Differences between air and ground temperatures are expected to narrow with the advance of the season in temperate regions (aka seasonal restriction in the availability of thermal microhabitats), ...which may activate behavioral and physiological responses of ectotherm species adapted to temperate climates. However, according to cost-benefit models of ectotherm thermoregulation, we hypothesize that these responses may also carry some costs. We quantified seasonal shifts in thermoregulatory precision, concentration of fecal glucocorticoid metabolites, and load of ectoparasites in a Mediterranean lizard, Psammodromus algirus. We also tested whether the proximity to a road, a putative source of chronic stress, can facilitate the glucocorticoid-mediated response of lizards to heat stress. As expected, differences between body and environmental temperatures narrowed during the reproductive season and lizards responded by increasing their thermoregulatory precision and the secretion of glucocorticoids, as indicated by metabolites in feces. Interestingly, lizards tended to have higher glucocorticoid concentration when captured far from the road. This might reflect either a putative impairment of the glucocorticoid-mediated response of the lizards to heat stress close to the road or the plastic capability of P. algirus to acclimate to sources of moderate chronic stress. In the latter direction, the increase of both glucocorticoid metabolites and thermoregulatory precision supported that this Mediterranean species responds to environmental thermal restrictions with adaptive behavioral and physiological mechanisms. However, this was also associated with an increase in its susceptibility to ectoparasites, which represents an added cost to the current cost-benefit models of ectotherm thermoregulation.
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•Climate may impose thermal restrictions to ectotherms in Mediterranean habitats.•Lizards increased thermoregulatory activity and glucocorticoids under heat stress.•Coping responses were not influenced by the distance to a road.•Seasonal increase of ectoparasites was explained by thermal restrictions.
•Mice recapture/total captures ratio is higher under predation risk.•Recaptured mice stress levels are lower in the presence of predator cues.•Under predation risk, the safety provided by traps may ...outweigh their risks.•The effects of two stressors do not result in the addition of both responses.
Live trapping is an essential element of field ecological studies. However, the act of trapping provides two types of conditional benefits (food from the bait when hungry, and refuge from a predator when threatened) against one type of drawback (confinement). Our understanding of how animals assess the two benefits against the lone risk determines how we interpret classic field studies in chemical ecology and wildlife management. Here, we studied wood mice responses to these risks and rewards of field trapping by examining experience through recapture and faecal corticosterone metabolites (FCM) as a physiological response indicator. Wood mice were live-trapped in two different plots subjected to two distinct phases: phase 1, absence of predator cues, and phase 2, in which traps were treated with red fox faeces. During phase 1, the recapture percentage was lower indicating that mice avoided traps while FCM levels in recaptured mice were higher. On the contrary, during phase 2, despite the total number of captures was lower we found an increase in the recapture percentage and FCM levels did not increase in recaptured mice. Our results suggest that under increased risk perception traps could be likely considered as a suitable shelter and thus, for some individuals the benefits of traps may outweigh their risks. In addition, we discovered that the effects of combining two stressors do not result in the addition of the response originated by each factor separately.
To date, there have been no studies of carnivores that have been specifically designed to examine the function of scent marks in trophic resource defence, although several chemical communication ...studies have discussed other functions of these marks. The aim of this study was to test the hypothesis that faecal marks deposited by wildcats (Felis silvestris) serve to defend their primary trophic resource, small mammals. Field data were collected over a 2-year period in a protected area in northwestern Spain. To determine the small mammal abundance in different habitat types, a seasonal live trapping campaign was undertaken in deciduous forests, mature pine forests and scrublands. In each habitat, we trapped in three widely separated Universal Transverse Mercator (UTM) cells. At the same time that the trapping was being performed, transects were conducted on foot along forest roads in each trapping cell and in one adjacent cell to detect fresh wildcat scats that did or did not have a scent-marking function. A scat was considered to have a presumed marking function when it was located on a conspicuous substrate, above ground level, at a crossroad or in a latrine. The number of faecal marks and the small mammal abundance varied by habitat type but not by seasons. The results of the analysis of covariance (ANCOVA) indicated that small mammal abundance and habitat type were the factors that explained the largest degrees of variation in the faecal marking index (number of faecal marks in each cell/number of kilometres surveyed in each cell). This result suggests that wildcats defended favourable hunting areas. They mark most often where their main prey lives and so where they spend the most time hunting (in areas where their main prey is more abundant). This practice would allow wildcats to protect their main trophic resource and would reduce intraspecific trophic competition.
We examined whether group size in red deer (
Cervus elaphus
L., 1758) and roe deer (
Capreolus capreolus
(L., 1758)) under predation risk by Iberian wolves (
Canis lupus
L., 1758) is affected by the ...type of habitat in which the deer reside. We hypothesized that group size (i) would be larger in open than in closed habitats, since it is an antipredator response, and (ii) would vary more with habitat type in the species that had higher wolf predation rates. In the study area, wolves were the only predator of wild ungulates, with roe deer being the main target prey. We performed monthly transects along paths to observe the group size of red and roe deer. In roe deer, the mean group size was significantly higher in open than in closed habitats, serving as an antipredator response. However, in red deer, habitat type did not affect group size. The results indicate that under predation risk by wolves the habitat type influences the grouping behavior of roe deer but not red deer. Furthermore, compared with forests, heaths offer less protection from predators and species in this habitat would benefit from larger group sizes.
