Resource Partitioning By Sympatric Brown And American Black Bears

Thesis (Ph.D.) University of Alaska Fairbanks, 2006The fundamental niche of a species is rarely if ever realized because the presence of other species restricts it to a narrower range of ecological conditions. Additionally, distribution theory predicts that for two competing species living in sympatry, the subordinate species will be constrained from optimal resources. This constraint would result in use of lower quality resources by the subordinate species and possible spatial segregation from the dominant species. I evaluated diet in relation to body condition and reproduction for sympatric brown bears (Ursus arctos) and American black bears (U. americanus) in southcentral Alaska during 1998-2000, and assessed spatial segregation and habitat selection in 2000. Based on isotopic analysis, salmon (Onchorhynchus spp.) predominated in brown bear diets (>53% annually) whereas black bears assimilated 0-25% salmon annually. Black bears did not exploit salmon during 1998, a year with below average spawning numbers, probably because brown bears deterred black bear access to salmon. Enhanced body condition (as indexed by increased percent body fat) from salmon consumption resulted in better body condition the following spring. Further, black bear reproduction was directly related to body condition; reproductive rates were reduced when body condition was poorer. Analyses of radio location data confirmed that 24-hour monitoring of bears was necessary to determine habitat use and that habitat use varied seasonally. Black bears avoided areas occupied by brown bears during summer, supporting the ideal despotic distribution model. In contrast, black bears selected areas where brown bears were present during spring, presumably because of spatially-restricted (i.e., restricted to low elevations) but dispersed availability of food. Similarities in preferred and potentially limited resources resulted in co-occupancy of areas at intermediate to coarse spatial resolutions; however, spatial avoidance of brown bears and black bears influenced population-level use of resources. Further, the realized niche of black bears was constrained by brown bears through partitioning of food resources, which varied among years. Reduced access to salmon caused black bears to forage more extensively in areas containing less nutritious food, resulting in lowered body condition and subsequent lowered reproduction. Coexistence of these species in this study area appears dependent on the distribution, abundance, and availability of salmon and berries

Comparison of Two Hair Snares for Raccoons

Author Institution: National Parks Service, Pictured Rocks Science CenterWe developed two types of snares incorporating barbed wire for obtaining hair samples from raccoons (Procyon lotor) suitable for DNA analyses. The hair snares were a wood box with a single strand of barbed wire positioned 20 cm above the lower edge of the entrance and a 5 gallon bucket with 2 strands of barbed wire in an inverted ‘V’ position. Snares were placed from August to November 2005 along forested roads in the central Upper Peninsula of Michigan. Both hair snares collected samples suitable for DNA analyses; however, the number of hair samples collected/100 snare nights was greater (P < 0.001) for bucket snares (n = 36) than for wood box snares (n = 5). Capture efficacy was also greater (P = 0.013) for bucket snares (91%, n = 35) than for box snares (68%, n = 44). The overall number of hairs collected at bucket snares was greater (P = 0.021) than the number of hairs collected at wood box snares. Barbed wire was an effective medium for obtaining hair samples from free-ranging raccoons. Because of greater performance, low cost, and ease of construction, we recommend use of bucket snares over wood box snares

Efficacy of a Multiple-Capture Live Trap for Small Mammals

Author Institution: National Park Service, Pictured Rocks Science CenterAuthor Institution: School of Forest Resources & Environmental Sciences, Michigan Technological UniversityWe compared the efficacy of Victor® Tin Cat® and Sherman live traps for capturing small mammals in northern hardwood and red pine (Pinus resinosa) stands in the north-central Upper Peninsula of Michigan during 2001. Overall mean capture rates (total captures/100 adjusted trap nights) by habitat were greater (P <0.030) for Sherman traps than for Tin Cat traps. Capture rates remained lower for Tin Cat traps in northern hardwood (P = 0.004) but not red pine (P = 0.936) habitat after adjusting for species (sciurids) unable to enter them. Greater species diversity values were obtained using Sherman traps in both habitats. We conclude that in sampling arrays tested, Victor Tin Cat traps were less effective than Sherman traps for estimating small mammal abundance and diversity

