Gut microbiome composition predicts summer home range size and habitat use in a generalist and specialist ungulate

Individuals use space non-uniformly relative to one another, this has important implications for both ecological processes and population management. Variation in an individuals used area, or home range, leads to differences in a multitude of factors, including reproductive behaviour, feeding strategy, and fitness. Ungulates exhibit species specific habitat use patterns that differ by season, sex, and age class, leading to variation in home range sizes among individuals occupying a similar geographic area. Likewise, the gut microbiome of animals varies by age, reproductive status, diet, and habitat quality and directly influences an individuals health and fitness. We combined movement and fecal microbiome data to assess the relationship between space use and the gut microbiome in a specialist and generalist ungulate. We found that an increase in gut diversity and Firmicutes to Bacteroides ratios corresponded to an increase in core range area. A negative relationship was seen between escape terrain selection, a critical landscape feature for mountain goats, and Firmicutes to Bacteroides ratio while no there were no significant habitat selection associations in a generalist. We hypothesize that larger Firmicutes to Bacteroides ratios would confer body size or fat advantages and result in larger home ranges. This is the first study to relate core range size to gut diversity in multiple wild ungulates, an important proof of concept that further advances the type of information that can be gleaned from non-invasive sampling.