Can poop be used to help wildlife managers and biologists determine the health of a population?
The answer is, yes! That's right, poop. The taboo subject that still makes the child in us giggle. But how and why is it that fecal matter can matter to wildlife professionals? The fact is, we can learn a lot about an animal from its poop, from diet and immune health to even their stress levels. Here, we define stress as the complex physiological response to an ecological stressor (or stimuli) that can affect the internal stability of one's equilibrium. While acute - or short bursts - of stress can be ecologically beneficial to a species (such as the "fight or flight" response due to a predator), prolonged or chronic stress can have negative effects on an individual's ability to survive and reproduce. Since wildlife managers and biologists' goal is to have healthy wildlife populations, one can see how important the examination of stress can potentially be.
For example, let us examine Northern Bobwhite quail (Colinus virginianus). Bobwhite are considered a species of conservation importance to many wildlife managers and biologists due to decades of habitat loss and their popularity as a game species. Additionally, management efforts to help bobwhite populations and their habitats often help other species in that habitat, making bobwhite an essential species in many grassland communities.
Wildlife managers and biologists addressing bobwhite population survival and reproduction rates often observe them at a broad landscape level to determine the health of a specific population. While it is necessary in management to have these estimates, it does not necessarily address the underlying internal mechanism that may be driving these rates, such as stress.
How can we examine the stress response of a wild bobwhite population?
That's right, through their poop!
Traditionally, the most common way to examine stress in animals was through blood sampling. However, this can be very difficult in wild populations since one would first need to capture an individual, which may inherently increase its stress response. To overcome this limitation, several non-invasive sampling methods have become more prevalent in recent years, such as fecal sampling. This is noteworthy as it can allow managers and biologists to potentially address if there is a stress response that may be driving population effects, such as reduced population numbers.
However, before any wildlife manager or biologist can decide to use fecal sampling to examine stress in a population of their study species, it iscritical that they first validate — or prove — that the method works. Validation is required as several factors can influence stress levels in fecal samples. Some of thefactors that can influence these levels are:
How exactly does one go about validating the use of fecal sampling?
The goal of validation is to ensure that within every fecal sample of whatever species you are examining, you are able to detect biologically meaningful changes in their stress hormones. This is determined by two different tests:
It is crucial for managers and biologists to use both methods to validate the use of fecal sampling in their chosen species. It is especially important to biologically validate a method for sampling wild populations, as an event we believe may be stressful to a specific individual may not be. Additionally, managers and biologists dealing with wild populations are more concerned about how a species reacts to a natural stress event and not a pharmaceutical stress event.
How does one set up a validation study?
There are a number of ways one can set up a validation study. For example, to validate the use of fecal sampling in bobwhite, we took samples from 24 captive-reared bobwhite, of different ages and sexes, over seven days every four-hours across four different treatments. See treatment schedule below:
In order to determine if a stress response could be detected within the excessive amount of excrement (1,000 + samples) that were collected, each sample was extracted and run through radioimmunoassay (RIA) to determine stress hormone levels.
Were we able to validate the use of bobwhite fecal sampling?
Our results indicated that bobwhite had a stress response to the physiological validation, but not to the biological validation. The lack of a stress response from the biological treatment may have been due to:
To determine what may have caused the lack of a stress response during the biological validation, more validation is suggested before large-scale deployment of using fecal sampling as a method in bobwhite. These results reiterate the importance of using both physiological and biological methods to validate the use of fecal sampling in a species before deployment, as managers and biologists dealing with wild populations are concerned about how a species reacts to natural and not pharmaceutical stress events.
How could this method be potentially used?
As one can see, fecal matter can matter to wildlife professionals. For bobwhite, this method could be used as an additional tool to evaluate the health of a population and aid in conservation and management efforts. Integrating this technique with traditional population measurements (e.g. mortality and reproduction rates) could better inform managers and biologists of the physiological constraints imposed by different types of habitat or disturbances, leading to a deeper knowledge of the adaptive management needed for bobwhite.
Currently, there is still a large disconnect between wildlife management and disciplines, such as physiology. These fields should not be thought of as mutually exclusive, as each can provide unique information on the status and health of a population. Integrating different biological and ecological disciplines can allow for more progressive and effective wildlife management and conservation.
Want to learn more about this study? Read the research publication here:
Jessica L Mohlman, Kristen J Navara, Michael J Sheriff, Theron M Terhune, II, James A Martin, Validation of a non-invasive technique to quantify stress in northern bobwhite (Colinus virginianus), Conservation Physiology, Volume 8, Issue 1, 2020, coaa026, https://doi.org/10.1093/conphys/coaa026