Studies on Anoplotaenia dasyuri beddard, 1911 (Cestoda: Taeniidae), a parasite of the Tasmanian devil: Life-cycle and epidemiology

Anoplotaenia dasyuri was found commonly in Tasmanian devils (Sarcophilus harrisi) and was also found in a tiger cat (Dasyurus maculatus), in feral cats (Felis catus) and in rural dogs in Tasmania. The Bennett's wallaby (Macropus rufogriseus) was a suitable experimental intermediate host, metacestodes localising in the heart, lungs and skeletal muscles. Natural infections were detected in pademelons (Thylogale billardieri) and potoroos (Potorous apicalis) as well as in M. rufogriseus. Metacestodes from wallabies developed into gravid worms when fed to Tasmanians devils and to a tiger cat but failed to develop in dogs. The development in Tasmanian devils is described.     

Source Odor,Intensity, and Exposure Pattern Affect Antipredatory Responses in the Subterranean Rodent Ctenomys talarum

Predation is a strong selective force, and prey species may show specific adaptations that allow recognition, avoidance, and defense against predators. Facing a situation of predatory risk, anxiety constitutes a reaction of adaptive value, allowing to evaluate the potential risk of this encounter as well as to generate a physiological and behavioral response. Previous studies in the subterranean rodent Ctenomys talarum revealed that exposure to predator odors (urine or fur) generates an anxiety state and induces behavioral changes. However, no differences between the responses generated by both odor sources were observed, although fur odors may indicate a higher level of predatory immanence. Therefore, the aim of this study was to evaluate the behavioral and physiological responses of C. talarum to different intensities of predator odors (urine and fur) and to the repeated exposition to the same odorous stimulus. When comparing the highest behavioral effects elicited by both predatory odors on C. talarum, our study supports the assumption that fur odors are more anxiogenic than urine, while the former provoked significant changes in the distance traveled, the number of arm entries and time in transparent arms in the elevated plus maze; cat urine only caused slight changes on those behavioral parameters. Furthermore, we also found that the intensity of natural predator odor presented to tuco‐tucos has a role on the appearance of defensive behaviors, although an amount‐dependent relationship between predator odor and anxiety levels was not observed. Finally, while individuals exposed for 1 day to fur odor displayed an evident anxiety state, those exposed repeatedly for 5 consecutive days did not differ with the control group in their behavioral response, indicating a clear habituation to the predatory cue. In our intensity and habituation experiments, we did not find differences in the measured physiological parameters among control individuals, exposed to different cues intensity (urine and fur odor) and exposed only once or for 5 days to fur odor. These results provide valuable evidence that the types of predatory odor, along with the frequency of exposition, are important determinants of the appearance, strength, and extinction of defensive behaviors in the subterranean rodent C. talarum.     

Chronic exposure of cat odor enhances aggression,urinary attractiveness and sex pheromones of mice

To test whether predator odor exposure negatively affects the behavior of prey, we exposed three groups of male house mice (Mus musculus) to the odors of cat (Felis catus) urine, rabbit (Oryctolagus cuniculus) urine and water (control), respectively, for consecutive 58 days and investigated how the treatments affected the response, aggressiveness, dominance, urinary attractiveness to females and pheromone composition of male mice. Compared to mice exposed to rabbit urine or water, those exposed to cat odor did not show any response habituation to the cat odor and became more aggressive, increased mark urine production and were more attractive to females when the latter were tested with their urine. Furthermore, gas chromatography coupled with mass spectrometry analysis revealed coincident elevations of the well-known male pheromones, E,E-α-farnesene, E-β-farnesene, R,R-dehydro-exo-brevicomin or S-2-sec-butyl-dihydrothiazole. In addition, rabbit urine exposure increased urinary attractiveness to females and pheromonal levels of the males in comparison with the mice exposed to water. This could be related to olfactory enrichment of heterospecific chemosignals, suggesting that predator odors were more beneficial. In light of these anti-intuitional findings in the chemical interaction between cats and mice, we conclude that predator odor affects prey more profoundly than previously believed and that its impact may not always be negative.     

