Large Predators Research Articles

Antipredator behaviour in semi-feral horses: innate response and the influence of external factors.

Rewilding can play a vital role in safeguarding biodiversity, with the grazing pressure exerted by large ungulates and controlled by their predators being a significant factor, particularly in European contexts. Domestic horses are becoming integral to such ungulates' biomass, but they may differ from truly wild species due to their domesticated origin. This raises concerns about whether feral horses retain adequate antipredator behaviours, especially in the presence of expanding, large predators like wolves. The field of antipredator behaviour research is hampered by inconsistent results and a lack of standardisation, and the behaviour of free-ranging horses remains underexplored. To address this gap, we conducted a playback experiment on semi-feral Exmoor ponies (n = 97) in the Czech Republic, exposing them to wolf howls, deer rut calls, and static noise as a control. We assessed alert behaviour and herd grouping while accounting for variables such as herd size, sex, time of day, weather conditions, environment type, presence of other ungulates, and habituation effects. Over 70% of the ponies exhibited alert behaviour in response to both wolf and deer calls. Although the magnitude of responses did not differ significantly between wolf and deer calls, both elicited distinct reactions compared to the control. Most of the studied external factors significantly affected the observed alert responses, highlighting that they must be carefully considered in such studies since these may explain the conflicting results observed in previous studies. The significant behavioural differences in reaction to the sounds indicate that the horses can differentiate them and likely still possess some innate memory, as reported in other ungulates. This is a positive sign towards reintroduction. Future research should carefully consider the validity of the testing environment, habituation effects, and other external factors to ensure robust results.

The Claws and the Spear: New Evidence of Neanderthal-Cave Lion Interactions

Throughout most of human evolutionary history, our ancestors were preyed upon by large predators such as lions. Until recently, it was believed that our species, Homo sapiens, was the first one with the ability to kill and exploit resources from dangerous predators. Our study suggests that Neanderthals hunted and killed cave lions and used their body parts as cultural objects.

Osteology and functional morphology of a transitional pterosaur Dearc sgiathanach from the Middle Jurassic (Bathonian) of Scotland

Pterosaurs were the first vertebrates to evolve active flight. The lack of many well-preserved pterosaur fossils limits our understanding of the functional anatomy and behavior of these flight pioneers, particularly from their early history (Triassic to Middle Jurassic). Here we describe in detail the osteology of an exceptionally preserved Middle Jurassic pterosaur, the holotype of Dearc sgiathanach from the Isle of Skye, Scotland. We identify new autapomorphies of the flight apparatus (humerus and sternum), which further support the distinctiveness of Dearc compared with other early-diverging pterosaurs and describe features, such as the vertebral morphology, shared with later-diverging pterosaurs that probably developed convergently to support a large body size or as a sign of modular evolution. We used extant phylogenetic bracketing to infer the principal cranial and antebrachial musculature, indicating that Dearc had large and anteriorly placed palatal musculature that compensated for weak temporal jaw adductors and wing musculature suggestive of flight style reliant on powerful adduction and protraction of the humerus. Comparisons with other pterosaurs revealed that non-pterodactyloids such as Dearc, despite their overall conservative bauplans, adapted various flight and feeding styles. The osteology and myology of Dearc are indicative of a large predator that flew and hunted above lagoons and nearshore environments of the Middle Jurassic.

Examination of Isotopic Signals to Determine Trophic Dynamics and Diet of Gulf of Maine Mysticetes Prior to an Oceanographic Regime Shift

