GPS Technology for Semi-Aquatic Turtle Research

Global positioning system (GPS) telemetry units are now small enough to be deployed on terrestrial and semi-aquatic turtles. Many of these GPS units use snapshot technology which collects raw satellite and timestamp data during brief periods of data recording to minimize size. We evaluated locations from snapshot GPS units in stationary tests and on wood turtles (Glyptemys insculpta) in northeastern Minnesota. Stationary GPS units were placed in wood turtle habitat to evaluate location accuracy, fix success rate, and directional bias. The GPS fix success rate and accuracy were reduced in closed canopy conditions and when the stationary GPS unit was placed under a log to simulate wood turtle hiding behavior. We removed GPS location outliers and used a moving average calculation to reduce mean location error in stationary tests from 27 m (SD = 38) to 10 m (SD = 8). We then deployed GPS units and temperature loggers on wood turtles and collected 122,657 GPS locations and 242,781 temperature readings from 26 turtles from May to September 2015 and 2016. Location outliers accounted for 12% of locations when the GPS receiver was on a turtle. We classified each wood turtle location based on the GPS location and by comparing temperature profiles from river, sun, and shaded locations to the temperature logger on the turtle. We estimated that wood turtles were on land 68% (SD = 12) of the time from May to September. The fix success rate for land locations was 38% (SD = 9), indicating that wood turtles often use habitats with obstructed views of the sky. Mean net daily movement was 55 m (SD = 192). Our results demonstrate that snapshot GPS units and temperature loggers provide fine-scale GPS data useful in describing spatial ecology and habitat use of semi-aquatic turtles

A NOVEL METHOD OF PERFORMING MOOSE BROWSE SURVEYS

We measured browse availability and use along foraging paths of GPS radio-collared moose (Alces alces) in northeastern Minnesota to estimate diet composition and browse species preference. On foraging paths during summer and winter we counted twigs via traditional methods for comparison with a novel method that attempted to better simulate moose foraging behavior. Twigs were collected and used to develop diameter at point of browsing – biomass regressions for each browse species. These regressions, different under open and closed canopy, were used to estimate biomass consumption on foraging paths and to compare 4 approaches. The average diets were similar to previously measured regional diets, and importantly, our data identified variance among individual seasonal diets. Our field method allowed us to better quantify and compare diet composition and browse selection of individual free-ranging moose directly on foraging paths

EFFECTIVE TEMPERATURE DIFFERENCES AMONG COVER TYPES IN NORTHEAST MINNESOTA

Climate is probably one of the ultimate influences on the southern boundary of moose (Alces alces) distribution because moose are sensitive to warm temperatures in both summer and winter. In 4 different cover types in northeastern Minnesota we compared ambient temperatures to black globe temperatures that measures mean radiant temperature of the environment. The 4 cover types were mixed forest, treed bogs, coniferous forest, and deciduous forest that comprised ~85% of home ranges of radio-collared moose in northeastern Minnesota. Ambient temperature measurements taken from a weather station within the study area exceeded assumed physiological thresholds of 14 and 20º C for 50 and 33% of the study period, respectively. Black globe temperatures varied among cover types and temperature differences increased within cover types as ambient temperature increased. The greatest difference between deciduous and conifer cover was 2º C in black globe temperature and occurred during warm periods when skies were clear. The biological significance of these temperature differences is not clear and suggests the presence of alternative cooling mechanisms of cover types, such as water and possibly soil and duff layers acting as heat sinks. Use of these potential alternative cooling mechanisms should be considered in future research

A METHODOLOGICAL COMPARISON AMONG DNA SOURCE TYPES FOR MOOSE GENOTYPING

Population genetic analyses for moose have been based on DNA extracted from blood and other body tissues. Non-invasive sampling of fecal pellets is another potential source of DNA. We compared DNA extraction from blood, liver tissue, and fecal pellet samples from moose in Minnesota and Yellowstone National Park, USA. Extracted DNA from all source types was sufficient for genotyping using 15 microsatellites. DNA extracted from fecal pellets was of lower quality and quantity than DNA extracted from blood and tissue. We provide comparisons of efficiency and effectiveness of DNA extraction protocols for blood, tissue, and fecal pellets, and demonstrate the suitability of using DNA extracted from non-invasively sampled material in moose

