Sonar jamming in the field: effectiveness and behavior of a unique prey defense

Wake Forest University, Department of Biology, Winston-Salem, NC 27106, USA.
Journal of Experimental Biology (Impact Factor: 3). 12/2012; 215(Pt 24):4278-87. DOI: 10.1242/jeb.076943
Source: PubMed

ABSTRACT Bats and insects provide a model system for integrating our understanding of predator-prey ecology, animal behavior and neurophysiology. Previous field studies of bat-insect interactions have been limited by the technological challenges involved with studying nocturnal, volant animals that use ultrasound and engage in battles that frequently last a fraction of a second. We overcame these challenges using a robust field methodology that included multiple infrared cameras calibrated for three-dimensional reconstruction of bat and moth flight trajectories and four ultrasonic microphones that provided a spatial component to audio recordings. Our objectives were to document bat-moth interactions in a natural setting and to test the effectiveness of a unique prey defense - sonar jamming. We tested the effect of sonar jamming by comparing the results of interactions between bats and Grote's tiger moth, Bertholdia trigona, with their sound-producing organs either intact or ablated. Jamming was highly effective, with bats capturing more than 10 times as many silenced moths as clicking moths. Moths frequently combined their acoustic defense with two separate evasive maneuvers: flying away from the bat and diving. Diving decreased bat capture success for both clicking and silenced moths, while flying away did not. The diving showed a strong directional component, a first for insect defensive maneuvers. We discuss the timing of B. trigona defensive maneuvers - which differs from that of other moths - in the context of moth auditory neuroethology. Studying bat-insect interactions in their natural environment provides valuable information that complements work conducted in more controlled settings.

1 Follower
  • Journal of Experimental Biology 11/2012; 215(24):ii-ii. DOI:10.1242/jeb.082784 · 3.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The feeding habits of insectivorous bats are of great interest to people, because they are considered to be important in the control of insect pests. Here we present a study showing the relationship of bat morphology to differences in prey selection by various bat species. We compared dietary data from 10,884 faecal pellets, bodyweight, cranial length, forearm length and echolocation calls from published peer-reviewed studies for 92 bat species. We demonstrated that insectivorous bats tend to prefer certain insect orders which we have grouped as soft bodied insects, hard bodied insects and Lepidoptera. Wing characteristics which we measured by bodyweight-forearm ratio showed the strongest relationship with hard insects followed by longest cranial length. The content of soft insects in bat diets was negatively related to bodyweight, forearm length and longest cranial length. Lepidoptera content was positively related to the echolocation frequency with the maximum intensity (FMAXE), bats with high FMAXE fed on more Lepidoptera than those with low frequencies. We propose that a combination of dietary analysis and morphological analysis is needed to make strong inference about prey preference rather than comparing the dietary analysis with the insect abundance at the location were the bat or faecal pellets were collected.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In 1909, Abbott Thayer suggested that the study of animal coloration lies in the domain of artists because it deals with optical illusions. He proposed, for example, that prey color patterns may obliterate the animal's outline to make the wearer appear invisible to its preda-tors. Despite a long history of research on the neuropsychology of visual illusions in humans, the question of whether they can occur in other animals has remained largely neglected. In this review, we first examine whether the visual effects generated by an animal's shape, coloration, movement, social environment, or direct manipulation of the environment might distort the receiver's perspective to form an illusion. We also consider how illusions fit into the wider conceptual framework of sensory perception and receiver psychol-ogy, in order to understand the potential significance of these (and other) visual effects in animal communication. Secondly, we con-sider traits that manipulate visual processing tasks to intimidate or mislead the viewer. In the third part of the review, we consider the more extreme cases of sensory manipulation, in which individuals or their traits disrupt, overstimulate, or inactivate receivers' sensory systems. Although illusions present just one form of sensory manipulation, we suggest that they are likely to be more common than previously suspected. Furthermore, we expect that research in this area of sensory processing will provide significant insights into the cognitive psychology of animal communication.
    Behavioral Ecology 01/2014; 25(3):450-463. DOI:10.1093/beheco/art118 · 3.16 Impact Factor

Full-text (2 Sources)

Available from
May 29, 2014