Journal of Zoology最新文献

Human-wildlife conflicts have increased and are particularly acute when predators are involved. A frequent source of conflict is some people's misbeliefs related to the alleged impact of predators on game species and livestock. In this context, quantifying the impact of expanding predators on their prey can be useful in designing conflict mitigation strategies. We estimated the predation impact of the Egyptian mongoose (Herpestes ichneumon), an expanding mesocarnivore in southwestern Europe, on European rabbit (Oryctolagus cuniculus) and red-legged partridge (Alectoris rufa) populations, two declining prey species highly valued by hunters. We estimated mongoose densities in three areas of central Spain through live capture, GPS/VHF tagging, camera-trapping and spatial mark-resight models. Rabbit and partridge densities were estimated through transect counts and distance sampling. We quantified the mongoose diet by scat analysis. Finally, we compared the number of individuals consumed by the predator population with the estimated total prey populations. European rabbits were the most important mongoose food in two of the study areas, whereas red-legged partridges were rarely consumed in all the areas. Rabbit density varied widely among study areas (14.0–881.4 rabbits/km²), while partridge density was low in all the areas (2.3–6.9 partridges/km2). The predation impact on rabbits was low in the area with the highest rabbit density (1.9–3.8% of estimated population) and higher (5.6–29%) in the other areas. In contrast, the predation impact on partridge populations was low (<9%) in all the study areas. This is the first study that estimates the Egyptian mongoose impact on small-game species, a necessary step to deal with the conflicts over the management of this expanding species. The study of predation impact may contribute to the effective management of human-wildlife conflicts involving predators, by improving the understanding of where additional management may take place to protect prey species or deter predator populations.

Autotomy in animals, the voluntary loss of a body part at a specific location, is a widespread behaviour observed across various groups. This mechanism provides several advantages, such as predator evasion, escape from entrapments, and even reduced injury costs from agonistic interactions. Lizards display tail autotomy in response to predation and intraspecific aggression. Moreover, it is common for these reptiles to have sexually dimorphic traits, such as colouration and body size, which may influence predation risk and consequently their antipredatory strategies. This study focuses on the Achala copper lizard (Pristidactylus achalensis) which inhabits an isolated highland ecosystem in central Argentina. This species is an ideal study model due to its territorial and aggressive behaviour, high intraspecific competition and sexual dichromatism. The aims of this study were to determine the influence of sex and body size on the occurrence of tail autotomy in P. achalensis. Additionally, we assessed the cost of autotomy by analysing the distance between the vent and the tail cut. Furthermore, we investigated the possibility of repeated tail autotomy by a single individual. Our results showed that in P. achalensis, sex and body size interacted significantly resulting in different patterns of tail autotomy. In females, the frequency of autotomy increased gradually with body size, whereas in males it increased more abruptly and reached its maximum frequency at smaller body sizes than in females. Males presented higher autotomy frequencies than females, likely because they are more likely to be perceived by avian predators than cryptic females. The findings of this study contribute to broadening the knowledge of lizard behaviour, shedding light on the complex interplay between predation, intraspecific competition and reproductive dynamics in this unique species.

Hair offers a non-invasive way to assess mercury exposure in diverse species, but variable and poorly understood molt patterns in wildlife may hamper the interpretation of tracer levels in hair. The reliability of using hair to precisely assess internal mercury burden, thus, varies across species, but few studies have assessed the reliability of using claw. Claws grow continuously, and growth rate may be easier to monitor than molt patterns. We quantified total mercury concentration (THg) in internal and keratinous tissues of 55 red foxes (Vulpes vulpes) legally harvested near Arctic tree line in Canada in winter (i.e., when mobility and opportunistic foraging are maximal) to compare the performance of hair and claw in predicting internal mercury burden, and examine the overall capacity of THg in keratinous tissues to predict internal THg at low exposure. Red foxes are widespread, occur at high densities and occupy a high trophic position, and thus could be a good sentinel species for monitoring mercury in the less-studied terrestrial food webs. We found generally low levels of THg in all fox tissues (range: 0.06 mg kg⁻¹ in brain to 1.13 mg kg⁻¹ in hair) indicating overall low contamination of this low-Arctic terrestrial food web. Relationships between THg of diverse internal organs were strong, but THg in both claws and hair were poor predictors of THg in internal organs. We thus advise caution when interpreting mercury levels in keratinous tissues of highly mobile species, as they may over- or underestimate the overall levels of exposure of a population because of non-continuous or seasonal growth. Adding a time component using segmental analysis of continuously growing keratinous tissues, or associating multiple tissues reflecting diverse timeframes and physiological processes, may offer a more accurate and complete understanding of toxicological risks.

