Population ecology of small mammals in clear cut areas of western Newfoundland and their short-term response to prescried burning

Nichols, Rina Kathryn (1995) Population ecology of small mammals in clear cut areas of western Newfoundland and their short-term response to prescried burning. Masters thesis, Memorial University of Newfoundland.

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Abstract

A study of small mammals was conducted from May to September 1994 in a heavily logged area in western Newfoundland, Canada. This study consisted of two main projects: 1) an ecological study of a population of small mammals with emphasis on meadow voles, Microtus pennsylvanicus. 2) a study of the short-term response of small mammals to prescribe burning. Both populations were studied via live-trapping and telemetry. -- The first project examined a population of small mammals on a 3.2 ha plot established in a 9-year-old clearcut. Three main habitat types were present in the plot: forest regeneration which comprised 89 percent of the area, and relatively small percentages of clearings and moist meadow patches. Three species were captured on the site during the study: meadow vole (Microtus pennsylvanicus), masked shrew (Sorex cinereus) and deer mouse (Peromyscus maniculatus). Only three Peromycus were captured over the four months of the study and Sorex were difficult to live-trap, therefore efforts were focused on meadow voles. Thirteen resident female Microtus, five adults and 8 eight juveniles, were radio-collared from June until late August 1994. -- Survival, recruitment and density of meadow voles peaked in June and then decreased to very low numbers in the fall. Density of voles in western Newfoundland were lower than those reported for continental vole populations. Only six percent of juvenile voles showed signs of sexual maturity in the summer of their birth. Several juveniles were sixty to ninety days old and still were not reproductively active. Microtus exhibited strong preference for the moist meadow patches in the 9-year-old clearcut. Seven of the eight juveniles radio-collared had a portion of their home range in the meadow habitat. Four of the five adults were located in the meadow or moist patches during excursions away from the nest. Plant species highly palatable to voles, as revealed by a food preference test, were most abundant in the small meadow areas. The highly palatable species could not be predicted by nitrogen concentration, phenol concentration or the ratio of nitrogen to phenols. The forage selection patterns of voles in western Newfoundland are still unknown. -- Space use of female voles in this study tended to differ from other vole populations. Periphery home range size and interfix distance were larger than those reported in the literature for similar species. Core home range sizes were smaller for adult females than juveniles females in the study area. Female voles tended to travel longer distances in the late morning than early morning possibly due to increased predator activity at dawn. -- The second project was an experimental manipulation study designed to examine the short-term response of small mammals to prescribed burning with an emphasis on the role of cover in this response. The design consisted of three treatments: prescribed burn, prescribed burn plus cover and control. Each treatment consisted of two 0.81 ha plots established in a two year-old clearcut. All treatment plots were placed at least 75 meters apart to ensure that animals did not move between plots. Plots were established in August 1994 and trapped for a week to ensure small mammals were present in the area. In September 1994, the burn and burn plus cover treatments were burned by Newfoundland Forest Service personnel. Following the burn, the burn plus cover plots were homogeneously covered with slash consisting of branches and tree tops with no living vegetation. The two remaining plots were left unburned to serve as controls. -- Three small mammal species were captured on the study area: meadow vole (Microtus pennsylvanicus), masked shrew (Sorex cinereus) and deer mouse (Peromyscus maniculatus). All species were relatively low in abundance. Almost twice as many voles were captured on the burn plus cover treatment than the burn or control treatments, however there was high variation within treatments. The length of time a vole remained on a plot did not vary between treatments. The catch per unit effort of Sorex was significantly higher on control plots than the burn or burn plus cover plots. Overall Peromyscus numbers were too low for comparisons between treatments. -- The Braun-Blanquet method of vegetation surveying revealed that herbaceous cover and total number of plant species were significantly lower on the burn plots than the control plots. Palatable cover was lower on the control plots relative to the burn and burn plus cover plots. The only habitat variable which differed between burn and burn plus cover plots was slash cover thereby validating this study as testing for the effects of cover independantly of food. Nutrient analysis revealed that nitrogen concentration was significantly higher in plant species on the burn and burn plus cover plots than the control plots. -- Four female voles were radio-collared for this second project. Females established home ranges on the control and burn plus cover sites, but not on the burn sites suggesting that cover is an important factor determining vole distribution. Three of four females established their home ranges in fairly close proximity to a small moist meadow similar to the spacing patterns exhibited by voles on the 9-year-old clearcut. Female Microtus on both study areas distributed themselves in relation to highly palatable plant species.

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