Responses of a top and a meso predator and their prey to moon phases

Ocelots in the moonlight: Influence of lunar phase on habitat selection and movement of two sympatric felids

Various landscape and environmental factors influence animal movement and habitat selection. Lunar illumination affects nocturnal visual perception of many species and, consequently, may influence animal activity and habitat selection. However, the effects of varying moon stage may differ across taxa. Prey species often reduce activity during highly visible periods of night while predators may increase activity or alter their habitat use. Ocelots (Leopardus pardalis) and bobcats (Lynx rufus), two nocturnal predatory felids that coexist in southern Texas, may also alter their behavior in response to the phase of the moon. To evaluate the effects of lunar phase on habitat selection of ocelots and bobcats, we executed a step selection analysis using high-frequency GPS-telemetry data collected on each species (ocelot, N = 8; bobcat, N = 13) in southern Texas during 2017-2021 and compared step length during new versus full moons. We predicted that ocelots would increase use of dense thornshrub to reduce their visibility during a full moon. However, as bobcats are habitat generalists and are more active during crepuscular periods, we predicted less influence of moon phase on activity. Ocelots did not alter habitat selection in response to lunar phase but moved shorter distances during full moon phases. Conversely, bobcats selected for greater vegetation cover during full moons, possibly to facilitate hunting during brighter periods, but exhibited no difference in movement across lunar phase. We provide, to our knowledge, the first example of habitat selection by predators in relation to lunar phase and show differences across new versus full moons by ocelots and bobcats such that ocelots alter step length but not habitat selection while bobcats altered habitat selection but not step length in response to shifting lunar phase. Further, we suggest the high potential for ocelot-vehicle collisions on darker nights due to increased movement by ocelots and poor visibility for drivers.

Lunar Cycle, Climate, and Onset of Parturition in Domestic Dromedary Camels: Implications of Species-Specific Metabolic Economy and Social Ecology

Given energy costs for gestating and caring for male offspring are higher than those of female newborns, external environmental conditions might be regarded as likely to affect the timing of delivery processes differentially depending on the sex of the newborn calf to be delivered. The aim of the present paper is to evaluate the association between environmental stressors such as the moon phase and weather-related factors and the onset of labor in female dromedaries. A binary logistic regression model was developed to find the most parsimonious set of variables that are most effective in predicting the probability for a gravid female dromedary to give birth to a male or a female calf, assuming that higher gestational costs and longer labor times are ascribed to the production of a male offspring. Although the differences in the quantitative distribution of spontaneous onset of labor across lunar phases and the mean climate per onset event along the whole study period were deemed nonsignificant (p > 0.05), a non-negligible prediction effect of a new moon, mean wind speed and maximum wind gust was present. At slightly brighter nights and lower mean wind speeds, a calf is more likely to be male. This microevolutionary response to the external environment may have been driven by physiological and behavioral adaptation of metabolic economy and social ecology to give birth to cooperative groups with the best possible reduction of thermoregulatory demands. Model performance indexes then highlighted the heterothermic character of camels to greatly minimize the impact of the external environment. The overall results will also enrich the general knowledge of the interplay between homeostasis and arid and semi-arid environments.

The rhythm of the night: patterns of activity of the European wildcat in the Italian peninsula

The European wildcat is a threatened carnivore, whose ecology is still scarcely studied, especially in Mediterranean areas. In this study, we estimated activity rhythm patterns of this felid, by means of camera-trapping at three spatial scales: (i) whole country (Italy); (ii) biogeographical areas; (iii) latitudinal zones. The activity rhythms patterns were also calculated according to temporal scales: (1) warm semester; (2) cold semester and (3) seasonal scales. Lastly, we also tested whether the effect of moon phases affected the wildcat activity. We conducted the analysis on a total of 975 independent events collected in 2009–2021, from 285 locations, in ~ 65,800 camera days. We showed that the wildcat in Italy exhibits a > 70% nocturnal behaviour, with 20% of diurnal activity, at all spatial scales, and throughout the whole year, with peaks at 10.00 p.m. and 04.00 a.m. We observed a high overlap of wildcat activity rhythms between different biogeographical and latitudinal zones. The wildcat was mainly active on the darkest nights, reducing its activity in bright moonlight nights. Diurnal activity was greater in the warm months and decreased with the distance from shrubs and woodlands, most likely according to activity rhythms of its main prey, water presence in summer, the care of offspring and the availability of shelter sites. Conversely, the distance to paved roads seems to have no significant effects on diurnal activity, suggesting that, in presence of natural shelters, the wildcat probably may tolerate these infrastructures. We suggested limited plasticity in activity rhythm patterns of the wildcat, emphasizing the importance of dark hours for this species.