Stable isotope analysis (SIA) is a useful tool to assess the health and foraging habits of large marine predators, metabolic stress, pregnancy, and migration patterns. This study provides baseline SIA data for four Gulf of Maine mysticete species and serves as a benchmark for future assessments. SIA was conducted on skin biopsies collected in two time periods: 1988 to 1992 (n = 15) and 1999 to 2005 (n = 187). Samples were collected from humpback whales (Megaptera novaeangliae; n = 116), fin whales (Balaenoptera physalus; n = 74), minke whales (Balaenoptera acutorostrata; n = 6), and North Atlantic right whales (Eubalaena glacialis; n = 6). There were statistically significant differences in isotopic value among species, years, and regions sampled. By species, North Atlantic right whale δ13C and δ15N levels were significantly different than the other species analyzed. Additionally, humpback whales had a δ15N value that was significantly higher than the value found in fin whales. By date, humpback whales showed significant difference in δ13C in 2002 from the two previous years. For fin whales, 2002 showed significant difference in δ13C for all other years’ samples (2000 to 2003). By region, two regions that were the greatest distance apart (Bay of Fundy and Great South Channel) showed significant differences in δ13C for humpback whales. Demographic analyses for humpback and fin whales found a significant difference between calves versus other age classes, presumably due to nursing. A decadal comparison of humpback whales at one site (Stellwagen Bank) found no significant difference between decades. This dataset provides a benchmark for stable isotope measurements in large baleen whales for this regional ecosystem.

Predation of sea turtles (Chelonia mydas) by southern sea lions (Otaria byronia) and its relationship with overfishing in northern Chile

The disruption of a new food chain in the South American sea lion (SSL, Otaria byronia), with predation on green sea turtles (GST, Chelonia mydas) is reported for Northern Chile, probably from “nutritional stress” as result of anchovy (Engraulis ringens) overfishing, its fundamental food, with implications that cross multinational barriers in the South Pacific due to the shared nature of the resource. From 2011 an increase in carcasses of GST turtles with damages attributable to attacks by larger predators was observed on beaches of Arica (18°28´S), for which a necropsy study for signs attributable to predation, was carried out between November 2013 and May 2019. Jointly, direct observations of SSL attacks were made between Arica (18°28´S) and Iquique (20°13´S), that document predation of GST by SSL. 195 strandings including 179 Chelonia mydas, 15 Lepidochelys olivacea y 1 Eretmochelys imbricatea were recorded. 96.01% were strandings, 2.23% concentrated in drift, 1.12% as ghost fishing and 0.56% by fishermen from a gillnet. The necropsies of 14 carcasses in stage 1 and 2, showed damage attributable to interaction (alive or dead) with predators and/or scavengers. Most part of the observed injuries (tears of breakage and detachment of skin, muscles, internal structures such as the trachea, esophagus, stomach and part of the intestines, heart and liver) were attributable to SSL attacks and agree with the direct observations. Attacks by sharks or killer whales, and death by immersion or health problems could not be confirmed. The effect of this new feeding strategy of the SSL casts a shadow of uncertainty about the success of the green sea turtle population recovery program of northern Chile started in 2012. The results also suggest the need for evaluation of anchovy management programs and standards and the incorporation of an ecosystem approach to management plans, including the trophic needs of top depredators of the system.

Two decades of three-dimensional movement data from adult female northern elephant seals

Northern elephant seals (Mirounga angustirostris) have been integral to the development and progress of biologging technology and movement data analysis, which continue to improve our understanding of this and other species. Adult female elephant seals at Año Nuevo Reserve and other colonies along the west coast of North America were tracked annually from 2004 to 2020, resulting in a total of 653 instrument deployments. This paper outlines the compilation and curation process of these high-resolution diving and location data, now accessible in two Dryad repositories. The code used for data processing alongside the corresponding workflow is available through GitHub and Zenodo. This data set represents 3,844,927 dives and 596,815 locations collected from 475 individual seals with 178 repeat samplings over 17 years. We anticipate that these data will stimulate further analysis and investigation into elephant seal biology and aid in developing new analytical approaches for large marine predators.

