Dental anomalies in the gray foxUrocyon cinereoargenteus and the red foxVulpes vulpes

We examined dental anomalies, including oligodonty, polydonty, connation, rotation, and misalignment in 510 gray foxes and 150 red foxes from southern Illinois (USA). Dental anomalies were significantly more common (x ² = 11.5, df = 1,p < 0.001) in gray foxes (n = 177; 34.7% of sample) than red foxes (n = 25; 16.6% of sample), and more common in male than female gray foxes (x ² = 3.88, df = 1,p < 0.05). Polydonty was very uncommon, as expected for species in which the normal dental complement is close to the primitive eutherian number. In both species, the most prevalent anomaly was loss of the last lower molar. Loss of the upper or lower first premolar was also common. Thus, oligodonty almost always involved the smaller anterior (P¹ and P₁) or posterior (M₃) teeth of the dental arcade. Conversely, the large carnassial teeth, with complex occlusal patterns and shearing surfaces, appeared to be highly conserved with only three anomalous individuals (0.4%) among all specimens.     

Den distribution and den use by the red foxVulpes vulpes japonica in Kyushu

The distribution of dens and den use by the red fox was studied in Kumamoto Prefecture between 1968 and 1982. A total of 80 dens were classified into natal, residential, and temporarily-visited dens. Natal dens comprised 12.4% of all dens. Relative proportions were quite stable for a long period. This indicates a constant number of reproducing females in the area for a considerable length of time. Seasonally the utilization of den showed three peaks in February, May and October. The peaks coincided well with the peaks of reproductive activity of female foxes. The results of multiple regression analysis of distribution of dens with respect to selected environmental parameters around densites indicated that the fox selectively utilize open land, rather than densely vegetated areas. The persistence of dens, the selective utilization by foxes of open land and the sizes of dens were all related to the breeding activities of female foxes inhabiting the area. Reproductive females usually used plural dens (“den group”) in one reproductive season. The numbers of those females occuring in the area were maintained at a steady level for fairy long periods. These indicate that the existence of a stable social relationship between females mediated through occupancy of “den groups.”     

Dental anomalies and dental variations in the red foxVulpes vulpes in the Czech Republic

Dental abnormalities including polydonty, oligodonty, extra roots, different root morphotype, root fusion, different crown morphotype, crown reduction, partial crown eruption, supernumerary cusp, irregularities in the position of the teeth, and malocclusion were studied in a set of 785 red foxVulpes vulpes (Linnaeus, 1758) skulls (401 males, 273 females, and 111 individuals of unknown sex) from the Czech Republic. Three hundred sixty one cases of deviations from normal were found in 170 specimens (21.7%). Most of the deviations were variants within a genetically determined range. The prevalent dental variants included an extra root of M¹ (5.7% specimens), and different root morphotype of P₁ (1.9% specimens). On the other hand, the real dental anomalies, eg polydonty, occurred seldom within the population. P₁ ¹ and M₃ were missing significantly more frequently among females than among males unlike the other deviations, which were divided equally between the sexes. No differences were found between the left and right side of the jaw. Irregularities in the position of the teeth and oligodonty (excluding P¹ ₁, M₃) appeared significantly more abundantly on mandible, whereas extra roots and polydonty were more common on the maxilla. There was no relationship between the incidence of dental abnormalities and the relative mandible and rostrum length.     

Geography of sexual dimorphism in the tooth size of the red fox Vulpes vulpes (Mammalia, Carnivora)

Geographic variation in sexual dimorphism of tooth size was assessed for the red fox Vulpes vulpes (Linnaeus, 1758) across the whole northern range of the species. Twenty-one measurements of tooth size and skull length were taken from 2849 specimens (1577 males and 1272 females) originating from 12 Nearctic and 25 Palearctic localities. The index of sexual dimorphism was calculated as a quotient of the mean measure of certain characters in males by the respective mean in females ( M _m/ M _f). In the whole range, the males were larger than females and mean dimorphism index of tooth size ranged from 1.01 to 1.06. On average, the tooth measurements in males were 3.6% larger than in females. The highest dimorphism was observed in the canines. Dimorphism of tooth size was higher in the Palearctic than Nearctic. Statistically significant differences between regions were found for lengths of C¹, C₁ and M₁. In the Palearctic, higher values of the dimorphism indices were observed particularly in the southern parts of the Eurasian range of the red fox and in Great Britain. For a few metrical traits, sexual dimorphism indices presented significant relations to some geo-climatic variables. The geographic pattern of size dimorphism in the red fox seems to be shaped by sexual selection, intraspecific and interspecific competition and population density.     

