Small Prey Research Articles

The dynamics of sea otter prey selection under population growth and expansion

AbstractSea otters (Enhydra lutris) were extirpated from much of their range in the North Pacific by the early 1900s but have made a remarkable recovery in Southeast Alaska. Sea otter populations have been particularly successful in Glacier Bay, Alaska, a protected tidewater glacier fjord with a diverse and productive nearshore habitat. Collection of sea otter foraging observations in Glacier Bay began in 1993, along with high‐resolution aerial surveys that provide estimates of sea otter abundance and distribution. We integrated these two data sources to investigate how sea otter diet changed in space and time as sea otters established and spread across Glacier Bay. Specifically, we developed a multilevel Bayesian model to capture how sea otter diet at a location (the number, type, and size of prey collected) changed as a function of local cumulative otter abundance and the year in which the location was first occupied. This framework enabled us to estimate the sequence of sea otter prey selection and switching as prey populations responded to sea otter foraging pressure. We found that local sea otter diet changed substantially as the population established, shifting away from large urchins, crabs, and clams to Modiolus mussels and small urchins, and lastly to small clams and Mytilus mussels. We also found that sea otter diet at newly occupied sites changed as otters spread over the main channel and into the arms of Glacier Bay. Further, by 2019, sea otters across the bay were primarily foraging on small prey, regardless of the local occupancy history. The absence of a spatial gradient in the size of prey captured late in the study suggests that feedbacks between the top‐down effects of sea otter foraging, sea otter dispersal processes, and local variation in habitat productivity may have homogenized the size structure of available prey across Glacier Bay.

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.

Isotopic evidence of diet breadth hunter-gatherers changes during the Holocene in the Central Pampean Dunefields (Argentina, South America).

Based on the analysis of stable carbon and nitrogen isotopes of bone collagen, stable carbon isotopes of bone apatite and an extensive AMS dating series (~10,000-299 years cal BP), the human paleodiets of 34 individuals from the Central Pampean Dunefields (Argentina, South America) are evaluated. These data are interpreted from the isotopic ecology of animals with archaeofaunal evidence of consumption and isotopic models of human diet. Multivariate carbon and nitrogen stable isotope model and Bayesian stable isotope ellipses were used to interpret human diets. Analysis of isotopic values indicates intake of enriched lipids and/or carbohydrates in relation to the proteins consumed throughout the Holocene. The isotopic values of Middle Holocene humans in relation to the values of exploited resources point out that individuals obtained protein mainly from guanaco. Subsequently, there was an increase in the human breadth diet during the Late Holocene, with a greater relevance of small prey of high trophic levels and vegetables. This contrasts with zooarchaeological information indicating generalist human diets during the Middle Holocene and specialized human diets in guanaco during the Late Holocene. It is proposed that during the Middle Holocene arid period, the combination of low human population density and high residential mobility in wide foraging ranges allowed the guanaco to be the main source of protein. During the Late Holocene humid period, there was an increase in human population density and a decrease in residential mobility, which caused greater pressure on foraging territories and increased dietary breadth.

Prey detection by a stepwise visual template matching mechanism.

Predators can improve prey capture using a search image, and recent prey provide a visual template with which subsequent prey are compared. Considering trout feeding responses to mayfly prey of different sizes and phenological availability across years, we tested if changing relative abundances (ratios) of prey of the same species, but different body sizes, shifted trout feeding behaviour. For example, we hypothesized that a feeding switch from larger to smaller prey required continuous exposure to the novel smaller prey. The hypothesis that continuous exposure to novel small prey results in their acceptance was not supported. Rather, we discovered that trout identify novel prey using a dynamic stepwise visual neural template prey matching process, which involves the formation of focal prey template based on size or type, rejection of novel prey that do not match the size or type templates and modification of the existing or development of multiple prey templates that eventually enabled recognition of novel, small prey. We also discovered trout store multiple visual prey templates in memory. These results have implications for predator and prey dynamics, optimal foraging, the persistence of rare prey, prey species coexistence and predator selection on prey phenology.

