Motion-triggered Cameras Research Articles

Daily Diet and Temporal Variation of Swainson's Hawk Prey Deliveries

ABSTRACT The quantity and timing of prey delivery affect the development of altricial young, can induce trade-offs in parental behavior, and ultimately influence fitness of the young. We investigated the dynamics of prey deliveries in a population of Swainson’s Hawks (Buteo swainsoni) in northern California to better understand its temporal component. We installed 12 motion-triggered cameras in nests between 2013 and 2018, and documented 466 unique prey deliveries. Of those, 455 prey items were identifiable to at least class. Mammals made up the majority of prey in terms of number of deliveries (88.2%) and estimated biomass delivered to the nest (97.1%). Of those, pocket gophers (Thomomys spp.) and voles (Microtus spp.) together made up almost half of the deliveries and biomass. Most prey was delivered to the nest in midday (i.e., 1000–1459 H), suggesting these are important foraging hours for this population. However, afternoon air temperatures in the study area can be high and may require that nestlings be shaded, setting up a potential trade-off between foraging and protecting the nestlings’ thermal homeostasis. Our study provides initial insight into the daily temporal dynamics of prey delivery for one of the latest-breeding raptors in North America.

Flexible grouping patterns in a western and eastern chimpanzee community.

Primate social organizations, or grouping patterns, vary significantly across species. Behavioral strategies that allow for flexibility in grouping patterns offer a means to reduce the costs of group living. Chimpanzees (Pan troglodytes) have a fission-fusion social system in which temporary subgroups ("parties") change in composition because of local socio-ecological conditions. Notably, western chimpanzees (P. t. verus) are described as showing a higher degree of bisexual bonding and association than eastern chimpanzees, and eastern female chimpanzees (P. t. schweinfurthii) are thought to be more solitary than western female chimpanzees. However, reported comparisons in sociality currently depend on a small number of study groups, particularly in western chimpanzees, and variation in methods. The inclusion of additional communities and direct comparison using the same methods are essential to assess whether reported subspecies differences in sociality hold in this behaviorally heterogeneous species. We explored whether sociality differs between two communities of chimpanzees using the same motion-triggered camera technology and definitions of social measures. We compare party size and composition (party type, sex ratio) between the western Gahtoy community in the Nimba Mountains (Guinea) and the eastern Waibira community in the Budongo Forest (Uganda). Once potential competition for resources such as food and mating opportunities were controlled for, subspecies did not substantially influence the number of individuals in a party. We found a higher sex-ratio, indicating more males in a party, in Waibira; this pattern was driven by a greater likelihood in Gahtoy to be in all-female parties. This finding is the opposite of what was expected for eastern chimpanzees, where female-only parties are predicted to be more common. Our results highlight the flexibility in chimpanzee sociality, and caution against subspecies level generalizations.

Nest predation of Cory's shearwater Calonectrisborealis (Aves, Procellariiformes) by introduced mammals on Terceira Island, Azores.

The Azores holds the largest population of Cory's shearwater Calonectrisborealis (Cory, 1881) (Aves, Procellariiformes) in the world. Apart from a few mammal-free islets, the bulk of the population breeds in coastal areas on the main human-inhabited islands, where several non-native predators have been introduced. Throughout the entire year of the 2019 breeding season, we used motion-triggered cameras and regularly visited three colonies of Cory's shearwater to identify nest predators and the factors affecting nest predation. A total of 292,624 photos were obtained, of which 97.7% were of Cory's shearwaters, 1.7% of non-target species (e.g. other birds, rabbits) and 0.52% of potential predators. Of the monitored nests, 25.7% were predated (n = 9), mainly by black rats (n = 8), but also by cats (n = 1). The relative abundance of black rats in the nests was the main factor explaining nest mortality. This variable was significantly and negatively related with the daily survival rate of Cory's shearwater nestlings. Identification of the main nest predators is crucial for the management and conservation of native bird populations, particularly on oceanic islands, which harbour an important number of threatened and endemic species.