Feral ungulate and macropod responses to resource scarcity and predation risk at savanna waterholes

Abstract

When exotic species are introduced to new environments, they often have a competitive advantage over native species. In northern Australia, pigs, cattle, and water buffalo have established widespread, feral populations. As ungulates have high water requirements, they typically congregate near waterpoints. We used a fencing experiment to test whether native macropods preferentially visited savanna waterholes where large ungulates were excluded. We also investigated whether water scarcity affected the visitation behaviour and temporal activity patterns of herbivores at waterholes and whether increasing prey aggregation at waterholes increased dingo presence. We found that macropods did not use fenced waterholes preferentially over unfenced ones. Cattle presence at waterholes increased as water became scarce, while macropod and pig presence peaked in the middle of the dry season. Macropod activity declined rapidly at the end of the dry season when cattle activity was greatest, suggesting that macropods may avoid waterholes in areas utilised by cattle when competition for resources is high. Macropods and all ungulates visited waterholes more during a drought year compared to an average rainfall year. Despite increasing prey activity, dingo presence at waterholes did not increase when water became scarce. However, dingo presence increased significantly on moonless nights. Our results suggest that competition between macropods and ungulates may intensify during periods of water scarcity. Climate change and pastoral intensification are likely to increase competition for resources between ungulates and macropods in Australian savannas, potentially threatening macropod populations across the landscape in the future.

Significance statement

In northern Australia, feral populations of pigs, cattle, and water buffalo compete with native wildlife for access to water sources. As interspecific competition favours species with a size advantage, we tested whether kangaroos and wallabies (macropods) preferentially use waterholes where large ungulates (cattle and buffalo) were excluded. We found that macropods avoided waterholes when cattle presence was high but did not preferentially use waterholes where livestock were excluded. When water scarcity peaked during a drought, macropods and all three feral ungulate species visited waterholes more. However, increased prey presence at waterholes during the drought did not correspond with increased predator (dingo) presence. Our study advances the understanding of behavioural interactions between invasive and native species at important shared resources, and how this may affect wildlife conservation in an increasingly unpredictable environment.

Assessing carnivore spatial co-occurrence and temporal overlap in the face of human interference in a semiarid forest

Apex predators drive top-down effects in ecosystems and the loss of such species can trigger mesopredator release. This ecological process has been well documented in human-modified small areas, but for management and conservation of ecological communities, it is important to know which human factors affect apex predator occurrence and which mediate mesopredators release at large scales. We hypothesized that mesopredators would avoid spatial and temporal overlap with the apex predator, the puma; but that human perturbations (i.e., cattle raising and trophy hunting) would dampen top-down effects and mediate habitat use. We installed 16 camera traps in each of 45, 10 × 10 km grid cells in the Caldén forest region of central Argentina resulting in 706 total stations covering 61,611 km² . We used single-season occupancy and two-species co-occurrence models and calculated the species interaction factor (SIF) to explore the contributions of habitat, biotic, and anthropic variables in explaining co-occurrence between carnivore pairs. We also used kernel density estimation techniques to analyze temporal overlap in activity patterns of the carnivore guild. We found that puma habitat use increased with abundance of large prey and with proximity to protected areas. Geoffroy's cats and skunks spatially avoided pumas and this effect was strong and mediated by distance to protected areas and game reserves, but pumas did not influence pampas fox and pampas cat space use. At medium and low levels of puma occupancy, we found evidence of spatial avoidance between three pairs of mesocarnivores. All predators were mostly nocturnal and crepuscular across seasons and mesopredators showed little consistent evidence of changing activity patterns with varying levels of puma occupancy or human interference. We found potential for mesopredator release at large scale, especially on the spatial niche axis. Our results suggest that a combination of interacting factors, in conjunction with habitat features and intervening human activities, may make mesopredator release unlikely or difficult to discern at broad scales. Overall, we believe that promoting the creation of new protected areas linked by small forest patches would likely lead to increased predator and prey abundances, as well as the interactions among carnivores inside and outside of protected areas.

