Influence Of Predation Risk Research Articles

Factors influencing risk of predation by subsidized predators on juvenile Mojave desert tortoises (Gopherus agassizii)

A persistent lack of juvenile recruitment in populations of the imperiled Mojave desert tortoise (Gopherus agassizii) has been attributed to artificially inflated populations of coyotes (Canis latrans) and common ravens (Corvus corax) in some areas. Subsidized by resources in the form of road-killed prey, movement corridors, or nesting perches provided by ever-expanding road and powerline networks, these “subsidized predators” threaten tortoises and other species thanks to subsidies that help support their populations in areas where they might otherwise have been less abundant. Here, we quantified the risk of predation from these subsidized predators on juvenile Mojave desert tortoises by quantifying attack rates on 3D-printed replicas. We evaluated predation risk as a function of replica size, distance from powerlines, and season—variables that can inform release strategies of head-started and translocated tortoises. We found significantly greater risk of predation from ravens in the spring than in the fall. Replica size did not significantly influence predation risk from ravens or coyotes. Replica distance from a powerline or road also did not significantly influence predation risk, supporting previous studies that have found the risk of predation can persist for up to 1.6 km from raven nesting structures. Our results support recommendations for releasing juvenile head-started and translocated tortoises in the fall and away from areas close to raven nesting structures. Our study provides insight into the interactions of prey and subsidized predators and helps guide management on potential mitigation strategies for minimizing the impacts of subsidized predators on species like the imperiled Mojave desert tortoise.

Maternal behaviors influence survival of ungulate neonates under heavy predation risk.

Predators impose top-down forces on prey populations, with the strength of those effects often varying over space and time and among demographic groups. In ungulates, predation risk is typically greatest for neonatal offspring, with some suggesting that predators can key in on adult activity to locate hidden neonates. However, few field studies to date have been able to directly assess the influence of maternal care on ungulate neonate survival. Using a population of white-tailed deer under heavy coyote predation pressure, we tested the maternal dispersion hypothesis, which suggests the dispersion of maternal activity temporally and spatially attenuates risk of predation for ungulate neonates during this vulnerable altricial phase. We compared support for this hypothesis with more commonly tested hypotheses regarding the influence of habitat conditions and intrinsic factors on neonatal survival. Fawn survival to 16 weeks was 27.7%, with coyotes accounting for 59% of fawn mortalities. In support of our maternal temporal diffusion hypothesis, we found that neonatal survival decreased as more maternal visits (proportionally) occurred at night. The only other significant (p < .1) predictor of fawn survival was birth timing, with fawn survival decreasing as the season progressed. Given that fawn survival declined as the proportion of nighttime visits increased, and that wild pig presence and human disturbance can push doe and fawn activity toward nocturnal hours, additional research is needed to determine whether managing pig and human disturbance can decrease fawn mortality. More broadly, given the importance of recruitment in ungulate population dynamics, our finding opens a potentially important new line of inquiry on how maternal behaviors influence predation risk in large animal predator-prey ecology.

White-tailed deer population dynamics in a multipredator landscape shaped by humans.

