Catherine J. Price

Predators Are Attracted to the Olfactory Signals of Prey

Background Predator attraction to prey social signals can force prey to trade-off the social imperatives to communicate against the profound effect of predation on their future fitness. These tradeoffs underlie theories on the design and evolution of conspecific signalling systems and have received much attention in visual and acoustic signalling modes. Yet while most territorial mammals communicate using olfactory signals and olfactory hunting is widespread in predators, evidence for the attraction of predators to prey olfactory signals under field conditions is lacking. Methodology/Principal Findings To redress this fundamental issue, we examined the attraction of free-roaming predators to discrete patches of scents collected from groups of two and six adult, male house mice, Mus domesticus, which primarily communicate through olfaction. Olfactorily-hunting predators were rapidly attracted to mouse scent signals, visiting mouse scented locations sooner, and in greater number, than control locations. There were no effects of signal concentration on predator attraction to their preys signals. Conclusions/Significance This implies that communication will be costly if conspecific receivers and eavesdropping predators are simultaneously attracted to a signal. Significantly, our results also suggest that receivers may be at greater risk of predation when communicating than signallers, as receivers must visit risky patches of scent to perform their half of the communication equation, while signallers need not.

Exploiting olfactory learning in alien rats to protect birds’ eggs

Predators must ignore unhelpful background “noise” within information-rich environments and focus on useful cues of prey activity to forage efficiently. Learning to disregard unrewarding cues should happen quickly, weakening future interest in the cue. Prey odor, which is rapidly investigated by predators, may be particularly appropriate for testing whether consistently unrewarded cues are ignored, and whether such behavior can be exploited to benefit prey. Using wild free-ranging populations of black rats, Rattus rattus, an alien predator of global concern, we tested whether the application of bird-nesting odors before the introduction of artificial nests (odor preexposure), enhanced the survival of birds eggs (prey) compared with areas where prey and nesting odors were introduced concurrently. In areas where predators had encountered prey odor before prey being available, the subsequently introduced eggs showed 62% greater survival than in areas where prey and odor were introduced together. We suggest that black rats preexposed to prey odor learned to ignore the unrewarding cue, leading to a significant improvement in prey survival that held for the 7-d monitoring period. Exploiting rapid learning that underpins foraging decisions by manipulating sensory contexts offers a nonlethal, but effective approach to reducing undesirable predatory impacts. Techniques based on olfactory preexposure may provide prey with protection during critical periods of vulnerability, such as immediately following a prey reintroduction. These results also highlight the potential benefits to species conservation to be gained from a greater understanding of the cognitive mechanisms driving alien predator behavior within ecological contexts.

Research Priorities from Animal Behaviour for Maximising Conservation Progress

Poor communication between academic researchers and wildlife managers limits conservation progress and innovation. As a result, input from overlapping fields, such as animal behaviour, is underused in conservation management despite its demonstrated utility as a conservation tool and countless papers advocating its use. Communication and collaboration across these two disciplines are unlikely to improve without clearly identified management needs and demonstrable impacts of behavioural-based conservation management. To facilitate this process, a team of wildlife managers and animal behaviour researchers conducted a research prioritisation exercise, identifying 50 key questions that have great potential to resolve critical conservation and management problems. The resulting agenda highlights the diversity and extent of advances that both fields could achieve through collaboration.

Deadly intentions: naïve introduced foxes show rapid attraction to odour cues of an unfamiliar native prey

Introduced predators have caused declines and extinctions of native species worldwide, seemingly able to find and hunt new, unfamiliar prey from the time of their introduction. Yet, just as native species are often naïve to introduced predators, in theory, introduced predators should initially be naïve in their response to novel native prey. Here we examine the response of free-living introduced red foxes (Vulpes vulpes) to their first encounter with the odour cues of a novel native prey, the long-nosed bandicoot (Perameles nasuta). Despite no experience with bandicoots at the study site, foxes were significantly more interested in bandicoot odour compared to untreated controls and to a co-evolved prey, the black rat (Rattus rattus). So what gives introduced predators a novelty advantage over native prey? Such neophilia towards novel potential food sources carries little costs, however naïve native prey often lack analogous neophobic responses towards novel predators, possibly because predator avoidance is so costly. We propose that this nexus between the costs and benefits of responding to novel information is different for alien predators and native prey, giving alien predators a novelty advantage over native prey. This may explain why some introduced predators have rapid and devastating impacts on native fauna.

Increased olfactory search costs change foraging behaviour in an alien mustelid: a precursor to prey switching?

