1,720,971 research outputs found
Offspring condition determines dispersal patterns in western whip snakes, Hierophis viridiflavus
No full text"Dispersal patterns from a communal nesting\/birth site of hatchlings of the oviparous colubrid snake Hierophis viridiflavus were investigated using capture-mark-recapture data from a 17-year study. We found that hatchlings lighter at birth dispersed more than heavier ones, whereas after one year there was no difference in body mass between the individuals which rested close to their birth site and those which dispersed further. We interpret this result as an adaptive dispersal behaviour in which heavier newborn snakes are less inclined to disperse from the hatching site, whereas lighter snakes move further away to increase their foraging efficiency.
Interpreting dispersal patterns of reproductive female Hierophis viridiflavus (LACEPEDE, 1789), around a communal nesting site (Squamata: Serpentes: Colubridae)
No full textSpring basking by Vipera aspis: Observations from Italy and France on the displacement distances of basking vipers from their hibernacula
No full textPatterns of movement are an important component in animal ecology. In temperate zone reptiles this includes movement soon after emergence from hibernation, often a crucial period for courtship and mating. Due to the effects of climate or habitat, intra-specific differences in movement in different areas might be expected. We examined this possibility using long-term data on the displacements of aspic vipers (Vipera aspis) from their hibernation dens in Italy and France; the two sites differed in latitude, altitude and vegetation cover. We found no statistically significant differences between Italy and France in displacement distances from the dens. However, in both countries displacements were significantly greater in the afternoon in both males and females. This was thought to be due to differences in cover between the localities. The likely explanation is that the movement of the sun across the sky may leave morning basking positions in the shade and require the snakes to move further from their dens to continue basking
Food Habits of a Pelomedusid Turtle, Pelomedusa subrufa, in Tropical Africa (Nigeria): The Effects of Sex, Body Size, Season, and Site RID F-2663-2011
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The turtle is in the details: Microhabitat choice by Testudo hermanni is based on microscale plant distribution
No full textAlthough research on habitat use and habitat selection is essential for understanding population ecology and behavior, most such zoological studies have used only general habitat categories describing main habitat features instead of using modern plant ecological approaches. Here, we analyze Testudo hermanni microhabitat use at a coastal Mediterranean site in central Italy by modeling tortoise presence/absence at three spatial scales, using a logistic regression design and quantitative vegetation and plant community analysis to reveal correlates of tortoise habitat use on a fine scale. Our analyses showed that only a few plant species among the many present, and these on a very small spatial scale, are important determinants of tortoise presence and site selection. We also find that tortoises chose a paradoxical combination of high levels of bare soil and high total vegetation cover. This suggests that these tortoises are selecting small patches of habitat in a matrix of less desirable habitat. Our findings also have important implications for habitat management, in that increasing the number of habitat patches containing the few significant plants is likely to be desirable, whereas increasing the size of such patches is probably less relevant. © 2011 Koninklijke Brill NV, Leiden
Population density of syntopic, differently sized lizards in three fragmented woodlands from Mediterranean central Italy
No full text""The population density of three lacertid lizards (Podarcis sicula, Podarcismuralis, Lacerta viridis)was studied along. several transects crossing agro-forest habitats inMediterranean central Italy. Overall, seven transects, in three different wooded. patches, were walked for lizards. Distance sampling (with uniformmodel design) was applied to the dataset in order to calculate. population size, dispersion, and coefficient of variation at each site. In order to detectwhich factorsmay influence lizard density,. a Generalized Linear Model (GLZ; multinomial distribution and cumulative log link function) was built, with environmental. variables and density of predators’ variables being included in the model as covariates (scale predictor). Density of the three. lizard species differed significantly among study sites, evidencing species-specific responses to local patch conditions. None. of the environmental variables taken separately in the GLZ model influenced significantly the lizard densities, whereas lizards. densities showed species-specific response to the considered environmental variables. The largest species (L. viridis) showed. the highest density in the fragment with the most irregular shape and largest wood size, whereas the two smaller Podarcis. species presented their highest population density in the site with the smallest wood patch and with a very low snake density.. Density of P. sicula was negatively correlated with both the woodland area and Colubridae density, and was positively corre-lated with woodland shape (i.e. with circularity)."
Attributes of basking sites of the European pond turtle (Emys orbicularis) in central Italy
No full textAttributes of basking sites are important elements to study in management plans of threatened freshwater turtles.
Here, we analyzed the basking-site characteristics of European pond turtle (Emys orbicularis) populations in aMediterranean
territory of central Italy (Tolfa Mountains, Latium). We used logistic regression and Principal Components Analysis to
characterize 29 presence sites versus 61 random sites, through 16 descriptive variables recorded within a 5 m radius from
the sighting/target spot. Our analyses revealed that some variables (i.e. water turbidity, presence of small coves, submerged
vegetation, and emergent tree-trunks) were those that influenced most strongly the presence of turtles on potential basking
sites. Maintenance of deadwood in water and preservation of submerged aquatic vegetation should be included in the
management planning for this turtle species in central Ital
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