Large terrestrial mammals increasingly rely on human-modified landscapes as anthropogenic footprints expand. Land management activities such as timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources and predation risk via changes in habitat, but these effects are not well understood in regions with diverse and changing predator guilds. In northeastern Washington state, USA, white-tailed deer (Odocoileus virginianus) are vulnerable to multiple carnivores, including recently returned gray wolves (Canis lupus), within a highly human-modified landscape. To understand the factors governing predator-prey dynamics in a human context, we radio-collared 280 white-tailed deer, 33 bobcats (Lynx rufus), 50 cougars (Puma concolor), 28 coyotes (C. latrans), and 14 wolves between 2016 and 2021. We first estimated deer vital rates and used a stage-structured matrix model to estimate their population growth rate. During the study, we observed a stable to declining deer population (lambda = 0.97, 95% confidence interval: 0.88, 1.05), with 74% of Monte Carlo simulations indicating population decrease and 26% of simulations indicating population increase. We then fit Cox proportional hazard models to evaluate how predator exposure, use of human-modified landscapes, and winter severity influenced deer survival and used these relationships to evaluate impacts on overall population growth. We found that the population growth rate was dually influenced by a negative direct effect of apex predators and a positive effect of timber harvest and agricultural areas. Cougars had a stronger effect on deer population dynamics than wolves, and mesopredators had little influence on the deer population growth rate. Areas of recent timber harvest had 55% more forage biomass than older forests, but horizontal visibility did not differ, suggesting that timber harvest did not influence predation risk. Although proximity to roads did not affect the overall population growth rate, vehicle collisions caused a substantial proportion of deer mortalities, and reducing these collisions could be a win-win for deer and humans. The influence of apex predators and forage indicates a dual limitation by top-down and bottom-up factors in this highly human-modified system, suggesting that a reduction in apex predators would intensify density-dependent regulation of the deer population owing to limited forage availability.

A study of nests and nesting materials used by house sparrow across different habitat scale of Bhavnagar, Gujarat, India

This study investigates the nests and nest materials used by House Sparrows across various habitat scales in Bhavnagar, Gujarat, India. House Sparrows are adaptable to urban environments but have faced declines due to nesting site scarcity. Nest design, placement and materials influence predation risk and affect reproductive success. Artificial nest-boxes serve as crucial alternatives in urban areas. Overall, this research sheds light on House Sparrows’ adaptability for nesting, aiding conservation efforts and expanding our understanding of avian nesting dynamics.

Habitat complexity and predator odours impact on the stress response and antipredation behaviour in coral reef fish.

Mass coral bleaching events coupled with local stressors have caused regional-scale loss of corals on reefs globally. Following the loss of corals, the structural complexity of these habitats is often reduced. By providing shelter, obscuring visual information, or physically impeding predators, habitat complexity can influence predation risk and the perception of risk by prey. Yet little is known on how habitat complexity and risk assessment interact to influence predator-prey interactions. To better understand how prey's perception of threats may shift in degraded ecosystems, we reared juvenile Pomacentrus chrysurus in environments of various habitat complexity levels and then exposed them to olfactory risk odours before simulating a predator strike. We found that the fast-start escape responses were enhanced when forewarned with olfactory cues of a predator and in environments of increasing complexity. However, no interaction between complexity and olfactory cues was observed in escape responses. To ascertain if the mechanisms used to modify these escape responses were facilitated through hormonal pathways, we conducted whole-body cortisol analysis. Cortisol concentrations interacted with habitat complexity and risk odours, such that P. chrysurus exhibited elevated cortisol levels when forewarned with predator odours, but only when complexity levels were low. Our study suggests that as complexity is lost, prey may more appropriately assess predation risk, likely as a result of receiving additional visual information. Prey's ability to modify their responses depending on the environmental context suggests that they may be able to partly alleviate the risk of increased predator-prey interactions as structural complexity is reduced.

Effects of human and nonhuman predation risk on antipredator movement behaviors of an upland game bird