Time-series models and biotelemetry identify behavioral dynamics within a spawning aggregation of a large marine predator

Fish spawning aggregations (FSAs) may persist for months and include behaviors such as spawning and foraging. Acoustic telemetry has been used to measure the movements of fishes to and from FSAs, but behaviors within the aggregation are harder to quantify. We used multi-sensor acoustic telemetry (depth, acceleration) combined with continuous wavelet transformation analysis and hidden Markov models to identify behaviors within a spawning aggregation of the goliath grouper Epinephelus itajara, a vulnerable marine predator. Tagged fish (n = 20) exhibited periods (over 2 spawning seasons, August-October) where multiple individuals displayed variability in depth just after the new moon. These events may represent spawning, and there was always one event each season that included a greater number of individuals and more variability in depth. Grouper were more active during the new moon, in shallow water (<15 m), and at night. We also identified several events with behaviors more consistent with benthic foraging where grouper were highly active while remaining at constant depth. As such, intensive foraging by multiple individuals may occur during more sporadic time periods. Grouper remained close to the seafloor as currents exceeded 0.4 m s-1 but moved up into the water column during cold-water incursions (<24°C). Abiotic conditions may limit vertical habitat use and could potentially influence spawning and foraging behavior. Multi-sensor telemetry combined with time-series analysis can be used to remotely measure individual behavior within spawning aggregations. The timing of these behaviors within the FSA may also have implications for the ecological role groupers play as predators and, potentially, in bottom-up processes.

Otolith shape variability of labrid fish from Rapa Nui (Easter Island), southeastern Pacific

Fish otolith shape provides valuable insights into fish species' taxonomic, phylogenetic, and ecological traits. This study aimed to assess and compare the phenotypic variation in otolith shape among four labrid species (Anampses femininus, Coris debueni, Pseudolabrus fuentesi, and Thalassoma lutescens) inhabiting Rapa Nui (Easter Island) in the southeastern Pacific Ocean, utilizing geometric morphometrics and aging methods. Age estimation based on otolith structure indicated that collected specimens were adults, ranging between 1 and 3 years old. Allometric analysis revealed low but significant variation (5.40 %), primarily driven by changes in otolith width, resulting in distinct morphologies. Principal Component Analysis (PCA) of sagittal otoliths elucidated significant morphospace variation among species, with the first two PCs explaining 60.3 % of the total variance. PC1 distinguished between elongated sagittal shapes (e.g., P. fuentesi) and robust sagittae (e.g., T. lutescens), while PC2 correlated with otolith roundness, delineating variations within species. Canonical variate analysis further highlighted differences in otolith shape, with significant variations detected among all species. The Discriminant function analysis showed high levels of discrimination accuracy for most of species’ pairs. Except for C. debueni-P. fuentesi (89 %) and C. debueni-T. lutescens (96 %), all other species pairs achieved 100 % discrimination, highlighting the reliability of otolith shape as a distinguishing characteristic for the studied species. Overall, our findings emphasize the value of otolith shape analysis for characterizing and distinguishing Rapa Nui labrid species. This offers potential applications such as identifying prey within the digestive systems of large fish or bird predators near this isolated island in the South Pacific Ocean or archaeofauna studies.

Updating the Species Inventory of Large- and Medium-Sized Mammals in China Based on 2009-2020 Field Observation Records.

Large- and medium-sized mammals (LMMs) are closely related to humans and perform critical functions in the ecosystem. China harbors one of the richest mammalian faunas in the world, whereas there is an urgent need among wildlife managers and researchers to update the inventory of China's LMM species based on recent empirical information. In this study, we compiled the occurrence records of terrestrial LMMs in China during 2009-2020, mainly from camera-trapping surveys, through a comprehensive literature search and systematical data collection. With a total of 42,937 occurrence records (12,397 after removing duplicates) from 5461 sites, we recorded 134 LMM species belonging to 8 orders and 23 families. Compared to the national species list, seven species are missing from field observation records, including four of Carnivora, two of Primates, and one of Lagomorpha. Yunnan is the province with the highest richness of recorded LMMs (n = 69), and Xizang is the only province where all seven large apex predators have been recorded. This study systematically updates the species inventory of LMMs in China based on observation records and will provide an important baseline to support and guide future studies, monitoring, and conservation management of this important functional group in China.

