Search

Many wildlife populations are experiencing a variety of environmental pressures due to the direct and indirect consequences of a changing climate. In the northeast, USA, moose Alces alces are declining in large part because of the increasing parasitism by winter tick Dermacentor albipictus, facilitated by high host density and optimal environmental conditions. To test this hypothesis, and better understand the influence of this interaction on the stability of the regional population, we constructed a population viability model using data collected through comprehensive survival and productivity studies in 2002–2005 and 2014–2018 in northern New Hampshire. Years of heavy tick infestation (epizootics) saw a marked reduction in calf survival (< 50%), adult calving (< 60%), twinning rate (< 5%) and complete loss of yearling productivity. We conducted population viability analysis using VORTEX ver. 10.2 to model this moose population for 40 years using mean demographics from both time periods, including environmental variation measured in the field during winter tick epizootic (2002, 2014, 2015, 2016) and non-epizootic (2003, 2004, 2005, 2017) years. This exercise highlights the influence of winter tick infestation on the trajectory of the population with the potential for rapid population growth or decline depending on the frequency of epizootics. We suggest a shift in moose management strategy focused on lowering moose density, assuming continued influence of climate change on the host–parasite relationship. [ABSTRACT FROM AUTHOR]

Many wildlife populations are experiencing a variety of environmental pressures due to the direct and indirect consequences of a changing climate. In the northeast, USA, moose Alces alces are declining in large part because of the increasing parasitism by winter tick Dermacentor albipictus, facilitated by high host density and optimal environmental conditions. To test this hypothesis, and better understand the influence of this interaction on the stability of the regional population, we constructed a population viability model using data collected through comprehensive survival and productivity studies in 2002--2005 and 2014--2018 in northern New Hampshire. Years of heavy tick infestation (epizootics) saw a marked reduction in calf survival (< 50%), adult calving (< 60%), twinning rate (< 5%) and complete loss of yearling productivity. We conducted population viability analysis using VORTEX ver. 10.2 to model this moose population for 40 years using mean demographics from both time periods, including environmental variation measured in the field during winter tick epizootic (2002, 2014, 2015, 2016) and non-epizootic (2003, 2004, 2005, 2017) years. This exercise highlights the influence of winter tick infestation on the trajectory of the population with the potential for rapid population growth or decline depending on the frequency of epizootics. We suggest a shift in moose management strategy focused on lowering moose density, assuming continued influence of climate change on the host--parasite relationship. [ABSTRACT FROM AUTHOR]

Recent decline in New Hampshire's moose (Alces alces) population is attributed to sustained parasitism by winter ticks (Dermacentor albipictus) causing high calf mortality and reduced productivity. Location of larval winter ticks that infest moose is dictated by where adult female ticks drop from moose in April when moose preferentially forage in early regenerating forest in the northeastern United States. The primary objectives of this study were to: 1) measure and compare larval abundance in 2 types of regenerating forest (clear-cuts and partial harvest cuts), 2) measure and compare larval abundance on 2 transect types (random and high-use) within clear-cuts and partial harvests, and 3) identify the date and environmental characteristics associated with termination of larval questing. Larvae were collected on 50.5% of 589 transects; 57.5% of transects in clear-cuts and 44.3% in partial cuts. The average abundance ranged from 0.11-0.36 ticks/m2 with abundance highest (P < 0.05) in partial cuts and on high-use transects in both cut types over a 9-week period; abundance was ~2 × higher during the principal 6-week questing period prior to the first snowfall. Abundance (collection rate) was stable until the onset of < 0°C and initial snow cover (~15 cm) in late October, after which collection rose temporarily on high-use transects in partial harvests during a brief warm-up. The higher abundance of winter ticks on high-use transects indicates that random sampling underestimates tick abundance and relative risk of infestation of moose. Calculating an annual index of infestation of winter ticks on moose is theoretically possible by integrating 3 factors: the infestation of harvested moose in October, the length of the questing period, and assuming a stable collection rate during the questing period. [ABSTRACT FROM AUTHOR]

Snow urine samples collected in northern New Hampshire, USA were used to measure urea nitrogen (UN) and creatinine (C) content to develop ratios for tracking the nutritional restriction of individual moose (Alces alces) through winter (2014-2017), inclusive of the adult winter tick (Dermacentor albipictus) engorgement period. Samples (n = 215) were collected from 55 moose (38 calves, 17 cows) on a twice monthly schedule from late January through snowmelt or calf mortality (March - early April). Early winter UN:C ratios from cows, surviving calves, and calves that ultimately died from infestation of winter ticks were similar and reflected a normal winter diet low in protein. A heightened UN:C ratio (> 3.5 mg/dL) was measured in March which aligned with peak feeding by adult winter ticks, and presumably reflected accelerated protein deficit associated with blood loss. This increase was not observed population-wide despite shared habitat, occurring only in calves with mortal weight loss and anemia associated with heavy winter tick infestation. Measurement of UN:C ratios from snow urine samples proved an effective method to measure the temporal impact of winter tick infestation, and March samples can support other metrics used to estimate calf mortality. [ABSTRACT FROM AUTHOR]