If generalist predators are to hunt efficiently, they must track the changing costs and benefits of multiple prey types. Decisions to switch from hunting preferred prey to alternate prey have been assumed to be driven by decreasing availability of preferred prey, with less regard for accessibility of alternate prey. Olfactory cues from prey provide information about prey availability and its location, and are exploited by many predators to reduce search costs. We show that stoats Mustela erminea, an alien olfactory predator in New Zealand, are sensitive to the search costs of hunting both their preferred rodent prey (mice) and a less desirable alternate prey (locust). We manipulated search costs for stoats using a novel form of olfactory camouflage of both prey, and found that stoats altered their foraging strategy depending on whether mice were camouflaged or conspicuous, but only when locusts were also camouflaged. Stoats gave up foraging four times more often when both prey were camouflaged, compared to when mice were conspicuous and locusts camouflaged. There were no differences in the foraging strategies used to hunt camouflaged or conspicuous mice when locusts were easy to find. Consequently, camouflaged mice survived longer than conspicuous mice when locusts were hard to find, but not when locusts were easy to find. Our results demonstrate that predators can integrate search costs from multiple prey types when making foraging decisions. Manipulating olfactory search costs to alter foraging strategies offers new methods for understanding the factors that foreshadow prey switching.

Food quality and conspicuousness shape improvements in olfactory discrimination by mice.

How animals locate nutritious but camouflaged prey items with increasing accuracy is not well understood. Olfactory foraging is common in vertebrates and the nutritional desirability of food should influence the salience of odour cues. We used signal detection analysis to test the effect of nutritional value relative to the conspicuousness of food patches on rates of foraging improvement of wild house mice Mus musculus searching for buried food (preferred peanuts or non-preferred barley). Olfactory cues were arranged to make food patches conspicuous or difficult to distinguish using a novel form of olfactory camouflage. Regardless of food type or abundance, mice searching for conspicuous food patches performed significantly better than mice searching for camouflaged patches. However, food type influenced how mice responded to different levels of conspicuousness. Mice searching for peanuts improved by similar rates regardless of whether food was easy or hard to find, but mice searching for barley showed significant differences, improving rapidly when food was conspicuous but declining in accuracy when food was camouflaged. Our results demonstrate a fundamental tenet of olfactory foraging that nutritional desirability influences rates of improvement in odour discrimination, enabling nutritious but camouflaged prey to be located with increasing efficiency.

Systematic reviews and maps as tools for applying behavioral ecology to management and policy

&NA; Although examples of successful applications of behavioral ecology research to policy and management exist, knowledge generated from such research is in many cases under‐utilized by managers and policy makers. On their own, empirical studies and traditional reviews do not offer the robust syntheses that managers and policy makers require to make evidence‐based decisions and evidence‐informed policy. Similar to the evidence‐based revolution in medicine, the application of formal systematic review processes has the potential to invigorate the field of behavioral ecology and accelerate the uptake of behavioral evidence in policy and management. Systematic reviews differ from traditional reviews and meta‐analyses in that their methods are peer reviewed and prepublished for maximum transparency, the evidence base is widened to cover work published outside of academic journals, and review findings are formally communicated with stakeholders. This approach can be valuable even when the systematic literature search fails to yield sufficient evidence for a full review or meta‐analysis; preparing systematic maps of the existing evidence can highlight deficiencies in the evidence base, thereby directing future research efforts. To standardize the use of systematic evidence syntheses in the field of environmental science, the Collaboration for Environmental Evidence (CEE) created a workflow process to certify the comprehensiveness and repeatability of systematic reviews and maps, and to maximize their objectivity. We argue that the application of CEE guidelines to reviews of applied behavioral interventions will make robust behavioral evidence easily accessible to managers and policy makers to support their decision‐making, as well as improve the quality of basic research in behavioral ecology.

Habitat augmentation for introduced urban wildlife: the use of piles of railway sleepers as refuge for introduced black rats Rattus rattus

ABSTRACT Despite their conspicuousness within urban environments, the ecology of commensal species is poorly understood. Urban environments are thought to provide abundant foraging and shelter reso...

Isolation and characterisation of microsatellite loci in the bush stone-curlew (Burhinus grallarius), a declining Australian bird

Abstract. The bush stone-curlew (Burhinus grallarius Latham), a ground-nesting nocturnal bird, is endangered in southern Australia due to habitat modification and introduced predators. To provide tools for conservation, ecological and behavioural studies, we isolated variable microsatellite repeat sequences and designed primers for PCR amplification in this species. Primer pairs were developed and levels of diversity were assessed for eight microsatellite loci, including one locus linked to the gene encoding Microtubule-Associated Protein 2, a protein important for behavioural imprinting in birds, and one sex-linked locus. Isolated loci contained allelic diversity of between 5 and 17 alleles.