Distribution, habitat utilization and age structure of a suburban fox (Vulpes vulpes) population

The occurrence of wild foxes in suburbia is discussed. It is shown that in London breeding populations of foxes are found 5 km from the city centre, and in the last 3 years foxes have been recorded in the very centre of the city. The fox population in London is shown to be heavily dependent on residential habitats for both daytime harbourage and when selecting sites for natal earths. The fox population is unevenly distributed in London, with a marked clumping of the adult population during most of the year. The age structure of the population is presented, and these data are compared with data for other canid populations. Conclusions are drawn as to the effects of conventional control techniques on the age structure of a fox population.     

Acute disseminated toxoplasmosis in a red fox (Vulpes vulpes)

A red fox (Vulpes vulpes) with signs of neurological disease was captured in Fairmount Park, Philadelphia, Pennsylvania (USA). The animal died in captivity and was examined because of suspected rabies. The liver had pale foci up to 4 mm in diameter. Foci of necrosis were associated with Toxoplasma gondii tachyzoites in several organs including liver, lungs and adrenal glands. Rabies antigen and distemper virus inclusions were not detected. The diagnosis of acute disseminated toxoplasmosis was confirmed by immunohistochemical staining.     

Identification of the Tibetan fox (Vulpes ferrilata) and the red fox (Vulpes vulpes) by copro-DNA diagnosis

Studies on feeding habits based on faeces dissecting are imperative to understand the natural history of Tibetan foxes and their functions in the transmission of a lethal zoonotic parasite, Echinococcus multilocularis. However, Tibetan foxes and red foxes live sympatrically on the Tibetan plateau, China. Therefore, the faeces of Tibetan foxes must be distinguished from those of red foxes. We established a diagnostic method to distinguish the faeces of the two species by amplifying a portion of the mitochondrial cytochrome b gene (cytb) and digesting with the restriction enzymes BamHI and SspI, to produce specific diagnostic banding patterns. This PCR-RFLP assay enabled rapid, accurate and easily performed identification and differentiation of the two species.     

The impact of sarcoptic mange Sarcoptes scabiei on the British fox Vulpes vulpes population

• 1 Disease epizootics can significantly influence host population dynamics and the structure and functioning of ecological communities. Sarcoptic mange Sarcoptes scabiei has dramatically reduced red fox populations Vulpes vulpes in several countries, including Britain, although impacts on demographic processes are poorly understood. We review the literature on the impact of mange on red fox populations, assess its current distribution in Britain through a questionnaire survey and present new data on resultant demographic changes in foxes in Bristol, UK.
• 2 A mange epizootic in Sweden spread across the entire country in < 10 years resulting in a decline in fox density of up to 95%; density remained lowered for 15–20 years. In Spain, mange has been enzootic for > 75 years and is widely distributed; mange presence was negatively correlated with habitat quality.
• 3 Localized outbreaks have occurred sporadically in Britain during the last 100 years. The most recent large‐scale outbreak arose in the 1990s, although mange has been present in south London and surrounding environs since the 1940s. The questionnaire survey indicated that mange was broadly distributed across Britain, but areas of perceived high prevalence (> 50% affected) were mainly in central and southern England. Habitat type did not significantly affect the presence/absence of mange or perceived prevalence rates. Subjective assessments suggested that populations take 15–20 years to recover.
• 4 Mange appeared in Bristol's foxes in 1994. During the epizootic phase (1994–95), mange spread through the city at a rate of 0.6–0.9 km/month, with a rise in infection in domestic dogs Canis familiaris c. 1–2 months later. Juvenile and adult fox mortality increased and the proportion of females that reproduced declined but litter size was unaffected. Population density declined by > 95%.
• 5 In the enzootic phase (1996–present), mange was the most significant mortality factor. Juvenile mortality was significantly higher than in the pre‐mange period, and the number of juveniles classified as dispersers declined. Mange infection reduced the reproductive potential of males and females: females with advanced mange did not breed; severely infected males failed to undergo spermatogenesis. In 2004, Bristol fox population density was only 15% of that in 1994.

     

Microevolutionary trends in the dentition of the Red fox (Vulpes vulpes)

Microevolutionary trends in dental traits were studied in a Polish population of the Red fox, Vulpes vulpes (Linnaeus, 1758). Changes in qualitative and quantitative traits over a 70‐year interval were analysed in 1453 museum specimens collected between 1927 and 1996. Over that period, there were qualitative trends towards increasing complication of occlusal crown surface in posterior premolars (i.e. P⁴, P₃, P₄) and I³. Other cheek teeth did not undergo directional change. Changes in trait correlations were assessed using samples from the 1960s and 1990s. The correlations between C¹–C₁ and M¹–M² increased, while correlation values in the incisor region (I₁–I₂, I¹–I₁, I¹–I₂, I³–I₂), carnassial region (P₄–M₁, P⁴–M₁ and M₁–M₁) and in P²–P₁ decreased. These changes may be related to increasing dietary opportunism of the Red fox during the 20th century.     

Photoperiodic regulation of reproduction in the male silver fox (Vulpes vulpes)

Six silver fox males were exposed to short days (6L:18D) from February, when the testes were fully developed, until June 1986 (Group 6L). Eight males maintained in natural daylight served as controls (Group N). Histological sections from the testes of 2 males in Group 6L killed in June indicated full spermatogenic activity. Three blue fox vixens inseminated the following year with semen collected and frozen in June from 3 males in Group 6L failed to produce litters. One possible explanation for the reproductive failures could have been that the high environmental temperatures in June influenced semen quality. There was no significant difference (P greater than 0.05) in LH release in response to GnRH stimulation in June, but testosterone response to LH release was significantly higher (P less than 0.01) in animals subjected to a restricted photoperiod, demonstrating that testicular testosterone production was maintained longer than in control animals. Two males in Group 6L were retained in 6L:18D from June until December 1986 and then exposed to natural daylight until the end of the study in May 1987 (Group 6L:6L:N). These males started to shed their winter coat and showed clinical signs of testicular regression in December, i.e. after approximately 11 months exposure to 6L:18D. The 2 remaining males in Group 6L were moved to cages with natural daylight in June 1986, where they were kept until the end of the experiment (Group 6L: N:N). These males displayed testicular regression soon after the change in photoperiod but maintained their capacity for testicular redevelopment during the following breeding season.(ABSTRACT TRUNCATED AT 250 WORDS)     

Variations of the chromosome number in the red fox (Vulpes vulpes)

The chromosome number in peripheral blood cells of five individuals of Vulpes vulpes (Red Fox) is shown to vary between 35 and 39. This variation is due to loss or gain of the smallest autosome, which it is suggested is heterochromatic and does not have any major influence on the phenotype. This species demonstrates variation in chromosome number both between and within individuals.     

Studies of disease in the Red fox (Vulpes vulpes) in Northern Ireland

Some 720 foxes were examined for signs of disease and parasites, incidental to an intensive ecological study. The epifauna, skin infections, intestinal helminths and lesions of internal organs are described and rates of infection given. Important diseases included sarcoptic mange, which is a major debilitating factor and probably a fatal infection. Leptospirosis was common, antibodies were recorded in the blood, and chronic interstitial nephritis was a frequent condition of the kidneys. The nematodes Uncinaria stenocephala and Toxocara spp. were often present as parasites of the alimentary canal and may be a mortality factor in cubs. The cestodes and ectoparasites alone would appear to be of little importance and largely reflect the diet of the fox.