GROWTH AND DEVELOPMENT RATES OF \u3ci\u3eMicrotus pinetorum\u3c/i\u3e UNDER DIFFERENT PHOTOPERIODS

Photo-period and nutrition are important variables affecting reproductive activity and growth in many rodents. Field and laboratory studies indicate that long photo-period (spring-summer) cause Increased growth while short photo-periods (fall-winter) inhibit these processes. In the montane vole (Microtus montanus) recently weaned animals gain weight at a much lower rate under short photo-periods or in total darkness than under long photo-periods (Vaughan et al., 1973; Peterborg, 1978). Adult M. montanus had more offspring and larger mean litter sizes under LD 18:6 than LD 6:18 (Pinter & Negus, 1965). Similarly, long (LD 16:8) or increasing photo-periods stimulated the onset of puberty in M. arvalis, while short (LD7:17) or decreasing photo-periods inhibited the onset of puberty (Lecyk, 1962). Short photo-periods caused reduced spennato-genesis and seminal vesicle weights in male M. arvalis, while long photo-periods induced increased ovulation in females. In contrast, photo-period had no effect on the reproductive rates of M. orchadensis (Marshall & Wilkinson, 1956). Dicrostonyx groenlandicus reared on LD 6:18 grew faster than those on LD 20:4, but the latter group had larger testes (Hasler, 1975). In M. agrestis, long photo-periods stimulated male reproduction and caused greater body weight gain than did short photo-period. Females produced fewer young, had lower ovarian and uterine weights, and fewer, smaller Graafian follicles under short photo-periods as compared to long. However, there was no effect on female body size (dark & Kennedy, 1967; Breed & Clarke, 1970; Baker and Ranson, 1932). Microtus pennsylvanicus juveniles and adults had higher body weights under LD 18:6 than LD 6:18 (Pistole, 1980). M. oregoni reproductive activity is stimulated by long photo-period, but due to fossorial habits this species appears to be less sensitive to light than more terrestrial forms (Cowan & Arsenault, 1958). There have been no reports of winter breeding in Clethrionomys gapperi possibly because of their behavioral avoidance of light during the winter (Evemden & Fuller, 1972)

No Evidence for a Trade-Off between Reproductive Investment and Immunity in a Rodent

Life history theory assumes there are trade-offs between competing functions such as reproduction and immunity. Although well studied in birds, studies of the trade-offs between reproduction and immunity in small mammals are scarce. Here we examined whether reduced immunity is a consequence of reproductive effort in lactating Brandt's voles (Lasiopodomys brandtii). Specifically, we tested the effects of lactation on immune function (Experiment I). The results showed that food intake and resting metabolic rate (RMR) were higher in lactating voles (6≤ litter size ≤8) than that in non-reproductive voles. Contrary to our expectation, lactating voles also had higher levels of serum total Immunoglobulin G (IgG) and anti-keyhole limpet hemocyanin (KLH) IgG and no change in phytohemagglutinin (PHA) response and anti-KLH Immunoglobulin M (IgM) compared with non-reproductive voles, suggesting improved rather than reduced immune function. To further test the effect of differences in reproductive investment on immunity, we compared the responses between natural large (n≥8) and small litter size (n≤6) (Experiment II) and manipulated large (11–13) and small litter size (2–3) (Experiment III). During peak lactation, acquired immunity (PHA response, anti-KLH IgG and anti-KLH IgM) was not significantly different between voles raising large or small litters in both experiments, despite the measured difference in reproductive investment (greater litter size, litter mass, RMR and food intake in the voles raising larger litters). Total IgG was higher in voles with natural large litter size than those with natural small litter size, but decreased in the enlarged litter size group compared with control and reduced group. Our results showed that immune function is not suppressed to compensate the high energy demands during lactation in Brandt's voles and contrasting the situation in birds, is unlikely to be an important aspect mediating the trade-off between reproduction and survival

Potential Use of Barn Owls to Control Vole Populations in Orchards

The development of control methods for pine and meadow voles in orchard habitats has met with limited success. Though numerous physical, mechanical, and chemical methods have been recommended for limiting vole populations, few have effectively reduced and maintained vole populations at minimal densities for extended periods of time. Though the use of chemicals has been the most effective control method developed it has not resulted in the extinction of pest populations. The initial application of rodenticides frequently causes a significant reduction in pest species, but due to their high intrinsic rate of increase, vole densities quickly rise. Because of high costs many orchard owners can not apply rodenticides frequently enough to continually suppress vole populations. What is needed for effective rodent control therefore, is a means of maintaining low vole populations after an initial rodenticide application. A potential means of achieving such control is through the use of natural predators

HABITAT UTILIZATION AND SPACING PATTERNS OF PINE AND MEADOW VOLES

Pine voles (Microtus pinetorum) and meadow voles (M. pennsylvanicus) co-occur in orchards but may exhibit mutual avoidance through temporal or spatial isolation. Though pine and meadow voles have exhibited overlapping home ranges, individuals of the two species seldom occupy the same 2m area at the same time (Pagano & Madison, 1981). Differences in habitat use by pine and meadow voles may contribute to their spatial separation in orchards. McAnich (1979) found a weak relationship between meadow vole numbers and soil compaction, soil moisture, thatch depth, and light intensity and no relationship between meadow vole occurrence and soil organic matter or cover density. However, Pagano and Madison (1981) report a strong correlation between meadow vole numbers and abundant cover during August. Pine voles exhibited a significant relationship with soil compaction, thatch depth, and light intensity. Studies concerning pine and meadow vole movements and habitat use have monitored established vole populations usually in maintained orchards. This paper reports on the ecological parameters associated with pine vole colonization of an abandoned orchard. Thus, site selection by pine voles and the effect of pine vole movement and establishment on meadow voles could be determined

