, and space use of experimental bank vole populations with females from two different age groups. Wi…
Loss of density-dependence and incomplete control by dominant breeders in a territorial species with density outbreaks
2011
Abstract Background A territory as a prerequisite for breeding limits the maximum number of breeders in a given area, and thus lowers the proportion of breeders if population size increases. However, some territorially breeding animals can have dramatic density fluctuations and little is known about the change from density-dependent processes to density-independence of breeding during a population increase or an outbreak. We suggest that territoriality, breeding suppression and its break-down can be understood with an incomplete-control model, developed for social breeders and social suppression. Results We studied density dependence in an arvicoline species, the bank vole, known as a terri…
The Bruce effect revisited: is pregnancy termination in female rodents an adaptation to ensure breeding success after male turnover in low densities?
2017
Pregnancy termination after encountering a strange male, the Bruce effect, is regarded as a counterstrategy of female mammals towards anticipated infanticide. While confirmed in caged rodent pairs, no verification for the Bruce effect existed from experimental field populations of small rodents. We suggest that the effect may be adaptive for breeding rodent females only under specific conditions related to populations with cyclically fluctuating densities. We investigated the occurrence of delay in birth date after experimental turnover of the breeding male under different population composition in bank voles (Myodes glareolus) in large outdoor enclosures: one-male–multiple-females (n = 6 p…
Use of large Acacia trees by the cavity dwelling Black-tailed Tree Rat in the Southern Kalahari
2006
Recent extensive harvesting of large, often dead Acacia trees in arid savanna of southern Africa is cause for concern about the conservation status of the arid savanna and its animal community. We mapped vegetation and nests of the Black-tailed Tree Rat Thallomys nigricauda to assess the extent to which the rats depend on particular tree species and on the existence of dead, standing trees. The study was conducted in continuous Acacia woodland on the southern and eastern edge of the Kalahari, South Africa. Trees in which there were tree rat nests were compared with trees of similar size and vigour to identify the characteristics of nest sites. Spatial analysis of tree rat distribution was c…
Variable mode of estrus affects female decision for multiple mating
2011
Investigating patterns of variation in mating strategies may shed light on their evolutionary importance as well as their impact on the strength and shape of sexual selection. Multimale mating (polyandry) and mate choice are intensely studied subjects in the area of sexual selection, but little is known about intraspecific patterns of variation that may respond to dynamic cost-benefit balances. In a laboratory study, we investigated the mating behavior of female bank voles (Myodes glareolus) with distinctly different time and energy budgets: They were either in cycling estrus (CE) or postpartum estrus (PPE) shortly after delivery. Postpartum mating is highly constrained by time and energy d…
Breeding state and season affect interspecific interaction types: indirect resource competition and direct interference.
2011
Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction in 14 experimental populations of bank voles Myodes glareolus in large outdoor enclosures with and without a dominant competitor, the field vole Microtus agrestis. We further compared vole behaviour using staged dyadic encounters in neutral arenas in both seasons. Survival of the non-breeding over…
State-dependent foraging: lactating voles adjust their foraging behavior according to the presence of a potential nest predator and season
2015
Parental care often produces a trade-off between meeting nutritional demands of offspring and the duties of offspring protection, especially in altricial species. Parents have to leave their young unattended for foraging trips, during which nestlings are exposed to predators. We investigated how rodent mothers of altricial young respond to risk of nest predation in their foraging decisions. We studied foraging behavior of lactating bank voles (Myodes glareolus) exposed to a nest predator, the common shrew (Sorex araneus). We conducted the experiment in summer (high resource provisioning for both species) and autumn (less food available) in 12 replicates with fully crossed factors “shrew pre…
Is reproduction really costly? Energy metabolism of bank vole (Clethrionomys glareolus) females through the reproductive cycle
2007
Energetic requirements during reproduction are important determinants of the onset of reproduction and of breeding strategy (e.g., breeding post-partum) and therefore affect female reproductive output in seasonally varying environments. To balance the energetic needs of breeding with energy availability, females must optimize energy allocation between their own energy use and energy allocated to their litter. Here, we studied energetic costs and potential energetic trade-offs of reproduction in female bank voles (Clethrionomys glareolus). We measured energy consumption, i.e., metabolic rates as determined from carbon dioxide production of females either with their pups (breeding unit) to fi…
Why do female bank voles, Clethrionomys glareolus, mate multiply?