MOOSE MODIFY BED SITES IN RESPONSE TO HIGH TEMPERATURES

Moose (Alces alces) employ physiological and behavioral mechanisms to enable them to dissipate excess heat when ambient temperature is above the upper critical temperature of their thermoneutral zone. In this note, we describe 2 cases where GPS radio-collared female moose modified summer bed sites as a potential thermoregulatory response to high temperatures. The first case occurred on 18 - 21 July 2011 when ambient temperatures averaged 25 °C (8 °C above the upper critical temperature of moose) and reached 32 °C and 96% relative humidity. Based on field observations of the bed site immediately after use, the moose cleared litter and duff to expose 3 m2 of mineral soil under a closed-canopy balsam fir (Abies balsamea) stand. The moose spent 64% of the time bedded during a 4-day event, with ≤11 individual bedding events in the same bed site. A second case was observed on 5 July 2013 during similar weather conditions (29 °C and 70% relative humidity) when a different moose cleared a bed site and used it continuously for 10 hours

The Canada Lynx (Lynx canadensis) of Isle Royale: over-harvest, climate change, and the extirpation of an island population

In the 1930s, the Canada Lynx (Lynx canadensis) was extirpated from Isle Royale, a 535-km2 island located in western Lake Superior, 22 km from the Ontario and Minnesota shorelines. The first half of the 20th century was a time of change on Isle Royale as Caribou (Rangifer tarandus) disappeared, Coyotes (Canis latrans) briefly appeared, Moose (Alces americanus), Grey Wolves (Canis lupus), and Red Foxes (Vulpes vulpes) became established, and the habitat was altered by fire, logging, and over-browsing. Although these changes may have contributed to the demise of the Canada Lynx, our results suggest that over-harvest was a primary cause. Assuming a peak carrying capacity of 75 Canada Lynx and harvest rates comparable to those reported from 1890–1935, a population viability analysis indicated that the island population had a 0% chance of surviving 50 years. The analysis also indicated that, even in the absence of harvest, the population had only a 14% chance of persistence for 250 years. However, when 10 Canada Lynx were added to the modeled population every 10th year, the probability of persistence increased to 100%. Our analyses suggest that the island’s Canada Lynx population maintained itself by periodic immigration across an ice bridge; therefore, natural recolonization should be possible. However, the probability of ice-bridge formation has declined from 0.8 in the winter of 1958–59 to 0.1 in 2012–13, likely as a result of climate change. The Isle Royale situation exemplifies another impact of climate change and the possible need to augment populations to mitigate the loss of connectivity

A METHODOLOGICAL COMPARISON AMONG DNA SOURCE TYPES FOR MOOSE GENOTYPING

Population genetic analyses for moose have been based on DNA extracted from blood and other body tissues. Non-invasive sampling of fecal pellets is another potential source of DNA. We compared DNA extraction from blood, liver tissue, and fecal pellet samples from moose in Minnesota and Yellowstone National Park, USA. Extracted DNA from all source types was sufficient for genotyping using 15 microsatellites. DNA extracted from fecal pellets was of lower quality and quantity than DNA extracted from blood and tissue. We provide comparisons of efficiency and effectiveness of DNA extraction protocols for blood, tissue, and fecal pellets, and demonstrate the suitability of using DNA extracted from non-invasively sampled material in moose

GPS Technology for Semi-Aquatic Turtle Research

Global positioning system (GPS) telemetry units are now small enough to be deployed on terrestrial and semi-aquatic turtles. Many of these GPS units use snapshot technology which collects raw satellite and timestamp data during brief periods of data recording to minimize size. We evaluated locations from snapshot GPS units in stationary tests and on wood turtles (Glyptemys insculpta) in northeastern Minnesota. Stationary GPS units were placed in wood turtle habitat to evaluate location accuracy, fix success rate, and directional bias. The GPS fix success rate and accuracy were reduced in closed canopy conditions and when the stationary GPS unit was placed under a log to simulate wood turtle hiding behavior. We removed GPS location outliers and used a moving average calculation to reduce mean location error in stationary tests from 27 m (SD = 38) to 10 m (SD = 8). We then deployed GPS units and temperature loggers on wood turtles and collected 122,657 GPS locations and 242,781 temperature readings from 26 turtles from May to September 2015 and 2016. Location outliers accounted for 12% of locations when the GPS receiver was on a turtle. We classified each wood turtle location based on the GPS location and by comparing temperature profiles from river, sun, and shaded locations to the temperature logger on the turtle. We estimated that wood turtles were on land 68% (SD = 12) of the time from May to September. The fix success rate for land locations was 38% (SD = 9), indicating that wood turtles often use habitats with obstructed views of the sky. Mean net daily movement was 55 m (SD = 192). Our results demonstrate that snapshot GPS units and temperature loggers provide fine-scale GPS data useful in describing spatial ecology and habitat use of semi-aquatic turtles