AbstractPredators elicit antipredator behaviors such as proactive and reactive movements in prey, but both are rarely investigated simultaneously. Impacts of human predation risk on antipredator behaviors can be greater than those of nonhuman predators, resulting in increased effects on populations and community structure. We compared the influence of human and nonhuman predation risk on proactive and reactive antipredator movement behaviors of male Eastern wild turkeys (Meleagris gallopavo, hereafter turkey). We used simultaneously collected GPS locations from 31 turkeys and 36 coyotes (Canis latrans) to investigate the antipredator behavior of turkeys to coyotes. To assess antipredator behaviors of turkeys to hunters, we used 1661 hunting tracks collected while monitoring 109 turkeys. For proactive movements, we quantified how predation risk influenced resource selection. To investigate reactive movements, we quantified changes in movement behavior of turkeys after encountering hunters and coyotes. Coyote and turkey home range overlap was high, but lack of core area overlap, encounters, and similar resource selection suggested the use of different areas on the landscape. Turkeys selected areas associated with decreased coyote risk and closer to hardwoods. Coyotes preferred shrubs and open areas, suggesting turkeys avoided coyote risk and the habitats coyotes preferred. We detected 17 coyote and turkey contacts, and the probability of contact decreased by 16.6% for every 100 m farther from a forest edge. Turkeys did not display reactive movement behaviors after a direct encounter with coyotes, as step lengths were similar prior to and after encounters, which did not differ from random step lengths. After hunting, turkeys selected areas farther from public access points and closer to private property, suggesting proactive avoidance of hunter risk. We detected 31 hunter and turkey contacts; increased step lengths after hunter contacts suggested fleeing behavior. The probability of a hunter–turkey contact decreased by 5.5% for every 100 m farther from a secondary road. Antipredator movement behaviors by turkeys suggest coyote risk to be low over a broad temporal window, while hunter risk is high for a narrow temporal window. We provide insight into how human‐induced fear can cause antipredator behavioral responses greater than nonhuman fear, potentially causing changes in species distribution and community structure.

Factors Affecting Nest Site Selection by Freshwater Turtles: A Systematic Review

Nest site selection is an important behavior, particularly in species that lack parental care, as nest microclimate can greatly impact embryos’ survival and offspring phenotype. Understanding which factors influence oviposition decisions is critical to identifying priority areas for conservation. This systematic review aimed to synthesize the factors that affect nest site selection by freshwater turtles. The search was conducted in the Web of Science database. In total, 35 publications met the eligibility criteria. The first study on the topic was published more than three decades ago, but only within the last ten years have studies started to be published annually. More than half of the studies were conducted in the United States and the most studied species was Chrysemys picta. Environmental factors, mainly vegetation characteristics, but also soil properties and beach morphology, are the most studied. Anthropogenic factors have been increasingly studied, especially residential areas and agricultural fields. Some studies suggest that human-altered habitats may act as ecological traps, emphasizing the need for further research on this topic. More studies are also needed on the influence of predation risk, co-species cues, female size, and offspring phenotype on nest site selection by freshwater turtles. We highlight that understanding the factors affecting nest site selection is important for identifying the habitat needs of nesting females, predicting possible ecological implications of nest site choice, assessing the adaptive potential of species to environmental change, and determining the vulnerability of populations to different threats.

Landscape characteristics and predation risk influence spatial variation in auditory courtship of an upland game bird

ContextNumerous wildlife species use a polygynous mating system, where males use auditory courtship behaviors to secure breeding opportunities. The acoustic adaptation hypothesis, risk reward, and landscape of fear theories suggest spatial variation in male auditory courtship will be influenced by areas in landscapes where sound transmission is increased, and predation risk is reduced. However, it is often unclear what landscape features drive spatial variation in courtship behaviors.ObjectivesWe quantified the influence of predation risk, land cover type, and resource selection on spatial trends in the auditory courtship behavior (gobbling activity) of Eastern wild turkeys (Meleagris gallopavo silvestris).MethodsWe used 53,025 gobbles coupled with GPS locations from 111 turkeys and 36 coyotes (Canis latrans), and distance metrics associated with hunter activity and land cover type, to investigate influences of predation risk, resource selection, and land cover type on spatial variation in gobbling activity in Georgia, USA.ResultsDistance to public access during hunting was the most influential predictor of gobbling activity, wherein the expected number of daily gobbles increased by 40% for every 500 m farther from public access. Daily gobbles decreased by 22% for every 500 m farther away from private property during hunting. We failed to find significant effects of land cover type and coyote use but found limited evidence that areas with increased predicted probability of turkey use was associated with increased gobbling.ConclusionsPredation risk associated with increased anthropogenic disturbance had the greatest influence on gobbling activity. Our findings suggest that altering hunter access by closing roads to vehicle use, reducing hunter activity, or creating refuge areas on the landscape could positively influence gobbling activity.