Carried away by a moonlight shadow: activity of wild boar in relation to nocturnal light intensity

An increase of nocturnal activity of ungulate species may represent a compensatory opportunity for energy intake, when activity in daylight is hindered by some disturbance events (e.g. hunting or predation). Therefore, mostly-diurnal and crepuscular species may be active in bright moonlight nights whereas others may shift their diurnal activity towards darkest nights to limit their exposure to predators. In natural and undisturbed conditions, the wild boar may be active both during the day and the night, with alternating periods of activity and resting. In this work, we tested whether activity patterns of wild boar, a species with poor visive abilities, were dependent on moon phases and environmental lightening. We aimed to assess if nocturnal activity could be better explained by variations of the lunar cycle or by the variations of environmental lightening conditions, evaluated by means of different measures of night brightness. Data were collected through camera-trapping in Central Italy in 2019–2020. Despite the poor visive abilities of the wild boar, we observed that this ungulate significantly reduced their activity by avoiding the brightest nights. In our study area, the wild boar has to cope with both human pressure (i.e. mostly hunters and poachers) and predation by the grey wolf. Furthermore, the nocturnal activity of wild boar peaked in mid-Autumn, i.e. when hunting pressure is the highest and when leaf fall may bring wild boar to range for long distances to find suitable resting sites for diurnal hours.

The influence of preferred habitat and daily range of the European hare on its contamination by heavy metals: a case study from the West Carpathians

The Spišská Magura mountain range, located in the Middle Spiš, is one of the regions in Slovakia most contaminated by heavy metals resulting from mining and smelting activities. Heavy metals and other potentially toxic elements have accumulated in mountain areas via atmospheric transport. The influence of the daily range size of the European hare on its contamination by heavy metals was investigated in three habitat types (forest, woodland edge, meadow) in the Spišská Magura mountain range in the West Carpathians. Individual hares (n = 21) were traced and located by GPS following snowfall. Pair samples of their faeces (n = 64) and food (n = 64) were collected from feeding sites. The maps created were used for determination of the size of the daily range as being small or large. All hares that have a small daily range avoid meadows and open spaces due to the higher predation risk. However, individuals with a large daily range feed in all habitats, including meadows. Hares with a small daily range in a forest habitat ingested higher amounts of bio-elements Ca, Cr, S, and Mn as well as higher amounts of heavy metals Ba and Pb than hares with a large daily range. Moreover, dominant hares with a small daily range, with access to abundant food sources in a forest habitat, may gradually take on higher levels of bio-elements including heavy metals that are present in their food source. In contrast, in the woodland edge, hares with a small daily range had a smaller concentration of Ca, Cr, Mn, S, Ba, and Pb compared to hares with a large daily range. Caecotrophy plays a very significant role as far as the intake of nutrients and other elements is concerned. We found significant dependence between concentrations of the elements Cr, S, Ba, Pb, and Cd in the food of European hares and in their faeces.

Abiotic and Biotic Influences on the Movement of Reintroduced Chinese Giant Salamanders (Andrias davidianus) in Two Montane Rivers

Understanding animal movement is a key question in ecology and biodiversity conservation, which is particularly important for the success of reintroduction projects. The movement of critically endangered Chinese giant salamander (Andrias davidianus) remains poorly understood due to the rareness of wild individuals of this species. We lack movement details about the full annual cycle after reintroduction, especially the abiotic and biotic influences that affect its movement. We utilized pilot reintroduction projects as opportunities to fill in some knowledge gaps on their movement ecology. We released 31 juvenile captive-reared Chinese giant salamanders of two age groups in two rivers in the Qinling Mountains of central China and monitored their daily movements for 16 months using surgically implanted radio transmitters. We examined the impacts of individual traits (body mass, body condition) and environmental conditions (temperature, precipitation, and moon phase) on their daily movement patterns. Data were analyzed using a mixed-effects logistic regression model to understand the drivers of their movement tendency (i.e., whether they move or not) and a linear mixed-effects model was used to understand the drivers of their movement distance. We found that movement tendency of the older salamander cohort was positively affected by the moon phase, increasing near the Full Moon, whereas the younger cohort of animals were not impacted by the moon phase. For daily distance moved, we found temperature had a strong positive effect on both cohorts, whereas precipitation had moderate but opposite effects on the two cohorts Body mass and body condition did not have any significant impacts on either age classes' movement tendency or distance. This study provides insight into the abiotic factors that impact the temporal and spatial movement ecology of reintroduced giant salamander, which will in turn help with designing best practices for future releases and conservation of this iconic montane aquatic predator.

