Challenges of Large Carnivore Conservation: Sloth Bear Attacks in Sri Lanka

Sloth bear (Melursus ursinus) attacks in Sri Lanka present a major challenge to their conservation as human populations grow and compete with bears for space and resources. Bear attacks on humans predominantly affect the rural poor and seem to be increasing in frequency. In 2004, we conducted the first island-wide survey of bear attacks in Sri Lanka. Our main goals were to 1) describe where and when attacks occurred, 2) describe the characteristics and outcome of bear attacks, and 3) evaluate the influence of human group size on the severity of bear attacks. We interviewed 271 individuals attacked by sloth bears between 1938 and 2004. Sloth bears rarely entered village compounds, damaged property, or raided crops; conflicts predominantly involved attacks on people in forests. Most sloth bear attacks took place during daylight hours (0900-1600 h) in the dry season, when humans were likely to engage in forest activities such as honey gathering. Most attacks (80 %) occurred when humans and bears surprised each other at close proximity (<10 m). Most (84 %) victims carried a weapon but 55 % said the attack was too sudden to effectively use the weapon in self-defense. Human injuries included lacerations and puncture wounds, broken limbs, skull fractures, and the loss of scalps, eyes, or other parts of the face. Almost all major injuries resulted from bites. In 61 attacks bears were wounded and in 39 attacks bears were killed. The severity of human injuries depended on human group size; solitary humans experienced more severe injuries than expected, suggesting that the presence of other humans may moderate the bear’s aggression and motivate it to flee. Widespread fear of sloth bears poses a significant challenge to modifying ineffective human responses to bear encounters (e.g., fleeing). Conservation outreach could emphasize that greater human safety may be achieved from remaining in groups and using extreme caution around thickets and rock outcrops likely to be used by bears.     

The trigger for barn owl (Tyto alba) attack is the onset of stopping or progressing of the prey

Aiming at the question of whether barn owls favor to strike a moving or a stationary prey, we scrutinized the timing of launching 50 attacks of five barn owls (10 attacks/owl) in a captive environment. Attacks on stationary voles outnumbered attacks on moving voles, but this could merely reflect the higher portion of time during which voles were stationary. Notably, the majority of attacks (85-100%) were launched in less than 2 s (measured at accuracy of 0.04 s) after the voles ceased to progress or initiated progression. Therefore, the trigger for launching an attack is the transition of the prey from locomotion to still posture or vice versa.     

New Cases of Intergroup Violence Among Chimpanzees in Gombe National Park,Tanzania

Despite considerable attention to chimpanzee intergroup violence, the number of observed cases remains small. We report 4 cases of intergroup violence that occurred in Gombe National Park, Tanzania, between 1993 and 2002. We observed (3 cases) or inferred (1 case) males from the Kasekela community to attack members of their 2 neighboring communities: Mitumba and Kalande. In 1993, Kasekela males killed and ate a female infant from Mitumba. In 1998, Kasekela males captured 2 infants (sex unknown) from Kalande, one of which escaped and the other was killed and eaten. Also in 1998, Kasekela males attacked an adolescent male from Kalande. The victim was alive but severely injured by the end of the attack. The intensity and duration of the attack are comparable to other attacks that resulted in fatal injuries. In 2002, observers found the body of an adolescent male from Mitumba following an incursion by Kasekela males into the area. The injuries inflicted on the Mitumba male together with circumstantial evidence suggest that Kasekela males killed him. The attacks support the view that intergroup violence is a persistent feature of chimpanzee societies and that the primary benefit attackers gain from them is reduced competition for resources.     

Detection distance influences escape behaviour in two parids, Parus major and P. caeruleus

When birds are attacked by aerial predators they should benefit by adjusting their escape to the prevailing attack situation. One important factor likely to affect escape decisions of prey, to our knowledge not previously studied, is the distance at which the attacking predator is detected. We investigated if great tits Parus major and blue tits P. caeruleus alter their escape behaviour to two different detection distances (2.3 m and 1m) by simulating surprise attacks using a predator model. Both species used the information about detection distance when escaping by increasing the escape angle at the shorter detection distance. In addition, blue tits adjusted to the shorter detection distance by dodging sideways more frequently. Great tits escaped initially steeper and faster than blue tits, whereas blue tits increased escape angle and speed more than great tits along the measured distance after taking wing.     