Predator pheromone elicits a temporally dependent non-consumptive effect in prey

1. The influence of predator cues on the behaviour of prey is well supported in the literature; however, a clear understanding of how predator cues affect prey in variable environmental conditions and over longer time scales is needed to better understand the underlying mechanisms. Here, we measure how predator odors affect herbivore colonization, abundance, oviposition, and plant damage across two growing seasons.
2. The study system consisted of Leptinotarsa decemlineata (Colorado potato beetle) as prey, and the aggregation pheromone of live Podisus maculiventris (spined soldier bug) as the predator cue in a potato field.
3. In 2016, the amount of feeding damage by early beetle colonists was lower in predator odor-treated plots, reducing plant damage by 22%. Larval abundance was also reduced in treated plots in 2016. Beetle abundance and damage in 2017 was similar in the treatment and control plots. Two mechanisms were investigated to better understand why prey response to the predator odor treatment weakened over the first season, including changes in predator odor cue strength and prey habituation. Predator odor cue strength emerged as a likely explanation, as dispensers, which released a synthetic predator pheromone over the entire season, reduced the probability of finding damage more consistently than the live predator treatment.
4. These results suggest that temporal patterns of predator cue release and strength may drive prey response across the season, underscoring the importance of cue release-rate and consistency in both species interactions and for the future application of modifying insect behaviour using non-consumptive effects in agricultural systems.

     

Prevalence of Salmonella in fecal samples of western grey kangaroos (Macropus fuliginosus)

This is the first extensive study of the prevalence of naturally acquired Salmonella infection in wild-caught kangaroos in Australia. Given the close association between kangaroos, livestock, and humans and the growing popularity of kangaroo meat, it is important to identify epidemiologic factors associated with infection in these marsupials in order to minimize the risk of Salmonella transmission. The overall prevalence of fecal Salmonella in 645 western grey kangaroos (Macropus fuliginosus) sampled across 10 locations in Western Australia was 3.6% (95% CI: 2.3-5.3). Seven Salmonella serovars were identified including Salmonella enterica serovar Muenchen, Kiambu, Rubislaw, Lindern, Champaign, Saintpaul and II 42:g,t:-. Prevalence was significantly associated with rainfall (P<0.05) and was highest in the April-June quarter (P<0.05). There was no association between age or sex and the prevalence of Salmonella in fecal samples. Our results suggest that, while kangaroos are infected with Salmonella in their natural habitat, infection is less common than in hand-reared joeys, pet kangaroos, and macropods raised in captivity. Care should be taken to maintain hygiene during the evisceration, processing, and handling of kangaroos and to adequately cook kangaroo meat prior to consumption to reduce the risk of salmonellosis.     

Predation by red foxes limits recruitment in populations of eastern grey kangaroos

We investigated the impact of red fox (Vulpes vulpes Linnaeus 1758) predation on juvenile eastern grey kangaroos (Macropus giganteus Shaw 1790) using a replicated predator removal experiment. In two sites in Namadgi National Park, south‐eastern Australia, a persistent 1080 poisoning campaign over 18 months reduced fox density by more than 85%, and to less than 10% of the fox density in two other sites with no fox baiting. Changes in the mother : young ratios and densities of kangaroo populations were monitored twice monthly along 2‐km transects in each site from July 1993 to February 1995. Compared to nonremoval sites, where foxes were controlled, 25–40% more females retained juveniles over the period when these young became emergent from the pouch. This higher survival of emergent pouch young resulted in a significantly higher proportion of juveniles in kangaroo populations at fox control sites, which resulted in a significantly higher annual growth rate. We conclude that predation upon juveniles is an important limiting factor for kangaroo populations in Namadgi NP.     

Age‐related variation in the trophic characteristics of a marsupial carnivore,the Tasmanian devil Sarcophilus harrisii