Nest predation in Patagonian wetlands: predator assemblage and microhabitat characteristics

ABSTRACT Multiple factors influence predation risk, ranging from habitat conditions to the composition and behaviour of predators. Although these factors are well documented for forest ecosystems, there is little evidence for wetlands, especially within Patagonia. Using artificial nests and camera traps, we documented the nest predation rates and predator assemblage of birds nesting in wetlands of the Patagonian steppe. We also determined the effect of vegetation cover on nest survival and studied the variation in predator groups according to nest placement: nests located in an open wetland, peripheral grassland to the wetland, and nests located in shrubs at different heights. We found 84% of nests failed, counting birds, mice, and armadillos as the main predators. Vegetation cover affected predation events of birds and small mammals, but not those of larger mammals. In turn, small mammals preyed on nests exclusively located in peripheral grassland, medium mammals preferred nests placed in open wetlands, and predation by birds was irrespective of open wetlands and grassland. We also found differences in nest predator assemblage between nests placed on the ground and in shrubs, with birds being the main predators of nests located above ground. These results can be attributed to differential habitat use and movement patterns specific to each predator group. Therefore, the identity, density, and behaviour of predators should be taken into account when planning conservation strategies for birds breeding in wetlands.

Hatching failure is greater in altricial bird species with cavity nests and large clutches

AbstractMortality rates are high for most avian species during early life stages, forming a critical source of natural selection that helps shape the diversity of avian life-history traits. We investigated hatching failure (i.e., non-predatory embryonic mortality, excluding abandoned or damaged eggs) and found significant variation among passerine species. Failure rates ranged from 1.0% to 12.7%, and species with cavity nests and larger clutches experienced greater rates of hatching failure. While past research has focused on the direct effects of predation on the nestling and fledgling stages, little is known about how predation may indirectly influence other sources of mortality such as hatching failure. We investigated the influence of nest predation risk and other factors on variation in hatching failure among 14 free-living grassland and shrubland songbird species. Across all species, 7.7% of 1,667 eggs failed to hatch. We found little evidence that variation in nest temperature influenced rates of hatching failure within and among species, although species with larger clutch sizes had more variable nest temperatures. Dissection of failed eggs revealed that most hatching failures occurred before or shortly after the onset of development; however, there was no difference between cavity and open-cup nesters in the rate of early-stage mortality. Our findings suggest there may be tradeoffs to having a large clutch, with a benefit of rearing more young at the cost of greater hatching failure, possibly due to delayed onset of incubation, poor incubation behavior, or inability to incubate large clutches. Additionally, as larger clutches are often laid in cavity nests, which have a relatively low predation risk, this may outweigh the costs of increased hatching failure. More experimental approaches, such as clutch size manipulations and egg-specific incubation behavior are needed to provide greater insight into factors driving variation in hatching failure across species.

Nesting and post‐fledging predation risk influence diel patterns of songbird fledging

Among stages of avian ontogeny, the act of nest departure or fledging is an abrupt transition into a new environment and a major leap toward independence for offspring. In altricial birds, the timing (i.e. time of day) of fledging is notable in that many species tend to fledge early in the morning. Past studies have proposed nest predation as a key factor driving birds to fledge earlier in the morning (the ‘survival hypothesis’), whereby offspring avoid peak times of nest predation that occur later in the day. A natural extension of this hypothesis is the predation of offspring post‐fledging, whereby offspring are also timing their fledging with future survival prospects outside of the nest. However, few studies have investigated fledging behaviour in the context of both nesting and post‐fledging predation. To help fill this knowledge gap, we investigated factors driving the timing and duration of fledging across six songbird species in the context of offspring predation: daily nest mortality, post‐fledging mortality and diel patterns of nest predation risk. We found that &gt; 60% of songbirds fledged early in the morning, whereas the peaks in nest predation risk occurred several hours post‐fledging. Furthermore, species under greater risk of nest predation fledged earlier in the day and in closer succession to their siblings. Parameters of post‐fledging mortality were poor predictors of fledging timing, but individuals from broods of species under higher risk of post‐fledging mortality fledged in closer succession to their siblings. These results provide evidence in support of the survival hypothesis, and suggest that songbirds fledge in the morning to avoid peak times of nest predation risk that occur later in the day (~ 8 h after civil dawn). Such results corroborate past research highlighting predation on dependent offspring as a key factor driving variation in life histories across animal taxa; however, estimates of post‐fledging mortality suggest that nest predation alone does not fully explain variation in fledging behaviour among species. Future research is therefore needed to investigate the contribution of other factors, such as energetics, parent–offspring conflict and diel patterns of post‐fledging survival, which may help to mediate diel patterns of fledging within and among songbird species.

