How does predation risk and forage quality/quantity affect white-tailed deer behavior, and selection for high-value crops?


In North America, deer cause more damage to agricultural crops than any other animal. As white-tailed deer continue to increase in many regions of western North America, deer depredation complaints will likely rise as well. But in many western regions, white-tailed deer ecology is poorly understood compared to other game species, making ecologically-informed management challenging.

In the Clearwater Region of Idaho, a highly productive agricultural area, white-tailed deer are thought to cause significant damage to high-value crops, yet the ecology of Clearwater white-tails remains unstudied, making prevention of deer depredation challenging.

Many solutions have been proposed and tested to deer depredation of valuable crops, with mixed success. Treatments typically aim to alter realized deer damages to crops by changing deer behavior or deer density. Deer density is typically reduced via targeted hunting (e.g., by issuance of depredation permits), but given the high fecundity and movement capability of white-tailed deer, resulting density reductions are likely to be localized and transient. As a result, treatments designed to cause changes to deer behavior are often used instead of or in addition to targeted hunting. 

Such behavior-modifying treatments can be broadly classified as either fear-increasing, or nutrition-reducing. Fear-increasing treatments include: techniques such as application of scents designed to mimic predator odors; playback of sounds that mimic predators or are very noisy and could reduce deer ability to hear predators; and visual and auditory stimuli that do not mimic predators but are designed to startle deer regardless. Nutrition-reducing treatments include: applications of bitter or foul-tasting compounds, including natural tannins, to crops.

Our research project will develop creative management tools for reducing white-tailed deer depredation of crops in the Clearwater Region. The goal of the program is to determine how various management treatments affect deer behavior and subsequent crop damage, with the goal of identifying the most effective actions for reducing deer damage to agriculture in the region. Primary research objectives are as follows:

1)    Characterize hierarchical deer behavioral response to treatments using GPS collared deer, from activity budgets, to movement patterns and habitat selection, to home range location and composition.

2)    Quantify nutritional value of primary natural and agricultural forage species through their growing-season phenology to construct a landscape of nutrition for white-tailed deer.

3)    Measure changes in deer depredation on crops using deer exclosures.

4)    Measure important covariates at each site, including relative abundance of carnivore species and conspecifics, using camera traps.