SEROSURVEY, HEMATOLOGY, AND CAUSES OF MORTALITY OF FREE-RANGING AMERICAN MARTENS ( MARTES AMERICANA) IN MICHIGAN.

To better understand the clinical pathology, diseases, and causes of mortality of reintroduced American martens ( Martes americana) in Michigan, a study was conducted from 2011 to 2015 in the Upper and Lower Peninsulas of Michigan. Samples obtained from live trapping ( n = 58) or harvested carcasses ( n = 34) were serologically tested for select pathogens. Antibodies against Toxoplasma gondii and canine distemper virus were detected in 58 and 3.4% of samples, respectively. All samples were seronegative for Leptospira spp. and negative for Dirofilaria immitis antigen. Urine samples tested for Leptospira spp. via immunofluorescent antibody assay ( n = 7), polymerase chain reaction ( n = 6) , or both ( n = 3) were all negative. Parvovirus DNA was detected in 9.1% of small intestine samples ( n = 22) collected from carcasses and in 3.7% of fecal samples ( n = 27) collected during live trapping. Complete blood counts ( n = 64) and serum biochemistries ( n = 63) were obtained from 49 live-trapped martens. Biochemical parameters found to be significantly different ( P < 0.05) between genders were calcium, creatinine, glucose, and phosphorus. There was no significant difference between genders for any hematologic parameter. Significant differences ( P < 0.05) between summer and winter seasons were found in total estimated white blood cell count, neutrophils, lymphocytes, monocytes, alkaline phosphatase, bicarbonate, calcium, creatinine, globulin, glucose, phosphorus, potassium, sodium, and total protein. There was no significant difference in blood cell count or serum biochemistry values between radio-collared ( n = 17) and noncollared ( n = 47) martens. Animals seropositive for T. gondii were found to have significantly higher ( P < 0.05) eosinophil and globulin levels than seronegative animals. The primary natural cause for mortality of radio-collared American martens was predation. Histologic examinations revealed a high percentage (60%) of martens with verminous or granulomatous pneumonia.

BIOACCUMULATION OF MERCURY IN A TERRESTRIAL CARNIVORE, AMERICAN MARTEN (MARTES AMERICANA).

Studies that assess mercury bioaccumulation in small carnivores in terrestrial habitats are limited. We quantified total mercury (THg) in American marten (Martes americana) that were harvested for fur in Michigan, US, during 2013 and 2014. We quantified THg (dry weight) in hair, kidney, and liver samples and further analyzed hair for potential demographic and ecological factors that influence THg bioaccumulation. We found THg concentrations to be the highest in hair (1.228±0.475 µg/g, n=40), followed by kidney (0.922±0.651 µg/g, n=29) and liver (0.344±0.219 µg/g, n=26). Total mercury distributed predictably and significantly between tissue types, and hair was moderately predictive at modeling THg in kidney (R2=0.50, P<0.001, n=29) and weakly predictive in liver (R2=0.35, P<0.001, n=26), suggesting that hair, which is easily obtained, could be a useful sample type for future biomonitoring programs. The concentrations of THg in hair were higher in adults relative to juveniles, and adult female martens had the highest levels of THg (1.980±0.188 µg/g), as compared to juveniles and adult males. Results of generalized linear modeling suggested that THg hair concentrations were positively associated with marten age and trophic position (stable isotope ratio, δ15N). An interaction between δ15N and the year marten carcasses were collected showed that δ15N alone could be highly predictive of THg in some years but not in others. Annual changes in diet could lead to differing rates of mercury bioaccumulation and alter the usefulness of δ15N to predict THg in marten tissues. Further research should explore the connections between changes in prey availability, types of prey consumed, and the influence on bioaccumulation rates of mercury in terrestrial system mesocarnivores.

EFFECTS OF LIVE-TRAPPING AND ISOFLURANE ANESTHESIA ON FREE-RANGING AMERICAN MARTENS (MARTES AMERICANA).

Seventy-two free-ranging American martens ( Martes americana ) in Michigan, US were immobilized using isoflurane from 2011 to 2015. In total, 129 anesthetic procedures were performed with no mortalities. Hypothermia and hyperthermia were the most common anesthetic complications, and the mean rectal temperatures were significantly higher during summer than in winter. Dental abnormalities were common; the majority of abnormal findings were broken or discolored teeth attributed to previous dental trauma and were not trap-induced. Blood (n=72) was analyzed from 53 martens for venous blood gas, lactate, hematocrit, and/or selected serum biochemistry analytes. Lactate concentration was measured by two different devices (VetScan i-STAT 1 and Lactate Plus) and compared for clinical agreement for 26 samples. Both methods for lactate measurement provided statistically similar results. Using domestic feline reference ranges, the acid-base status and relative arterial oxygen saturation of anesthetized martens in this study were normal as determined by blood pH and pulse oximetry, respectively. Serum biochemistry parameters, multiple environmental parameters, and marten-specific attributes were evaluated for their influence on lactate in American martens using linear regression and an information-theoretic approach with model averaging. Blood urea nitrogen was in all of the top models and was positively related to lactate (ß=0.02, 95% confidence interval: 0.00-0.04). Initial body temperature, ambient temperature, and time from trap discovery until immobilization of martens were informative predictors for lactate level. Recommendations for the live-trapping and isoflurane anesthesia of free-ranging martens include using caution during warmer summer months, minimizing disturbance prior to induction, monitoring lactate in addition to vital rates, and being prepared to prevent or treat both hypothermia and hyperthermia during any time of year.

Post-disturbance plant community dynamics following a rare natural-origin fire in a Tsuga canadensis forest.

Opportunities to directly study infrequent forest disturbance events often lead to valuable information about vegetation dynamics. In mesic temperate forests of North America, stand-replacing crown fire occurs infrequently, with a return interval of 2000-3000 years. Rare chance events, however, may have profound impacts on the developmental trajectories of forest ecosystems. For example, it has been postulated that stand-replacing fire may have been an important factor in the establishment of eastern hemlock (Tsuga canadensis) stands in the northern Great Lakes region. Nevertheless, experimental evidence linking hemlock regeneration to non-anthropogenic fire is limited. To clarify this potential relationship, we monitored vegetation dynamics following a rare lightning-origin crown fire in a Wisconsin hemlock-hardwood forest. We also studied vegetation in bulldozer-created fire breaks and adjacent undisturbed forest. Our results indicate that hemlock establishment was rare in the burned area but moderately common in the scarified bulldozer lines compared to the reference area. Early-successional, non-arboreal species including Rubus spp., Vaccinium angustifolium, sedges (Carex spp.), grasses, Epilobium ciliatum, and Pteridium aquilinium were the most abundant post-fire species. Collectively, our results suggest that competing vegetation and moisture stress resulting from drought may reduce the efficacy of scarification treatments as well as the usefulness of fire for preparing a suitable seedbed for hemlock. The increasing prevalence of growing-season drought suggests that silvicultural strategies based on historic disturbance regimes may need to be reevaluated for mesic species.