Age distribution,sex ratio and mortality of the red foxVulpes vulpes in Tochigi,central Japan: an estimation using a museum collection

One hundred and thirty carcasses of the red fox were collected in Tochigi Prefecture, by the Tochigi Prefectural Museum, from 1981 to 1991. The young/adult ratio of the sample was 1.60, which suggests that the hunting pressure has been relatively low in this area. Six percent of the animals were 5 years or older which compares to those taken in Hokkaido, but is higher than those in Europe and North America. The sex ratio for all specimens had a tendency towards male bias (0.587), but this bias was higher for the adult (0.605) than for the young (0.576). Among young (0 year-old) foxes, more individuals were killed on roads than by trapping or shooting (P<0.02, chisquare test). This mortality pattern was caused by high mortality of young males (P<0.02). The proportions of adults killed by the three mortality factors were similar, though only one of the 14 foxes older than 4 years old was shot, probably due to age-linked activity patterns. Most road-kills of young foxes occurred in May when juveniles began exploiting and in November when sub-adults began dispersal. The ratios of road-kills for the whole sample and for adults alone were 42% and 34%, respectively. These high rates of road-kills suggest that the mortality pattern in Tochigi has been affected by factors characteristic of urban environments.     

Environmental factors influencing the use of habitat in the red fox, Vulpes vulpes

The seasonal variation in habitat selection and its determinants were assessed weekly for a sample of three dog-foxes and two vixens in an ecotonal area of the Tuscan coast, in Italy. The most utilized habitats were the maquis (scrubwood), meadows and pinewood. In the cold season the maquis was preferred to any other habitat, but in the warm months foxes made extensive use of meadows. On the other hand, no clear seasonal pattern of use was detectable for the pinewood. Food habits showed a seasonal variation: juniper berries were the staple food, forming by far the greatest part of the diet during the whole study, except in late spring through midsummer, when beetles and grasshoppers predominated. Availability indices for each main food category were calculated on a weekly basis. Distribution of juniper berries was found to be clumped, whereas insects were dispersed. It was also assessed that the former occurred almost entirely in the pinewood, while the latter inhabited mainly meadows and, to a lesser extent. the pinewood. Measures of fox activity in the three habitats were also taken. The fox diet correlated well to the seasonal abundance of the important food resources, which in turn was significantly correlated to meteorologic factors (temperature, number of rainy days). Surprisingly, the seasonal activity in the pinewood was inversely correlated to local food availability, i.e. juniper berries. This can be explained by the clumpedness of this food resource which, when abundant, allows foxes to become quickly satiated and to retreat to other, more preferred habitat such as the maquis. Such results caution against assuming that extensive time spent in a habitat is an indication of proportional feeding dependence on it.     

Analysis of climatic and geographic factors affecting the presence of chytridiomycosis in Australia

Chytridiomycosis is an emerging fungal disease that has been implicated in the global decline of amphibian populations. Identifying climatic and geographic factors associated with its presence may be useful in control and prevention measures. Factors such as high altitude, cool temperature, and wet climate have been associated with chytridiomycosis outbreaks. Although some of these factors have been studied in a laboratory setting, there have been few studies in a natural setting. In this investigation, the relationship between altitude, average summer maximum temperature, or the amount of rainfall and the presence or absence of chytridiomycosis are statistically tested using data from 56 study sites in Australia. Currently, in Australia, 48 native species of wild amphibians have been found infected with chytridiomycosis. The 56 sites in the present study, extending along approximately 50% of the coastline of Australia, have been identified as either a chytrid site, where > or = 1 species are infected with chytridiomycosis, or a no-decline site, where none of the species present at the site are experiencing a decline or are known to be infected. The odds-ratio test and two-proportions test applied to this data indicate that the presence of chytridiomycosis in Australia is significantly related to temperature. In particular, the presence of chytridiomycosis is more likely at sites where the average summer maximum temperature is < 30 degrees C. The results of the analyses do not indicate a significant relationship between the presence of chytridiomycosis and altitude or rainfall.     

Family studies of tooth size factors in the permanent dentition.

Correlations between dimensions of the permanent teeth in Australian Aboriginals were studied by factor analysis to disclose the main sources of shared variability. Findings indicated that in both males and females most of the common variability in the tooth dimensions could be accounted for by factors representing mesiodistal size of anterior teeth, buccolingual size of anterior teeth, generalized size of the premolars and generalized size of the molars. Factor scores derived from the analysis were used to calculate intraclass correlations among brothers and among sisters. These correlations tended to be higher for the factors contributing most to the common variability indicating that the factors might represent fields under direct genetic control. There was no trend for intraclass correlations among siblings derived from multivariate scores to be consistently higher than those based on observed tooth dimensions. The main advantage to the user of factor analysis is the ability to interpret associations between interrelated variables more objectively than is possible by conventional correlation methods.     