Stable Isotope Evidence of Puma concolor (Felidae) Feeding Patterns in Agricultural Landscapes in Southeastern Brazil

We evaluated puma (Puma concolor) feeding patterns in southeastern Brazilian agricultural landscapes using carbon and nitrogen stable isotope analyses of hair collected from fecal samples (N = 64). We classified the samples into three groups: feeding patterns based on forest remnants, on the agricultural matrix or both. We observed a predominance of consumption of C₃ prey (~47% of individuals) in the area with the highest proportion of forest coverage. Conversely, C₄ prey were highly consumed (~40% of individuals) where the agricultural matrix was predominant. The δ¹³C values for pumas in both areas indicated that their food resources come from both forest remnants and the agricultural matrix and that some individuals preferentially consumed C₄ prey, indicating that food resources from the agricultural matrix make up most of their diet (~46% of prey individuals). The wide range of puma's δ¹⁵N values in both areas indicated a diet based on different types of prey. However, the C₄ group had higher values, indicating that both pumas and their prey feed on enriched resources from the agricultural matrix. The results confirm the high behavioral plasticity of pumas in using highly anthropogenic habitats. The stable isotope analyses conducted in this study yielded new information on large carnivore trophic ecology that might be useful in the development of new conservation strategies in disturbed areas.     

Foraging behavior of the scale-eater Plecodus straeleni (Cichlidae,Teleostei) in Lake Tanganyika,Africa

Synopsis Sixty-nine individuals of Plecodus straeleni were followed for 1 h each in the field with the aid of SCUBA, and time budgets, hunting techniques and prey selection were investigated in relation to sex and body size. The time of cruising in midwater and on the substrate amounted to 3/4 of the total time. The rest of the time was mainly spent on five hunting techniques named pursuing, waiting, mingling, aiming and stealthy approaching. Pursuing (following a flying prey at high speed) was frequently used by adults, especially males, mainly to attack the spiny eel Afromastacembelus moorii. Waiting (keeping motionless on the substrate, waiting for a known prey) was used by some adult females when they tried to steal eggs of the mouthbrooder Cyathopharynx furcifer on the bower and by adult males when they targeted an eel having hidden under a rock. Mingling (mixing in a school of prey to attack school members) was a favorite tactic of subadults to attack plankton-feeders. Aiming (directing the head to a target fish for a moment) commonly occurred when both adults and subadults attacked solitary fishes. In stealthy approaching, the scale-eater approached an unwary prey from behind or sideway. Attacks by these hunting techniques amounted to 97% of the total attacks, which were made on 38 cichlid species and 7 non-cichlid species. Hunting techniques and prey preference varied not only with sex and size but even among consexuals of similar sizes. A number of individuals successively attacked only one or a few prey species in 1 h. Food specialization among individuals was attributed to their learning of the behavior and life style of preferred prey species.     

Relationships Between Attack and Escape Rates, Cannibalism, and Intraguild Predation in Larvae of Two Predatory Ladybirds

We compared incidences of cannibalism and intraguild (IG) predation (IGP) and quantified attack and escape rates—mechanisms which possibly account for the difference in incidences of these interactions—in laboratory experiments with Harmonia axyridis and Coccinella septempunctata. There was a tendency for H. axyridis to act as an IG predator and C. septempunctata as an IG prey. Cannibalism was also often observed in both species. The incidences of both IGP and cannibalism were different between the species. The average attack rates of C. septempunctata were less than 20%, but those of the more aggressive H. axyridis exceeded 50%. Larvae of both species attacked conspecifics and heterospecifics H. axyridis larvae successfully escaped when attacked by both conspecifics and by heterospecifics, while larvae of C. septempunctata escaped from attacks of conspecifics but not from those of heterospecifics. Thus the aggressive behavior of H. axyridis, in particular, of the third and fourth instars, negatively affects the larval survival of C. septempunctata. It may contribute to the dominance of H. axyridis in ladybird assemblages and its displacement of other ladybird species in several places in the world.     