The great snipe Gallinago media, as a long-distant migrant wintering in Africa, faces the challenge of accumulating sufficient energy reserves before departing from European breeding grounds. Despite possible trade-offs in resource allocation, this species additionally initiates moult of flight feathers before southward migration. Here, we discuss the strategy of flight feather moult and fuelling for female and male great snipes from the Eastern European lowland population, exploring their scheduling constrained by the timing of breeding and departure. We found significant intersexual differences in both moult initiation date and the speed of moult. Males start flight feather replacement more than 2 weeks earlier and moult at a faster rate compared to females. However, neither sex completed this process on breeding grounds before the migration, as late in the season all males and half of the females had suspended their primary moult, with the remaining females not moulted at all. Moult of secondaries rarely occurred in the studied population. We observed non-linear energetic stores gain in the studied period, where both sexes maintained stable and low energy stores until the end of July, coinciding with the primary moulting period. Subsequently, there was an increase in energy stores of approximately 1% of the lean body mass per day, indicating a shift towards fuelling for migratory flight. The overlap between stages of stable and low energy stores and moulting suggests a resource allocation towards feather growth before initiating fuelling. Besides limiting a trade-off in resource allocation, this strategy may also contribute to minimizing predation risk, as both increased body mass and missing flight feathers may impair flight. Our study describes moult strategy in great snipe conducted on their breeding grounds, highlighting intersexual differences likely resulting from different parental duties of males and females of this lekking species.

Several animals present ornamental colouration which acts as signals in sexual or other social contexts by indicating some trait of the bearer. This colouration is often present only in one sex and may be produced by a varied combination of structural elements and several pigments. Given that colours may be produced in different ways, the traits the colouration is indicating, and the costs or trade?offs associated, may differ according to the colour and the species studied. Here, I study a dark ventral colouration present in males of the gecko Quedenfeldtia trachyblepharus, a high-altitude, semi-colonial lizard endemic to the High Atlas in North Africa. I tested for the correlation between the extension of the dark colouration and several morphological traits (body size, head size and limb length) in the gecko, as well as parasitism by mites and age. No relationship was found between dark colouration and parasitism, age and limb length, but the extension of the dark colouration was positively correlated with head size controlled for body size. Given that head size is usually a good indicator of fighting capacity, and this gecko shows a strong social structure, the findings suggest that the dark colouration is used in agonistic encounters among males, allowing for evaluation of the fighting capacity of the rivals.

Anthropogenic landscape change due to urbanization, agriculture, and resource extraction results in barriers within the landscape. Artificial structures such as roads, fences, levees, and dams limit the movement of some species and further fragment residual habitat. In this study, we investigated the ability of Eastern long-necked turtles (Chelodina longicollis) to cross various terrestrial obstacles commonly encountered throughout their habitat. We tested two types of fences (chicken wire and hinged joint exclusion fencing) commonly used in agricultural systems and three sizes of rocks (gravel, cobbles, and boulders) often used for road construction, erosion control, and waterway stabilization. We examined the success rates of turtles in crossing obstacles, the effect of fatigue on crossing attempts, and the impact of individual boldness on movement behaviour. Turtles had high success rates in crossing gravel (85.4%), cobbles (86%), boulders (73.3%) and hinged joint exclusion fencing (94.7%). Turtles did not successfully cross chicken wire fencing (0%) despite 276 attempts. A significant fatigue effect occurred throughout the experiment, with turtles making an average of 3.94 (±1.42 SE) fewer attempts at the end of the experiment (day 18) than on day 1. Bolder turtles were faster at crossing obstacles, but boldness had no influence on obstacle-crossing success. Our results highlight the need for thoughtful selection of waterway, wetland, and riparian bordering infrastructure and the fatiguing impact of constant exposure to anthropogenic barriers for wildlife.