We studied the habitat selection patterns of badgers
Meles meles (Linnaeus, 1758) in Mediterranean semi-arid ecosystems. Fifty-seven plots were sampled in two semi-arid regions of Spain. In each ...plot, badger latrines were located along 2.6 km transects. The number of badger latrines per km was used as a surrogate of badger abundance and as an index of habitat selection by badgers. For each plot, a series of environmental variables were measured at two spatial scales. These variables were related to land use and vegetation formation parameters that are considered potentially important for habitat requirements (i.e., food and shelter). The habitat selection model was carried out using generalised linear models (GLM) and an information-theoretic approach. Results indicated that badgers prefer fruit orchards, and shrub and rock-covered areas, which provide additional trophic and shelter resources, and avoid intensively cultivated fields and human settlements. We conclude that badger conservation in semi-arid environments of the Iberian Peninsula requires the existence of fruit orchards and the limitation of human development. Policies restraining agriculture intensification would encourage traditional or new non-intensive agricultural practices and increase shrub-patch availability, which would benefit this species.
► We model the habitat selection patterns of badgers in Mediterranean semi-arid ecosystems. ► Badgers select fruit orchards, shrub and rock-covered areas, and avoid intensively cultivated fields and human settlements. ► Policies that encourage traditional agricultural practices would benefit badgers. ► Badgers would benefit policies that restrict human development.
The function of wolf,
Canis lupus, faeces in chemical communication and the selection of raised and conspicuous substrates to increase their effectiveness as visual scent marks are well documented. ...Therefore, I hypothesized that faecal marks are not placed randomly on plants, and that wolves will select specific plants according to characteristics that enhance faeces as visual scent marks and ensure greater support and persistence of these marks over time. Analysis of the physical properties of plants marked by Iberian wolves showed that the choice of plants was clearly not random. The factors that determined selection were plant diameter, height and species. The mean height and diameter of faeces-marked plants were significantly greater than those of unmarked plants. Furthermore, plant use in relation to size (diameter and height) and species did not depend on availability in the environment. Persistence time was independent of the substratum type, height and altitude, but did depend on the scat content, being longer when the scat contained bone than when it contained hair or undetermined matter. These results indicate that the physical appearance of the plant is important for the wolf when deciding where to deposit faecal marks. Thus, the use of standard species and sizes of plants maximizes visual localization of faecal marks deposited by intruder and resident wolves.
The determination of gender in wild animals is essential for behavioural and ecological studies, and also for conservation. The objectives of this study were (i) the determination of gender in faecal ...samples of Iberian wolf based on the differential concentrations of sexual steroid hormones (SSH) and (ii) to analyse the profiles of SSH in males and females (considering the gender determination carried out previously) during the non-reproductive and reproductive periods. The quantification of androgens (testosterone, T), progestin (progesterone, P) and oestrogen (oestradiol, E) was conducted by means of enzyme immunoassay. The k-means conglomerate analysis showed that the 59 faecal samples grouped into three different conglomerates, considering SSH levels. Groups 1 and 2 showed higher levels of T than group 3. Therefore, the faecal samples included in groups 1 and 2 (17 samples) corresponded to males and those of group 3 (42 samples) to females. The levels of T + P + E and T/P were higher in the group of males than in the group of females. The results of this study also showed that levels of T in males were higher during the reproductive period than in the non-reproductive period. However, the concentrations of P and E turned out to be higher during the non-reproductive season. In females, the levels of the three hormones (T, P and E) were higher during the reproductive period.
Small sized felids, such as wild and domestic cats, are one of the most common predators in the nature and in sites occupied by humans in archaeological and historical contexts. Wildcats have ...ingestion/digestion traits highly destructive for their prey, i.e.: teeth to chew causing extreme breakage, and digestion along the entire digestive tract with low pH gastric juices causing extreme bone corrosion. Small sized cats are also well known to play with the prey and select skeletal parts to ingest. The present study is focused on the taphonomic analysis of micromammal remains recovered from scats produced by European wildcats (Felis silvestris silvestris) during several months and years. Excrements were collected from the Montes do Invernadeiro Natural Park (Galicia, Spain). Following the taphonomic methodological protocols, anatomical representation, bone breakage and degrees of digestive corrosion were evaluated. Results obtained from the skeletal representation indicate a high abundance of cranial skeleton and a high fracture pattern. Most dental elements show digestion, reaching extreme grades of corrosion, but the proportions of micromammal prey elements affected varies between taxonomic groups. The large sample size collected during 2 years, including different seasons, show no differences in either taxonomic composition or degree of digestion between the four seasons. The scat contents provide a basic and general pattern of alterations caused by carnivorous mammals on the bony elements of their prey. Some differences between felid predator species have also been observed, thus pointing out the necessity of more actualistic taphonomic analysis that will allow us to obtain a more accurate indication of modifications produced by small carnivorous mammals and specific differences.
•Neotaphonomy allows us to identify predators from digestion of their prey = 75.•Wild and domestic cats are common predators in sites occupied by humans = 73.•European cat scats were not yet studied in depth to characterize their prey = 77.•Glirid teeth, femora and humeri in all digestion grades are sketched here = 75.•The sample collected along several years and seasons helps to establish a solid pattern = 89.
Microcalorimetric techniques were used to investigate the kinetics of glucose uptake during exponential growth of soil microorganisms. Experiments were carried out using a
humic cambisol soil amended ...with a nutrient solution containing different amounts of glucose (1.25–50.00 mg glucose g
−1 soil). It was found that glucose uptake velocities increased up to a concentration corresponding to 15 mg of glucose in 0.2 ml of distilled water g
−1 soil. Further increases of glucose gave similar
μ
max values (20 mg) or the velocity decreased (30–50 mg). Chemical analyses showed that, in all the cases the glucose was practically exhausted (>99%) at the peak time. Relevant kinetic parameters such as the Michaelis–Menten constant,
K
m
=4.070±0.910 mM, maximum apparent growth rate
μ
max=0.069±0.003 h
−1 and the inhibitory nutrient concentration were determined from the power–time curves recorded.
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