Prey responses to predation risk under chronic road noise

AbstractAnthropogenic noise has dramatically increased over the past decades with potentially significant impacts on wildlife and their community interactions. Using giving‐up densities (GUDs) paired with camera traps, we examined the concurrent influence of chronic road noise and predation risk on free‐living small mammals. Specifically, we looked for differences in foraging and vigilance behavior during various noise treatments. We found that small mammals significantly reduced food intake when exposed to predation risk; however, concurrent exposure to road noise eliminated this effect; small mammals increased food intake when exposed to road noise and risk compared to risk alone. Furthermore, road noise reduced the number of visits and time spent at foraging trays while it increased vigilance behavior of small mammals in risky situations, meaning they were able to increase their foraging efficiency. Mice also ate less when moon illumination was greater; however, this had no effect on our overall results. This is one of the first studies to concurrently examine the effects of road noise and predation risk on free‐living prey. It shows the complex responses of prey exposed to chronic noise conditions as they attempt to gain reliable information about predation risk and respond appropriately. We highlight the potential consequences road noise may have on the survival of prey as it interferes with their appropriate risk responses.

A rodent herbivore reduces its predation risk through ecosystem engineering

Predator-prey interactions are ubiquitous and powerful forces that structure ecological communities.1-3 Habitat complexity has been shown to be particularly important in regulating the strength of predator-prey interactions.4-6 While it is well established that changes in habitat structure can alter the efficacy of predatory and anti-predatory behaviors,7-9 little is known about the consequences of engineering activity by prey species who modify the external environment to reduce their own predation risk. Using field surveys and manipulative experiments, we evaluated how habitat modification by Brandt's voles (Lasiopodomys brandtii) influences predation risk from a principal avian predator (shrike; Lanius spp.) in a steppe grassland, located in Inner Mongolia, China. We found that voles actively modify habitat structure by cutting down a large, unpalatable bunchgrass species (Achnatherum splendens) in the presence of shrikes, a behavior that disappeared when these avian predators were excluded experimentally. The damage activities of these voless dramatically decreased the volume of unpalatable grasses, which in turn reduced visitations by shrikes and thus mortality rates. Our study shows that herbivorous prey that act as ecosystem engineers can directly reduce their own predation risk by modifying habitat structure. Given the ubiquity of predation risks faced by consumers, and the likely ability of many consumers to alter the habitat structure in which they live, the interplay between predation risk and ecosystem engineering may be an important but unappreciated mechanism at play in natural communities.

Cumulative effects of human footprint, natural features and predation risk best predict seasonal resource selection by white-tailed deer

Land modified for human use alters matrix shape and composition and is a leading contributor to global biodiversity loss. It can also play a key role in facilitating range expansion and ecosystem invasion by anthrophilic species, as it can alter food abundance and distribution while also influencing predation risk; the relative roles of these processes are key to habitat selection theory. We researched these relative influences by examining human footprint, natural habitat, and predator occurrence on seasonal habitat selection by range-expanding boreal white-tailed deer (Odocoileus virginianus) in the oil sands of western Canada. We hypothesized that polygonal industrial features (e.g. cutblocks, well sites) drive deer distributions as sources of early seral forage, while linear features (e.g. roads, trails, and seismic lines) and habitat associated with predators are avoided by deer. We developed seasonal 2nd -order resource selection models from three years of deer GPS-telemetry data, a camera-trap-based model of predator occurrence, and landscape spatial data to weigh evidence for six competing hypotheses. Deer habitat selection was best explained by the combination of polygonal and linear features, intact deciduous forest, and wolf (Canis lupus) occurrence. Deer strongly selected for linear features such as roads and trails, despite a potential increased risk of wolf encounters. Linear features may attract deer by providing high density forage opportunity in heavily exploited landscapes, facilitating expansion into the boreal north.

