Wildlife Monographs
Red Fox Predation on Breeding Ducks
in Midcontinent North America
Tables
Table 11. Estimated number of dabbling ducks taken by red foxes in 2 physiographic regions comprising Barnes, Kidder, and Stutsman counties, North Dakota, during the fox denning seasons, 1969-73.
| Area & Year | Predation rate (surface ducks/den) |
Ducks/fox familya |
Total fox familiesb |
Total ducks taken |
Ducks/km2 | |
| Drift Plain (7304 km2) | ||||||
| 1969 | 2.94 | 65.9 | 219 | 14432 | 1.98 | |
| 1970 | 1.65 | 37.0 | 365 | 13505 | 1.85 | |
| 1971 | 0.72 | 16.1 | 730 | 11753 | 1.61 | |
| 1972 | 1.27 | 28.5 | 657 | 18725 | 2.56 | |
| 1973 | 0.78 | 17.5 | 803 | 14053 | 1.92 | |
| Avg. | 33.0 | 14494 | 1.98 | |||
| Missouri Coteau (6224 km2) | ||||||
| 1969 | 2.58 | 57.8 | 373 | 21559 | 3.46 | |
| 1970 | 2.00 | 44.8 | 498 | 22310 | 3.58 | |
| 1971 | 1.59 | 35.6 | 622 | 22143 | 3.56 | |
| 1972 | 1.92 | 43.0 | 871 | 37453 | 6.02 | |
| 1973 | 1.13 | 25.3 | 996 | 25199 | 4.05 | |
| Avg. | 41.3 | 25733 | 4.13 | |||
| Combined area (13528 km2) | ||||||
| 1969 | 592 | 35991 | 2.66 | |||
| 1970 | 863 | 35815 | 2.65 | |||
| 1971 | 1352 | 33896 | 2.51 | |||
| 1972 | 1528 | 56178 | 4.15 | |||
| 1973 | 1799 | 39252 | 2.90 | |||
| Avg. | 40326 | 2.97 | ||||
aDerived by multiplying the annual predation rate by the expansion factor of 22.4. The expansion factor accounts for ducks at dens that were not detectable in surface remains, ducks taken by foxes but not found at dens, and average number of dens used by fox families to rear litters.
bPopulation estimate is based on fox family densities provided in Table 10.