MIGRATION AND DISPERSAL OF LAUGHING GULLS IN THE UNITED STATES

The 3662 recovery records for Laughing Gulls (Larus atriczlla) banded in North America from 1924 to 1991 were analyzed to determine migration and dispersal patterns for Northeast (Maine to Virginia) and Gulf Coast (west coast of Florida to Texas) populations. Autumn migration for Northeast Laughing Gulls was initiated in October. Northeast Laughing Gulls migrated greater distances and were recovered farther south during winter than Gulf Coast gulls. Significantly more Gulf Coast Laughing Gulls wintered along the Gulf Coast than did Northeast Laughing Gulls. In contrast, significantly more Northeast Laughing Gulls wintered in Central and South America. Adult Laughing Gulls returned to breeding areas between March and May. Sixty-four percent of adult recoveries during subsequent breeding seasons were within 50 km of their natal banding locations. Significantly more Laughing Gulls were recovered north of their natal banding location than south during subsequent breeding seasons. Autumn dispersal of hatching-year Laughing Gulls was characterized by northward movements before migration. There was little interchange between Northeast and Gulf Coast populations

Small Mammal Abundance and Diversity in Forests With and Without Canada Yew, Taxus canadensis

Canada Yew (Taxus canadensis) has been extirpated from much of its former range in northeastern North America possibly due to logging, fire, agriculture, and browsing by White-tailed Deer (Odocoileus virginianus). We compared the relative abundance and species diversity of small mammals in five northern hardwood stands containing Canada Yew to five adjacent stands without Canada Yew in the Upper Peninsula of Michigan, during October-November 2000. Overall, 72 individuals were captured (53 in yew, 19 in non-yew); dominant species were Short-tailed Shrew (Blarina brevicauda), Deer Mouse (Peromyscus maniculatus), and Red-backed Vole (Clethrionomys gapperi). Overall mean (+ sd) capture rate (individuals/100 adjusted trap nights) in sites with yew (5.5 + 2.2) was greater (P = 0.04) than mean capture rate in sites without yew (1.9 + 1.0). Three indices of species diversity suggested greater small mammal diversity in stands with Canada Yew understories in northern hardwood forests

MIGRATION AND DISPERSAL OF LAUGHING GULLS IN THE UNITED STATES

The 3662 recovery records for Laughing Gulls (Larus atriczlla) banded in North America from 1924 to 1991 were analyzed to determine migration and dispersal patterns for Northeast (Maine to Virginia) and Gulf Coast (west coast of Florida to Texas) populations. Autumn migration for Northeast Laughing Gulls was initiated in October. Northeast Laughing Gulls migrated greater distances and were recovered farther south during winter than Gulf Coast gulls. Significantly more Gulf Coast Laughing Gulls wintered along the Gulf Coast than did Northeast Laughing Gulls. In contrast, significantly more Northeast Laughing Gulls wintered in Central and South America. Adult Laughing Gulls returned to breeding areas between March and May. Sixty-four percent of adult recoveries during subsequent breeding seasons were within 50 km of their natal banding locations. Significantly more Laughing Gulls were recovered north of their natal banding location than south during subsequent breeding seasons. Autumn dispersal of hatching-year Laughing Gulls was characterized by northward movements before migration. There was little interchange between Northeast and Gulf Coast populations

Effects of Sex and Age on Winter Diet of American Martens in Michigan

Author Institution: Department of Biology, Northern Michigan UniversityAuthor Institution: Department of Wildlife and Fisheries, Mississippi State UniversityWe investigated whether sex or age influenced winter diet in American martens (Martes americana) from the Upper Peninsula of Michigan by analyzing gut content of 151 individuals trapped during 2000–2004. We identified 433 occurrences of 10 prey species and classified them into six groups based on body size. Overall, marten diets were similar to those reported previously. Proportion of prey groups and kilocalories consumed were generally similar between male and female marten diets, as well as between juveniles and adults. Average dietary breadth (0.46) was comparatively high but within the range reported for other North American studies. Dietary overlap (0.99) was high between males and females and between juveniles and adults. Comparable diets between sexes suggest that size sexual dimorphism was unrelated to prey species consumed. Similarly, diets of juveniles and adults were comparable. Mice and voles occurred most frequently in marten diets; however, squirrels represented the greatest proportion of kilocalories consumed. Future studies of marten diet should emphasize prey abundance

