Juvenile moose stress and nutrition dynamics related to winter ticks, landscape characteristics, climate-mediated factors and survival

Abstract

Moose populations in the northeastern United States have declined over the past 15 years, primarily due to the impacts of winter ticks. Research efforts have focused on the effects of winter tick infestation on moose survival and reproduction, but stress and nutritional responses to ticks and other stressors remain understudied. We examined the influence of several environmental factors on moose calf stress hormone metabolite concentrations and nutritional restriction in Vermont, USA. We collected 407 fecal and 461 snow urine samples from 84 radio-collared moose calves in the winters of 2017–2019 (January–April) to measure fecal glucocorticoid metabolites (fGCM) concentrations and urea nitrogen:creatinine (UN:C) ratios. We used generalized mixed-effects models to evaluate the influence of individual condition, winter ticks, habitat, climate and human development on stress and nutrition in calf moose. We then used these physiological data to build generalized linear models to predict calf winter survival. Calf fGCM concentrations increased with nutritional restriction and snow depth during adult winter tick engorgement. Calf UN:C ratios increased in calves with lighter weights and higher tick loads in early winter. Calf UN:C ratios also increased in individuals with home ranges composed of little deciduous forests during adult winter tick engorgement. Our predictive models estimated that winter survival was negatively related to UN:C ratios and positively related to fGCM concentrations, particularly in early winter. By late March, as winter ticks are having their greatest toll and endogenous resources become depleted, we estimated a curvilinear relationship between fGCM concentrations and survival. Our results provide novel evidence linking moose calf stress and nutrition, a problematic parasite and challenging environment and winter survival. Our findings provide a baseline to support the development of non-invasive physiological monitoring for assessing environmental impacts on moose populations.

Population and community consequences of perceived risk from humans in wildlife

“…Although this antipredator behaviour alone is not likely to directly cause NCEs, it can be a proxy for reduced foraging rates and associated costs. Increases in vigilance in response to predation risk have been tied to decreased foraging and increased stress and energetic costs in large mammals (Say-Sallaz et al, 2019). Heightened vigilance has also been widely observed as a response to human cues (Clinchy et al, 2016;Nhleko et al, 2022).…”

“…Human activities have also been linked to demographic costs of increased heart rate in Humboldt penguins ( Spheniscus humboldti ; Ellenberg et al., 2006) and lower antibody titres in great tits ( Parus major ; Bötsch et al., 2020). However, in many other cases, human activities were not found to affect stress hormones, body condition or nutrition (Bötsch et al., 2020; Dheer et al., 2022; Morgan et al., 2012; Northrup et al., 2021; Rosenblatt et al., 2021; Villanueva et al., 2012; Weterings et al., 2022). As in the behavioural studies, these results indicate that physiological human‐induced NCEs are context‐dependent and do not show consistent patterns across human disturbance types or taxa.…”

A Review of Non-Invasive Sampling in Wildlife Disease and Health Research: What’s New?

“…The cell-mediated immune response has been also monitored from urine in a range of primates by the quantification of neopterin, a biomarker that increases when an acute inflammation is present [114,[118][119][120][121][122][123]. Metabolic state has also been assessed by measuring urine triiodothyronine in macaques [114], by determining C-peptide and ketone bodies in orangutans [124], and by assessing the nitrogen:creatinine ratio in wild moose [125,126].…”

“…In arboreal mammals, urine can often be collected from the ground or leaves immediately after spontaneous urination or by spreading plastic sheets under known roost or sleeping sites [103,[105][106][107][108][114][115][116][117][118][119][120][121]123,124]. In cold climates, it may be possible to collect naturally frozen urine samples from the snow, however, the dilution effect of the snow needs to be taken into account for analysis [125,126]. If mammals are anaesthetised for other procedures, it is likely that they will urinate during recovery, so sample collection can be attempted in this phase [123].…”

Canada Jay Predation of Winter Ticks (Dermacentor Albipictus)

“…The impact of Winter Ticks on Moose is of special interest because the numbers of ticks on a single Moose during epizootics can exceed 30,000 individuals (Samuel and Welch 1991), leading to extensive hair loss from excessive grooming by the host, which then weakens the host, sometimes fatally. Regional declines in Moose populations have been attributed to Winter Tick infestations interacting with other factors such as severe winter weather (Samuel 2007; Rosenblatt and others 2021).…”