Ontogenic patterns of scent marking in red foxes, Vulpes vulpes (Carnivora: Canidae)

Scent marking is widely recognised to have a crucial function in many species. Most research has focussed on adults and very little is known about scent marking patterns during juvenile development. Using video records of juvenile red fox Vulpes vulpes across 6 years, we tested whether scent marking rates varied with age or sex, or whether juveniles remaining on the natal territory (philopatry) marked more frequently than those that disappeared. Our data show that male juvenile red foxes scent marked more than females during early development, but rates rapidly declined as they aged. In contrast, females showed a significantly later and slower rate of decline. Within females, individuals that remained in the natal area had higher scent marking rates than those that disappeared, suggesting that scent marking has a role in social group affiliation within litters. These results demonstrate that scent marking plays an important role in juveniles, including their intra-litter social interactions

Lunar illumination shapes small mammal activity in lowland agricultural landscapes

The behavioural patterns of small mammalian prey species have been shown to be widely impacted by predator avoidance. Cues to avoid predation may come from the predator itself or environmental cues, such as moonlight and available vegetative cover. We investigated how the activity of the bank vole Myodes glareolus, field vole Microtus agrestis, wood mouse Apodemus sylvaticus and the common shrew Sorex araneus were impacted by changes in habitat and lunar light conditions across a range of habitats (mainly grassland protected sites) in Lincolnshire (UK). Microhabitat vegetation density as well as weather conditions were recorded across all trap sites, with Longworth traps set overnight and the successfully captured species recorded the following morning. Overnight temperature was found to positively influence capture rate across all species. The lunar phase was found to significantly impact capture rate, with the gibbous lunar phase providing the highest capture rate across species. The interaction between illumination and vegetation density was also found to impact activity levels in the bank vole and wood mouse, with the bank vole showing higher activity in thick vegetation at low light levels and across habitats at higher light levels, whereas wood mice were more often captured in intermediate cover at low and intermediate illumination but across a range of habitats at brighter illumination. In combination, it suggests that small mammal activity is altered to potentially reduce predation risk. However, in this community at least, brighter lunar illumination leads to increase activity. &nbsp

Genetic Patterns of Paternity and Testes Size in Mammals

Background: Testes size is used as a proxy of male intrasexual competition, with larger testes indicative of greater competition. It has been shown that in some taxa, social mating systems reflect variance in testes size, but results are not consistent, and instead it has been suggested that genetic patterns of mating may reflect testes size. However, there are different measures of genetic patterns of mating. Multiple paternity rates are the most widely used measure but are limited to species that produce multi-offspring litters, so, at least for group living species, other measures such as loss of paternity to males outside the social group (extra group paternity) or the proportion of offspring sired by the dominant male (alpha paternity) might be appropriate. This study examines the relationship between testes size and three genetic patterns of mating: multiple paternity, extragroup paternity and alpha paternity. Methodology/Principal Findings: Using data from mammals, phylogenetically corrected general linear models demonstrate that both multiple paternity and alpha paternity, but not extra group paternity, relate to testes size. Testes size is greater in species with high multiple paternity rates, whereas the converse is found for alpha paternity. Additionally, length of mating season, ovulation mode and litter size significantly influenced testes size in one model. Conclusions/Significance: These results demonstrate that patterns of mating (multiple paternity and alpha paternity rates) determined by genetic analysis can provide reliable indicators of male postcopulatory intrasexual competition (testes size)

Sexually-trimorphic interactions with colour polymorphism determine nectar quality in a herbaceous perennial

Amongst gynodioecious plant breeding systems, there can exist intermediate morphs with a reduction in their male function (i.e. reduced number of functional anthers). Along with this sexual trimorphism, plants can also show floral colour polymorphism. Such intricate mixtures of phenotypes within a species may have complex effects on floral rewards. Floral rewards are known to vary between sexually dimorphic species and to a lesser extent between colour morphs. However, the interactive effect of sexual trimorphism and colour polymorphism is unexplored. We measured nectar’s sugar content in the sexually trimorphic Geranium sylvaticum, a gynodioecious plant with a light/dark floral polymorphism. We found that nectar reward differed across genders and colour morphs. Results were not however consistent within the three genders; dark female and hermaphrodite flowers had higher sugar content than light morphs, whereas intermediate flowers did not. As expected, females and hermaphrodites had different nectar reward, with intermediate morphs being midway between the other genders. In intermediates, the sugar content was positively correlated to the number of functional stamens. We show for the first time the existence of sex-specific differences between flower gender and colour morphs. Our results demonstrate the importance of considering multiple and conflicting selection pressures to explain rewards