Re-examining safety in numbers: interactions between risk dilution and collective detection depend upon predator targeting behaviour

Many studies document that individuals visually scan for predators less frequently when in the safety of larger groups. This widely replicated effect has generally been explained in terms of distinct predator detection and risk-dilution effects. We show that a strict distinction between detection and dilution disappears when information about attacks is imperfectly shared (as it is in reality). Furthermore, dilution and detection effects change depending on when during an attack the predator targets a particular prey individual for pursuit. Realistic detection and dilution effects probably interact with each other and also with the targeting behaviour of predators. Instead of considering detection and dilution effects on vigilance, it may be more profitable to consider each prey''s probability of being targeted during an attack and its probability of escaping if attacked. This perspective emphasizes that a full understanding of safety in numbers requires an understanding of predator targeting strategies.     

Nuisance Ecology: Do Scavenging Condors Exact Foraging Costs on Pumas in Patagonia?

Predation risk describes the energetic cost an animal suffers when making a trade off between maximizing energy intake and minimizing threats to its survival. We tested whether Andean condors (Vultur gryphus) influenced the foraging behaviors of a top predator in Patagonia, the puma (Puma concolor), in ways comparable to direct risks of predation for prey to address three questions: 1) Do condors exact a foraging cost on pumas?; 2) If so, do pumas exhibit behaviors indicative of these risks?; and 3) Do pumas display predictable behaviors associated with prey species foraging in risky environments? Using GPS location data, we located 433 kill sites of 9 pumas and quantified their kill rates. Based upon time pumas spent at a carcass, we quantified handling time. Pumas abandoned >10% of edible meat at 133 of 266 large carcasses after a single night, and did so most often in open grasslands where their carcasses were easily detected by condors. Our data suggested that condors exacted foraging costs on pumas by significantly decreasing puma handling times at carcasses, and that pumas increased their kill rates by 50% relative to those reported for North America to compensate for these losses. Finally, we determined that the relative risks of detection and associated harassment by condors, rather than prey densities, explained puma “giving up times” (GUTs) across structurally variable risk classes in the study area, and that, like many prey species, pumas disproportionately hunted in high-risk, high-resource reward areas.     

Vessel collision injuries on live humpback whales,Megaptera novaeangliae,in the southern Gulf of Maine

North Atlantic humpback whales (Megaptera novaeangliae) in the Gulf of Maine overlap with both recreational and commercial vessel activity. Vessel strikes are one source of anthropogenic impact that has the potential to inhibit the recovery of this protected species. There are currently no regulations or guidelines specifically devised to reduce the likelihood of collisions for vessels transiting in the vicinity of humpback whales, except for vessels actively engaged in whale watching. To understand interactions between vessels and humpback whales better, we analyzed injuries on 624 individuals photographed in the southern Gulf of Maine from 2004 to 2013. Multiple reviewers evaluated 210,733 photos for five categories of injury consistent with a vessel strike. In total, 14.7% (n = 92) of individuals photographed showed injuries consistent with one or more vessel strikes. These results likely underestimate vessel collision rates and impacts because multiple events, events resulting in mortality, and those that involved only blunt force trauma could not be detected. Nevertheless, our results indicate that vessel strikes are underreported and that healing is dependent on the severity and location of the injury. We recommend that a management strategy be developed for all classes of vessels transiting in the vicinity of whales.     

Living in the fast lane: effects of cost of locomotion on foraging behaviour in juvenile Atlantic salmon

Stream-dwelling, juvenile Atlantic salmon, Salmo salar L., feed mainly on drifting invertebrates, usually by swimming upstream from a stationary position to intercept individual prey items. Laboratory experiments tested the prediction that individual salmon should reduce the distance over which they would travel (attack distance) to intercept drifting food items as the energy cost of swimming increases with increasing current velocity. Attack distance varied inversely with current velocity as expected. The fish's average speed of upstream movement relative to the substrate remained constant and the duration of individual attacks therefore declined as current velocity increased. Calculated reaction distances and a second ecperiment using tethered prey drifting at speeds independent of current velocity confirmed that these relationships were due to fish actually delaying attacks on perceived prey for longer periods as current velocity increased. Using estimated metabolic rates for burst swimming, it appears that energy expenditure per attack varies little with current velocity. Therefore, by reducing their reaction and attack distances in response to increasing current velocity, the fish reduced their energy cost of travel per attack.     