Age‐related changes in diet have implications for competitive interactions and for predator–prey dynamics, affecting individuals and groups at different life stages. To quantify patterns of variation and ontogenetic change in the diets of Tasmanian devils Sarcophilus harrisii, a threatened marsupial carnivore, we analyzed variation in the stable isotope composition of whisker tissue samples taken from 91 individual devils from Wilmot, Tasmania from December 2014 to February 2017. Both δ¹³C and δ¹⁵N decreased with increasing age in weaned Tasmanian devils, indicating that as they age devils rely less on small mammals and birds, and more on large herbivores. Devils <12 months old had broader group isotopic niches, as estimated by Bayesian standard ellipses (SEA_B mode = 1.042) than devils from 12 to 23 months old (mode = 0.541) and devils ≥24 months old (mode = 0.532). Devils <24 months old had broader individual isotopic niches (SEA_B mode range 0.492–1.083) than devils ≥24 months old (mode range 0.092–0.240). A decrease in δ¹⁵N from the older whisker sections to the more recently grown sections in devils <24 months old likely reflects the period of weaning in this species, as this pattern was not observed in devils ≥24 months old. Our data reveal changes in the isotopic composition of devil whiskers with increasing age, accompanied by a reduction in isotopic variation both among population age classes and within individuals, reflecting the effect of weaning in early life, and a likely shift from an initially diverse diet of small mammals, birds, and invertebrates towards increasing consumption of larger herbivores in adulthood.     

Effectiveness of odour repellents on red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) and roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>): a field test

Chemical repellents are promoted as a method to reduce ungulate–vehicle collisions and ungulate browsing damages to agricultural and forestry resources. We tested the effectiveness of two odour repellents (Mota FL and Wolf Urine) on the foraging behaviour and area avoidance of free-ranging roe deer (Capreolus capreolus) and red deer (Cervus elaphus). The effects of the repellents were assessed by comparing deer visitation rates to sand arenas before and after application of repellents and visitation rates to control arenas. Neither of the tested products reduced deer visitation rates. Rapid habituation to olfactory stimuli and lack of sensitivity to predator odours may explain the ineffectiveness of the repellents to alter the behaviour of the deer. The results indicate that the tested products have no effects on roe deer and red deer behaviour and suggest that the effectiveness of the chemical area repellents as a measure to reduce deer–vehicle collision risk and browsing damages is questionable.     

Nutrient digestibility and fecal characteristics are different among captive exotic felids fed a beef‐based raw diet

Nutrient digestibility has not been well characterized in exotic felids. The objective of this experiment was to evaluate differences in nutrient digestibility and fecal characteristics in five large exotic captive felid species, including bobcats, jaguars, cheetahs, Indochinese tigers, and Siberian tigers. All animals were individually housed and adapted to a beef‐based raw diet (Nebraska Brand^® Special Beef Feline, North Platte, NE) for 16 d. Total fecal collections were conducted from days 17 to 20. Fecal samples were weighed and scored on collection. Diet and fecal samples were evaluated for dry matter, organic matter, protein, fat, and energy to determine total tract digestibility. Fresh fecal samples were collected to determine fecal pH, ammonia, phenol, indole, short‐chain fatty acid, and branched‐chain fatty acid concentrations. Fecal scores were greater (P<0.01) in Indochinese tigers when compared with all other species, and cheetahs had greater (P<0.01) fecal scores than jaguars and bobcats. Fat digestibility was greater (P<0.01) in Siberian tigers, Indochinese tigers, and bobcats (96%) compared with cheetahs and jaguars (94%). Digestible energy was greater (P<0.05) in bobcats and Indochinese tigers at 93.5 and 92.9%, respectively, compared with cheetahs and jaguars, 91.6%. Fecal pH was greater (P<0.01) in bobcats compared with all other species evaluated. Indole concentrations were greater (P<0.05) in cheetahs and jaguars compared with bobcats and Indochinese tigers. Fecal ammonia concentrations were increased (P<0.05) in cheetahs compared with all other species. The beef‐based raw diet was highly digestible; however, differences in fat and digestible energy suggest that species should be considered when determining caloric needs of exotic felids. Zoo Biol 27:126–136, 2008. © 2008 Wiley‐Liss, Inc.     

Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse‐ or beef‐based diets: use of the domestic cat as a model for exotic felids

The objective of this study was to determine the effects of feeding commercially available beef‐ and horse‐based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef‐based diet (57% protein; 28% fat) and a horse‐based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse‐based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef‐based diet compared with the horse‐based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse‐based diet compared with the beef‐based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse‐based diet. Fecal total short‐chain fatty acid (SCFA), branched‐chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef‐based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data. Zoo Biol 29:432–448, 2010. © 2009 Wiley‐Liss, Inc.     