An exceptionally preserved fossil assemblage from the early Jurassic of Chongqing (China) reveals a complex lacustrine ecosystem

One of the five greatest mass extinction events in the history of life occurred at the end of the Triassic (~ 201 million years ago), as confirmed by profound loss of life in marine realm. Terrestrial ecosystems were also suffered but the extent of life loss and timing of subsequent recovery remain equivocal, largely because of scarcity of fossil record. Here we report an exceptionally-preserved fossil assemblage, Yuzhou Biota, from the Sinemurian (~ 199–193 Ma), Early Jurassic lacustrine deposits of northern Chongqing, China. The biota documents the first known trophically complex lacustrine ecosystem after the end-Triassic extinction in China, including various representative species ranging from primary consumers (e.g., ostracods, conchostracans, gastropods and bivalves) to large predators (e.g., a variety of jawed fishes and pliosauroids). The most striking feature is its diversified aquatic vertebrates; the hybodontiforms, ceratodontiforms, ptycholepiformes, ginglymodians and pliosauroids from the biota all represent their first occurrences above the Triassic-Jurassic boundary in China. As such, the discovery enriches our understanding of the faunal turnover of aquatic vertebrates following the end-Triassic mass extinction, and provides a novel window on the Early Jurassic lacustrine ecosystems.

The relationship between body size and diet breadth in non‐web building spiders

Abstract The handling hypothesis assumes that large animals have broader diets than small animals because small animals are restricted to small prey while large animals can handle both small and large prey. On the other hand, the optimal foraging hypothesis assumes no relationship between predator body size and diet breadth because large predators should shift from small prey to large prey to maximize the net energy intake. Using the diets and body sizes of 89 non‐web building spider species obtained from public databases (World Spider Trait database, Spiders of Europe and World Spider Catalogue), we investigated the relationship between body size and diet breadth in this group of terrestrial arthropod predators. We found that the taxonomic niche diet breadth measured by Hill numbers (i.e., prey richness, Shannon index of diversity and Simpson index of equitability) had no significant relationship with spider body size. The minimum prey size did not show any relationship with spider body size. On the other hand, mean, maximum, range and variability in prey size increased with spider body size. The results provide support for both hypotheses. The pattern in prey taxonomic dimension supports the optimal foraging hypothesis, while the pattern in prey size dimension supports the handling hypothesis. Overall, the observed distinct patterns between the taxonomic and prey size niche axes can be caused by the fact that the non‐web building spiders utilize similar prey types that are however highly size‐structured.

Spider waste enhances soil nutrient content, soil respiration, and plant growth

Abstract Predators can alter the movement of nutrients through ecosystems by depositing waste products following predation. Whilst the benefits of predator waste for large predators (e.g. bears) or dense accumulations of predators (e.g. seabirds on islands) seem clear, less is known about whether smaller, solitary predators can have measurable effects on local ecosystem processes. In separate experiments with web‐building and wandering spiders, we tested if the presence of predators affected soil nutrient content, soil respiration, soil microbial communities, and plant growth. In the first experiment with black widow spiders, total nitrogen and nitrate were not affected by spider presence, but ammonia and phosphorus were higher from soil under the edge of the spider web than soil away from the spider. Soil respiration and plant growth were both higher in soil collected from under the spider retreat compared with soil collected away from the spider web. In a second experiment with wolf spiders, we tested for interactions between spiders and soil microbial communities. There were positive effects of wolf spider presence on all soil nutrients and there were interactions between spiders and soil type (i.e. field‐collected versus autoclaved) for total carbon, total nitrogen, nitrate, and pH. Spider presence and soil type also affected soil respiration and spider presence had a large effect on the composition of the microbial community of the soil. There were also positive effects of wolf spider presence on plant biomass and plant height, with a significant interaction between spiders and soil type for plant height. Overall, our results show that two spiders with different life histories (i.e. web‐building and wandering) both have significant positive effects on plant growth through the deposition of their waste products. These effects may occur through the direct deposition of nutrients and changes in soil microbial communities. Although, further work is needed to resolve these interactions. Read the free Plain Language Summary for this article on the Journal blog.