2007
Females of many species actively engage in multiple mating, with either a single male or several males, but the adaptive function of this behaviour is often unclear. We conducted a laboratory experiment on a small mammal species, the bank vole, testing the possible benefits of multiple mating on a female's short-term reproductive success (pregnancy rate, litter size and early postnatal survival). Such benefits may affect a female's fitness either directly or indirectly (genetic benefit). We assigned females to three treatments: a single mating treatment in which females mated once with a single male and two multiple mating treatments in which females mated either twice with a single male or…
SPACE USE, CIRCADIAN ACTIVITY PATTERN, AND MATING SYSTEM OF THE NOCTURNAL TREE RAT THALLOMYS NIGRICAUDA
2004
We present results of a radiotracking study of the black-tailed tree rat Thallomys nigricauda, based on 3 males and 4 females in the breeding season and 2 males and 5 females in the nonbreeding season. The study was conducted in the southern Kalahari thornveld, South Africa, a savanna landscape of acacia trees and patchy acacia bush. Nocturnal activity patterns, vegetation use, space use, and interactions were followed for 8–17 days. During the breeding season, males were active with 2 synchronous activity peaks shortly after sunset and late at night. Home ranges included the nests of 8–10 females, 6 different daytime resting places, and 3–5 areas of high activity. Males were mobile within …
Direct interference or indirect exploitation? An experimental study of fitness costs of interspecific competition in voles
2002
Studies on competing mammalian species in the past have focused mainly on the competitive exclusion of one species from the preferred habitat of the other. Investigations on effects of competition and coexistence on individual fitness are rare. In this study we were able to measure effects of interspecific competition on major fitness components, using a system with two vole species in asymmetric competition. Survival, reproduction and space use of bank vole Clethrionomys glareolus females were monitored in 32 enclosed populations over four replicates of eight parallel run enclosures. Into half of the enclosures we introduced an additional number of field voles Microtus agrestis, a dominant…
Does quality of winter food affect spring condition and breeding in female bank voles (Clethrionomys glareolus)?
2004
We studied the effects of food supplementation on 16 bank vole populations in spring. We manipulated food quantity and quality in eight populations that were enclosed and eight other populations th...
Costs of coexistence along a gradient of competitor densities: an experiment with arvicoline rodents
2006
Summary 1 Costs of coexistence for species with indirect resource competition usually increase monotonically with competitor numbers. Very little is known though about the shape of the cost function for species with direct interference competition. 2 Here we report the results of an experiment with two vole species in artificial coexistence in large enclosures, where density of the dominant competitor species (Microtus agrestis) was manipulated. Experimental populations of the subordinate vole species (Clethrionomys glareolus) were composed of same aged individuals to study distribution of costs of coexistence with a dominant species within an age-cohort. 3 Survival and space use decreased …
Long-term fitness benefits of polyandry in a small mammal, the bank vole Clethrionomys glareolus.
2008
Polyandry, i.e. mating with multiple males within one reproductive event, is a common female mating strategy but its adaptive function is often unclear. We tested whether polyandrous females gain genetic benefits by comparing fitness traits of monandrous (mated twice with a single male) and polyandrous (mated twice with two different males) female bank volesClethrionomys glareolus. We raised the offspring in the laboratory until adulthood and measured their body size, before releasing them to outdoor enclosures to overwinter. At the onset of the breeding season in the following spring, we found that offspring of polyandrous females performed significantly better at reproduction than those o…