Managing predators: The influence of kangaroo rat antipredator displays on sidewinder rattlesnake hunting behavior

Upon sensing predators in their vicinity, many prey species perform antipredator displays that are thought to provide information to the predator that deters it from attacking (predator‐deterrent signals). These displays can be complex, incorporating a variety of signaling elements as well as direct physical harassment of the predator. Although the display behaviors in these communication systems are often well characterized, evidence of the efficacy of these displays in deterring predators is limited due to the challenges associated with studying free‐ranging predators. Here, we examine how the anti‐snake signals of the desert kangaroo rat (Dipodomys deserti) influence the ambush hunting behaviors of sidewinder rattlesnakes (Crotalus cerastes). We found that, although desert kangaroo rats incorporate a number of signal elements into their antipredator display, only sand kicking behavior was a significant factor in motivating sidewinder rattlesnakes to cease hunting: high rates of sand kicking led to early abandonment of ambush coils. These results indicate that anti‐snake displays of small mammals may be especially effective at mitigating the threat posed by rattlesnakes when those displays incorporate physical harassment as well as signaling.     

Hamsters Use Predator Odors as Indirect Cues of Predation Risk

Golden hamsters (Mesocricetus auratus) use olfactory cues to assess traits of conspecifics such as kinship, individual identity, and reproductive status. The environment, however, is full of a wide variety of other olfactory information such as signals emitted by some of the hamster’s primary predators. Given this, we hypothesized that hamsters use odors from predators as an indirect sign of increased predation risk in the environment. In addition, based on data that show that wild hamsters are diurnal while laboratory hamsters are nocturnal, we hypothesized that if golden hamsters did respond to the predator odors, perceived predator risk might influence daily activity patterns in hamsters. We tested male and female hamsters over 5 d with scent gland secretion from domestic ferrets (Mustela putorius furo) and compared their behavior to that observed when they were exposed to a clean arena. In response to the predator odor, subjects significantly decreased the amount of time active outside of their burrow, returned to their burrow more quickly, and spent less time near the predator odor than the clean control stimulus. These results strongly support our hypothesis that hamsters, like other species of small mammals, avoid predator odors. The results did not, however, support our second hypothesis that exposure to predator odors during the dark phase of the light cycle would elicit a switch to a more diurnal pattern of activity. More work is needed to understand how environmental cues and internal mechanisms interact to shape activity patterns.     

Olfactory predator recognition in the brown mouse lemur (Microcebus rufus) in Ranomafana National Park,Madagascar

Predator odors such as urine and feces are known to elicit antipredator behaviors in prey including avoidance, fear, and curiosity. We measured how wild brown mouse lemurs (Microcebus rufus) responded to odors of mammalian, avian, and snake predators as well as nonpredator controls. The first experiment took place under controlled conditions in a laboratory where we recorded the occurrence of four behavioral categories (ignore, curiosity, alert, and fear) in response to a single odor. Subjects exhibited behavioral change significantly more often in response to the predator than to control stimuli, but did not distinguish between familiar and unfamiliar predators. Mammalian predator urine and feces were most likely to elicit behavioral change. The owl was the only predator to never elicit behavioral change, possibly because owls do not provide relevant odor cues. A second experiment employing live traps in the forest found that neither predator nor control odors affected the likelihood of capture. Due to their longevity, odors do not provide accurate information of spatial and temporal risk, and while mouse lemurs may have initially hesitated to enter a trap, in the absence of additional information about risk, they may have eventually ignored the stimuli. This study found that brown mouse lemurs are able to distinguish between predator and nonpredator odors, and that risk assessment may be affected by the experience, as well as predator and sensory stimulus quality.     

Using Scent-Matching Dogs to Identify Individual Amur Tigers from Scats

Abstract: Scent-matching dogs have previously been used to identify caged individual Amur tigers (Panthera tigris altaica) by fecal material (scat), but this technique has not been tested in the wild. We tested the hypothesis that trained dogs can identify individual tigers by unique characteristics present in scat. To conduct this work, we used 5 dogs and 58 scats from 25 known individual tigers in independent trials. Dogs correctly selected matched test scats at an average rate of 87% (SE ± 1.4%, n = 521 trials). The average accuracy rates for 4 dogs increased to 98% (SE ± 1.6%, n = 86 sets of repeated-trials) using repeated-trial tests. Each of 5 dogs made correct choices better than expected by chance (dog 1 χ²₁ = 507.9, P ≤ 0.001; dog 2 χ²₁ = 882.1, P ≤ 0.001; dog 3 χ²₁ = 374.1, P ≤ 0.001; dog 4 χ²₁ = 379.2, P ≤ 0.001; and dog 5 χ²₁ = 103.9, P ≤ 0.001). Four dogs were able to match 11 scats deposited over a 4-year period from one tiger with an accuracy of 100% (n = 40 trails). This method may be a useful alternative to genetic analyses that are used in conjunction with scat-sampling schemes in studies for which DNA genotyping is impractical or ineffective. Used with mark—recapture surveys to estimate species abundance, scent-matching dogs have the potential of being important tools in the study of wild Amur tigers, as well as other wildlife species.     

