invertebrate prey on the ground that may have consumed toxic bait. Lesser short-tailed bats (Mystacina tuberculata) may be vulnerable to secondary poisoning from 1080 because they feed on. Aerial application of the toxin sodium monofluoroacetate (1080) is currently the most costeffective method of controlling rats across large spatial extents. Introduced mammalian predators, in particular rats (Rattus spp.), are a major threat to New Zealand bat populations.
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We provide an overview of the sensory ecology of information use in hunting in bats and, by identifying current gaps in knowledge, highlight fruitful directions for future research. We investigate diverse strategies of information use and examine the effects different predatory strategies have on predator sensory systems. We discuss the costs and benefits of using private and social information for foraging. We focus our enquiry on bats, an ideal group to shed light on these questions given their ecological diversity, varied foraging strategies and wide range of social behaviours. We review the sensory strategies used by predators that rely on private information (attending directly to cues and signals generated by their prey) and those that gather social information (attending to the signals and behaviours of others). Examinations of the sensory strategies implemented by predators to detect their prey, as well as the ecological consequences of these interactions, are at the crux of understanding and predicting predator–prey. In the evolutionary arms race between predators and their prey, prey often evolve to be as cryptic as they can, while predators in turn hone their sensory strategies to detect prey. Therefore, bats may be alert to the approach of predators and be less responsive to chemical cues compared to other times of the year. During late spring, female bats often avoid torpor for thermoregulatory or reproductive reasons. This suggests olfactory cues may not be representative of live snakes, or that auditory cues may be more important than olfactory cues for predator recognition. Bats tended to avoid the arm with live snakes, although results were non-significant. In a second experiment, bats were exposed to olfactory and potentially auditory cues of live black rat snakes. We found that big brown bats do not avoid cues from raccoon urine and there was a non-significant trend for bats to choose the arm with black rat snake cues. during the assessment of potential roost sites, so avoidance of predator cues could affect roost selection. These chemical cues are most likely encountered by bats. Using a Y-maze, we tested the hypothesis that female big brown bats (Eptesicus fuscus) avoid olfactory cues from known predators - raccoons (Procyon lotor) and black rat snakes (Elaphe obsoleta). Predation places selection pressure on the behaviour of organisms, but the effect of predation risk on bat behaviour has gone largely untested. Iron and volcanic deposits subtract from or add to the field shown to give the total field. c) The intensity of the field also varies geographically, being strongest at the magnetic poles in Antarctica and Canada and weakest at the magnetic equator. Modified from Wiltschko & Wiltschko (1996). The relative strength of the field is indicated by the length of the arrows. The angle of the inclination is perpendicular to the Earth's surface at both magnetic poles and parallel to the Earth's surface at the magnetic equator. Both are created by the Earth's core which acts like a bar magnet. The field also includes a considerably weaker non dipole component (not shown). The majority of the Earth's main magnetic field is produced by the magnetic dipole in the Earth's core (inclination, →). b) As magnetic poles differ from geographic poles the magnetic equator (double line) also differs from the geographic equator (dashed line). The angle between H and Z is the inclination (I). Magnetic North (H) is not the same as Geographic North (X), the angle between the two (D) is known as the declination. a) Elements of the total field magnetic field vector (F) can be resolved into component vectors (→): X (true north), Y (east) and Z (vertical). Diagrams illustrating the nature and components of the Earth's magnetic field.
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