Crop Depredation by White-Tailed Deer at Sand Lake National Wildlife Refuge, South Dakota

Damage to agricultural crops by white-tailed deer (Odocoileus virginianus) was investigated at Sand Lake National Wild life Refuge (SLNWR), Brown County, South Dakota in 1995 and 1996. To quantify depredation in corn (Zea mays) and soybean (Glycine max) fields on SLNWR and surrounding private lands, biomass removed by foraging was estimated using exclosures and paired open (exposed) plots. Amount removed was related to total standing crop of each field. For 1995, no significant production loss occurred for soybean. For corn in 1995, dry total plant matter was significantly affected by deer, but kernel production was not affected. Conversely, in 1996, dry total plant matter was not affected, but kernel production was affected. By combining years, I found that dry total plant matter and kernel production were both significantly affected by deer with percent production losses of 8.0 % and 1 0.7 % respectively. To assess dietary composition of white-tailed deer at SLNWR, microhistological analysis of feces was performed. Fecal samples were collected on the refuge and in agricultural fields during four separate two-week sampling intervals during each month of the g rowing season (June-September). Corn consumption ranged from 5 to 18 % of deer diets, and soybean consumption ranged 0 to 3 %. Throughout the growing season grasses were the most important forage class ranging from 35 to 52% followed by forbs at 32 to 48 %. During this study eight forage categories were identified. Order of importance of forage categories was the same for 1995 and 1996; categories were grasses, forbs, corn, alfalfa (Medicago sativa), shrubs, soybean, and wheat (Triticum aestivum). The effect of surrounding habitats on the amount of depredation that occurred around SLNWR was examined. Amount of alfalfa adjacent to cornfields explained 75 % of the variation in depredation in 1995, and 5 % in 1995 and 1996 combined. Wood lands adjacent to cornfields did not affect depredation. Distance from the refuge did not affect deer use of agricultural fields and deer diets did not differ throughout the growing season. Study results indicated that white-tailed deer at SLNWR are causing slight but not unreasonable damage to adjacent agricultural lands. Adjustments in timing of deer harvests, use of deterrents, and placement of high-value cash crops may aid farmers and refuge personnel in reducing damage caused by white-tailed deer around SLNWR.