The repatriation of wolves to Isle Royale alters the foraging of meso-carnivores

Abstract Due to the disproportionate role that large carnivores can have on communities and their global decline over the last century, carnivores are increasingly being repatriated across their historic ranges. The reintroduction of gray wolves (Canis lupus) can precipitate substantive changes to communities and ecosystems. Notably, wolves could have strong effects on smaller and subordinate carnivores, especially in altering their foraging behavior and prey selection. Past studies investigating wolf effects on other carnivores, however, have generally been conducted in relatively complex communities featuring a diverse assemblage of carnivores and prey and have lacked baseline (i.e., pre-repatriation) data. Consequently, researchers have quantified what a community looks like after wolf return, with little information on how the community behaved before. To better understand the effect of large carnivore repatriation on the foraging ecology of a carnivore community, we investigated the impact of reintroduced gray wolves on 2 meso-carnivores: Red Fox (Vulpes vulpes); and American Marten (Martes americana) within an insular and simple vertebrate community at Isle Royale National Park before and after wolf reintroduction. We analyzed >600 scats from 20 individual martens and 63 individual foxes as well as the stable isotopes of 9 and 22 tissue samples from martens and foxes, respectively, at both individual and population levels. We found that the wolf reintroduction had little effect on marten diet but strongly influenced fox diet depending on the analysis conducted. At the population level, our analysis revealed that both foxes and martens were dietary generalists consuming an array of food items including small prey, berries, and human food regardless of wolf presence. However, at the individual level, we found that prior to wolf repatriation foxes primarily consumed berries and small prey but following wolf repatriation the diet of foxes shifted to berries and human foods as well as large carrion. This post-wolf reintroduction shift in diet increased the dietary overlap between foxes and martens. Our work provides new insights into how the return of a large carnivore can alter the foraging ecology of small-bodied carnivores and act both to provision carrion resources as well drive other carnivores to consume more human food and increase dietary overlap.

Alternating carnivore and Neanderthal activities at Escoural Cave: insights from the taphonomic and machine learning analysis of leporid remains

Exploring the varied subsistence strategies and cave occupation patterns of Neanderthals is key to understanding their complex behaviors and ecological adaptations. Small game consumption, in particular, is considered a relevant indicator of their behavioral complexity. Rabbit assemblages from Pleistocene cave sites provide valuable insights into Neanderthal interactions with small prey and potential competition with carnivores. Here, we present the first detailed taphonomic analysis of faunal remains from Escoural Cave (Portugal), where a European rabbit (Oryctolagus cuniculus) assemblage was found alongside Middle Paleolithic stone tools and some macromammal remains. This study combines traditional zooarchaeological and taphonomic analysis of the rabbit remains with multivariate statistics and machine learning methods to establish the origin of the accumulation, and the implications for Neanderthal subsistence and cave use. Results from the taphonomic analysis show no evidence of human consumption but abundant evidence of small terrestrial carnivore activity, primarily from lynxes. This could indicate a sequential occurrence of Neanderthal and carnivore activities in the cave, with Neanderthal activities likely related to something other than rabbit consumption. Our study contributes to characterizing Iberian carnivore fossil accumulations and differentiating between faunal assemblages accumulated by carnivores and those by hominins. Additionally, we show that the use of machine learning analysis provides a robust and objective method for identifying and classifying taphonomic signatures, enhancing the accuracy and reliability of our interpretations. Future work will focus on analyzing additional faunal collections from both past and new excavations at Escoural, to test whether carnivores and Neanderthals focused on different prey types and how they shared the cave space.

Effects of High-Temperature Stress on Biological Characteristics of Coccophagus japonicus Compere.

The parasitoid, Coccophagus japonicus Compere (Hymenoptera: Aphelinidae) is a dominant natural enemy of Parasaissetia nigra Nietner (Hemiptera: Coccidae), an important pest of rubber trees. Much of Chinese rubber is cultivated in hotter regions such as Yunnan and Hainan, exposing applied parasitoids to non-optimal temperatures. Therefore, C. japonicus must adapt to avoid temperature-related impacts on survival and population expansion. In this study, we monitored the survival rate, developmental duration, parasitism rate, and fecundity of C. japonicus during short-term exposures to 36 °C, 38 °C, and 40 °C for 2, 4, and 6 h, as well as continuous exposures to 32 °C and 34 °C for 3 days. The results show that short-term exposure to high-temperature stress leads to decreased survival rate of C. japonicus larvae and pupae, with survival rates declining as temperature and duration increase. High-temperature stress also delayed insect development, reduced mature egg production, shortened the body length of newly emerged females, and decreased female lifespans. Moreover, continuous high-temperature stress was found to significantly impact the development and reproduction of C. japonicus. Compared with the CK (27 °C), 3 d of continuous exposure to 34 °C prolonged developmental duration, shortened the body length and lifespan of newly emerged females, reduced survival rate and single female fecundity, and significantly decreased offspring numbers and parasitism rates. Temperatures of 36 °C, 38 °C, and 40 °C decreased the mortality time of adult females to 28.78, 16.04, and 7.91 h, respectively. Adverse temperatures also affected the insects' functional response, with 8 h of stress at 36 °C, 38 °C, and 40 °C causing the control efficiency of C. japonicus on P. nigra. This level of stress in the parasitoids was found to reduce the immediate attack rate and search effect, prolong processing time, and attenuate interference between small prey. Parasitoid efficiency was lowest following exposure to 40 °C. In this study, we determined the range of high temperatures that C. japonicus populations can tolerate under short- or long-term stress, providing guidance for future field applications.