Age, field-dressed body weight, and antler spread data collected from 11,566 harvested moose (Alces alces) were analyzed to assess whether temporal change has occurred in the physical characteristics of bull moose from 1980-2009 in Maine. The annual proportion and antler spread of trophy bulls (spread ≥ 137 cm; n = 851) were also analyzed. There was no evidence of a measurable decline in the body weight or antler spread of adult bull moose (≥1.5 years old), similar to findings in Vermont and New Hampshire in a recent >20 year temporal analysis. There was a slight increase in physical characteristics of yearlings that contrasted with the trend in New Hampshire and Vermont where it is speculated that parasitism by winter ticks (Dermacentor albipictus) reduces growth rate and recruitment by yearlings. The proportion of trophy bulls in the harvest declined proportionally ~26% (9.3 to 6.9%) as harvest increased >2x from 1980-1987 to 2005-2009; however, the mean spread of trophy bulls declined by only 2% (P = 0.002). Additionally, there were no differences (P > 0.05) in the proportion of harvested bulls within each age class between 1980-1987 and 2005- 2009, and the relatively stable proportion of mature bulls (>5 years old) in the harvest across time periods (30-44%) does not suggest selective harvest of older, trophy bulls. In the face of the declining regional population, continued monitoring of harvested moose is warranted to best manage the largest and longest harvested population in the northeastern United States. [ABSTRACT FROM AUTHOR]

In New Hampshire, winter ticks (Dermacentor albipictus) probably have more influence on the moose (Alces alces) population than other mortality factors, and predicting the frequency of tick epizootics is an important management consideration. Weather, moose density, and habitat use influence abundance and distribution of winter ticks. We evaluated the usefulness of 3 techniques to index winter tick abundance in 3 regions with variable moose density: 1) flagging for tick larvae, 2) line-transect counts of ticks on harvested moose, and 3) roadside surveys of tick-induced hairloss on moose. Although counts of tick larvae from fall flagging were not significantly different between years or regions, absolute tick abundance was measurably different (>50%) relative to moose density and years. Tick abundance on harvested moose reflected annual and regional differences; in general, abundance was correlated positively with moose density and annual trends within regions were similar. Tick abundance was highest for calves and lowest for cows. Hair-loss surveys indicated that hair loss was generally related to moose density, and similar annual differences were reflected in all regions. We suggest measuring tick abundance on harvested moose and conducting annual roadside hair-loss surveys to create indices and threshold values useful in predicting an epizootic of winter ticks. [ABSTRACT FROM AUTHOR]

Biological data collected from harvested moose (Alces alces) were analyzed to assess whether temporal change has occurred in the physical and reproductive condition of moose from 1988-2009 in New Hampshire. Measurements included age and field-dressed body weight of both sexes, number of corpora lutea (CL) and ovulation rate of females, and antler beam diameter (ABD) and antler spread of males. Similar data were obtained from Maine and Vermont for comparative analysis. The only significant changes (P <0.05) occurred in the yearling age class: mean body weight of both sexes, number of CL, and ABD all declined in New Hampshire. The current ovulation rate (~20%) and mean body weight (<200 kg) of yearling females in New Hampshire and Vermont were considered low. The declines measured in yearlings, yet relative stability in adults, are consistent with the presumption that winter ticks (Dermacentor albipictus) impact the productivity of moose populations through reduced calf survival and growth and fecundity of yearlings. Density-dependent factors related to habitat change are also discussed given the recent, rapid expansion of moose in the 3 states. Continued monitoring of physical parameters and productivity of harvested moose, particularly the yearling cohort, is warranted to better assess the relationships among winter ticks, habitat quality, and moose populations. [ABSTRACT FROM AUTHOR]

The impact of moose (Alces alces) browsing on the regeneration of commercial hard- wood and softwood tree species was evaluated in 3 regions with different moose population densities (0.26-0.83 moose/km2) in northern New Hampshire. Regeneration surveys were conducted in 4 age classes of clear-cuts (0-5, 6-10, 11-15, and 16-20 years) in June-August 2009. Stocking rate, tree height, and damage of dominant commercial stems were measured to assess regeneration and browse damage among age classes and regions. We assumed that a stocking rate of 40-60% (stems/plot) dominant commercial tree species without severe damage was an acceptable threshold of browse damage to achieve a fully stocked stand at 80 years. Mean stocking rate of all age classes was above the threshold in all regions (47-85%); the lowest stocking rates (47-52%) occurred in the 0-5 year age class but increased thereafter in all regions. The CT Lakes region (highest moose density) had more damage than both the North and White Mountain regions in the 11-15 year age class (F= 3.05; df; 6; P = 0.0002 and 0.0058, respectively). Tree heights were lower in the CT Lakes region (F = 2.30; df 6; P = 0.04). Most damage was restricted to a few isolated clear-cuts at higher elevation near moose wintering areas that were possibly shifting to conifer dominance. Regeneration of commercial tree species was not considered a regional problem at any moose density in northern New Hampshire. [ABSTRACT FROM AUTHOR]

