Date of Completion
Chadwick Rittenhouse, Jason Vokoun, Ashley Helton
University Scholar Major
Advances in technology and availability associated with camera traps have resulted in a rapid rise in their use to monitor wildlife distribution, abundance, and behavior. We focus on assessing body condition, a new application of camera traps. Body condition indices must relate to the percent body fat if they are to be useful. To acquire measurements of body fat, most body condition indices require capture or mortality of animals to estimate, which has limitations when applied to free-ranging animals. We developed a non-invasive, visual body condition index (VBCI) to assess body condition of mule deer that can be applied to camera trap images or videos. The VBCI was based on the visibility of five bone regions, the scapula, spinal ridge, ribs, tuber ischium, and tuber ilium, which are covered in varying amounts of subcutaneous fat. We compared the VBCI to known values of ingesta-free body fat, obtained from ultrasonography and physical palpation of captured mule deer. Our VBCI was positively related to percent ingesta-free body fat (R2=0.23, p<0.001). Additionally, the bone regions evaluated were each correlated with the percent ingesta-free body fat. Using Spearman’s correlation, the scapula is the region most highly correlated to ingesta-free body fat (0.44, p<0.001), followed by the ischium (0.36, p<0.001), ilium (0.35, p<0.001), spinal ridge (0.31, p<0.001), and ribcage (0.12, p<0.01). Based on the relationships between VBCI and ingesta-free body fat, we developed two visual body condition indices, one that requires a broadside orientation to the camera (VBCI-1) and one that is applicable when a deer is quartered towards the camera (VBCI-2). Potential applications of the VBCI include evaluating relationships between body condition and habitat enhancements, habitat disturbances, population performances, and weather.
Smiley, Rachel A. 6820420, "Beyond Capture: Development and Validation of a Method to Assess Body Condition in Mule Deer (Odocoileus hemionus) Using Camera Traps" (2017). University Scholar Projects. 36.