Sequential mountings of a possible immature male by an adult male in Victoria’s Riflebird (Ptiloris victoriae)

Sexual behaviour in the Birds-of-paradise (family Paradisaeidae) is poorly understood and few studies have offered detailed descriptions of copulatory behaviours. We recorded courtship behaviours of Victoria’s Riflebird Ptiloris victoriae in the Atherton Tablelands in Queensland, Australia using motion triggered cameras and report a rare case of three sequential mountings by an adult male. While the recipient of these mountings performed female-typical sexual behaviours, it also briefly performed a male courtship display behaviour, suggesting that it may be an immature male. This observation raises several questions about the courtship behaviour of this species. Females may, for instance, occasionally solicit multiple copulations from preferred males to maximize the amount of transferred sperm. Another intriguing possibility is that immature males tolerate being mounted and potentially even mimic female sexual behaviours when learning from adult male displays. We also describe a novel adult male courtship behaviour, namely ‘nape-pecking’.

Empowering Wildlife Guardians: An Equitable Digital Stewardship and Reward System for Biodiversity Conservation Using Deep Learning and 3/4G Camera Traps

The biodiversity of our planet is under threat, with approximately one million species expected to become extinct within decades. The reason: negative human actions, which include hunting, overfishing, pollution, and the conversion of land for urbanisation and agricultural purposes. Despite significant investment from charities and governments for activities that benefit nature, global wildlife populations continue to decline. Local wildlife guardians have historically played a critical role in global conservation efforts and have shown their ability to achieve sustainability at various levels. In 2021, COP26 recognised their contributions and pledged USD 1.7 billion per year; however this is a fraction of the global biodiversity budget available (between USD 124 billion and USD 143 billion annually) given they protect 80% of the planets biodiversity. This paper proposes a radical new solution based on “Interspecies Money”, where animals own their own money. Creating a digital twin for each species allows animals to dispense funds to their guardians for the services they provide. For example, a rhinoceros may release a payment to its guardian each time it is detected in a camera trap as long as it remains alive and well. To test the efficacy of this approach, 27 camera traps were deployed over a 400 km2 area in Welgevonden Game Reserve in Limpopo Province in South Africa. The motion-triggered camera traps were operational for ten months and, using deep learning, we managed to capture images of 12 distinct animal species. For each species, a makeshift bank account was set up and credited with GBP 100. Each time an animal was captured in a camera and successfully classified, 1 penny (an arbitrary amount—mechanisms still need to be developed to determine the real value of species) was transferred from the animal account to its associated guardian. The trial demonstrated that it is possible to achieve high animal detection accuracy across the 12 species with a sensitivity of 96.38%, specificity of 99.62%, precision of 87.14%, F1 score of 90.33%, and an accuracy of 99.31%. The successful detections facilitated the transfer of GBP 185.20 between animals and their associated guardians.

Surveying Cory Shearwater colonies with camera traps and identifying potential invasive nest predators.

The Azores holds the largest population of Cory's shearwater Calonectrisborealis (Cory, 1881) (Aves, Procellariiformes, Procellariidae) in the world. One of the major threats of this species in the Azores is the predation by invasive mammals, which were introduced during European colonisation of the islands.The present study provides a dataset from a camera-trapping survey performed in colonies of Cory's shearwater. The sampling was conducted between 7 April and 23 October 2019, covering the entire breeding season, in three colonies of the Terceira Island (Azores). A total of 32 nests were sampled using motion-triggered cameras. The aims of this study are to provide information about the ecological patterns of the Cory shearwater and to identify potential nest predators. Our results include a total of 6972 records of 15 species (nine species of birds, five of mammals and one reptile), of which 5414 records are of Cory's shearwater, 478 of potential mammal predators and 1080 of another vertebrate species. Information about the biology of the species is also provided, as species circadian behaviour and habitat description.