Occupational Injury Risk Assessment Using Injury Severity Odds Ratios: Male Falls from Heights in the Danish Construction Industry, 1993-1999

To allow for an improved targeted approach to occupational injury research and prevention, detailed risk analyses of fatal, serious, and minor occupational injuries were completed with a focus on male falls from heights in construction. Reported lost-time injuries in Denmark (1993 to 1999) were analyzed for proportions, relative rates, and an injury severity odds ratio to assess relative hazards and reporting. Different types of injury risks, such as elevation falls through surfaces, were identified by contrasting fatal, serious and minor injuries. Trade-specific analyses provided evidence that the carpentry-trade group merits increased attention, as this group has excessively high proportions, rates and hazards for falls from heights, compared to the entire construction industry. Age-specific analyses of workers aged 20 to 59 revealed that the rates of serious-injury falls from heights increase with increasing age. This relationship was inverted for elevation fall injuries from roof surfaces. A focus on construction and falls from heights is necessary not only in terms of fatal injuries, but also for serious injuries. The use of an injury severity odds ratio to assess relative hazards and reporting is a useful supplement to proportions and injury rates in contributing to more precise targeting of subgroups for primary injury prevention.     

Dead or Alive? Factors Affecting the Survival of Victims during Attacks by Saltwater Crocodiles (Crocodylus porosus) in Australia

Conflicts between humans and crocodilians are a widespread conservation challenge and the number of crocodile attacks is increasing worldwide. We identified the factors that most effectively decide whether a victim is injured or killed in a crocodile attack by fitting generalized linear models to a 42-year dataset of 87 attacks (27 fatal and 60 non-fatal) by saltwater crocodiles (Crocodylus porosus) in Australia. The models showed that the most influential factors were the difference in body mass between crocodile and victim, and the position of victim in relation to the water at the time of an attack. In-water position (for diving, swimming, and wading) had a higher risk than on-water (boating) or on-land (fishing, and hunting near the water''s edge) positions. In the in-water position a 75 kg person would have a relatively high probability of survival (0.81) if attacked by a 300 cm crocodile, but the probability becomes much lower (0.17) with a 400 cm crocodile. If attacked by a crocodile larger than 450 cm, the survival probability would be extremely low (<0.05) regardless of the victim’s size. These results indicate that the main cause of death during a crocodile attack is drowning and larger crocodiles can drag a victim more easily into deeper water. A higher risk associated with a larger crocodile in relation to victim’s size is highlighted by children’s vulnerability to fatal attacks. Since the first recently recorded fatal attack involving a child in 2006, six out of nine fatal attacks (66.7%) involved children, and the average body size of crocodiles responsible for these fatal attacks was considerably smaller (384 cm, 223 kg) than that of crocodiles that killed adults (450 cm, 324 kg) during the same period (2006–2014). These results suggest that culling programs targeting larger crocodiles may not be an effective management option to improve safety for children.     

The effect of zooplankton abundance on feeding behaviour and prey size selection in Atlantic salmon,Salmo salar,alevins1

In an experiment on the effect of zooplankton density on feeding behaviour and prey size selection in Atlantic salmon (Salmo salar) alevins, total behavioural activity (feeding, social, ambiguous) was positively related to prey abundance up to a density of 350 items 1^?1, after which activity peaked. Feeding error (missed attacks and/or rejected ingestions) increased with prey density. The likelihood that an alevin would attack an item upon which it had binocularly fixed (no. bites/no. visual fixes) peaked at densities of 270 items 1^?1 and then declined. Feeding success (no. ingestions per bite or per fixation) also peaked and then declined. Changes in success were reflected in total number of items found in the gut. At high prey abundance (608 items 1^?1) only 0.5 – 0.9 mm copepods were preferred components of alevin diets. Over all prey densities, preferred sizes of cladocerans and copepods did not overlap. These results may reflect a perceptual constraint (at high zooplankton densities) on alevin feeding behaviour.     