Lunar Phases and Wildlife-Vehicle Collisions: Application of the Lunar Disk Percentage Method

Simple Summary

The moon is ubiquitous in the night sky and considered an important abiotic factor that influences animal activity. However, little is known about the relationship between moonlight and the daily, monthly, or seasonal frequency of wildlife–vehicle collisions (WVCs). Traditionally, the influence of moonlight on WVCs has been analyzed using the lunar phase (quarters) approach, which evaluates moonlight on a rough scale (only four 25% steps of the visible moon disc and a strict arrangement of phases over time). We used a different approach; we compared WVCs to the actual lunar disc illumination that is based on the specific daily percentage of the visible lunar disk (LDP). Our findings indicated a significant trend of increasing WVC frequencies with increasing LDP at night. We also examined the correlation between the daily numbers of WVCs and LDP for different months and seasons. Positive correlations between LDP and WVCs were stronger at night and during the late autumn–winter months, particularly in December, suggesting the importance of lunar illumination on WVCs. Our study suggests that the LDP approach may provide more possibilities for the evaluation and quantification of WVCs and lunar light relationships than the traditional lunar phase approach. The results can be useful for predicting and reducing WVCs at different times of the lunar illumination cycle and in different seasons.

Abstract

We investigated the relationship between lunar illumination based on the percentage of the visible lunar disk (LDP) and the frequency of wildlife–vehicle collisions (WVCs) in Lithuania. We analyzed WVC frequency during ten 10% LDP intervals to more precisely reflect the relationship between LDP and WVC. The 10% LDP interval approach showed a significant trend of increasing WVC frequencies with an increasing LDP at night. We also examined the correlation between the daily numbers of WVCs and LDP for different months and seasons. The relationship seemed to be stronger at night and during the late autumn–winter months, particularly in December, suggesting the importance of lunar illumination on WVCs. There was a weak positive correlation between LDP and overall daily number of WVCs (r_s = 0.091; p < 0.001) and between LDP and night WVCs (r_s = 0.104; p < 0.001). We found significant positive correlations for winter (December–February) (r_s = 0.118; p = 0.012) and autumn (August–November) (r_s = 0.127; p = 0.007). Our study suggests that the LDP interval approach may provide more possibilities for the evaluation and quantification of WVCs and lunar light relationships than the traditional lunar phase approach.

Spatiotemporal Overlap between the European Brown Hare and Its Potential Predators and Competitors

Analysis of spatiotemporal partitioning is pivotal to shed light on interspecific coexistence. Most research effort has involved large-sized carnivores and their prey, whereas little attention has been devoted to lagomorphs. We assessed spatiotemporal overlap among the European brown hare Lepus europaeus and its potential competitors and predators through camera-trapping in an area in Central Italy. We estimated the interspecific patterns of the spatiotemporal activity rhythms of brown hares, its potential predators (the red fox Vulpes vulpes, the pine marten Martes martes, the domestic cat Felis catus, and the domestic dog Canis familiaris), and a competitor, the roe deer Capreolus capreolus. Brown hare activity was studied in natural conditions as well as in a fenced area that excluded terrestrial predators and competitors. Free-ranging hares developed a more nocturnal behavior to avoid diurnal predators (i.e., domestic carnivores and martens). Although high temporal overlap was observed between free-ranging brown hares and both red foxes (82%) and roe deer (81%), hares avoided fox by being more active on darkest nights, as well as avoided roe deer through spatial partitioning. We suggest that hares may adapt their spatiotemporal behavior to avoid potential predators and competitors.

Plasticity in daily activity patterns of a key prey species in the Iberian Peninsula to reduce predation risk

Abstract ContextSome prey species can shift their daily activity patterns to reduce the risk of encountering predators, and, in turn, predators develop strategies to increase their chances of meeting prey. European rabbit (Oryctolagus cuniculus) is a key species in Iberian Mediterranean ecosystems. It is the main prey for many vertebrate predators. It is also a game species and is often the target of management measures such as translocations. AimsTo test whether rabbits adjust their activity patterns in response to differing predation regimes in a management context. MethodsRabbits were translocated from a donor area, with a high rabbit density, to a release area in central Spain, with a semi-permeable fenced plot and an unfenced plot, which had no rabbits before the translocation. We estimated daily activity patterns and relative abundance index (RAI) for mesocarnivores and rabbits by using camera-traps, and calculated Jacobs selection index (JSI) to classify each species in a diel period. Additionally, we calculated the activity overlap between prey and mesocarnivores in the different areas. Key resultsRabbits were nocturnal in the donor area, where only two mesocarnivore species were detected, red fox (Vulpes vulpes, with a high RAI) and Egyptian mongoose (Herpestes ichneumon, with a low RAI). However, in the unfenced area, where five mesocarnivore species were present, rabbits showed a crepuscular trend with two activity peaks, around sunrise and around sunset. In contrast, rabbits showed a nocturnal activity in the fenced plot, where four mesocarnivore species were detected but where only the Egyptian mongoose (strictly diurnal) had a high RAI value. Conclusions and implicationsThe results suggest that rabbits in the fenced plot adapted their activity to avoid the diurnal mongooses. Conversely, rabbits in unfenced areas showed a trend towards day/twilight activity patterns as an adaptation to a diverse community of mesocarnivores. Rabbits can adapt their daily activity patterns to reduce predation risk depending on the pressure exerted by different predator species, with conservation and management implications. These adaptations would allow higher success of rabbit translocations despite the risk of predation by carnivores and could help in the management design of future translocations of this key species.

