High-quality habitats and refuges from tourism reduce individual stress responses in a forest specialist

Abstract

Context. The assessment of suitable habitat for a species is often evaluated based merely on where the species is most abundant. However, a variety of environmental factors such as temperature, resources and human disturbances might force animals to avoid otherwise high-quality habitats. Additionally, individuals' capacities to cope with such factorsas reflected in physiological stress responsesmay also contribute to avoidance. Combining measures of stress response of individual animals with habitat suitability models may contribute essential insights to the development of species conservation plans. Aims. We used a landscape-level approach to assess whether habitat quality, abiotic factors and human disturbance affect the physiological stress response of a forest specialist, the capercaillie (Tetrao urogallus), and to what extent these relationships are determined by variation between individuals. Methods. We applied a noninvasive approach by collecting 1096 droppings across the entire species range in two adjacent national parks spanning the border between the Czech Republic and Germany. We measured faecal corticosterone metabolites (FCMs) to evaluate the physiological stress response. To test the influences of temperature, habitat quality, season and sex, as well as forest management and tourism intensity on FCM levels, we used generalised additive mixed effect models (GAMMs). The same models were applied for a reduced subset of randomly selected samples that were attributed to individuals via DNA profiling using 10 microsatellite loci. This approach allowed us to control for possible individual differences (through repeated measures within individual genotypes). Key results. Both models revealed decreasing FCM levels with increasing habitat quality and showed no relationship between increasing forestry intensity and FCMs. When accounting for individual identity, we found a significant positive effect from increasing tourism intensity, although this relationship was not significant in the full dataset. Conclusions. Our results highlight three conclusions for the conservation of capercaillie: (1) high-quality habitats reduce stress levels; (2) tourism-free refuge areas are important, and (3) individuality appears to be a strong determinant of response to environmental factors. Implications. Generalising management recommendations from observations for single individuals to an entire population may be inappropriate.

Identifying and Counting Avian Blood Cells in Whole Slide Images via Deep Learning

“…The physiological conditions and the stress of birds can be determined in several ways, e.g., by assessing the body weight or the fat and muscle scores in migratory birds [3,4]. Other frequently used methods are investigating the parasite loads, measuring the heart rates, and measuring the levels of circulating stress hormones, such as corticosterone [5][6][7][8][9]. Depending on the research questions studied, these methods can be a good choice for assessing long-term stress or the investment in immunity.…”