Coexistence mechanisms of sympatric ungulates: Behavioral and physiological adaptations of blue sheep (Pseudois nayaur) and red deer (Cervus elaphus alxaicus) in Helan Mountains, China

Studying the coexistence mechanisms of sympatric wildlife helps to shed light on why the earth has so many different species. When ungulates share ranges, food and habitat requirements may partially or fully overlap. Therefore, the aim of this study was to determine how sympatric ungulates share limited resources. Carcasses of 27 adult blue sheep (Pseudois nayaur) and three adult red deer (Cervus elaphus alxaicus) were collected in the Helan Mountains, China. Nutritive indices of plant species foraged and morphometric measurements of the digestive system of the two sympatric ungulates were determined. In addition, 120 passive, infrared motion-triggered cameras recorded spatial overlap and temporal overlap between the two species. Camera trapping revealed relatively limited spatial overlap and significantly different activity rhythms between blue sheep and red deer. Differences were also observed in stomach weight, surface enlargement factor of the rumen, and intestine length between the two species. However, the combined relative weight of the stomach and intestine was not different between species. The low spatiotemporal overlap decreased opportunities for encounters between sympatric blue sheep and red deer, and significant differences in digestive systems allowed the two species to consume different plant species or different parts of the same species. Thus, the two sympatric ungulates coexist harmoniously in the Helan Mountains because of long-term evolutionary behavioral and physiological adaptations that eliminate negative effects on the survival of the other species.

CONTRASTING ACTIVITY TIMES BETWEEN RACCOONS (PROCYON LOTOR) AND VIRGINIA OPOSSUMS (DIDELPHIS VIRGINIANA) IN URBAN GREEN SPACES

As urbanization increases, impacts on urban wildlife behavior are becoming more apparent. Using camera traps, we compared activity times of Raccoons (Procyon lotor) with those of Virginia Opossums (Didelphis virginiana) in natural areas of Seattle, Washington. Previous studies found that Virginia Opossums and Raccoons are significantly more active at night than at any other time. However, these studies occurred exclusively in forested or agricultural landscapes. We deployed motion-triggered camera traps in greenspaces of Seattle to test the hypothesis that Raccoons and Virginia Opossums are both primarily active at night in an urban environment. Our results demonstrated a statistically significant difference in activity time distributions between the species. Virginia Opossums were exclusively nocturnal, whereas Raccoons allocated their activity between nocturnal and crepuscular periods. This study provides a snapshot of mesopredator behavior in an environment heavily influenced by humans and informs the effective management of Raccoons in urban areas.

A method for marking individual animals in motion-triggered camera studies

A method for marking individual animals in motion-triggered camera studies

Translocating Wild California Valley Quail to Texas: An Evaluation of Survival, Dispersal, Tracking Efficacy, and Roost Preference

Quail translocations are becoming increasingly popular in regions of suitable habitat where local quail populations have declined. In northeastern Texas, USA, northern bobwhite (Colinus virginianus) populations have drastically declined for over a century and have reached undetectable levels in many areas. As a result, the number of quail hunters and quail conservation funding have also declined. California valley quail (Callipepla californica; hereafter, valley quail) have increased across their range and have been translocated to many states and countries. Thus, the goal of this study was to determine whether translocating wild valley quail to Texas was feasible, and evaluate their survival, dispersal, roost location preference, and potential predator impacts. We translocated 748 wild valley quail from Idaho, USA to northeastern Texas in 2019 and 2020. We collected quail location data from very high frequency (VHF) and digital transmitters. Motion-triggered cameras, scent stations, simulated nests, and raptor transects were used to record predator presence and potential predator impacts. Survival of birds with tracking devices was 63% (VHF) in 2019, and 38.8% (VHF) and 92.5% (digital tag) in 2020. Survival was greater for quail with digital transmitters. Median dispersal distance was 633.5 m in 2019 and 246.6 m in 2020 for valley quail with VHF transmitters, and 310.4 m for quail with digital transmitters. Minimum convex polygon area medians were 4.3 ha in 2019 and 3.1 ha in 2020 for quail with VHF transmitters, and 16.1 ha in 2020 for quail with digital transmitters. Roost sites were primarily in young stands of oak trees. Median simulated nest survival was 2 days (minimum [min] = 1, interquartile range [IQR] = 2–5.4, maximum [max] = 23) in 2019, and 7.5 days (min = 2, IQR = 4.5–15.2, max = 23) in 2020. The most frequent mammalian predators observed were raccoons (Procyon lotor), feral hogs (Sus scrofa), and white-tailed deer (Odocoileus virginianus). Red-tailed hawks (Buteo jamaicensis) were the most frequent aerial predator. We completed the first documented translocation of wild California valley quail to Texas, demonstrating it is feasible. Future translocation may benefit from translocating more birds over a longer period of time, with more consistent methodology. The establishment of a sustainable population may require ≥7 years of translocation at a rate of 500 birds per year with >2,000 ha of suitable habitat.