Flash behaviors protect prey from avian predators

Abstract It has been proposed that flash behaviors, defined as the transient display of conspicuous color patches during escape, serve as an anti-predator defense in camouflaged prey. While recent studies in humans have demonstrated the effectiveness of flash behaviors in improving the survival of artificial prey, it remains unclear whether these benefits also arise in more natural systems involving non-human predators. This study investigated the adaptive significance of flash behaviors using chicks (Gallus gallus domesticus) as predators and virtual prey. Our experiments revealed that prey employing flash behaviors consistently enhanced their survival rate compared to non-flashing prey. Additionally, prey with non-conspicuous escape colors, though distinct from their resting colors, also showed a higher survival rate than non-flashing prey, challenging the conventional belief that conspicuous colors are required for search interference. An interplay between prey size and flash behaviors in enhancing survival was evident, with larger prey benefiting more than smaller prey. We found no evidence to suggest that being hidden before initiating an escape confers a survival advantage to flashing prey compared to being visible before escape. This study sheds light on the adaptive benefits of flash behaviors against natural predators and contributes to our understanding of the widespread occurrence of hidden color signals in camouflaged prey. We encourage further studies to explore the effectiveness of remaining hidden in flashing prey when confronted with natural predators, as well as how predators might learn to overcome the deception of flash behaviors.

Collective exploitation of large prey by group foraging shapes aggregation and fitness of cnidarian polyps

Group living is widespread and beneficial to metazoans. It improves protection and survival opportunities, reinforcing interspecific competitiveness. Benthic cnidarians often colonize large surfaces. Evidence of collective capture and exploitation of large prey by small, clumped polyps suggests that aggregation is functional to access food resources hardly achievable by isolated individuals. In turn, the chance to catch large prey may represents a driver of aggregation in polyps, whether beneficial to their fitness. Here, the effects of group foraging on aggregation, asexual reproduction, and growth rates of Aurelia coerulea von Lendenfeld 1884 polyps were experimentally tested by providing them with either small or large prey, or a mix of both to simulate the co-occurrence of preys at sea. As expected, some polyps were not able to reach the large prey. Hence, the population was a posteriori divided into group-foragers and solitary-feeders. In general, the large prey diet resulted in higher population fitness and when simultaneously supplied with the small prey represented an energetic booster resulting beneficial for all group-members. The decrease of interindividual distances was reported among group-foragers, that converged towards each other. Cnidarians are basal in metazoan evolution, and the comprehension of their collective foraging behavior, as well as the processes leading to the selective feature driving them to forage in group or not, may be essential to better understand the evolution and spread of social foraging in animals. Moreover, the access to large prey by sessile polyps of Aurelia coerulea could be pivotal in determining the increase in abundance of adult bloom-forming medusae.

BIOLOGICAL ASPECTS OF Ameivula nigrigula (SQUAMATA: TEIIDAE): FEEDING HABIT, SEXUAL DIMORPHISM, REPRODUCTION AND MATURATION OF FEMALES

Life history information plays a crucial role in comprehending the evolutionary processes that shape ecological patterns within species, but there is limited information available on the reproductive and other aspects of tropical Squamata. In this study, we present a comprehensive analysis of dietetic and morphometric data, specifically related to the size and sex determination of Ameivula nigrigula, aiming to investigate if there is sexual dimorphism and identify the onset of sexual maturity in female individuals. By thoroughly examining the stomach contents, we observed that the majority of specimens retain food remnants, with a prevalence of small prey items such as Hymenoptera and Isoptera. Our findings reveal a lack of sexual dimorphism in terms of body size, indicating that males and females possess similar dimensions and proportions. Moreover, our investigations suggest that different color patterns do not correspond to distinct stages of female development, as chromatic variations are observed in both juvenile and ovigerous females. Consequently, dorsal coloration may not serve as a reliable indicator of sexual maturity. The observed chromatic variation is likely a form of polymorphism within the population, lacking the potential to determine life stages. Furthermore, our examination of female fertility reveals the presence of one to two eggs per female, consistent with findings in other Teiidae species.