Habitat dimensionality and feeding strategies but not temperature as determinants of body size-trophic structure relationship in a marine food web.

Disentangling the determinants of trophic structure is central to ecology. The capacity to capture subjugate and consume a prey (i.e. gape limitation) is a relevant limitation to acquire energy for most organisms, especially those in smaller size ranges. This generates a size hierarchy of trophic positions in which large organisms consume small ones. Body size is tightly correlated to gape limitation and explains a large fraction of variance in the body size-trophic position relationship. However, a considerable fraction of variance still remains to be explained. Consumer search space dimensionality (2D or 3D) and feeding strategies, temperature and the size structure of primary producers can alter the trophic structure, but tests based on information from natural food webs are scarce. We generated specific predictions about the body size trophic position relationship and evaluated them using information from a subtropical South Atlantic coastal marine ecosystem: benthic realm (2D, rocky shore and sandy beach) and the pelagic realm (3D). We characterized this marine coastal food web based on stable isotopes of carbon and nitrogen from 256 samples from primary producers (macroalgae and phytoplankton) to large predators (sand shark) in summer and winter. Consumer body size encompassed six orders of magnitude in weight from 10-2 to 6 × 104 g. Isotopic signal corresponded to an integration of carbon sources from basal consumers to top predators. The body size-trophic position relationship showed a linear positive association with different slopes for the benthic and pelagic environments. This implies a smaller predator prey size ratio for pelagic (3D) with respect to benthic consumers (2D) as theoretically expected. No seasonal differences were found in slopes and most of the overall variance in benthic environments was largely explained by feeding strategies of the different taxonomic groups. We provide an integrated evaluation on the role of body size, consumer search space and feeding strategy to understand the determinants of trophic position. Results demonstrate that integrating gape limitation hypothesis, the dimensionality of consumer search space and feeding strategies into a formal robust framework to understand trophic structure is feasible even in complex natural ecosystems.

Paleoecology and diversity of Pliocene to Pleistocene fossorial mammals in the Pampean region of Argentina based on a quantitative analysis of fossil burrows

Pliocene and Pleistocene sedimentary successions in the Pampean region of Argentina contain abundant and diverse fossil mammalian burrows. In this paper, we report fossil burrows from eight localities from near Miramar to the northern area of Mar del Plata, spanning the Early Pliocene to the Late Pleistocene, and analyze burrow size patterns. The minimum width of each fossil burrow was measured as an indicator of its diameter. Available allometric equations for extant burrowing vertebrates were used to estimate the body size of potential producers based on burrow diameter. Size distribution patterns indicate that, in the Early Pliocene to Early Pleistocene levels, small burrows (attributed to rodents, typotheres, and small armadillos) were abundant, while medium- to large-sized burrows (attributed to large cingulates) were less common. In the Middle to Late Pleistocene levels, small burrows are very scarce, and medium-sized burrows are most abundant, together with giant burrows (attributed to ground sloths). Our findings indicate a significant size diversity for Pliocene–Pleistocene burrowing mammals in the studied area, from small rodents to giant ground sloths. Although present in Pliocene to Early Pleistocene times, the largest ground sloths began to build subterranean galleries only later in the Middle to Late Pleistocene. Small burrowers were comparatively less active during that time. These patterns are discussed in the light of paleoclimate and paleoecology of the putative guild of extinct burrowers, to develop working hypotheses for future studies. A paleoclimatic shift from Pliocene Climate Optimum to more arid and colder conditions from the Late Pliocene to Late Pleistocene, and the incursion of large predators to the region, are proposed as major factors promoting large ground sloths to adopt a fossorial lifestyle.

Predator-prey space use and landscape features influence movement behaviors in a large-mammal community.