Captivity and habituation to humans raise curiosity in vervet monkeys

The cognitive mechanisms causing intraspecific behavioural differences between wild and captive animals remain poorly understood. Although diminished neophobia, resulting from a safer environment and more “free” time, has been proposed to underlie these differences among settings, less is known about how captivity influences exploration tendency. Here, we refer to the combination of reduced neophobia and increased interest in exploring novelty as “curiosity”, which we systematically compared across seven groups of captive and wild vervet monkeys (Chlorocebus pygerythrus) by exposing them to a test battery of eight novel stimuli. In the wild sample, we included both monkeys habituated to human presence and unhabituated individuals filmed using motion-triggered cameras. Results revealed clear differences in number of approaches to novel stimuli among captive, wild-habituated and wild-unhabituated monkeys. As foraging pressure and predation risks are assumed to be equal for all wild monkeys, our results do not support a relationship between curiosity and safety or free time. Instead, we propose “the habituation hypothesis” as an explanation of why well-habituated and captive monkeys both approached and explored novelty more than unhabituated individuals. We conclude that varying levels of human and/or human artefact habituation, rather than the risks present in natural environments, better explain variation in curiosity in our sample of vervet monkeys.

Unexpectedly low paternal diversity is associated with infrequent pollinator visitation for a bird-pollinated plant.

The behaviour of pollinators has important consequences for plant mating. Nectar-feeding birds often display behaviour that results in more pollen carryover than insect pollinators, which is predicted to result in frequent outcrossing and high paternal diversity for bird-pollinated plants. We tested this prediction by quantifying mating system parameters and bird visitation in three populations of an understory bird-pollinated herb, Anigozanthos humilis (Haemodoraceae). Microsatellite markers were used to genotype 131 adult plants, and 211 seeds from 23 maternal plants, from three populations. While outcrossing rates were high, estimates of paternal diversity were surprisingly low compared with other bird-pollinated plants. Despite nectar-feeding birds being common at the study sites, visits to A. humilis flowers were infrequent (62 visits over 21,552 recording hours from motion-triggered cameras, or equivalent to one visit per flower every 10days), and the majority (76%) were by a single species, the western spinebill Acanthorhynchus superciliosus (Meliphagidae). Pollen counts from 30 captured honeyeaters revealed that A. humilis comprised just 0.3% of the total pollen load. For 10 western spinebills, A. humilis pollen comprised only 4.1% of the pollen load, which equated to an average of 3.9 A. humilis pollen grains per bird. Taken together, our findings suggest that low visitation rates and low pollen loads of floral visitors have led to the low paternal diversity observed in this understory bird-pollinated herb. As such, we shed new light on the conditions that can lead to departures from high paternal diversity for plants competing for the pollination services of generalist nectar-feeding birds.

