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Assessing Factors That May Predispose Minnesota
Farms To Wolf Depredation on Cattle

Results


All but 3 of the 11 farm characteristics and management practices we assessed were similar for chronic and matching farms, with one factor being equivocal (Tables 1-4). The 3 factors that differed were size of farm, number of livestock, and distance of livestock from human dwelling and these factors were correlated (r2 = 0.09-0.37, P = 0.001-0.05). The chronic farms were larger (491 vs. 292 ± 71 ha), had more cattle (158 vs. 82 ± 18), and had herds farther (mean maximum distance = 2.8 km vs. 1.8 ± 0.5 km) from human dwellings (Table 1).

Table 1.  Mean (95% confidence limits) values of Minnesota farm characteristics for 41 farms suffering chronic wolf depredations on cattle and 41 nearby matching farms that experienced no such losses, 1989-98.
  Chronic a Match a
Farm size (ha) 491 292 71
Number of cattle 158 82 18
Number of years raising cattle 38 35 8
Amount (arc°) of pasture bordered by brush-forest 213 205 38
Longest distance livestock is from house (km) 2.8 1.8 0.5
a Chronic farms represented a complete population, except for 2 farms, whereas matching farms were a sample.

Table 2.  Types of pasture where cattle were located at 41 Minnesota farms suffering from chronic wolf depredations on cattle and 41 nearby matching farms experiencing no such losses, 1989-98.
Type of pasture Total chronic a Total matching a
Brushy 0 2
Open 13 14
Wooded 0 0
Open-brushy 4 4
Open-brushy-wooded 11 7
Open-wooded 13 14
Total 41 41
a Chronic farms represented a complete population, except for 2 farms, whereas matching farms were a sample. (= 2.96, P = 0.56).

Table 3.  Calving locations for 41 Minnesota farms suffering chronic wolf depredations on cattle and 41 nearby matching farms that experienced no such losses, 1989-98.
Location of calving Total chronic a Total matching a
Barn 3 4
Barnyard 29 25
Barn and barnyard 0 3
Pasture 7 6
Pasture and barn 1 0
Pasture and barnyard 1 1
No calves 0 2
Total 41 41
a Chronic farms represented a complete population, except for 2 farms, whereas matching farms were a sample. (= 6.52, P = 0.37).

Table 4.  Number of times/week Minnesota farmers checked cattle at 41 farms suffering chronic wolf depredations on cattle and 41 matching farms that experienced no such losses, 1989-98.
Times stock checked Chronic farms a Matching farms a
0 1 0
1 1 3
2 5 5
3 3 1
4 2 6
7 21 20
14 7 4
Almost daily 1 0
More than twice/day 0 2
Total 41 41
a Chronic farms represented a complete population, except for 2 farms, whereas matching farms were a sample. (= 8.84, P = 0.36).

The equivocal factor was method of carcass disposal. Contrary to expectations, more farms with chronic losses reported properly disposing of carcasses than did matching farms not suffering cattle depredations (Table 5). However, WS personnel indicated that they had observed evidence of at least an intermittent carcass dump on all except 2 of the 41 farms with chronic losses. Number of carcasses that matching farms disposed of varied from 2 to 10/year.

Table 5.  Carcass disposal methods for 41 Minnesota farms suffering chronic wolf depredations on cattle and 41 nearby matching farms that experienced no such losses, 1989-98.
Carcass disposal method Total chronic farms a Total matching farms a
Bury 24 13
Burn 3 4
Carcass dump 1 3
Carcass dump and burn 0 1
Rendering plant 3 2
Leave in pasture 2 10
Bury and lime 1 0
Bury and burn 2 3
Leave in pasture and burn 1 0
Leave in pasture and feed to dogs 1 1
Leave in pasture and bury 1 1
Rendering plant and bury 1 1
Rendering plant and feed to dogs 1 0
Rendering plant and pasture 0 1
Unknown 0 1
Total 41 41
a Chronic farms represented a complete population, except for 2 farms, whereas matching farms were a sample. (= 6.15, P = 0.30).

Habitat-land-use characteristics for chronic farms and their matches were similar in all respects that we could measure for the 1.6-km and 4.8-km radii (Table 6). In other words, neither habitat nor land-use proportions within 1.6 or 4.8 km around farms differed between chronic and matched farms.

Table 6.  Percentage of habitat types within circles of 1.6-km and 4.8-km radii around the farms summed for 41 Minnesota farms suffering chronic wolf depredation on cattle and 41 nearby matching farms that experienced no such losses, 1989-98.
Habitat Type 1.6-km radius 4.8-km radius a
Chronic farms b Matching farms b Chronic farms b Matching farms b
Bog-marsh-fen 12 9 17 14
Brushland 10 10 9 9
Cultivated 19 22 15 16
Forested 35 34 43 43
Hay-pasture-grassland 23 22 13 14
Mining 0 0 0 0
Urban-rural development 1 1 1 1
Water 1 1 2 3
a Chronic farm without a matching farm not included in analysis.
b One chronic farm and its match removed as the 4.8-km buffer extended outside of habitat coverage. Because results were so obviously similar, they were not tested statistically, in keeping with Chatfield (1995) and Cherry (1998).


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