What attributes are relevant for drainage culverts to serve as efficient road crossing structures for mammals?

Roads increase wildlife mortality and present a movement barrier for many species. While wildlife passages have been advocated as a solution to many of the problems associated with roads, they are expensive and many roads still have none. However, roads usually have a series of drainage culverts designed to allow water to cross underneath the road, which might also be used by some mammals. This study aims to (1) determine what variables influence the number of successful passages of drainage culverts by mammals, and to (2) parse the effects that these variables have on the entry into and subsequent full passage of drainage culverts by individual mammals, using cameras and animal track stations along a 20 km stretch of autoroute 10 in Southern Quebec (Canada). Overall, 20 species were observed outside of the drainage culverts, but only about half of them were detected making full crossings. While various species were often seen outside, only animals highly tolerant to water, including raccoons (Procyon lotor) and American mink (Neovison vison), were observed fully crossing the structures with regularity, whereas the number of full crossings was small (<8) for all other species. High-water levels and use of polyethylene as a construction material were the strongest deterrents for both the number of successful passages and the probability of entry into the culverts. While several variables (e.g., water level, structure material, moon luminosity, distance to forest) influenced culvert entry, none had an influence on a mammal's probability of complete passage once it had entered. The results imply that ordinary drainage culverts are unsuitable as substitutes for designated wildlife passages for mammals. We recommend the installation of designated wildlife passages and fences, and that in places where wildlife passages are not feasible, dry ledges be installed in existing drainage culverts to better allow small and medium-sized mammals to safely cross under roads while avoiding the water inside of the culverts. To our knowledge, this study is the first to successfully combine trail cameras inside of drainage culverts with track-box data in the adjacent habitat.

Lunar synchronization of daily activity patterns in a crepuscular avian insectivore

Biological rhythms of nearly all animals on earth are synchronized with natural light and are aligned to day-and-night transitions. Here, we test the hypothesis that the lunar cycle affects the nocturnal flight activity of European Nightjars (Caprimulgus europaeus). We describe daily activity patterns of individuals from three different countries across a wide geographic area, during two discrete periods in the annual cycle. Although the sample size for two of our study sites is small, the results are clear in that on average individual flight activity was strongly correlated with both local variation in day length and with the lunar cycle. We highlight the species' sensitivity to changes in ambient light and its flexibility to respond to such changes in different parts of the world.

Gimme shelter: The effect of rocks and moonlight on occupancy and activity pattern of an endangered rodent, the garden dormouse Eliomys quercinus

Information on spatial behaviour and temporal activity patterns is paramount for the conservation of animal species. This is particularly true for endangered taxa that are threatened by ongoing climatic and environmental changes. The garden dormouse Eliomys quercinus is a native European rodent (family Gliridae), whose populations are declining throughout the Continent. Notwithstanding this, neither International nor National laws explicitly require mandatory monitoring of populations. As a result, compelling information on the spatiotemporal behaviour of dormouse is lacking. We aimed to fill this gap by investigating occupancy patterns in relation to environmental features and activity rhythms in relation to moonlit nights in an Alpine population of dormouse within the Stelvio National Park, northern Italy. Data were collected between May and October 2015. Twenty camera-traps were deployed in a 500 ha coniferous forest, using a random tessellation approach; camera trap data were analyzed with occupancy models and kernel smoothers. Camera-traps provided a reliable assessment of the presence of the garden dormouse, with only 1 % of false absence and a high detection probability (68 %). The occurrence of the garden dormouse was positively influenced by the percentage of rock coverage on the ground. The species showed a strictly nocturnal behaviour, with an activity peak before midnight, negatively related to moonlit nights. The use of rocky areas for nesting, shelter site and thigmotactic movements and moonlight avoidance may represent adaptations of the garden dormouse to avoid predation risk. Our results shed some light on the habitat requirement of a poorly known, near-threatened species, and provide baseline information for future monitoring and conservation activities.