Colony characteristics influence nest survival of Caribbean Roseate Terns

AbstractDetermining how site characteristics influence reproductive success can help guide conservation planning for declining wildlife populations. For colonially breeding seabirds, nest survival and predation risk can be influenced by both colony and nest site characteristics such as colony size, nest density, and nest location. We evaluated the reproductive success of a declining population of Roseate Terns (Sterna dougallii) in the United States and British Virgin Islands to identify primary causes of nest failure and investigate the influence of colony and nest site covariates on nest survival. In addition, we measured the influence of colony characteristics on chick provisioning to determine if resource competition in larger colonies affected foraging rates. Monitoring was conducted in 2017–2018 via motion-triggered cameras, which enable 24-hr monitoring with minimal nest disturbance. Nest survival was defined by both hatch success and early chick success, defined as a chick surviving from hatching through the fourth post-hatch day. We monitored 118 nests in 6 colonies over the 2 breeding seasons. We found that predation was the primary cause of nest failure. Both hatch and nest success increased with colony size, and neither nest survival nor predation probability was influenced by individual nest site characteristics. Provisioning rates were comparable among colony sites and did not vary with colony size. Our results suggest that directing management efforts toward enhancing colony size, rather than focusing on nest site characteristics, can be beneficial for tropical seabird conservation.

Age- and sex-dependent vigilance behaviour modifies social structure of hunted wild boar populations

Abstract Context Human activities in general, and hunting in particular, often have significant impacts on the behaviour of wildlife through the anti-predator behaviours they evoke. Wild boar populations are rapidly expanding worldwide and their population densities are increasing. Aims To examine hunting effects in combination with different land-use factors on the behaviour and social structure of wild boars (Sus scrofa) in Israel. Specifically, to examine differences in vigilant behaviour and social structure in agricultural areas (hunting permitted) and nature reserves (hunting prohibited). Methods Motion-triggered cameras were installed to record wild boars’ social structure and vigilance behaviour along movement trails. Age and sex of individual wild boars were identified, as were the size and structure of their social groups, and hunting in each of the studied areas was quantified. Key results Results indicated significant differences in the vigilance behaviour of wild boars between agricultural areas and nature reserves. In agricultural areas, adult females were significantly more vigilant (P < 0.001) compared with adult males (P = 0.150). Additionally, in these areas there were significantly more adult males and fewer females leading family groups (P < 0.001). Furthermore, male yearlings were significantly more vigilant in agricultural areas (P < 0.001) compared with female yearlings (P = 0.164). Male yearlings tended to roam significantly more with family groups in agricultural areas compared with nature reserves, where they tended to roam alone or in groups (P = 0.029, P = 0.035). Conclusions These results indicate social and behavioural differences in wild boars between agricultural areas and nature reserves, suggesting that hunting may have a substantial impact on their social structure and behaviour. Implications Overall, the findings support the behavioural and social consequences of human hunting. Long-term implications of altered behavioural and social responses should be considered in management and conservations strategies. For instance, the high proportion of male yearlings in family groups in agricultural areas in autumn (October–December, mating season) may offer young males early access to reproductive females, even within the same social group. This may eventually lead to an increase in the reproductive potential of female wild boars.

Insight into occupancy determinants and conflict dynamics of grey wolf (Canis lupus) in the dry temperate zone of Hindukush Range

The grey wolf (Canis lupus) is a widespread but locally endangered species across Pakistan. The current study investigates the occupancy of grey wolf and conflict with humans in Khanbari Valley Gilgit Baltistan. The study was conducted from the 5th of December 2014 to the 11th of January 2015. The study area was delineated into blocks following natural watersheds, and overall 47 motion-triggered cameras were installed in various locations encompassing an area of 810 km2 with an effort of 1428 trap nights. A human-wolf conflict survey was carried out through questionnaires, where 57 respondents were randomly chosen from 08 villages in the valley. Grey wolf was photo-captured at 11 different camera stations, occupancy estimated at 0.37 ± 0.22 S.E., and detection probability of 0.29 ± 0.19 S.E was obtained. A total of 166 livestock were killed which incurred an economic loss of USD 17,046 (USD 299 per household) in five years. Predation on goat was highest, though consumed as per availability. Sheep predation indicates selection for this animal because predation was much higher than availability. Cattle was predated as per availability and accounts for the least part of the livestock loss. Predation of livestock was greatly influenced by four factors: habitat, prey type, prey age, and time of predation. We recommend conservation initiatives like compensation for economic losses, construction of predator-proof corrals, and awareness campaigns to promote human-wolf co-existence in the area.

