How can wildlife ecologists study the long-term effects of environmental and social stress in animals without introducing stress during the process? This is the problem scientists from the Division of Wildlife Conservation at the Alaska Department of Fish and Game have begun to solve by validating a new collection method for non-invasive wildlife sampling with the Alexander Archipelago wolves (Canis lupus ligoni) of Prince of Wales Island, AK.Â
Innovative Sampling Methods
Their research, published in the Wildlife Society Bulletin, focused on the collection and analysis of keratinized tissue (hair and claws) to look at how steroid hormone concentrations varied over time. Standard sampling methods, such as blood, urine, and feces, only give a snapshot of the wolves’ hormone levels and require repeated sample collection to conduct longitudinal studies. In addition, blood collection is known to induce immediate elevation of stress-related hormones, which complicates analysis.
In contrast, using keratinized tissues enables a single, less invasive sample collection event and provides several months to years of the animal’s hormone history. Furthermore, these sample types are far easier to handle in the field and provide stable hormone readings even after decades of archival storage.
Key Findings and Implications
To validate their analytical methods, the group sampled the guard hair, undercoat hair, and claw tip clippings from 31 wolves living on the island during 1993-1994 (archived samples) and 2012-2014. They cleaned and pulverized each clipping and used standard methanol extraction techniques to prepare samples. The researchers used Arbor Assays’ commercially available cortisol (K003-H), progesterone (K025-H), and testosterone (K032-H) DetectX® ELISA kits to quantitatively measure hormone levels.
They found higher levels of testosterone and progesterone in the guard and undercoat hair in the 1990s samples compared to those collected in the 2010s. This correlated with a known increase in human wolf harvest (regulated hunting) on the island in the 1990s that led to unstable social structures in wolf packs and increased reproductive activity trends. In addition, hormone trends observed across the three sample types aligned with previous work from scientists working with other wildlife species. This significant finding marks the first known time claw clippings were used to measure steroid hormones in wolves, and unlocks an analytical option that is storage stable, minimally invasive, and can provide information across several years.
Let Wildlife be Wild with Non-Invasive Sampling Techniques
Innovative sampling and analysis techniques like these play a critical role in significantly increasing our understanding of wildlife behavior and conservation while reducing unintended ecological consequences of invasive sample collections.
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