Dietary Shift in a Barn Owl (Tyto alba) Population Following Partial Abandonment of Cultivated Fields (Central Apennine Hills, Italy).

While most studies focused on the impact of intensive agriculture on the barn owl's diet, little is known about the effect of cropland abandonment. We compared the taxon composition/evenness and feeding guild structure of small mammal prey identified in pellets collected before (2004) and after (2012) the abandonment of 9% of cultivated fields within a cultural landscape. Data on prey abundance per pellet were analysed through non-metric multidimensional scaling and permutational, paired tests. Prey taxon evenness in 2012 was significantly lower than in 2004. That induced a shift in prey taxon composition as indicated by the significantly lower dietary similarity compared with the random expectation. The increasing and declining abundance of Murinae and Crocidurinae, respectively, had the largest contribution to the differentiation of the diet spectrum. Insectivorous prey was significantly more abundant in 2004 compared to 2012, while the opposite was true for omnivorous prey. Our results suggest that even a small fraction of abandoned crops in the landscape might induce a detectable shift in the barn owl's food niche. The dietary effects are similar to those observed after agricultural intensification, that is, an increase in the abundance of generalists to the detriment of specialist mammal prey.

Prey size and ecological separation in spinosaurid theropods based on heterodonty and rostrum shape.

Members of the dinosaur clade Spinosauridae had numerous traits attributed to feeding in or around water, and their feeding apparatus has often been considered analogous to modern crocodylians. Here we quantify the craniodental morphology of Spinosauridae and compare it to modern Crocodylia. We measured from spinosaurid and crocodylian skeletal material the area of alveoli as a proxy for tooth size to determine size-heterodonty. Geometric morphometrics were also conducted on tooth crowns and tooth bearing regions of the skull. Spinosaurids overall had relatively large alveoli, and both they, and crocodylians, had isolated regions of enlarged alveoli. Spinosaurines also had enlarged alveoli along the caudal dentary that baryonychines lacked, which instead had numerous additional caudal tooth positions. Size-heterodonty was positively allometric, and spinosaurids overlapped with generalist/macro-generalist crocodylians of similar sizes. Spinosaurid crown shape morphologies overlapped with certain slender-longirostrine crocodylians, yet lacked molariform distal crowns typical of most crocodylians. Spinosaurid rostra and mandibles were relatively deep with undulating margins correlating with local tooth sizes, which may indicate a developmental constraint. Spinosaurines had a particularly long concavity caudal to their rosette of anterior cranial teeth, with a corresponding bulbous rostral dentary. The spinosaurid feeding apparatus was well suited for quickly striking and creating deep punctures, but not cutting flesh or durophagy. The jaws interlocked to secure prey and move it deeper into the mouth. The baryonychines probably did little oral processing, yet spinosaurines could have processed relatively large vertebrates. Overall, there is no indication that spinosaurids were restricted to fish or small aquatic prey.

Commercial fishery no-take zones for African penguins minimize fisheries losses at the expense of conservation gains

Abstract The African penguin population has declined precipitously in recent decades, and if current rates of decline persist, this species could become extinct in the wild by 2035. Resource extraction of small pelagic fish prey by the purse-seine fishery around African penguin breeding colonies has been identified as a demographically meaningful threat to African penguins. Consequently, long-term, effective no-take zones around breeding colonies have been endorsed by an expert panel of scientists constituted by the South African government. Here, we consider the six largest South African penguin colonies that currently hold 76% of the global population. We evaluate the adequacy of different no-take zone options using a trade-off mechanism recommended by the expert panel. For all six colonies except Bird Island, Algoa Bay, which is subject to the least fishing pressure, the current no-take zone delineations are assessed as having little benefit to the African penguin and little to no cost to the purse-seine fishery. Four of the six current no-take zones include ≤50% of the African penguins’ core foraging areas. Alternative no-take zones that approximate a more balanced trade-off offer more impactful alternatives to the current fisheries restrictions. Given the urgent need to implement evidence-based conservation interventions for the endangered African penguin, we recommend the substitution of the current no-take zones with those proposed herein.