Abundance indices suggested that the moose Alces alces population in northern New Hampshire was stable despite favourable habitat and conservative harvest. Causes and rates of mortality were unknown because moose reproduction and survival was unstudied in the region. Our study was designed to investigate the dynamics of the regional population in 2002-2005.Atotal of 92 moose (33 cows and 59 calves) were captured and fitted with radio-collars (VHF=83, GPS= 9). Parturition ranged from 8 May to 13 July (median = 19 May) with 78% of births occurring during 13-27 May. Calving rate of yearlings and adults (>2 years old) averaged 30 and 85%, respectively; twinning rate was 11%. Analysis of reproductive data from harvested cows (1988-2004) indicated that the average weight of adult cows increased but their corpora lutea count declined from ; 1.4 to 1.2/cow. Both ovulation rate and average weight of yearling cows declined about 25 and 4%, respectively. There were 39 mortalities (49% calves) with winterkill/parasite (41%), vehicle collision (26%) and hunting (18%) as the leading causes. Major sources of mortality of radio-marked cows were human-related; survival was 0.87. Annual calf survival was 0.45. Unmarked calf (0-2 months of age) survival was 0.71 with 76% of mortality in the first month of life. Radio-marked calves (∼7-12 months of age) had a survival rate of 0.67; 74% of the mortality was winterkill/parasite related. Calf mortality was concentrated (88%) in late winter-early spring. The unseasonably warm and snowless fall in 2001 probably favoured high tick transmission and increased tick loads on moose that resulted in high calf mortality (0.51) and measurable cow mortality (10%) in mild winter-spring 2002. Documentation of substantial tick-related mortality of radio-marked moose calves was unique to this study. The stability of the moose population probably reflects the variation in annual recruitment and lower fecundity of yearling cows associated with heavy infestations and epizootics of winter tick. Given that fertility, calving rate and body condition of adult cows, and summer calf survival are annually high, the population should recover from tick epizootics that periodically inhibit population growth. [ABSTRACT FROM AUTHOR]

Habitat use by parturient moose (Alces alces) may have important implications for calf survival and subsequently influence population dynamics. Because neonatal habitat may be limiting or specialized and little descriptive information exists in the northeastern United States, this study was conducted to measure the physical and vegetative characteristics associated with neonatal habitat of 30 maternal moose. There was no difference (P > 0.10 for each parameter) in 22 of 23 physical and vegetative parameters measured at neonatal (n = 30) and random sites (n = 30). However, neonatal sites were about 2X farther (P = 0.032) than random sites from cut/regeneration habitat where no neonatal site occurred. Most neonatal sites (> 63%) were located in pole or saw timber stands comprised of mixed or coniferous habitat (> 75%); conifers were the dominant canopy species at 67% of neonatal sites. Characteristics related to forage availability suggest that forage resources were probably not influential in location of neonatal habitat. Mature, mixed, and coniferous habitats may provide microhabitat that helps conceal neonates from potential predators such as black bears (Ursus americana), particularly in the absence of islands and open water that are believed to mitigate predation. [ABSTRACT FROM AUTHOR]

Measures standard metabolic rate (SMR) and the effects of temperature on metabolism of adult eastern wild turkeys during each season of the year. Minimal thermoregulatory costs for turkeys at normal winter temperatures in south central New Hampshire; Further data analysis.

Abundance estimates for black bears (Ursus americanus) are important for effective management. Recently, DNA technology has resulted in widespread use of noninvasive, genetic capture–mark– recapture (CMR) approaches to estimate populations. Few studies have compared the geneticCMRmethods to other estimation methods. We used genetic CMR to estimate the bear population at 2 study sites in northern New Hampshire (Pittsburg and Milan) in 2 consecutive years. We compared these estimates to those derived from traditional methods used by the New Hampshire Fish and Game Department (NHFG) using hunter harvest and mortality data. Density estimates produced with genetic CMR methods were similar both yearsand were comparable to those derived from traditional methods. In 2006, the estimated number of bears in Pittsburg was 79 (95% CI ¼ 60–98) corresponding to a density of 15–24 (95% CI) bears/ 100 km2; the 2007 estimate was 83 (95% CI ¼ 67–99; density ¼ 16–24 bears/100 km2). In 2006, the estimated number of bears in Milan was 95 (95% CI ¼ 74–117; density ¼ 16–25 bears/100 km2); the 2007 estimate was 96 (95% CI ¼ 77–114; density ¼ 17–25 bears/100 km2). We found that genetic CMR methods were able to identify demographic variation at a local scale, including a strongly skewed sex ratio (2 M:1 F) in the Milan population. Genetic CMR is a useful tool for wildlife managers to monitor populations of local concern, where abundance or demographic characteristics may deviate from regional estimates. Future monitoring of the Milan population with genetic CMR is recommended to determine if the sex ratio bias continues, possibly warranting a change in local harvest regimes. [ABSTRACT FROM AUTHOR]