Macroparasite fauna of alien grey squirrels (Sciurus carolinensis): composition, variability and implications for native species.

Introduced hosts populations may benefit of an "enemy release" through impoverishment of parasite communities made of both few imported species and few acquired local ones. Moreover, closely related competing native hosts can be affected by acquiring introduced taxa (spillover) and by increased transmission risk of native parasites (spillback). We determined the macroparasite fauna of invasive grey squirrels (Sciurus carolinensis) in Italy to detect any diversity loss, introduction of novel parasites or acquisition of local ones, and analysed variation in parasite burdens to identify factors that may increase transmission risk for native red squirrels (S. vulgaris). Based on 277 grey squirrels sampled from 7 populations characterised by different time scales in introduction events, we identified 7 gastro-intestinal helminths and 4 parasite arthropods. Parasite richness is lower than in grey squirrel's native range and independent from introduction time lags. The most common parasites are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) and Trichostrongylus calcaratus (6.5%), red squirrel flea Ceratophyllus sciurorum (26.0%) and Holarctic sucking louse Neohaematopinus sciuri (17.7%). All other parasites are European or cosmopolitan species with prevalence below 5%. S. robustus abundance is positively affected by host density and body mass, C. sciurorum abundance increases with host density and varies with seasons. Overall, we show that grey squirrels in Italy may benefit of an enemy release, and both spillback and spillover processes towards native red squirrels may occur

Factors affecting male and female reproductive success in a chipmunk (Tamias sibiricus) with a scramble competition mating system

While sexual selection in mammals with female defense systems has historically received considerable attention, much less is known about the factors affecting reproductive success in mammalian species with scramble competition mating systems. Using mark–recapture techniques and DNA microsatellite loci to assign parentage, we examined the mating system and factors affecting the variation of the annual reproductive success in an introduced population of the Siberian chipmunk, Tamias sibiricus, a small, monomorphic, solitary squirrel. Our analyses showed that breeding females were spatially dispersed, setting the stage for a scramble competition mating system. Male reproductive success was positively associated with the size of the home range. The strength of sexual selection on this behavioral trait was very strong, equaling previous estimates for morphological traits in female defense mating systems. These findings suggest that a behavioral trait, space use, strongly influences the annual reproductive success in males, which is consistent with expectations in a scramble competition mating system. In both sexes, reproductive success was influenced by habitat, with twice as many juveniles produced in semi-open than in closed habitat, possibly due to differences in food availability between the two habitats

Spondylurus martinae (Saint Martin Skink). Distribution

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Spondylurus martinae (Saint Martin Skink). Distribution

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L'élaboration progressive d'une stratégie d'éradication adaptée à une population micro insulaire de rongeurs aux îles Marquises

L'élaboration progressive d'une stratégie d'éradication adaptée à une population micro insulaire de rongeurs aux îles Marquise

L'élaboration progressive d'une stratégie d'éradication adaptée à une population micro insulaire de rongeurs aux îles Marquises

L'élaboration progressive d'une stratégie d'éradication adaptée à une population micro insulaire de rongeurs aux îles Marquise

Inter-annual and inter-individual variations in survival exhibit strong seasonality in a hibernating rodent

International audienceMost research on the demography of wild animal populations has focused on characterizing the variation in the mortality of organisms as a function of intrinsic and environmental characteristics. However, such variation in mortality is difficult to relate to functional life history components (e.g. reproduction, dispersal, hibernation) due to the difficulty in monitoring biological processes at a sufficiently fine timescale. In this study, we used a 10-year individual-based data set with an infra-annual timescale to investigate both intra- and inter-annual survival patterns according to intrinsic and environmental covariates in an introduced population of a small hibernating rodent, the Siberian chipmunk. We compared three distinct periods related to particular life history events: spring reproduction, summer reproduction and hibernation. Our results revealed strong interactions between intrinsic and temporal effects. First, survival of male chipmunks strongly decreases during the reproduction periods, while survival is high and equal between sexes during hibernation. Second, the season of birth affects the survival of juveniles during their first hibernation, which does not have long-lasting consequences at the adult stage. Third, at an inter-annual scale, we found that high food resource availability before hibernation and low chipmunk densities specifically favour subsequent winter survival. Overall, our results confirm that the well-known patterns of yearly and inter-individual variation of mortality observed in animals are themselves strongly variable within a given year, suggesting that they are associated with various functional components of the animals’ life history

Ectoparasite load in the crested porcupine Hystrix cristata Linnaeus, 1758 in Central Italy

The crested porcupine Hystrix cristata is a large body-sized rodent, occurring in Europe only in the Italian Peninsula, where it may have been introduced in early Medieval times. Its parasite fauna is currently poorly known and limited to few anecdotal observations. We have analyzed the ectoparasite load of 165 crested porcupines from Tuscany and Latium (Central Italy). Both captured and road-killed individuals were checked for fleas and ticks. Overall, only 39 porcupines were infested by four species of ticks and five of fleas. Abundance of ectoparasites was higher in areas with higher habitat richness, with respect to densely wooded areas. The most frequent species was the flea Pulex irritans (25 %), whose prevalence peaked in winter probably because of optimal abiotic conditions in the porcupine’s den. The remaining species of both hard ticks (Rhipicephalus bursa, Pholeoixodes hexagonus, and Ixodes ventalloi) and fleas (Paraceras melis, Ctenocephalides canis, Dasypsyllus gallinulae, and Hystrichopsylla talpae), all with prevalence lower than 5 %, could be due to den sharing with other vertebrates, mainly carnivores such as, e.g., red foxes and badgers. The second most prevalent species was the generalist tick Ixodes ricinus (21 %). An adult male-biased parasitism for ticks has been detected, suggesting a possible role of testosterone related immune-depressive effect. The low richness in dominant ectoparasite species, built up by locally acquired generalist taxa, provides support to the allochthonous origin of this rodent in Italy

Seasonal demography of different black rat (Rattus rattus) populations under contrasting natural habitats in Guadeloupe (Lesser Antilles, Caribbean).

12 pagesInternational audienceThe black rat (Rattus rattus) is one of the most widespread rodents on islands worldwide, introduced over the last five centuries. However, reliable information concerning how biotic or abiotic factors influence key parameters of black rat population biology in insular contexts is currently unavailable. Here we aim to document the relative abundance of rat populations and evaluate how the age structure and the body mass of adult individual vary seasonally in different forest environments under contrasting climatic conditions. Rats were captured during wet and dry seasons in 2017–2018 at one or two sites in each of the four natural forested environments of Guadeloupe, all of which experience widely different annual rainfall (semi-deciduous dry forest, seasonal evergreen forest, mountain rainforest and Pterocarpus officinalis swamp forest). A total of 171 black rats were captured during a 1018 trap-night effort. Overall capture results confirm this species to thrive in all the natural forested environments we investigated. With the exception of the P. officinalis swamp forest, black rat populations reach higher relative abundances during the wet season due to juvenile and sub-adult recruitment at the end of the dry season. In contrast, in the P. officinalis swamp forest, breeding activity continues during both seasons and relative rat abundance appears to fluctuate less seasonally. The relative abundance of adult black rats is also higher in the seasonal semi-evergreen and rainforests that experience little or no water stress. These contexts therefore appear the most favourable for sustaining black rat populations, a pattern that is most likely connected to a combination of climatic and/or edaphic parameters that condition the year-round availability and abundance of food resources