Impacts of "supermoon" events on the physiology of a wild bird

The position of the Moon in relation to the Earth and the Sun gives rise to several predictable cycles, and natural changes in nighttime light intensity are known to cause alterations to physiological processes and behaviors in many animals. The limited research undertaken to date on the physiological responses of animals to the lunar illumination has exclusively focused on the synodic lunar cycle (full moon to full moon, or moon phase) but the moon's orbit-its distance from the Earth-may also be relevant. Every month, the moon moves from apogee, its most distant point from Earth-and then to perigee, its closest point to Earth. Here, we studied wild barnacle geese (Branta leucopsis) to investigate the influence of multiple interacting lunar cycles on the physiology of diurnally active animals. Our study, which uses biologging technology to continually monitor body temperature and heart rate for an entire annual cycle, asks whether there is evidence for a physiological response to natural cycles in lunar brightness in wild birds, particularly "supermoon" phenomena, where perigee coincides with a full moon. There was a three-way interaction between lunar phase, lunar distance, and cloud cover as predictors of nighttime mean body temperature, such that body temperature was highest on clear nights when the full moon coincided with perigee moon. Our study is the first to report the physiological responses of wild birds to "supermoon" events; the wild geese responded to the combination of two independent lunar cycles, by significantly increasing their body temperature at night. That wild birds respond to natural fluctuations in nighttime ambient light levels support the documented responses of many species to anthropogenic sources of artificial light, that birds seem unable to override. As most biological systems are arguably organized foremost by light, this suggests that any interactions between lunar cycles and local weather conditions could have significant impacts on the energy budgets of birds.

Wood mouse feeding effort and decision-making when encountering a restricted unknown food source

Animals making foraging decisions must balance the energy gained, the time invested, and the influence of key environmental factors. In our work, we examined the effect of predation risk cues and experience on feeding efforts when a novel food resource was made available. To achieve this, we live-trapped wood mouse Apodemus sylvaticus in Monte de Valdelatas (Madrid), where 80 Sherman traps were set in four plots. Traps were subjected to two food-access difficulties in treatments consisting of three consecutive nights: open plastic bottles (easy) and closed bottles (difficult), both using corn as bait. To simulate predation risk, we set fox faeces in half of the traps in each plot. We also considered moonlight (medium/low) as an indirect predation risk cue. We analysed whether bottles had been bitten by mice and the gnawed area of each bottle was measured. Our results indicated that food access difficulty, experience, and predation risk determined mice feeding decisions and efforts. The ability of mice to adapt feeding effort when a new food source is available was demonstrated because a higher proportion of closed bottles exhibited bite marks and the gnawed area was bigger. Moreover, mouse experience was determinant in the use of this new resource since recaptured mice gnawed broader orifices in the bottles and the gnawed area increased each time an individual was recaptured. Additionally, direct predation risk cues prompted mice to bite the bottles whereas the effect of different moon phases varied among the food access treatments. This study provides direct evidence of formidable efficacy of wild mice to exploit a new nutrient resource while considering crucial environmental factors that shape the decision-making procedure.

Living with roommates in a shared den: Spatial and temporal segregation among semifossorial mammals

Positive interspecific interactions in animal communities (i.e. den sharing) have long been overlooked in animal ecology. The assessment of spatiotemporal overlap among species living within the same burrow system is paramount to explain their strategies of interspecific coexistence. We studied spatiotemporal behavioural patterns of coexistence among four den-sharing mammal species (i.e. the crested porcupine Hystrix cristata, the Eurasian badger Meles meles, the red fox Vulpes vulpes and the European pine marten Martes martes), inhabiting a hilly area of central Italy. Intensive camera trapping (September 2015-September 2018) was used to estimate the interspecific overlap of both temporal and spatial activity patterns for all species combinations. An extensive nocturnal temporal overlap was recorded among all the species, except the diurnal pine marten. However, crested porcupines were mostly active in the darkest nights, whereas bright moonlight enhanced the hunting success of the red fox. Activity of badgers was limited in bright nights only during cold months, when predation pressure and poaching risk were the highest. Crested porcupines avoided spatial sharing outside the den with both nocturnal carnivores, particularly during the winter, when its cubs are in the den. Overlap in ranging areas and activity rhythms between the red fox and the Eurasian badger may be promoted by a remarkable food niche partitioning. Conversely, spatiotemporal overlap between red foxes and pine martens suggested a significant interspecific spatial partitioning, due to the overlap in feeding habits. Den-sharing represents a form of positive interspecific interaction which may limit energy waste and increase local species diversity and densities. Species using the same burrow system may show both spatial and temporal niche partitioning throughout the year, thus allowing a non-competitive coexistence.