Impact of introduced nest predators on insular endemic birds: the case of the Azores Woodpigeon (Columba palumbus azorica)

Nest predation is the main cause of reproductive failure in many bird species. Identification of predators is crucial to understand and interpret the factors that affect nest predation. Although nest predation is a natural top-down regulator of bird populations, its effect is usually more dramatic when introduced predators are involved, particularly in oceanic islands. In the Azores archipelago, the endemic Azores Woodpigeon (Columba palumbus azorica) is believed to be under high predation pressure. We used motion-triggered cameras to monitor nests of the Azores Woodpigeon on two islands of the archipelago (Pico and Terceira) in order to identify nest predators, quantify their impact on this bird and better understand the determinants of predation rates. We sampled 56 nests, during 569 camera trap days, obtaining around 125,000 photographic records. Two introduced predators were identified, black rat (on both islands) and feral cat (only on Terceira), both depredating eggs and chicks. Breeding success, calculated using the Mayfield method, was estimated at 19% on Pico and only 9% on Terceira. Overall, predation was the main cause of breeding failure. General linear models showed that predation rates are positively correlated to fruit availability and negatively correlated to elevation, human population density and adult Woodpigeon attendance at the nest. Edge distance, nest height or cover of trees did not affect predation. Camera traps also provided additional and useful information on predator behaviour when approaching a nest and on daily activity patterns of both adult Woodpigeon and nest predators.

Predators May Lose Interest in Turtle Acclimation Pens: Implications for Translocations Using Soft Release

We opportunistically investigated predator visits to enclosed acclimation pens containing juvenile eastern box turtles (Terrapene carolina) over a 34-d acclimation period using motion-triggered cameras. Daily visitation probability by raccoons (Procyon lotor) and fox squirrels (Sciurus niger; the only predator species observed visiting) decreased from a peak of 36% probability of a visit on the first day turtles were penned to nearly zero probability by day 34 (the release day). Our findings indicate predators lose interest in pens over time, and we suggest animals should be released from acclimation pens after predators have lost interest in pens to avoid heightened predation risk of translocated animals.

Identification of Factors Affecting Predation Risk for Juvenile Turtles using 3D Printed Models.

Simple SummaryTurtles are one of the most threatened vertebrate groups. High rates of juvenile predation may contribute to population declines for many species, but predator identities and factors contributing to predation risk for juveniles are largely unknown due to their highly secretive nature. Alternatives to studying live juveniles are needed. By monitoring three-dimensional printed models resembling juvenile box turtles (Terrapene carolina) with motion-triggered cameras in the Midwestern USA, we found raccoons (Procyon lotor) were the dominant predator that interacted with models, followed by rodents (Sciuridae). Mesopredator interactions with models were less likely in habitats with higher vegetative ground cover. However, availability of sensory cues (visual or olfactory) provided by models did not influence mesopredator interactions, suggesting they used multiple senses to detect models. Rodents interacted with models that were closer to woody structure, likely because they commonly utilize such small-scale habitat features. Rodents interacted with exposed models more than concealed models, reflecting their predominantly visual foraging behavior. Overall, our results suggest juvenile turtle habitat selection could affect predator-specific predation risk but behavioral differences between particular predators are also important determinants of risk. These findings have implications for management efforts aimed at reducing encounters between juvenile turtles and their major predators.Although it is widely accepted that juvenile turtles experience high levels of predation, such events are rarely observed, providing limited evidence regarding predator identities and how juvenile habitat selection and availability of sensory cues to predators affects predation risk. We placed three-dimensional printed models resembling juvenile box turtles (Terrapene carolina) across habitats commonly utilized by the species at three sites within their geographical range and monitored models with motion-triggered cameras. To explore how the presence or absence of visual and olfactory cues affected predator interactions with models, we employed a factorial design where models were either exposed or concealed and either did or did not have juvenile box turtle scent applied on them. Predators interacted with 18% of models during field trials. Nearly all interactions were by mesopredators (57%) and rodents (37%). Mesopredators were more likely to attack models than rodents; most (76%) attacks occurred by raccoons (Procyon lotor). Interactions by mesopredators were more likely to occur in wetlands than edges, and greater in edges than grasslands. Mesopredators were less likely to interact with models as surrounding vegetation height increased. Rodents were more likely to interact with models that were closer to woody structure and interacted with exposed models more than concealed ones, but model exposure had no effect on interactions by mesopredators. Scent treatment appeared to have no influence on interactions by either predator group. Our results suggest raccoons can pose high predation risk for juvenile turtles (although rodents could also be important predators) and habitat features at multiple spatial scales affect predator-specific predation risk. Factors affecting predation risk for juveniles are important to consider in management actions such as habitat alteration, translocation, or predator control.