Preliminary investigation of social interactions and feeding behavior in captive group-housed Tasmanian devils (Sarcophilus Harrisii)

As the number of Tasmanian devils (Sarcophilus harrisii) in captivity increases, an understanding of captive social dynamics and behavior is becoming increasingly important. In the wild, devils are solitary, although sometimes, they congregate to feed on a large carcass. However, it is common to house devils in groups as a form of social enrichment. This study investigated how behavior at feeding time of captive Tasmanian devils varied in groups of different sizes. Observations were made of individually housed devils and devils in groups of two, three, five, and six, when presented with a carcass on which to feed. Total feeding duration ranged from 6.5 to 47.4 minutes per observation period (70 minutes). There was no significant interaction between feeding duration and group size during the experiment. Feeding duration varied daily and depended on carcass size. Social housing of Tasmanian devils enabled them to display dyadic and agonistic behaviors during feeding. Observing behaviors and learning from the outcomes of these interactions can improve husbandry techniques. Creating a captive environment that encourages natural behaviors may enhance survival in the wild following translocation.     

Temporal partitioning of activity: rising and falling top‐predator abundance triggers community‐wide shifts in diel activity

Top predators cause avoidance behaviours in competitors and prey, which can lead to niche partitioning and facilitate coexistence. We investigate changes in partitioning of the temporal niche in a mammalian community in response to both the rapid decline in abundance of a top predator and its rapid increase, produced by two concurrent natural experiments: 1) the severe decline of the Tasmanian devil due to a transmissible cancer, and 2) the introduction of Tasmanian devils to an island, with subsequent population increase. We focus on devils, two mesopredators and three prey species, allowing us to examine niche partitioning in the context of intra‐ and inter‐specific competition, and predator–prey interactions. The most consistent shift in temporal activity occurred in devils themselves, which were active earlier in the night at high densities, presumably because of heightened intraspecific competition. When devils were rare, their closest competitor, the spotted‐tailed quoll, increased activity in the early part of the night, resulting in increased overlap with the devil's temporal niche and suggesting release from interference competition. The invasive feral cat, another mesopredator, did not shift its temporal activity in response to either decreasing or increasing devil densities. Shifts in temporal activity of the major prey species of devils were stronger in response to rising than to falling devil densities. We infer that the costs associated with not avoiding predators when their density is rising (i.e. death) are higher than the costs of continuing to adopt avoidance behaviours as predator densities fall (i.e. loss of foraging opportunity), so rising predator densities may trigger more rapid shifts. The rapid changes in devil abundance provide a unique framework to test how the non‐lethal effects of top predators affect community‐wide partitioning of temporal niches, revealing that this top predator has an important but varied influence on the diel activity of other species.     

Effects of Novel and Historic Predator Urines on Semi-Wild Western Grey Kangaroos

Abstract: Classic studies in fear ecology have been inconclusive regarding whether predator waste products repel herbivores and whether the deterrent effect, if any, is based on repulsion or fear. Other studies imply that the predator must have co-evolved with prey to maximize the efficacy of response. We used chemosensory cues from the urine of native and nonnative canines to manipulate the behavior of the western grey kangaroo (Macropus fuliginosus). One-choice feeding trials were located along a distance gradient, and administered to 28 free-ranging, semi-wild, western grey kangaroos. Foods closer to the chemical source (within 12 m) were less likely to be eaten than those further from the source when the urine came from a native predator, the dingo (Canis dingo). Flight behavior was more likely to be observed on occasions when the dingo urine had been presented. A lesser effect occurred (to within 6 m) when urine was presented from the nonnative canid (coyote [Canis latrans]), while the flight behavior occurred once. Neither human urine, nor tap-water control, had any effect. We offer the first evidence that native predator-based chemical cues affect patch selection, while increasing fear, for this herbivore.     