Fine scale spatial variability in the influence of environmental cycles on the occurrence of dolphins at coastal sites

Environmental cycles often influence the presence of animals, creating patterns at different temporal scales, which may mean that their effects overlap and/or interact. Interactions between diel and seasonal cycles have been reported to influence fish behaviour but little is known about such interactions in marine top predators. Here, we studied the combined effect of seasonal, tidal and diel cycles on the occurrence of bottlenose dolphins (Tursiops truncatus) within a Marine Protected Area in Scotland. Our analyses were based on echolocation detections from passive acoustic devices (CPODs) deployed at three coastal sites between 2010 and 2016. We described patterns of dolphins' occurrence using circular statistics and then used generalised additive mixed models to explore the relative importance of each cycle and any interactions between them. We found site-specific cyclical patterns of presence that remained constant across years. There was a highly significant interaction between seasonal and diel cycles at two sites around deep channels, where occurrence was diurnal in summer but became nocturnal in autumn. The study demonstrates the highly plastic behaviour of bottlenose dolphins and shows a previously unreported behaviour that has management implications for this and other marine protected areas.

Aerial-hawking bats adjust their use of space to the lunar cycle

BACKGROUND

Animals change their habitat use in response to spatio-temporal fluctuation of resources. Some resources may vary periodically according to the moonphase. Yet it is poorly documented how animals, particularly nocturnal mammals, adjust their use of space in response to the moonphase.Here, we asked if an obligate nocturnal mammal, the aerial-hawking common noctule bat (Nyctalus noctula), adjusts its 3-dimensional flight behaviour and habitat use to the lunar period. Using miniaturized GPS loggers, we recorded 3-dimensional flight tracks of N. noctula and related these to a canopy height model derived from aerial laser scans to investigate whether bats adjust forest strata use to moonlight intensities.

RESULTS

Noctules frequently foraged above the canopy of coniferous forest at low moonlight intensities, but switched to using open grasslands and arable fields in nights with high moonlight intensities. During the few occasions when noctules used the forest during moonlit nights, they mostly restricted their use of space to flying below the canopy level. The median overall flight altitude of N. noctula equalled 13 ± 16 m but reached up to 71 m above ground (97.5% quantile).

CONCLUSIONS

Our findings argue against general lunar phobic behaviour of aerial-hawking bats. We suggest that the preferred use of open fields around full moon may be a strategy of noctules to increase the success of hunting airborne insects at night. Specifically, the adjustment in use of space may allow bats to hunt for insects that emerge and disperse over open fields during bright moonlight.

Receivers matter: the meaning of alarm calls and competition for nest sites in a bird community

Animal communities may constitute information networks where individuals gain information on predation risk by eavesdropping on alarm calls of other species. However, communities include species in different trophic levels, and it is not yet known how the trophic level of the receiver influences the informative value of a call. Furthermore, no empirical study has yet tested how increased competition may influence the value of alarm calls for distinct receivers. Here, we identify the importance of alarm calls emitted by a small owl, the little owl (Athene noctua), on the structure of a cavity-nesting bird community including mesopredators and primary prey under variable levels of competition for nest holes. Competitors sharing top predators with the callers and prey of the callers interpreted alarm and non-alarm calls differently. Competitors chose preferentially alarm and non-alarm patches over control patches to breed, while prey selected alarm patches. In contrast, competition for nest sites affected habitat selection of prey species more than that of competitors of the callers. This study provides support for a changing value of alarm calls and competition for nest sites for distinct receivers related to niche overlapping among callers and eavesdroppers, therefore, calling attention to possible cascading effects by the use of information in natural communities.

Temporal Variation in Trophic Cascades

The trophic cascade has emerged as a key paradigm in ecology. Although ecologists have made progress in understanding spatial variation in the strength of trophic cascades, temporal variation remains relatively unexplored. Our review suggests that strong trophic cascades are often transient, appearing when ecological conditions support high consumer abundance and rapidly growing, highly edible prey. Persistent top-down control is expected to decay over time in the absence of external drivers, as strong top-down control favors the emergence of better-defended resources. Temporal shifts in cascade strength—including those driven by contemporary global change—can either stabilize or destabilize ecological communities. We suggest that a more temporally explicit approach can improve our ability to explain the drivers of trophic cascades and predict the impact of changing cascade strength on community dynamics.

