MOWED SOIL GLY2.5 UNMOW TILLED GLY 1.5 CRNVCH HAYSTW 

 GROUNDCOVER TYPE 



Figure 1. Percent of plots with evidence of vole activity (as determined by the apple activity 

 index) for 8 groundcover treatments at the Cornell Orchard, Ithaca, NY. Key to 

 groundcovers: MOWED = mowed sod; SOIL = bare soil; GLY 2.5 = glyphosate-treated sod, 

 2.5 yards wide; UNMOW = unmowed, but treated sod; TILLED = clean tilled soil; GLY 1.5 

 = glyphosate-treated sod, 1.5 yards wide; CRNVCH = crownvetch; and HAYSTW = hay/ 

 straw mulch. 



through 1988 to keep the number of voles in 

 check. Researchers never attempted to deter- 

 mine the total number of voles on the site but 

 instead relied on indices of their presence. Evi- 

 dence of vole presence and activity (e.g., 

 feedings, runs, tunnels, nest sites) within each 

 groundcover type was monitored and extent of 

 damage was estimated. In 1990, all application 

 of rodenticide ceased and vole activity was as- 

 sessed using an apple activity index and feeding 

 index. These techniques both involve examin- 

 ing apple slices placed in runs for evidence of 

 feeding by voles (i.e., tooth marks). 



Results 



Highest levels of vole activity were found on 

 plots covered by crownvetch and by hay/straw 

 mulch; whereas, rototilled, mowed sod, and bare 

 soil strips were infrequently used by voles. 

 Feeding damage by voles on apple trees also was 

 more extensive under crownvetch (field-wide 



average of 40% injury) and hay/straw mulch. 

 Based on apple slice indices, 100% of the apple 

 bait stations placed in hay/straw mulch and 96% 

 of those placed in crownvetch were visited by 

 voles; activity at bait stations was lowest in 

 mowed sod, bare soil, and 2.5-yard herbicide- 

 treated strips (Figure 1). 



Discussion 



Based on the results of this study, it is clear 

 that groundcovers need not be edible to be of 

 importance to voles. In fact, the structural 

 qualities of a groundcover (i.e. the escape or 

 hiding cover it provides) appear to be of equal, if 

 not greater, importance to these animals than 

 the food potential such groundcover may offer. 

 Hay/straw mulch was not used as food yet it 

 provided excellent cover under which voles 

 would be concealed while feeding. Similarly, 

 crownvetch provide a thick, protective canopy 

 under which voles could move about without 



Fruit Notes, Summer, 1991 



