Red fox prey demands and implications to prairie duck production

摘要: Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, growth rates using natural foods. Pups began eating the 4th week after birth. Then, consumption averaged 1.38 1.90 kg/pup/week for weeks 58 9-12 of denning season respectively, 2.54 postdenning period. Feeding by adults 2.25 kg/adult/week. Free water was not needed either pups or adults. About 90 percent offered on simulated diets consumed; remains varied availability type. Prey biomass required a typical fox family estimated at 18.5 kg/km2 12-week 2.4 kg/km2/week Because large ducks could represent small part foxes' diet yet be consequence productivity particular species. An example is provided mallard (Anas platyrhynchos). J. WILDL. MANAGE. 42(3):520-527 Many studies (e.g., Errington 1935, Scott 1943) show that are largely carnivorous, but few document quantities required. Knowledge requirements useful assessing impact populations. During winter individual eat 0.38-0.57 kg per day (Scott 1943, Lockie 1959, Vogtsberger 1972, Ryszkowski et al. 1973). Red have high assimilation 85-97 being digestible depending food type (Vogtsberger Barrett 1973, Litvaitis Mautz 1976); 87 ingested energy used body maintenance noted gorging carrying heavy fat loads; thus, survival seems depend regular feeding. Behavioral traits such as caching (Murie 1936, Macdonald 1976) insure periods scarcity. The purpose this paper provide quantitative estimates demands (including nonconsumed parts) adult pup pup-rearing period, relate these predation prairie nesting Emphasis approximate which in northern region begins early April coincides duck (Sargeant 1972). This period because caring then can affect production local areas. I appreciate assistance S. H. Allen R. T. Eberhardt capturing foxes, numerous individuals from Northern Prairie Wildlife Research Center North Dakota Game Fish Department providing prey, L. E. Dwyer conducting tests, G. Pearson diagnostic services. D. Johnson statistical advice together Krapu Greenwood critically reviewed manuscript; drafting C. W. Shaiffer. Dane unpublished data weights spring.