Behavioral responses to ecological disturbances influence predation risk for a capital breeder

Behavioral responses to ecological disturbances influence predation risk for a capital breeder

Examining shark bite scars on dolphins off Bimini, The Bahamas: Comparisons between bottlenose and Atlantic spotted dolphins

AbstractShark predation risk impacts many facets of dolphin life, including habitat use and foraging strategies. Because direct predation is rarely observed, researchers instead examine dolphins in situ for past injuries that can be attributed to sharks. We analyzed existing photo‐ID catalogs of common bottlenose (Tursiops truncatus) and Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas. A minimum of 29% of individual T. truncatus had evidence of a past, nonlethal shark bite, while for S. frontalis this was only 15%. For both species, shark‐induced injuries were predominantly on the dorsal side. Regression analyses indicated that T. truncatus were more likely to have shark bite scars than S. frontalis and the likelihood of documenting a shark bite scar increased with a higher percentage of the body photographed. T. truncatus were less likely to have scars in the dorsal region, but sampling differences could have influenced these results. While the shark species responsible for scars was not determined, T. truncatus and S. frontalis overlap spatially and temporally with tiger (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas) off Bimini. This study builds on the understanding of dolphin/shark interactions from longitudinal studies of dolphins in this region, providing insight into factors influencing predation risk.

Does Experimental Non-Reclaimed Sites Differ from Technically Reclaimed Areas in the Risk of Artificial Bird Nest Predation?

Abstract Areas left to natural development have been found to be sites with higher diversity and conservation value of local communities, including bird communities, compared to artificial reclamation of post-industrial areas. Most of the studies conducted so far have focused primarily on bird communities of post-mining areas, in terms of the diversity and richness of species. Our study dealt with bird nest predation on specific case of two experimental sites (20 and 32 ha) with more than a 20-year history of primary spontaneous succession established within the technical reclamation of the Radovesická spoil heap (approx. 1,200 ha, North Bohemia, Czech Republic). In the spring of 2018, we conducted a predation experiment using artificial nests (ground and elevated), installed within both succession areas and beyond, in the adjacent artificially reclaimed areas. We monitored the way of restoration and the distance of the nest placement from the succession-reclamation sites edge. The rate of predation was very high: 92.5 % in reclaimed area and 89.4 % in spontaneous successions. None of the observed factors analysed in the generalised linear model (GLM) have conclusively explained the risk of predation. The two experimental succession sites did not differ from the surrounding reclaimed sites in terms of the risk of predation, nor did they significantly influence predation risk on reclaimed sites. We believe that both relatively small and mutually isolated areas do not provide enough of an inner environment without or with at least a limited effect of predation pressure coming from adjacent reclaimed areas.

Pond-adjacent grass height and pond proximity to water influence predation risk of pond fish by amphibians in small fish ponds of Kakamega County, western Kenya

The study investigated predation risk to pond-reared Nile Tilapia Oreochromis niloticus and African Catfish Clarias gariepinus by amphibians, whether this is driven by height of pond-side grass or pond proximity to surface-water source and how this varies with fish stocking options. Based on small-scale freshwater aquaculture farms in western Kenya, field surveys were conducted during three sampling seasons spread across 6 months. These involved the following: (1) a sociological survey of 29 fish farming households; (2) sampling of amphibians for density, species richness and encounter rates and (3) measuring grass height, pond dimensions and water-source proximity across 24 ponds. Overall, 131 individual frogs from three families were recorded in 78 encounters. Amphibian density increased with pond-side grass height, presumably increasing predation risk, but decreased with water-source proximity. Amphibian encounter rate also decreased with water-source proximity, but was unaffected by grass height, while species richness responded positively to pond-side grass height, but not to water-source proximity. Amphibian encounter likelihood was higher in tilapia-only than in catfish-only or tilapia and catfish ponds irrespective of habitat variables. We demonstrate here that management practices for mitigating fish loss to predatory amphibians should include trimming pond-side vegetation, siting ponds close-to-moderate distances from water-sources and including catfish in pond polycultures.

