Evaluation of an animal-activated scarecrow and a monofilament fence for reducing deer use of soybean fields

We measured the efficacy of an animal-activated scarecrow (AAS) and a 5-strand monofilament fence (MF) at reducing white-tailed deer (Odocoileus virginianus) use of 0.4-ha soybean plots in Missouri, USA. Our study design consisted of 9 soybean plots; 3 served as controls, 3 were surrounded by an MF, and 3 were surrounded by an AAS. Data collected for each protected plot included soybean height and weight taken from within and immediately adjacent to 10 unprotected, equally spaced 1-m² exclosures. A measure of deer use for each plot was collected with video cameras. A mixed-effects analysis of variance (ANOVA) indicated that heights of protected and unprotected soybean plants were significantly different for MF plots (F₂ = 93.6, P = 0.01) and controls (F₂ = 47.6, P = 0.02) but not different for AAS plots (F₂ = 2.16, P = 0.272). Soybean plants in AAS plots were heavier than those from MF or control plots (F₂ = 10.2, P = 0.01). Plant weight differences in protected and unprotected areas for AAS plots were less than those from MF plots (t₆ = 2.55, P = 0.04) or control plots (t₆ = 4.46, P = 0.004). Plant weight differences between MF and control plots were marginally significant (t₆ = 1.192, P = 0.10). Deer spent less time in AAS plots than MF (t₆ = 2.55, P = 0.04) or control plots (t₆ = 2.55, P = 0.01). Scarecrow activations increased over time in all 3 AAS plots (all 95% confidence intervals >0), suggesting that deer were habituating to the devices. We suggest that AAS may be useful for short-term deterrence of deer from small areas.