Predator hunting strategies, such as stalking versus coursing behaviors, are hypothesized to influence antipredator behaviors of prey and can describe the movement behaviors of predators themselves. Predators and prey may alter their movement in relation to predator hunting modes, yet few studies have evaluated how these strategies influence movement behaviors of free-ranging animals in a multiple-predator, multiple-prey system. We fit hidden Markov models (HMM) with movement data derived from >400 GPS-collared ungulates and large predators in eastern Washington, USA. We used these models to test our hypotheses that stalking (cougars [Puma concolor]) and coursing (gray wolves [Canis lupus]) predators would exhibit different broad-scale movement behaviors consistent with their respective hunting strategies in areas that increased the likelihood of encountering or capturing ungulate prey (e.g., habitats selected by deer [Odocoileus spp.]). Similarly, we expected that broadscale movement behaviors of prey would change in response to background levels of predation risk associated with each predator's hunting strategy. We found that predators and ungulate prey adjusted their broadscale movements in response to one another's long-term patterns of habitat selection but not based on differences in predator-hunting strategies. Predators changed their movement behaviors based on the type of prey, whereas ungulates generally reduced movement in areas associated with large predators, regardless of the predator's hunting strategy. Both predator and prey movements varied in response to landscape features but not necessarily based on habitat that would facilitate specific hunting behaviors. Our results suggest that predators and prey adjust their movements at broad temporal scales in relation to long-term patterns of risk and resource distributions, potentially influencing their encounter rates with one another at finer spatiotemporal scales. Habitat features further influenced changes in movement, resulting in a complex combination of movement behaviors in multiple-predator, multiple-prey systems.

Etruscan Wolf Canis etruscus (Canidae, Carnivora) from the Early Pleistocene of Crimea (Taurida Cave).

The cranial and mandibular fragments of the medium-sized canid from the Early Pleistocene locality of Taurida cave (about 1.8-1.5 Ma) in Crimea are described and included in the hypodigm of the species Canis etruscus Forsyth Major, 1877, a common member of the Late Villafranchian fauna of the Circum-Mediterranean region. This species is reported for the first time from the Northern Black Sea region. The discovered evidence reinforce previous published idea regarding the periodically use of the Taurida cave by canids and other large predators as a den and shelter.

Bluefin tuna sperm production is hastened by surrogacy in small Euthynnus

Pacific bluefin tuna (Thunnus orientalis) remains heavily depleted due to overexploitation. Aquaculture and stock enhancement based on artificial seedlings could be effective solutions to this problem. However, widespread adoption of seedling production is limited because spawning in captivity of bluefin tuna, a large pelagic top predator, requires much space, time, cost, and labour. To downsize and shorten their generation time, here, we show that xenogeneic germ cell transplantation enables a surrogate production of functional bluefin tuna sperm in hybrid little tuna (genus: Euthynnus), which attain sexual maturity at a smaller body size and shorter time. Intraperitonially transplanted bluefin tuna germ cells migrate towards and are incorporated into the gonads of little tuna larvae. These recipients produce functional donor-derived bluefin tuna sperm at a mere 8 months of age and 1 kg of body size. This result represents an advance toward compact, low-cost, and time-efficient seedling production that will improve the efficiency of bluefin tuna aquaculture.

Perceptions and tolerance of American crocodiles and their management by South Florida residents

