How Stress Hormones and Habitat Affect Bird Conservation

Greg Howard
25th March, 2024

How Stress Hormones and Habitat Affect Bird Conservation

Key Findings

  • Study from University of Nevada found stress hormones in birds indicate habitat quality
  • Birds with higher stress-induced hormone levels have more suitable living areas
  • This discovery could help manage and conserve wildlife in human-altered landscapes
In an era where human activities have dramatically reshaped landscapes, wildlife populations are constantly adapting to survive in these altered environments. The assessment and monitoring of these populations are crucial for effective wildlife management and conservation efforts. A recent study from the University of Nevada, Reno[1], investigates the use of glucocorticoid (GC) hormone levels as a biomarker to reflect the state of bird populations in relation to the landscape characteristics they inhabit. Glucocorticoids, specifically corticosterone in birds, are hormones that are released during times of stress and can influence various physiological processes. These hormones are often measured to gauge how animals are coping with environmental challenges. The study aimed to determine if GC levels, both at rest (baseline) and in response to stress (stress-induced), correlate with the amount of usable habitat within a bird species' range. To do this, researchers analyzed publicly available data including hormone measurements from HormoneBase, covering 51 bird species, alongside natural history information and US national land cover data. The findings revealed that stress-induced corticosterone levels, but not baseline levels, were positively associated with the percentage of usable land cover for birds both within and across species. This suggests that higher stress-induced GC levels could indicate a greater availability of suitable habitat for birds. It's an important distinction that while baseline GC levels show what's normal for a bird at rest, stress-induced levels reflect how birds react to their environment when challenged. This reactivity could be a more sensitive indicator of habitat suitability. These results are particularly noteworthy when compared to previous studies. For instance, a prior investigation[2] found that some endocrine traits, like baseline corticosterone and testosterone, were linked to urban tolerance in birds, with the implication that hormone levels could reflect a species' ability to thrive in certain habitats. However, that study did not find a connection between stress-induced corticosterone and urban tolerance. The current research expands upon this by suggesting that stress-induced GC levels do have a broad application in assessing habitat suitability across different landscapes, not just urban environments. Additionally, another earlier study[3] explored the speed and scope of the acute glucocorticoid response in birds, finding that species with faster glucocorticoid responses tended to live in more variable environments and had shorter lifespans. This supports the idea that the dynamics of the glucocorticoid response are shaped by environmental pressures and life history traits, which is in line with the findings of the current study that stress-induced GC levels can vary with habitat availability. The research also indirectly ties into concerns about anthropogenic noise and light pollution affecting bird populations[4]. While the current study does not specifically address these sensory pollutants, it suggests that stress-induced GC levels could potentially serve as a biomarker for monitoring how such environmental stressors impact wildlife. By advocating for more physiological studies on a wider variety of species and populations, the researchers from the University of Nevada, Reno highlight the potential for GC concentrations to become a practical tool for wildlife management. This could enable land and wildlife managers to make more informed decisions to support conservation efforts, particularly as they work to understand and mitigate the effects of human-altered landscapes on bird populations. In summary, the study presents evidence that stress-induced GC levels in birds are indicative of the quality and availability of their habitat. This finding is a step forward in the application of physiological biomarkers for large-scale wildlife population monitoring, offering a new lens through which to view the health and resilience of bird species in the face of ongoing environmental change.



Main Study

1) Glucocorticoids and land cover: a largescale comparative approach to assess a physiological biomarker for avian conservation.

Published 25th March, 2024

Related Studies

2) Among-species variation in hormone concentrations is associated with urban tolerance in birds.

3) The relative speed of the glucocorticoid stress response varies independently of scope and is predicted by environmental variability and longevity across birds.

4) Sensory pollutants alter bird phenology and fitness across a continent.

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