Experimental replication of early human behaviour in bird preparation: a pilot-study focusing on bone surface modification and breakage patterns

The origin of complex behaviour amongst early humans is a subject of heated debate within the scientific community, and the study of small prey remains has become a significant aspect when examining such modern behaviour. Nonetheless, the consumption of small prey by human populations poses analytical difficulties due to the often negligible, or entirely absent, traces on bone surfaces. To address this difficulty, an experimental study focusing on terrestrial avifauna has been prepared, and here we present a preliminary phase of this research. The aim is to distinguish potential modifications on bird bone surfaces and fracture patterns that might facilitate the recognition of human manipulation of avian skeletal remains. Building upon the challenges encountered in the study of archaeological findings recovered from recent excavations in Iberian Middle Palaeolithic sites, the experimental protocol was formulated to encompass the processing of two uncooked and three roasted birds; and the lithic use-wear analysis of the flint flake used in the processing of raw birds. The results showcase distinct patterns of bone surface modifications and breakage between cooked and uncooked birds. Higher numbers of cut marks and manual disarticulation breaks are found on raw animals, whereas roasted animals show no cut marks, local-specific burns and higher bone loss. This pilot-study provides a baseline for future research to further explore the role of avifauna in Neanderthal subsistence and food processing, which may help highlight cultural choices.

Social and genetic relationships among individuals in urban kit fox social groups

Smaller canids, such as most foxes, individually hunt small prey, and therefore, social groups typically consist of just a mated pair. However, these smaller canids occasionally form groups in which the members have been presumed to be genetically or socially related. We studied social and genetic relationships among urban San Joaquin kit fox ( Vulpes macrotis mutica Merriam, 1902) groups in Bakersfield, California. Of 59 groups, 42.4% had extra adults in addition to the parents. Foxes were field classified as either mothers, fathers, helpers (extra adults), or pups. We then assessed relatedness of foxes within social groups using 11 microsatellites in DNA from tissue or hair samples. Mated pairs were significantly less related than mothers and helpers, with fathers and helpers being intermediate. Twelve pairs of females were mother–daughter dyads, but we also found two cases of sisters and two cases where the females were unrelated. Pups were always related to a female identified as their mother. Father–pup pairs were less related than mother–pup pairs, with helper–pup pairs being intermediate. The extra-pair paternity rate (multiple fathers per litter) was 39%. The social flexibility exhibited by kit foxes may increase their resiliency to marked fluctuations in resource availability, thereby reducing extinction risk.

Dynamic interactions at birdfeeders: Attracting both prey and predators across urban and rural habitats

Winter is a critical period for the survival of local bird species in temperate regions. Some wintering birds may rely on transient food, such as that provided at birdfeeders, but bird communities around birdfeeders may also attract predators. However, these effects of birdfeeders on interspecific interactions between birds and their predators remain largely unexplored and have so far not been tested experimentally. We hypothesized that birdfeeders indirectly attract predators in winter because of the attraction of small birds, and tested this hypothesis using experimental feeders at 52 different urban and rural sites across western Poland. We found that the number of small birds increased around birdfeeders, particularly those with provided food. We found that birdfeeders that attracted more small birds (regardless of whether they provided food) attracted also more predators, such as sparrowhawks Accipiter nisus and feral cats Felis domesticus. Moreover, birdfeeders in urban habitats attracted relatively fewer small birds but not fewer predators compared to those in rural areas. Altogether, birdfeeders with food provided attracted small prey birds but they attracted also more predators, whose presence may hinder small birds from fully utilizing available resources, potentially impacting their winter survival through direct (mortality) and indirect (increased monitoring and vigilance) effects.

Hunting tactics of southern elephant seals Mirounga leonina and anti-predatory behaviours of their prey

For air-breathing marine predators that must save energy during dives, the ability to adopt hunting tactics that minimise the risk of triggering an escape reaction from the prey is crucial for efficient foraging. Female southern elephant seals (SES) Mirounga leonina forage on small mesopelagic prey that they must hunt almost continuously to meet their high-energy requirements. Here we aimed at understanding how these large time-limited deep-divers can efficiently exploit their small-sized prey. To do so, we used data recorded by a new biologger, the sonar tag, deployed on SES during their post-breeding foraging trips. This tag combines an active acoustic sensor with ultra-high-resolution movement and bioluminescence sensors. This combination of sensors offers a unique opportunity to simultaneously describe SES hunting tactics and defence mechanisms of their prey. We analysed more than 5800 prey capture events in 9 SES and show that they adopt a ‘stalking’ hunting behaviour, allowing them to get as close as possible to their prey before attacking. The ability of SES to adopt stealth approach tactics, minimising the risk of initiating a flight reaction from their prey, might be a key factor in the success of this far-ranging generalist predator.