AbstractThe American crocodile (Crocodylus acutus) is a federally and state‐protected species classified as threatened by the United States Fish and Wildlife Service and the State of Florida; however, its population has increased since gaining legal protection in 1967. Concurrently, the number of reported human–crocodile conflicts has also increased, analogous to known conflicts surrounding other large (typically terrestrial) predators recovering from historical population declines. Although biology and ecology are the foundation of effective wildlife management strategies, human dimensions need to be considered to develop realistic and attainable conservation objectives. To better understand how South Florida residents perceive American crocodiles and their management, we used a mixed‐mode internet and mail survey. We obtained survey data from 28 May 2021 to 20 September 2021 from people living within the range of the American crocodile in Florida. There was little variation in opinions of 6 management actions presented for consideration under each of 3 different human–crocodile interaction scenarios. The strongest consensus was around euthanizing a crocodile (highly unacceptable under all 3 scenarios) with the management action of leaving the crocodile alone and monitoring the situation showing the least amount of consensus and shifting from slightly acceptable to slightly unacceptable the closer a hypothetical crocodile was in proximity to a resident's private property. Regression modeling showed respondents who were older, female, and those with children at home were less likely to prefer an increase in the crocodile population. Respondents who perceived more benefits from crocodiles and less risk from them tended to be relatively knowledgeable about crocodiles, had higher trust in the Florida Fish and Wildlife Conservation Commission (FWC), and were more likely to prefer a larger crocodile population. Further, spatial mapping revealed variation in tolerance for crocodiles and trust in FWC's ability to manage them. We reveal opportunities for targeted education and outreach efforts with the potential to affect tolerance of a large reptilian carnivore in a region experiencing rapid human development.

Mesocarnivores in residential yards: influence of yard features on the occupancy, relative abundance, and overlap of coyotes, grey fox, and red fox

Context As conversion of natural areas to human development continues, there is a lack of information about how developed areas can sustainably support wildlife. While large predators are often extirpated from areas of human development, some medium-bodied mammalian predators (hereafter, mesocarnivores) have adapted to co-exist in human-dominated areas. Aims How human-dominated areas such as residential yards are used by mesocarnivores is not well understood. Our study aimed to identify yard and landscape features that influence occupancy, relative abundance and spatial-temporal overlap of three widespread mesocarnivores, namely, coyote (Canis latrans), grey fox (Urocyon cineroargenteus) and red fox (Vulpes vulpes). Methods Over the summers of 2021 and 2022, we deployed camera-traps in 46 and 96 residential yards, spanning from low-density rural areas (<1 home per km2) to more urban areas (589 homes per km2) in north-western Arkansas, USA. Key results We found that mesocarnivore occupancy was marginally influenced by yard-level features as opposed to landscape composition. Fences reduced the occupancy probability of coyotes, although they were positively associated with the total area of potential shelter sites in a yard. We found that relative abundance of grey fox was highest in yards with poultry, highlighting a likely source of conflict with homeowners. We found that all three species were primarily nocturnal and activity overlap between the species pairs was high. Conclusions Thus, these species may be using spatio-temporal partitioning to avoid antagonistic encounters and our data supported this, with few examples of species occurring in the same yards during the same 24-h period. Implications As the number of residential yards continues to grow, our results suggested that there are ways in which our yards can provide resources to mesocarnivores and that homeowners also have agency to mitigate overlap with mesocarnivores through management of their yard features.

Developmental stage shapes the realized energy landscape for a flight specialist.

The heterogeneity of the physical environment determines the cost of transport for animals, shaping their energy landscape. Animals respond to this energy landscape by adjusting their distribution and movement to maximize gains and reduce costs. Much of our knowledge about energy landscape dynamics focuses on factors external to the animal, particularly the spatio-temporal variations of the environment. However, an animal's internal state can significantly impact its ability to perceive and utilize available energy, creating a distinction between the 'fundamental' and the 'realized' energy landscapes. Here, we show that the realized energy landscape varies along the ontogenetic axis. Locomotor and cognitive capabilities of individuals change over time, especially during the early life stages. We investigate the development of the realized energy landscape in the Central European Alpine population of the golden eagle Aquila chrysaetos, a large predator that requires negotiating the atmospheric environment to achieve energy-efficient soaring flight. We quantified weekly energy landscapes using environmental features for 55 juvenile golden eagles, demonstrating that energetic costs of traversing the landscape decreased with age. Consequently, the potentially flyable area within the Alpine region increased 2170-fold during their first three years of independence. Our work contributes to a predictive understanding of animal movement by presenting ontogeny as a mechanism shaping the realized energy landscape.