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

Environmental stressors affect sex ratios in sexually dimorphic plant sexual systems

• Revealing the environmental pressures determining the frequency of females amongst populations of sexually dimorphic plants is a key research question. Analyses of sex-ratio variation have been mainly done in dioecious plants, which misses key plant sexual systems that might represent intermediate stages in the evolution of dioecy from hermaphroditism. • We investigated female frequency across populations of sexually dimorphic plant species in relation to environmental stressors (temperature, precipitation), totaling 342 species, 2011 populations, representing 40 orders and 3 different sexual systems (dioecy, gynodioecy, and subdioecy). We also included the biome where the population was located to test how female frequency may vary more broadly with climatic conditions. • After correcting for phylogeny, our results for gynodioecious systems showed a positive relationship between female frequency and increased environmental stress, with the main effects being temperature-related. Subdioecious systems showed also strong positive relationships with temperature and positive and negative relationships related to precipitation, whilst no significant effects on sex ratio in dioecious plants were detected. • Combined, we show that female frequencies in intermediate sexual system on the pathway from hermaphroditism to dioecy respond strongly to environmental stressors and have different selective agents driving female frequency

Seasonal and sex-specific differences in feeding site attendance by red foxes Vulpes vulpes

Food provided by householders represents a key resource for urban red foxes Vulpes vulpes. Using long-term video footage, we examined how patterns of feeding site attendance varied with season, sex and likely residence status. For foxes attending frequently (>15%) we found feeding site attendance highest for females in spring, probably because of feeding dependent young, and lowest for both sexes in autumn because of changes in seasonal food abundance or in time spent in other activities. For infrequent attenders (<15%), females attended most often in autumn and winter, coinciding with the dispersal period. Male attendance was not higher during the breeding season. Our combined results show how feeding site attendance changes throughout the year relative to potential intrinsic and extrinsic factors

Structural biomechanics determine spectral purity of bush-cricket calls

Bush-crickets (Orthoptera: Tettigoniidae) generate sound using tegminal stridulation. Signalling effectiveness is affected by the widely varying acoustic parameters of temporal pattern, frequency and spectral purity (tonality). During stridulation, frequency multiplication occurs as a scraper on one wing scrapes across a file of sclerotized teeth on the other. The frequency with which these tooth–scraper interactions occur, along with radiating wing cell resonant properties, dictates both frequency and tonality in the call. Bush-cricket species produce calls ranging from resonant, tonal calls through to non-resonant, broadband signals. The differences are believed to result from differences in file tooth arrangement and wing radiators, but a systematic test of the structural causes of broadband or tonal calls is lacking. Using phylogenetically controlled structural equation models, we show that parameters of file tooth density and file length are the best-fitting predictors of tonality across 40 bush-cricket species. Features of file morphology constrain the production of spectrally pure signals, but systematic distribution of teeth alone does not explain pure-tone sound production in this family

Does physical activity age wild animals?

There is considerable interest in why the process of ageing varies between individuals, both in humans and other animals. However, in animals, ageing in terms of survival (demographic senescence) is understood in considerably more detail than in terms of decline in the body’s functional capacity (functional senescence). Oxidative damage is probably an important component of the ageing process in many species. Oxidative stress typically increases as a result of physical activity, and many animals exhibit long and intense periods of active behaviour. These observations raise a question that has not yet been addressed: while in humans, at least, activity is considered beneficial to health, could high intensity activity play a part in the rate that wild animals age? Studies to date suggest that increased ‘effort’ can lead to reduced survival in free-living animals, but ‘effort’ refers to different processes in different studies, and is rarely clarified or quantified. To understand the role of activity in functional senescence, studies must measure the detailed activity of free-ranging animals, possibly describing it in terms of intensity, frequency and duration, coupled with records of resultant physiological and DNA damage

Demonstrating frequency-dependent transmission of sarcoptic mange in red foxes

Understanding the relationship between disease transmission and host density is essential for predicting disease spread and control. Using long-term data on sarcoptic mange in a red fox Vulpes vulpes population, we tested long-held assumptions of density- and frequency-dependent direct disease transmission. We also assessed the role of indirect transmission. Contrary to assumptions typical of epidemiological models, mange dynamics are better explained by frequency-dependent disease transmission than by density-dependent transmission in this canid. We found no support for indirect transmission. We present the first estimates of R0 and age-specific transmission coefficients for mange in foxes. These parameters are important for managing this poorly understood but highly contagious and economically damaging disease