Beyond the Fields Edge: Understanding How Adjacent Habitats Influence Ungulate Crop Damage

View the project final report

Commodities

• Agronomic: corn, soybeans

Practices

• Natural Resources/Environment: wildlife
• Pest Management: prevention

Crop damage is a persistent issue faced by farmers nationwide, resulting in staggering costs to farmers in crop loss. Ungulate species such as white-tailed deer (Odocoileus virginianus) and sika deer (Cervus nippon) are a major source of agricultural damage through extensive browsing. Often a farmer’s only solution to mitigate browsing losses is through crop damage permits to hunt deer on their farm. However, deer populations occur over larger scales than a single property, limiting farmers’ abilities to actually reduce local deer densities through hunting and leaving them ineffective in reducing crop damage by ungulates. Surrounding habitats can reduce or exacerbate impacts on crop damage – reducing damage by providing additional food that lowers the intensity of deer browsing on crops or exacerbating damage by providing refuge to deer that actively browse on agricultural fields. My research looks to examine both the effect that adjacent habitat composition and configuration has on crop damage as well as quantify the impact that dietary overlap of two co-occurring ungulates has on crop damage. High-resolution dietary analysis using metabarcoding plant DNA present in ungulate fecal pellets allows crop damage to be quantified. Combining the dietary profile of ungulates with landscape level metrics of the surrounding habitats will reveal how habitats in close proximity to agriculture influence crop damage. Through informing famers, policy makers and state agencies about the influence of adjacent habitats on crop damage, this work will develop management polices beyond deer culling to effectively mitigate crop damage.

The specific objectives of this research are to:

(1) Determine the impact that the composition and configuration of neighboring habitats (forests, marshes, fallow fields) within agricultural landscapes have on the proportion of agricultural crops in a deer’s diet.

Hypothesis 1: Overall area, number of patches, and connectivity of neighboring habitats will decrease the proportion of agricultural species present in the diet of the deer.

Hypothesis 2: The proportion of agricultural species present in the diet of the deer can be explained by the composition and configuration of neighboring habitats.

Hypothesis 3: Reliance on plant species present in neighboring habitats will vary through time depending upon the abundance and availability of crops.

(2) Evaluate the impact of dietary niche overlap of sympatric deer species has on crop damage.

Hypothesis 1: We will observe higher overall deer densities in regions where both deer species occur than regions where just white-tailed deer or sika deer occur in isolation.

Hypothesis 2: Agricultural species will make up a smaller proportion of the diet of white-tailed deer and sika deer in regions where they co-occur due to interspecific competition for crop resources.

Hypothesis 3: Despite lower per capita crop consumption, crop damage will be greater in areas where the species co-occur due to higher densities.

Hypothesis 4: Higher deer densities will be supported by a greater reliance on plant species from neighboring habitats, and we expect to see a wider dietary breadth in regions where both species co-occur.