Foraging, feeding, and physiological stress responses of wild wood mice to increased illumination and common genet cues

In nature, animals are exposed to a broad range of threats imposed by predators, which may strongly influence the ecology of prey species directly or indirectly by affecting their behavior via fear of predation. Here, we studied wood mice Apodemus sylvaticus behavioral and physiological responses to simulated predation risk. Risk avoidance was analyzed by live trapping with control traps and traps treated with feces of common genet Genetta genetta (direct cue of risk) under new moon nights and following by simulated full moon conditions (indirect cue). The time devoted to foraging behavior and capture time were analyzed by video recording mice activity around traps. Food intake was calculated based on the amount of bait remaining in each trap. Fecal corticosterone metabolites (FCMs) were measured by enzyme-immunoassay as indicators of physiological stress responses. Fewer wood mice were captured during full moon, yet only non-breeding adult males clearly avoided common genet odor. Mice were captured sooner at night during the simulated full moon conditions and later in predator-treated traps. Foraging activity was lower when individuals faced predator’s feces, but neither food intake nor FCM levels were affected by predation risk cues. Direct and indirect cues of predation risk selectively affected wood mice behavior, although behavioral responses seem to be modulated by different costs–benefit balances related to the individual’s perception of risk. The lack of physiological responses to predation risk cues suggests that wood mice did not perceive them as reliable stressors or the response was too small or transient to be measured by FCM.

Tracking neighbours promotes the coexistence of large carnivores

The study of competition and coexistence among similar interacting species has long been considered a cornerstone in evolutionary and community ecology. However, understanding coexistence remains a challenge. Using two similar and sympatric competing large carnivores, Eurasian lynx and wolverines, we tested the hypotheses that tracking among heterospecifics and reactive responses to potential risk decreases the probability of an agonistic encounter when predators access shared food resources, thus facilitating coexistence. Lynx and wolverines actively avoided each other, with the degree of avoidance being greater for simultaneous than time-delayed predator locations. Wolverines reacted to the presence of lynx at relatively short distances (mean: 383 m). In general, lynx stayed longer, and were more stationary, around reindeer carcasses than wolverines. However, when both predators were present at the same time around a carcass, lynx shortened their visits, while wolverine behavior did not change. Our results support the idea that risk avoidance is a reactive, rather than a predictive, process. Since wolverines have adapted to coexist with lynx, exploiting lynx-killed reindeer carcasses while avoiding potential encounters, the combined presence of both predators may reduce wolverine kill rate and thus the total impact of these predators on semi-domestic reindeer in Scandinavia. Consequently, population management directed at lynx may affect wolverine populations and human-wolverine conflicts.

Waddling on the Dark Side: Ambient Light Affects Attendance Behavior of Little Penguins

Visible light on Earth largely comes from the sun, including light reflected from the moon. Predation risk is strongly determined by light conditions, and some animals are nocturnal to reduce predation. Artificial lights and its consequent light pollution may disrupt this natural behavior. Here, we used 13 years of attendance data to study the effects of sun, moon, and artificial light on the attendance pattern of a nocturnal seabird, the little penguin Eudyptula minor at Phillip Island, Australia. The little penguin is the smallest and the only penguin species whose activity on land is strictly nocturnal. Automated monitoring systems recorded individually marked penguins every time they arrived (after sunset) at or departed (before sunrise) from 2 colonies under different lighting conditions: natural night skylight and artificial lights (around 3 lux) used to enhance penguin viewing for ecotourism around sunset. Sunlight had a strong effect on attendance as penguins arrived on average around 81 min after sunset and departed around 92 min before sunrise. The effect of moonlight was also strong, varying according to moon phase. Fewer penguins came ashore during full moon nights. Moon phase effect was stronger on departure than arrival times. Thus, during nights between full moon and last quarter, arrival times (after sunset) were delayed, even though moonlight levels were low, while departure times (before sunrise) were earlier, coinciding with high moonlight levels. Cyclic patterns of moon effect were slightly out of phase but significantly between 2 colonies, which could be due to site-specific differences or presence/absence of artificial lights. Moonlight could be overridden by artificial light at our artificially lit colony, but the similar amplitude of attendance patterns between colonies suggests that artificial light did not mask the moonlight effect. Further research is indeed necessary to understand how seabirds respond to the increasing artificial night light levels.