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

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

Estimating biomass of berries consumed by gray wolves

Gray wolves (Canis lupus) consume berries and other wild fruits seasonally when available or abundant. However, a method to convert percent frequency of occurrence or percent volume of berries in wolf scats to percent biomass has not yet been developed. We used estimates of the average number of blueberry (Vaccinium spp.) seeds in 10 individual wolf scats collected in and adjacent to Voyageurs National Park, Minnesota, USA, along with published values of the number of seeds per blueberry and blueberry masses to estimate that a wolf scat containing only berries equated to an average of 0.468 kg of berries consumed. We recommend using this berry conversion factor (0.468 kg/scat) to convert the percent frequency of occurrence or percent volume of berries and other wild fruits to percent biomass when estimating wolf diets from scats

Where and How Wolves (Canis lupus) Kill Beavers (Castor canadensis)

Beavers (Castor canadensis) can be a significant prey item for wolves (Canis lupus) in boreal ecosystems due to their abundance and vulnerability on land. How wolves hunt beavers in these systems is largely unknown, however, because observing predation is challenging. We inferred how wolves hunt beavers by identifying kill sites using clusters of locations from GPS-collared wolves in Voyageurs National Park, Minnesota. We identified 22 sites where wolves from 4 different packs killed beavers. We classified these kill sites into 8 categories based on the beaver-habitat type near which each kill occurred. Seasonal variation existed in types of kill sites as 7 of 12 (58%) kills in the spring occurred at sites below dams and on shorelines, and 8 of 10 (80%) kills in the fall occurred near feeding trails and canals. From these kill sites we deduced that the typical hunting strategy has 3 components: 1) waiting near areas of high beaver use (e.g., feeding trails) until a beaver comes near shore or ashore, 2) using vegetation, the dam, or other habitat features for concealment, and 3) immediately attacking the beaver, or ambushing the beaver by cutting off access to water. By identifying kill sites and inferring hunting behavior we have provided the most complete description available of how and where wolves hunt and kill beavers

The role of forage availability on diet choice and body condition in American beavers (\u3ci\u3eCastor canadensis\u3c/i\u3e)

Forage availability can affect body condition and reproduction in wildlife.Weused terrestrial and aquatic vegetation sampling, stable isotope analysis, and livetrapping to investigate the influence of estimated forage biomass on diet, body condition, and reproduction in American beavers (Castor canadensis) in the Namakan Reservoir, Voyageurs National Park, Minnesota, USA, May 2008–September 2009. Available terrestrial and emergent aquatic forage varied greatly among territories, but floating leaf aquatic forage was low in abundance in all territories. Variation in estimated biomass of available emergent and terrestrial vegetation did not explain variation in respective assimilated diets, but variation in floating leaf vegetation explained 31% of variation in assimilated floating leaf diets. No models using available vegetation explained variation in body condition. Body condition of individual females in spring did not affect kit catch per unit effort, and overwinter body condition of subadults and adults was similar between territories with and without kits. We found no evidence that available aquatic vegetation affected beaver body condition or fitness. Available forage may be above minimum thresholds to detect differences in diet choice or body condition. Other factors such as water level fluctuations or climatic variables may also explain variation in beaver body condition

A management model for Cercospora leaf spot of sugarbeets

1 online resource (PDF, 8 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Using Beaver Works to Estimate Colony Activity in Boreal Landscapes

Beaver ponds and beaver-impounded vegetation are indicators of past or present beaver activity that can be detected from aerial photography. A method to quantitatively relate these beaver works with the density of active beaver colonies could benefit beaver management, particularly in areas lacking beaver population data. We compared historical maps (1961–2006) of beaver works at Voyageurs National Park, Minnesota, USA with concurrent aerial surveys of beaver colonies. We tested 2 landscape-scale models of beaver colony density previously developed for a period of beaver population expansion (1940–1986), but they failed to predict colony density after 1986, a period of declining beaver population. We developed a new landscape-scale regression, calculating that 2.15% of the landscape would be flooded by every 100 additional beaver colonies (R2 = 0.53, P = 0.027). Classification tree analysis of individual pond sites showed that open water pond and impounded marsh area were the primary predictors of beaver colony presence or absence, but that the classification trees were far better at identifying inactive sites (\u3e 93% correct) than active sites (35–38% correct). The area of open water in beaver ponds is a good but not perfect indicator of beaver activity that can be used by wildlife managers as a landscape-scale indicator of beaver colony density