Local prey vulnerability increases with multiple attacks by a predator

Theory and empirical evidence suggest that predator activity makes prey more wary and less vulnerable to predation. However if at least some prey in the population are energetically or spatially constrained, then predators may eventually increase local prey vulnerability because of the cumulative costs of anti‐predation behaviour. We tested whether repeated attacks by a predator might increase prey vulnerability in a system where redshanks on a saltmarsh are attacked regularly by sparrowhawks from adjacent woodland. Cumulative attack number led to a reduction in redshank numbers and flock size (but had no effect on how close redshanks fed to predator‐concealing cover) because some redshanks moved to safer but less profitable habitats, leaving smaller flocks on the saltmarsh. This effect held even though numbers of redshank on the saltmarsh increased with time of day. As a result of the change in flock size, predicted attack‐success increased up to 1.6‐fold for the sparrowhawk, while individual risk of capture for the redshank increased up to 4.5‐fold among those individuals remaining on the saltmarsh. The effect did not arise simply because hawks were more likely to attack smaller flocks because attack rate was not dependent on flock size or abundance. Our data demonstrate that when some individual prey are constrained in their ability to feed on alternative, safer foraging sites, their vulnerability to predation increases as predator attacks accumulate, although those, presumably better quality individuals that leave the immediate risky area will have lower vulnerability, so that the mean vulnerability across the entire population may not have changed substantially. This suggests that the selective benefits of multiple low‐cost attacks by predators on prey could potentially lead to 1) locally heightened trait‐mediated interactions, 2) locally reduced interference among competing predators, and 3) the evolution of active prey manipulation by predators.     

The effect of stride length on the dynamics of barefoot and shod running

A number of interventions and technique changes have been proposed to attempt to improve performance and reduce the number of running related injuries. Running shoes, barefoot running and alterations in spatio-temporal parameters (stride frequency and stride length) have been associated with significant kinematic and kinetic changes, which may have implications for performance and injury prevention. However, because footwear interventions have been shown to also affect spatio-temporal parameters, there is uncertainty regarding the origin of the kinematic and kinetic alterations. Therefore, the purpose of this study was to independently evaluate the effects of shoes and changes in stride length on lower extremity kinetics. Eleven individuals ran over-ground at stride lengths ±5 and 10% of their preferred stride length, in both the barefoot and shod condition. Three-dimensional motion capture and force plate data were captured synchronously and used to compute lower extremity joint moments. We found a significant main effect of stride length on anterior–posterior and vertical GRFs, and sagittal plane knee and ankle moments in both barefoot and shod running. When subjects ran at identical stride lengths in the barefoot and shod conditions we did not observe differences for any of the kinetic variables that were measured. These findings suggest that barefoot running triggers a decrease in stride length, which could lead to a decrease in GRFs and sagittal plane joint moments. When evaluating barefoot running as a potential option to reduce injury, it is important to consider the associated change in stride length.     