LHRH and LH release in the red fox Vulpes vulpes L

Pituitary responsiveness to exogenous LHRH was studied in vivo and in vitro in the female red fox, a mono-oestrous species. In vivo, the ability of the pituitary to release LH in response to a single injection of LHRH (2 micrograms/kg) was determined at various stages of the reproductive cycle. The greatest responsiveness is observed during the preovulatory period, the lowest during the luteal phase. During the anoestrus phase, the responsiveness is reduced by more than 50% in lactating females compared to non lactating females. In vitro, dispersed fox anterior pituitary cells were exposed four times to LHRH (10(-9) M), hourly, for 8 min. Pituitary cells were taken from lactating and non lactating females. The cells are not sensitive to LHRH in lactating females but become more and more sensitive after weaning. It is suggested the inhibitory influence of lactation could be the result of prolactin-ovarian steroids-gonadotrophins interactions.     

Ecological factors affecting body size of Japanese adolescents

Prefectural data of 17-year-old Japanese adolescents' body size were excerpted from the annual series of Reports on School Health Statistics (Ministry of Education) for the last 35 years, and were correlated with the mean annual temperature of prefectural capitals. A negative correlation was found for both height and weight. Thus, it can be stated that children in colder climates conform to Bergmann's rule that they are larger in their height and weight than children growing up in warmer climates. Partial correlation coefficients indicate that body weight is primarily related to the temperature. Further, the results of a multiple regression analysis, using temperature, daily energy intake (National Nutrition Surveys), and annual per capita income (Annual Reports of Prefectural Accounts) as the independent variables among the 12 districts (groups of prefectures) for the last 25 years, suggest that the observed Bergmann's phenomenon is related to geographical differences in nutrition; people in colder regions consume more calories than those in warmer regions. © 1993 Wiley-Liss, Inc.     

Some factors affecting oxygen uptake by red blood cells in the pulmonary capillaries

In this study we investigate the equations governing the transport of oxygen in pulmonary capillaries. We use a mathematical model consisting of a red blood cell completely surrounded by plasma within a cylindrical pulmonary capillary. This model takes account of convection and diffusion of oxygen through plasma, diffusion of oxygen through the red blood cell, and the reaction between oxygen and haemoglobin molecules. The velocity field within the plasma is calculated by solving the slow flow equations. We investigate the effect on the solution of the governing equations of: (i) mixed-venous blood oxygen partial pressure (the initial conditions); (ii) alveolar gas oxygen partial pressure (the boundary conditions); (iii) neglecting the convection term; and (iv) assuming an instantaneous reaction between the oxygen and haemoglobin molecules. It is found that: (a) equilibrium is reached much more rapidly for high values of mixed-venous blood and alveolar gas oxygen partial pressure; (b) the convection term has a negligible effect on the time taken to reach a prescribed degree of equilibrium; and (c) an instantaneous reaction may be assumed. Explanations are given for each of these results.     

Equilibrium flock size and factors affecting arrival and departure in feeding house sparrows

One way in which the size of flocks of sparrows feeding on barley seed was found to be limited was through the attainment of an equilibrium flock size (EFS). The two most important factors influencing the EFS were the size of the densest patch of seed at a feeding site and seed density outside the patch. Birds appeared to arrive at random but to depart in response to a giving up time (GUT) the length of which was positively related to preceding interpeck intervals. The GUT correlates best with the average interval for the last three pecks before leaving. The rate of fighting per bird increased with flock size. Some birds remained behind when others left and appeared to be those whose low peck rate increased when other birds left.     

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.     

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.     

Fecundity and egg output by Toxocara canis in the red fox, Vulpes vulpes

The role of the red fox Vulpes vulpes in the dissemination of eggs of Toxocara canis into the environment is considered with reference to female worm fecundity and egg output in the faeces of infected foxes collected from four localities in southern England. A significant positive correlation was found between female worm size and the number of eggs in the uterus but there was no significant relationship between T. canis worm numbers and egg output in fox faeces. Reliable estimates of worm burdens in foxes could not, therefore, be determined from faecal egg counts alone. The highest mean egg output of 2145.0 epg recorded from adult foxes indicated that fox cubs are not necessarily the main sources of environmental contamination with T. canis eggs. Saturated magnesium sulphate was found to be a more effective flotation solution than zinc sulphate and sodium chloride for recovering eggs from fox faecal samples.