Various species inhabit cities around the world, and numerous changes in their biology can be observed. Among them, changes in the time of reproduction or productivity are often recorded in urban populations. Firstly, we compared selected reproductive features (i.e., litter size and time of breeding) of two red fox (Vulpes vulpes) populations, one living in the city of Warsaw and the other inhabiting a forest-field mosaic in Central Poland. Secondly, we investigated fox reproductive and social behaviour in an extensive camera trap study in Warsaw (2018–2021). By means of generalized linear mixed effects models, we identified which factors (fox social group size, share of natural food, and level of urbanization, created by using principal components analysis for habitat and landscape variables) affected the reproduction and/or social group size of urban foxes. We found that urban foxes started breeding about 2 weeks earlier than their rural counterparts and produced bigger litters (3.98 vs. 3.48 cubs). Opposite to rural foxes where only pairs of adult foxes were reported, in the urban population, social groups were observed with a mean number of 2.37 individuals. Interestingly, none of the studied factors affected group size or litter size in urban foxes, while breeding time was influenced by the level of urbanization and share of natural food. Earlier reproduction in urban areas is fairly frequently observed and may be attributed to altered environmental conditions in urban habitats, while higher productivity is probably a consequence of higher food availability.

Osteoderms, bone plates in the skin, are widely but discontinuously distributed across the phylogeny of tetrapods. This and their pronounced morphological disparity has inspired many hypotheses on possible osteoderm functions. Most of these have not been systematically studied or summarised based on the published disparate literature. We provide here a comprehensive overview of the current state of knowledge in this field with a focus on extant non-avian reptiles. We also discuss functions in other extant osteoderm-bearing taxa and those inferred from the fossil record. The hypotheses are categorised into protection, lifestyle and locomotion, physiology, and visual functions. A comprehensive overview of future directions in this field is provided. With this review, we hope to encourage future research to investigate the functional aspect of osteoderms. This might inspire biomimetics and shed light on the role that osteoderm expression may have played in shaping present-day biodiversity.

Organisms facing anthropogenic activities usually exhibit phenotypic responses assumed to enhance coping with disturbance. These responses include a decreasing degree of reaction toward potentially risky situations (“behavioral tolerance”) with increasing disturbance. Though melanin is associated with many phenotypic traits, including pigmentation and behavior, the potential relationship between behavioral tolerance and melanin has never been explored. Such relationship may potentially result from either direct association between melanin and behavior (e.g., genetic correlation) or indirectly through a coloration-dependent behavior-modulating factor (e.g., differential predation or human preferences in cities toward color morphs). Feral pigeons (Columba livia) represent an ideal biological system to test for these hypotheses, due to their presence in cities worldwide, their considerable variation in eumelanin-based coloration, ranging from white to black plumage, and their close proximity to humans. We measured Flight Initiation Distance (FID, classically used for behavioral tolerance assessment) of feral pigeons of 4 different eumelanin-based color morphs in sites differing in their urbanization rate and pedestrian traffic within the restricted scale of a city center (Paris). Urbanization rate and pedestrian traffic had no effect on FID, maybe because of the small spatial scale considered. FID varied with eumelanin-based coloration: white pigeons had lower FID (104.6 cm; i.e., higher behavioral tolerance) than darker morphs (232.3 cm for Blue bar, 184.4 cm for T-pattern & Checker, and 181.8 cm for Spread color morphs). Though the exact underlying causes remain to be identified, we propose different possible mechanisms for this relationship that remain to be investigated in future work.