How to measure chimpanzee party size? A methodological comparison.

Chimpanzees (Pan troglodytes) live in fission-fusion societies where community members form temporary parties that frequently change in size and composition. Chimpanzee party size and composition have been widely studied to identify proximate causes of grouping patterns, and party size estimates are used to assess population sizes and densities. Numerous socio-ecological factors influence chimpanzee party size, but findings differ across studies. Various methods to measure party size exist, including direct observations, motion-triggered camera (MTC) observations, and nest counts. However, comparative analyses of these methods are lacking. Here, we assess relative differences in four commonly used party size methods and we examine socio-ecological factors influencing party size of unhabituated chimpanzees (P. t. verus) at Seringbara, Nimba, Guinea. We also assess which method(s) best reflect the influence of socio-ecological factors on party size. Using data collected over 69months, we show that night nest counts resulted in relatively larger party size estimates than the other methods, and day nest counts resulted in relatively smaller party size estimates. Direct and MTC observations did not differ in relative estimates of party size and composition. Both fruit abundance and presence of estrous females positively influenced party size, but this effect was only evident when measuring party size with MTCs. Methods thus differ in relative party size estimates and their ability to assess the impact of socio-ecological factors. We conclude that MTC observations best represent party size and the effect of socio-ecological factors at Nimba. MTCs show promising potential for studying grouping patterns in unhabituated chimpanzees.

Key Ecological Function Peaks at the Land–Ocean Transition Zone When Vertebrate Scavengers Concentrate on Ocean Beaches

Ecotones can form hot spots of biodiversity by containing species from multiple ecosystems. Because biodiversity is often linked to ecological function, we posit that rates of key ecological functions are highest at ecotones and decline away from them. Here we test this hypothesis by measuring spatial decays in the function of carrion scavenging on a gradient ranging from ocean beaches upland into abutting coastal dunes. A large field experiment in Eastern Australia, at the ecotone formed by ocean beaches, employed multiple carrion placements and motion-triggered cameras to identify the animals consuming carcasses and the removal rates of necromass. Significantly more carrion was consumed by vertebrate scavengers at the beach interface (50–80% of total necromass removed) and declined significantly with distance (max. 350 m) into the abutting coastal dunes (20–25%). This marked cline was due to the consumption of carrion by both dune-dwelling and beach-dwelling animals at the beach–dune interface and a decline in scavenging activity by both groups farther upland. These spatial effects were consistent between sites, but the lower carrion removal away from the beach became less pronounced as the carcasses putrefied, suggesting that microbial actions can modify carrion suitability for vertebrate scavengers and hence change spatial patterns in ecological function. Our findings provide quantitative support for the widespread notion that ecological transition zones are hot spots of ecological functions and highlight the importance of managing functionally important species at ecotones.