Genetic Tagging Free-Ranging White-Tailed Deer Using Hair Snares

Author Institution: National Park Service, Pictured Rocks Science CenterAuthor Institution: Dept of Agriculture, National Wildlife Research CenterAuthor Institution: Wildlife Genetics InternationalUse of noninvasive DNA-based tissue sampling (e.g., hair, scats) for individual identification in wildlife studies has increased markedly in recent years. Although field techniques for collecting hair samples have been developed for several species, we are unaware of their use with free-ranging ungulates. From December 2004 to August 2005 we evaluated the efficacy of barbed wire for snaring hair samples suitable for genetic analyses from white-tailed deer (Odocoileus virginianus) on trails and at baited sites. During initial trials on a semi-captive deer herd in northern Ohio, deer demonstrated avoidance of barbed wire positioned on game trails through four weeks but entered baited sites with barbed wire in <3 days. Field trials on free-ranging deer in Michigan using two snare configurations at baited sites checked at one-or-two-week intervals also were successful in obtaining hair samples suitable for extracting DNA. Number of hair samples appeared to increase with deer activity. Number of hair samples and amount of hair in individual samples were greater during winter and spring than during summer. Adequate genetic material was present in 98% (n = 53) of samples collected during winter. Obtaining hair samples noninvasively from white-tailed deer has numerous applications including determining natal origin, population monitoring, and density estimates. We recommend use of baited sites encircled with a single strand of 15.5 gauge, four-point, barbed wire 80 cm above ground attached to >3 trees. In treeless areas, metal or wood posts could be substituted. Hair snare height and configuration could be adapted for other ungulate species

Genetic Tagging Free-Ranging White-Tailed Deer Using Hair Snares

Use of noninvasive DNA-based tissue sampling (e.g., hair, scats) for individual identification in wildlife studies has increased markedly in recent years. Although field techniques for collecting hair samples have been developed for several species, we are unaware of their use with free-ranging ungulates. From December 2004 to August 2005 we evaluated the efficacy of barbed wire for snaring hair samples suitable for genetic analyses from white-tailed deer (Odocoileus virginianus) on trails and at baited sites. During initial trials on a semi-captive deer herd in northern Ohio, deer demonstrated avoidance of barbed wire positioned on game trails through four weeks but entered baited sites with barbed wire in \u3c3 days. Field trials on free-ranging deer in Michigan using two snare configurations at baited sites checked at one-or-two-week intervals also were successful in obtaining hair samples suitable for extracting DNA. Number of hair samples appeared to increase with deer activity. Number of hair samples and amount of hair in individual samples were greater during winter and spring than during summer. Adequate genetic material was present in 98% (n = 53) of samples collected during winter. Obtaining hair samples non-invasively from white-tailed deer has numerous applications including determining natal origin, population monitoring, and density estimates. We recommend use of baited sites encircled with a single strand of 15.5 gauge, four-point, barbed wire 80 cm above ground attached to \u3e3 trees. In treeless areas, metal or wood posts could be substituted. Hair snare height and configuration could be adapted for other ungulate species

A simple and improved PCR-based technique for white-tailed deer (Odocoileus virginianus) sex identification

We describe a simple single-reaction technique for identifying the sex of white-tailed deer (Odocoileus virginianus) based on the PCR amplification of a zinc-finger intron using one pair of primers. Although Sry-coamplification confirmed sex identities, use of the Sry marker was unnecessary due to dimorphic alleles on the X and Y chromosomes at the zinc-finger locus. Insertions in intron 7 of the Y-linked allele (417 bp) make it nearly twice as long as the X-linked allele (236 bp) and thus the amplification products are easily discernable by simple agarose gel electrophoresis. The relatively short size of these products makes them useful for DNA-based sex identification from potentially low-yield tissue samples (e.g., hair, feces). This technique will provide ecologists, conservation geneticists and wildlife managers with a mechanism to readily and reliably identify the sex of un- known white-tailed deer tissue samples, and likely similar samples from other cervid species