Testing Whether Camera Presence Influences Habitat Specific Predation Pressure on Artificial Shorebird Nests in the Arctic

When monitoring the breeding ecology of birds, the causes and times of nest failure can be difficult to determine. Cameras placed near nests allow for accurate monitoring of nest fate, but their presence may increase the risk of predation by attracting predators, leading to biased results. The relative influence of cameras on nest predation risk may also depend on habitat because predator numbers or behaviour can change in response to the availability or accessibility of nests. We evaluated the impact of camera presence on the predation rate of artificial nests placed within mesic tundra habitats used by Arctic-breeding shorebirds. We deployed 94 artificial nests, half with cameras and half without, during the shorebird-nesting season of 2015 in the East Bay Migratory Bird Sanctuary, Nunavut. Artificial nests were distributed evenly across sedge meadow and supratidal habitats typically used by nesting shorebirds. We used the Cox proportional hazards model to assess differential nest survival in relation to camera presence, habitat type, placement date, and all potential interactions. Artificial nests with cameras did not experience higher predation risk than those without cameras. Predation risk of artificial nests was related to an interaction between habitat type and placement date. Nests deployed in sedge meadows and in supratidal habitats later in the season were subject to a higher risk of predation than those deployed in supratidal habitats early in the season. These differences in predation risk are likely driven by the foraging behaviour of Arctic fox (Vulpes lagopus), a species that accounted for 81% of observed predation events in this study. Arctic fox prey primarily on Arvicoline prey and goose eggs at this site and take shorebird nests opportunistically, perhaps more often later in the season when their preferred prey becomes scarcer. This study demonstrates that, at this site, cameras used for nest monitoring do not influence predation risk. Evaluating the impact of cameras on predation risk is critical prior to their use, as individual study areas may differ in terms of predator species and behaviour.

Effects of artificial light at night and predator cues on foraging and predator avoidance in the keystone inshore mollusc Concholepas concholepas.

The growth of Artificial Light At Night (ALAN) is potentially having widespread effects on terrestrial and coastal habitats. In this study we addressed both the individual effects of ALAN, as well as its combined effect with predation risk on the behaviour of Concholepas concholepas, a fishery resource and a keystone species in the southeastern Pacific coast. We measured the influence of ALAN and predation risk on this mollusc's feeding rate, use of refuge for light and crawling out of water behaviour. These behavioural responses were studied using light intensities that mimicked levels that had been recorded in coastal habitat exposed to ALAN. Cues were from two species known to prey on C.concholepas during its early ontogeny: the crab Acanthocyclus hassleri and the seastar Heliaster helianthus. The feeding rates of C.concholepas were 3-4 times higher in darkness and in the absence of predator cues. In contrast, ALAN-exposed C.concholepas showed lower feeding activity and were more likely to be in a refuge than those exposed to control conditions. In the presence of olfactory predator cues, and regardless of light treatment, C.concholepas tended to crawl-out of the waterline. We provide evidence to support the hypothesis that exposure to either ALAN or predation risk can alter the feeding behaviour of C.concholepas. However, predator cue recognition in C.concholepas was not affected by ALAN in situations where ALAN and predator cues were both present: C.concholepas continued to forage when predation risk was low, i.e., in darkness and away from predator cues. Whilst this response means that ALAN may not lead to increased predation mortality in C.concholepas, it will reduce feeding activity in this naturally nocturnal species in the absence of dark refugia. Such results may have implications for the long-term health, productivity and sustainability of this keystone species.