Analysis of the nonlinear reverberation of titanium alloys fatigued at high amplitude ultrasonic vibration

6 pages.-- PACS nr.: 81.40.-Z.-- Communication presented at: Forum Acusticum Sevilla 2002 (Sevilla, Spain, 16-20 Sep 2002), comprising: 3rd European Congress on Acoustics; XXXIII Spanish Congress on Acoustics (TecniAcústica 2002); European and Japanese Symposium on Acoustics; 3rd Iberian Congress on Acoustics.-- Special issue of the journal Revista de Acústica, Vol. XXXIII, year 2002.The strong amplitude dependence of material parameters of microinhomogeneous materials can be used to link observations of nonlinearity to micro-scale damage. We have measured the amplitude dependence of the resonance frequency and damping characteristics in the reverberation field of the fundamental eigenmode of titanium alloy samples at regular instances during dynamic fatigue loading at high strains. The analysis of the reverberation is performed in the frequency domain using classical time-windowed FFT, as well as in the time domain using analytical functions with iteratively optimised parameters over each time window. The results show a significant increase of the nonlinearity in the frequency and damping characteristics of the signals observed during the fatiguing process.The authors would like to thank the ESF organisation for support of this research in the frame of the PESC-program NATEMIS (www.polito.it/research/natemis/).Peer reviewe

Finding wolf homesites: improving the efficacy of howl surveys to study wolves

Locating wolf (Canis lupus) homesites is valuable for understanding the foraging behavior, population dynamics, and reproductive ecology of wolves during summer. During this period wolf pack members (adults and pups) readily respond to simulated wolf howls (i.e., howl surveys), which allows researchers to estimate the location of the homesite via triangulation. Confirming the actual locations of homesites via ground truthing is labor intensive because of the error surrounding estimated locations. Our objectives were (1) to quantify observer error during howl surveys and compare amongst experience levels, (2) provide a simple method for locating homesites in the field by incorporating observer error, and (3) further document the value of this method for monitoring wolf packs throughout the summer. We located 17 homesites by howl surveys during 2015–2017 in the Greater Voyageurs Ecosystem, Minnesota, USA. Of 62 bearings taken by observers during howl surveys, bearings erred by an average of 7.6° ± 6.3° (SD). There was no difference in observer error between novice and experienced observers. A simple way to increase efficiency when searching for homesites is to search concentric areas (bands) based on estimated observer error, specifically by: (1) adding ±10° error bands around howl survey bearings when ≥3 bearings can be obtained, (2) ±10° and ±20° error bands when 2 bearings are obtained, and (3) ±10° and ±26° error bands when 1 bearing is obtained. By incorporating observer error and understanding how frequently and how far wolves move homesites, it is possible to monitor wolf packs and confirm most, if not all, homesites used by a pack from at least June until August without having a collared individual in a pack

FINE-SCALE TEMPERATURE PATTERNS IN THE SOUTHERN BOREAL FOREST: IMPLICATIONS FOR THE COLD-ADAPTED MOOSE

Moose (Alces alces) respond to warm temperatures through both physiological and behavioral mechanisms. Moose can reduce heat load via habitat selection when spatial and temporal variation exists within the thermal environment. We recorded operative temperatures (To) throughout the Kabetogama Peninsula of Voyageurs National Park, Minnesota for 1 year to describe seasonal patterns in the thermal environment available to moose and identify physical and landscape characteristics that affect To in southern boreal forests. Significant predictors of To varied by season and time of day and included vegetation cover type, canopy cover, and slope/aspect. Vegetation cover type influenced To during summer and fall afternoons with additional variation during summer afternoons explained by percent canopy cover. Slope/aspect was the main driver of To during winter and spring afternoons. Slope position was not a significant predictor of temperature, likely because of low topographic relief in our study area. The Tos were significantly warmer in open versus closed habitats during the day with the pattern reversed at night. Our results can be used to test if moose display a behavioral response to To at various spatial and temporal scales