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The reproductive performance of female red foxes, Vulpes vulpes , in central-western New South Wales during and after a drought

2001; NRC Research Press; Volume: 79; Issue: 4 Linguagem: Inglês

10.1139/z01-003

1480-3283

John McIlroy, Glen Saunders, Lyn A. Hinds,

Veterinary Equine Medical Research

The reproductive condition of 295 female red foxes, Vulpes vulpes, collected during and shortly after a severe drought in central-western New South Wales, Australia, was assessed to assist research on the potential use of immunocontraception. The ovulation and conception rates per vixen for the 222 foxes that ovulated were 4.62 ± 1.50 and 3.58 ± 2.18 (mean ± SD), respectively. The resorption rate and mean litter size per vixen for the 188 foxes that were pregnant were 0.47 ± 0.92 and 3.75 ± 1.91, respectively. Details of the parameters are provided for each age-class. The proportion of the overall population that was pregnant was 0.847. Conception rates and litter sizes peaked in fifth- and sixth-year vixens, but vixens over 8 years of age produced as many cubs as first-year breeders did. Vixens collected during 1996, when rainfall was above average, contained significantly more corpora lutea than vixens collected during the drought years 1994 and 1995. There were no significant differences in other reproductive parameters (i.e., conception and resorption rates, litter size, and proportion of the population that was pregnant) between the 3 collection years. Mating occurred within a 3- to 7-week period from mid-June to the end of July and births from early August to late September. From a practical point of view, vixens will need to be targeted with immunocontraceptive baits in autumn.