Fatal attacks by American black bear on people: 1900–2009

At least 63 people were killed in 59 incidents by non-captive black bear (Ursus americanus) during 1900–2009. Fatal black bear attacks occurred in Canada and Alaska (n = 49) and in the lower 48 states (n = 14). There were 3.5 times as many fatal attacks in Canada and Alaska but only 1.75 times as many black bears, and much less human contact for black bears in Canada and Alaska. There was a weak positive correlation (r_s = 0.56, P ≤ 0.000) between the estimated size of a bear population within a given jurisdiction and the number of fatal black bear attacks. Some jurisdictions had no fatal black bear attacks but had large estimated black bear populations. Of fatal attacks, 86% (54 of 63, 1.08/yr) occurred between 1960 and 2009. There was positive linear relationship between the number of fatal black bear attacks per decade and human population size in the United States and Canada per decade (r² = 0.92, β = 0.000, P ≤ 0.001). Of fatal attacks, 91% (49 of 54) occurred on parties of 1 or 2 persons. In 38% (15 of 40) of incidents, peoples' food or garbage probably influenced the bear being in the attack location. We judged that the bear involved acted as a predator in 88% (49 of 56) of fatal incidents. Adult (n = 23) or subadult (n = 10) male bears were involved in 92% (33 of 36) of fatal predatory incidents, reflecting biological and behavioral differences between male and female bears. That most fatal black bear attacks were predatory and were carried out by 1 bear shows that females with young are not the most dangerous black bears. As a result of our research agencies managing black bear can more accurately understand the risk of being killed by a black bear, and can communicate this to the public. With training, people can learn to recognize the behaviors of a bear considering them as prey and can act to deter predation. © 2011 The Wildlife Society.     

Levels of diurnal predation on a school of flat-iron herring,Harengula thrissina

Synopsis The incidence of diurnal predation (0800–1600h) on schools of several hundred thousand adult flat-iron herring,Harengula thrissina, was quantified. Nine species of piscine predators perpetrated 653 attacks and 158 captures during 42.5 h of observation. Four predators: cabrilla,Mycteroperca rosacea, cornetfish,Fistularia commersonii, green jack,Caranx caballus, and black skipjack,Euthynnus lineatus, were responsible for 92% of the attacks and 96% of the successes. Among these predators attack rates (attacks × time^–1) and success rates (successes × attacks^–1) varied with respect to time of day, although all predators were active throughout the day. As a consequence, the herring school experienced fairly homogeneous attack and success rates. These rates were estimated as roughly half the crepuscular attack rates but they were sustained over a much longer period. Piscivorous predators, particularly those species frequently found in association with schooling prey, may be focusing their attacks on opportunities, not specific times of day and/or light levels. More direct information needs to be gathered on diurnal as well as crepuscular attack and success rates in order to assess the impact that piscine predators have on schooling prey.     

Context-dependent running speed in funnel-web spiders from divergent populations

1.  Locomotor performance can influence individual fitness through several ecological contexts, such as prey capture and predator escape. One means of determining which contexts act as significant selective forces on running speed is to quantify individual speed in each context. The underlying hypothesis is that animals will exhibit their highest speeds in contexts most crucial to fitness.
2.  We measured running speeds in three ecological contexts (prey capture, fleeing predators and territory defence) in lab-reared offspring of the funnel-web spider Agelenopsis aperta collected from two arid grassland and two riparian populations. Arid populations experience little predation pressure, are prey limited, and are highly territorial; riparian populations experience high predation, have high prey availability, and are less territorial in nature.
3.  The offspring of arid individuals exhibited their highest burst speeds in territory defence, and ran more slowly in response to predator threats. The offspring of riparian populations, however, ran fastest when responding to predatory threats and displayed lower velocities in prey capture and territory defence. Thus, our findings support the hypothesis that A. aperta are selected to exhibit their highest speeds in contexts most important to their fitness.
4.  Contextual use of running speed can differ among conspecific populations experiencing differing selective forces on locomotion.     

Northern bats, Eptesicus nilssonii, use vision but not flutter-detection when searching for prey in clutter

We investigated the detection cues used by the aerial-hawking bat Eptesicus nilssonii foraging in a cluttered environment. The bats can detect and attack rapidly moving targets within the clutter, i.e. below grass panicles, by using prey motion as a cue. Stationary objects are attacked only above the grass, but still within the clutter overlap zone. To test if the bats were guided by flutter from moth wings or by vision when searching for stationary targets, they were presented with male ghost swifts mounted on top of steel wires. There was no difference in attack frequency on live, fluttering moths compared to dead and spread ones. However, when comparing white and dark moths, we found a significantly higher attack frequency on white ones. As the attacks always were guided by echolocation calls, we hypothesize that northern bats, at least in the initial search phase, use visual cues as a complement to detect stationary ghost swifts.