A preliminary study assessing risk to Tasmanian devils from poisoning for red foxes

The recent introduction of red foxes (Vulpes vulpes) to Australia's island state of Tasmania represents a major threat to native fauna. In response, the Tasmanian government has begun a fox eradication program using Foxoff®, a bait containing the poison sodium monofluoroacetate (commonly known as 1080). The bait is potentially attractive to native Tasmanian carnivores as well as to foxes. Of particular concern is the endangered Tasmanian devil (Sarcophilus harrisii), which is already at risk from an emergent infectious disease, devil facial tumor disease (DFTD). In both a captive and a field study using non-toxic Foxoff bait, we assessed bait palatability and possible effects of demographics, hunger level, bait age, and bait burial method on the likelihood of bait uptake by Tasmanian devils. Captive devils showed varying interest in the bait, but wild devils appeared to find it uniformly palatable. In the captive study, males and younger, captive-born animals were more likely to excavate and remove bait. Subterranean burial at 15 cm was the most effective deterrent to bait excavation; effectiveness decreased at shallower depths and with surface-level bait buried beneath soil mounds. Our findings suggest that the current fox-baiting campaign may negatively impact individual devils. More extensive study is necessary to assess potential risk at the population level. © 2011 The Wildlife Society.     

Olfactory eavesdropping: The odor of feathers is detectable to mammalian predators and competitors

The role of olfactory eavesdropping in interactions between mammalian predator and prey species is well established. Bird plumage can be odorous and consequently nest predators could use odor to identify and locate avian prey, and nest competitors could use odor to assess occupancy of nest cavities by birds. However, despite extensive research on avian nest predation and competition, the costs of olfactory eavesdropping on plumage odor by nest predators or competitors remain largely unknown. We used two experiments to investigate whether feather odor is detected by marsupial species which are competitors for nest hollows and predators of eggs and nestlings of crimson rosellas, Platycercus elegans. In the first experiment, odor presentation at nest boxes utilized by ringtail possums (Pseudocheirus peregrinus) and rosellas showed that the latency of possums to enter the nest was shorter when crimson rosella odor was present compared to the controls. In the second experiment, carried out away from nest hollows, brushtail possums (Trichosurus vulpecula) discriminated odors of two predators (dingo, Canis lupus dingo, and cat, Felis catus) from crimson rosella and control odors; however, they did not discriminate between crimson rosella odor and a control. We show that marsupials may use feather odor cues to assess nest hollow status, information which could aid their detection of avian prey or their vigilance at nest hollows (for which they compete with parrots). To our knowledge, our study is the first to show that wild mammalian predators and competitors of birds respond to plumage odor at nests and suggest that odor signaling may have hitherto unrecognized costs for birds.     

Weights of gaur (Bos gaurus) and banteng (Bos javanicus) killed by tigers in Thailand

The primary prey of tigers across much of South‐East Asia has been depleted, reducing the ability of already limited habitat to support tigers. To better understand the extent to which two of the largest prey species, gaur (Bos gaurus) and banteng (Bos javanicus), contribute to the tiger's diet, we estimated the average size of these species killed by tigers. This information is needed to more accurately calculate biomass of these species in the tiger's diet and to devise strategies to increase tiger carrying capacity where habitat is fragmented and limited in west‐central Thailand. We used temporally clumped locations of 24 satellite radio‐collared tigers to identify their kill sites and obtained mandibles from 82 gaur and 79 banteng. Kills were aged by teeth eruption sequence, sectioning the M1 molar and counting cementum annuli. Of all gaur killed, 45.2% were adults; of all banteng killed, 55.7% were adults. The average weight of banteng killed was 423.9 kg, which was similar to the 397.9 kg average weight for gaur. The mean weight of both prey species is 3.5–4.5 times greater than the predicted 1:1 preferred prey to predator ratio. In the absence of medium‐sized prey, killing these larger animals may be especially critical for female tigers provisioning nearly independent young when male offspring are already larger than the mother. This is the first study to present data on the average weights of gaur and banteng killed in South‐East Asia, and these results suggest that these are key prey species to target in tiger prey recovery efforts.