Finally, we expect that the accuracy of wet-fat-mass estimation will improve if researchers pay more attention to assessing the habitat water content of the region in which they have caught the subject. This assessment is relatively inexpensive and poses little additional labor if conducted prior to euthanasia of the snakes. Furthermore, water movement is a natural occurrence that will cause all snakes to gain or lose weight at some point during their lives. Thus, without a need to account for changes in prey availability, water content will likely be the best single variable to assess against a variable like body condition. We recommend that researchers conduct water-content assessments of the environment in which they conduct their BCI studies, but we leave to them whether to conduct these assessments prior to euthanasia of the subject or use water-content data collected from similar environments during euthanasia.
For example, snakes do not enter or leave the water alone. Snakes use the water to cool themselves and to catch prey. Snakes rarely remove the water from the immediate environment of their enclosure or even shed water. When we examine the weight changes of wild snakes that are active during the day, the maximum weight changes are always around 0.5% of their initial weights [ 35 ].
Thus, we expect a population of healthy wild snakes in an aquatic environment to be more likely to have a wet-fat-mass ratio of about 0.5%, and, more generally, wild snakes with a higher initial weight would likely have a more consistent ratio. We encourage researchers who have access to water-content information for the region in which they conduct snake studies to incorporate this information into their body-condition assessments. 3d9ccd7d82