Intraguild processes drive space-use patterns in a large-bodied marine predator community.

Interspecific interactions, including predator-prey, intraguild predation (IGP) and competition, may drive distribution and habitat use of predator communities. However, elucidating the relative importance of these interactions in shaping predator distributions is challenging, especially in marine communities comprising highly mobile species. We used individual-based models (IBMs) to predict the habitat distributions of apex predators, intraguild (IG) prey and prey. We then used passive acoustic telemetry to test these predictions in a subtropical marine predator community consisting of eight elasmobranch (i.e. shark and ray) species in Bimini, The Bahamas. IBMs predicted that prey and IG prey will preferentially select habitats based on safety over resources (food), with stronger selection for safe habitat by smaller prey. Elasmobranch space-use patterns matched these predictions. Species with predator-prey and asymmetrical IGP (between apex and small mesopredators) interactions showed the clearest spatial separation, followed by asymmetrical IGP among apex and large mesopredators. Competitors showed greater spatial overlap although with finer-scale differences in microhabitat use. Our study suggests space-use patterns in elasmobranchs are at least partially driven by interspecific interactions, with stronger spatial separation occurring where interactions include predator-prey relationships or IGP.

Low hunting costs in an expensive marine mammal predator.

Many large terrestrial mammalian predators use energy-intensive, high-risk, high-gain strategies to pursue large, high-quality prey. However, similar-sized marine mammal predators with even higher field metabolic rates (FMRs) consistently target prey three to six orders of magnitude smaller than themselves. Here, we address the question of how these active and expensive marine mammal predators can gain sufficient energy from consistently targeting small prey during breath-hold dives. Using harbor porpoises as model organisms, we show that hunting small aquatic prey is energetically cheap (<20% increase in FMR) for these marine predators, but it requires them to spend a large proportion (>60%) of time foraging. We conclude that this grazing foraging strategy on small prey is viable for marine mammal predators despite their high FMR because they can hunt near continuously at low marginal expense. Consequently, cessation of foraging due to human disturbance comes at a high cost, as porpoises must maintain their high thermoregulation costs with a reduced energy intake.

Rewilding landscapes with apex predators: cheetah (Acinonyx jubatus) movements reveal the importance of environmental and individual contexts

Rewilding landscapes through species or population restoration is an increasingly applied practice in biological conservation. There is expanding interest in wildlife release projects for apex predator population augmentation or reintroductions in historical ranges. Cheetahs (Acinonyx jubatus) are an IUCN Vulnerable-listed species with a declining global population facing major threats, which in southern Africa primarily include lethal persecution on livestock farms and bush encroachment transforming open habitats to woody areas. We used GPS radiocollars to monitor ten adult cheetahs from 2007 – 2018 in the Central Plateau of Namibia encompassing an area restored as an open savanna field (13.7 km2) located in a matrix of woodland savanna affected by bush encroachment. We generated a set of a priori hypotheses that tested the effects of various factors on cheetah movements indexed by step length. We compared cheetah movement metrics based on their history as wild, rehabilitated, and/or translocated individuals. Day/night activity, habitat type, and habitat edges were significant predictors of cheetah movement. Wild resident cheetahs displayed significantly longer steps than the other cheetah classes, possibly suggesting increased territorial behaviour in response to the presence of introduced cheetahs. Some cheetahs temporally segregated by moving extensively during daytime, but most individuals were primarily active during crepuscular periods. Small prey remained constant across time, whereas large prey declined over the study period. Cheetahs appeared to adjust behaviourally by increasing movements in years when large prey were scarce. Cheetahs appeared to be ecologically adaptable and behaviourally flexible in response to varying prey populations and when translocated to new environments, specifically at the interface between bush-encroached woodland and open savanna. Environmental settings and animal history need to be carefully considered in rewilding and ecosystem restoration, and monitoring of released and resident individuals, if present, is important to understand ecological dynamics at release sites.