COLONIZATION OF AN ABANDONED ORCHARD BY PINE VOLES (\u3ci\u3eMicrotus pinetorum\u3c/i\u3e)

Habitat selection by pine voles (Microtus pinetorum) has been attributed to cover density (Goertz, 1971; Paul, 1970) soil condition (Benton, 1955; Fisher and Anthony, 1980), and food resources (Noffsinger, 1976; Paul, 1970). Goertz (1971) reported that pine voles were distributed in diverse habitats, but there was a close correlation with height and diversity of grass. Miller and Getz (1969) found populations in sloping upland woods, Benton (1955) in dry woods, and Paul (1970) in hardwood slopes with a close correlation between distribution and amount of ground cover. Soil type has been examined by Benton (1955) and Fisher and Anthony (1980) and they have shown that pine voles are associated with light soils containing moderate layers of humus. These factors are important to reduce predation, moderate the effect of rain and temperatures, and permit the excavation of fossorial nests and tunnels. Noffsinger (1976) has demonstrated that the amount of digestible energy and availability of food sources were important factors affecting birth and death rates of pine voles when abandoned and maintained orchards were compared. Behavioral characteristics of pine voles have been associated with decreased meadow vole density as pine voles appear to be a more aggressive species (Smith, 1975). Paul (1970) has shown that pine voles appear to replace meadow voles when they are sympatric in favorable habitats. Trapping and telemetry methods indicate that pine voles have low dispersal capacity and home ranges 100 m2 or less in size (Gettle, 1975). All these reports are from established pine vole populations and not from the initial colonizing event and subsequent development of a local population. Therefore, this research project is directed at understanding what site qualities permit pine vole colonization in areas where they have been historically absent, but where its competitor, the meadow vole (Microtus pennsylvanicus), is common

Initial Results of Chemical Inhibitors and Photoperiodic Influences on Growth and Reproduction in \u3ci\u3eMicrotus pennsylvanicus\u3c/i\u3e

Recently Berger et al. (1977) have demonstrated reproductive in¬hibition in Microtus montanus as a result of specific plant compounds in natural vegetation. Naturally occurring cinnamic acids and their related vinyl phenols have been demonstrated to have marked effects on uterine weight, inhibition of follicular development and cessation of breeding activity. Compounds having antigonadotrophic and antithryo-tropic activities have been identified in a wide variety of plants (Chury 1967). Bickoff et al. (1959) report that alfalfa contained a non-estrogenic compound which would over ride the estrogenic effect of the plant estrogen coumestrol. Adler (1962) demonstrated that a non-estrogenic compound in alfalfa could inhibit estrogenic responses of natural animal estrogens. Allison and Kitts (1964) extracted yellow pine needles and demonstrated that they contained a factor which would depress the uterine weight of immature weanling mice thereby delaying sexual maturation. Other investigators have reported similar findings but all failed to identity the compounds producing the effect. Gasser et al. (1963) isolated an inhibitory substance named lithospermic acid and other investigators have demonstrated it deactivates pituitary gonadotrophins in vitro

Driver Bias in Intentional Wildlife-Vehicle Collisions

Expansive road systems have a negative effect on wildlife populations through increased mortality by animal-vehicle collisions. In the United States, an estimated one million vertebrates are killed each day on public roadways. It is unclear what percentage of the mortality is due to intentional collisions. We tested three hypotheses: 1) drivers who intentionally hit wildlife possess species bias, 2) trucks are more likely to intentionally hit wildlife, and 3) the distance from the Murray city center positively affects intentional wildlife-vehicle collisions. A realistic model of a snake and a turtle and a red cup were used for this study. We selected 45 mph roadways located varying distances from the city center. Models and roadways were randomly selected per trial, and data on 50 vehicles were collected. We compared model type, vehicle type, and distance from city center to the number of intentional vehicle hits to determine the presence of a driver bias. Snakes were hit by vehicles significantly more often than turtles or cups. Drivers of cars hit a model significantly less frequently compared with drivers of vans and trucks. Information gained from this study spotlights the factors that influence intentional wildlife-vehicle collisions which can help nature conservationist efforts to mitigate the negative effects of expansive roadway

FIRST Paired ATI Survey 22 Questions

The associated data file contains responses to 22 items of the Approaches to Teaching Inventory. See more about the 16-item and 22-item versions of the instrument in K. Trigwell, M. Prosser, Development and use of the approaches to teaching inventory. Educ Psychol Rev 16, 409-424 (2004).and in K. Trigwell, M. Prosser, P. Ginns, Phenomenographic pedagogy and a revised Approaches to teaching inventory. Higher Educ Res Dev 24, 349-360 (2005).This data file contains results from 20 complete faculty pairs using the 22-item ATI