The flea epifauna of a suburban fox (Vulpes vulpes) population

Five hundred and thirteen fleas, of eight different species, were collected from a sample of 252 foxes killed in suburban London. 25–8% of foxes carried fleas, with a mean of 204 fleas per fox. Levels of infestation of male and female hosts did not differ significantly. Possible sources of the fleas infesting foxes are discussed with respect to their seasonal occurrence and fox prey composition. No evidence was found to support the suggestion that foxes obtain the majority of their fleas from prey items, although occasional heavy infestations of some flea species were probably derived from recent meals. Although Pulex irritans, Paraceras m. melis and Ctenocephalides canis , which contributed 35 % of the flea epifauna, could be considered parasitic on the fox, it seems probable that foxes pick up the majority of their fleas from the habitat through which they move. Thus, two particularly heavily infested categories of foxes were found: (1) juveniles during July-September, their fleas probably being accumulated during exploratory and play activities, and (2) all animals during the period October-December.     

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.     

The food of suburban foxes (Vulpes vulpes), with special reference to London

The food of foxes in suburban London was examined using stomach contents and den litter analysis. A great diversity of food was taken. Adult foxes killed nearer to the city centre were found to eat significantly fewer earthworms, domestic pets and wild mammals, but more scavenged food items, than foxes killed closer to the suburban fringe. Cubs killed closer to the city centre ate significantly fewer earthworms and insects, and more pet birds, pet mammals and scavenged food items than cubs killed nearer the periphery of the suburban area. Although seasonal trends in food selection were apparent, they were not as pronounced as those observed in studies of rural foxes. At no time of the year did a single food item predominate in the diet of adult foxes. Passeriformes were the most important single food item in the diet of young cubs, but there was no correlation between the number of Passeriformes eaten and their abundance, nor between annual changes in the abundance of small birds and mean fox birth litter size and productivity. Most foxes examined were in good body condition; there was no seasonal variation in body weight, although fat content did vary seasonally. A complementary survey in Bristol on losses of domestic pets to foxes revealed that 07% of pet cats and 80% of other pets kept outdoors were killed in a year. Damage to garden Crops was negligible.     

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.     

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.     

Observations on the diet of the Red fox (Vulpes vulpes) in South Devon

The results of an 18-month survey of fox diet in the Stoke Gabriel area of South Devon are presented. Attention is drawn to the variety of prey consumed, and some features not previously recorded are noted. The probable factors influencing the diet are discussed and availability suggested to be the most important.     

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.     

Physiological responses of red foxes (Vulpes vulpes) to surgery

Radio transmitters were surgically implanted into the abdomens of red foxes (Vulpes vulpes). Blood samples were taken before, immediately after, and 8 hr after surgery and analyzed for hormonal, biochemical, electrolyte and hematologic changes. Samples were taken at the same times from control foxes. Adrenocorticotropin increased after surgery (P less than 0.05), but returned to pre-surgery values after 8 hr. Cortisol increased and remained elevated in the surgery group relative to pre-surgery values or to control values (P less than 0.05); Triiodothyronine and thyroxine both decreased from post-surgery values 8 hr later (P less than 0.05). Creatine kinase, total bilirubin and aspartate aminotransferase increased after 8 hr in both surgery and control groups (P less than 0.05). Carbon dioxide increased under anesthesia in both groups, but returned to initial values after 8 hr (P less than 0.05). The white blood cell count increased after 8 hr only in the surgery group (P less than 0.05). There were no differences between the groups for any value obtained from the initial blood sample. These data indicate that abdominal surgery results in prolonged adrenocortical activity and decreased thyroid hormone levels, but otherwise has minimal systemic effects in red foxes.     

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.     

Changes in the numbers of foxes (Vulpes vulpes) in Scotland

More foxes were killed in Scotland from 1971 to 1978 than in the previous decade, but in some parts the rate of increase was not being maintained. Fluctuations in the numbers of foxes killed were associated with big changes in the numbers of Field voles.     

Reproductive management of silver foxes (Vulpes vulpes) in captivity

Specific protocols need to be developed that take into consideration the requirements of silver foxes. This study was designed to investigate the reproduction of 26 pairs of silver foxes (Vulpes vulpes). Reproduction parameters (breeding season, age at puberty, fecundity and fertility) of the foxes were examined under experimental conditions, and new techniques to optimize fox breeding were assessed. Staining of the vaginal smears with the double Harris-Schorr stain allowed for the precise detection of estrus and proved to be more reliable than simply measuring vaginal resistance. Ultrasonography was demonstrated to be useful for pregnancy diagnosis and prediction of parturition. Results demonstrate that the methods reported in this paper are easily applicable to similar studies carried out on small groups of animals within the framework of fox animal experimentation.     

Lynx (Lynx lynx) killing red foxes (Vulpes vulpes) in boreal Sweden – frequency and population effects

We studied the frequency and pattern of lynx Lynx lynx predation on red foxes Vulpes vulpes in boreal Sweden by the radio tracking of foxes and the snow tracking of lynx. We also assessed the population trend of red foxes after the re-establishment of lynx in the region, based on various population indices. Fifty per cent of recorded fox mortalities in the radio-tracking study (four of eight) were lynx kills. Adult-sized foxes killed by lynx during radio tracking were in normal condition and of prime age, and were killed after the assumed annual population bottleneck. Albeit based on a small number of kills, this pattern may suggest that lynx predation, at least to some extent, is additive to other mortality in foxes. The annual lynx predation rate was 14% on radio-tracked foxes and 4% on snow-tracked foxes. The population indices of foxes in the main study area decreased by about 10% annually during the study period. The population decrease could potentially be explained by lynx predation alone, but we acknowledge some alternative explanations. Our results point out the possibility that red fox populations can be significantly limited by allowing lynx populations to recover.