Are cats ambush predators12/5/2023 We suggest more experiments investigating response time to different predatory types and explicitly manipulating state to elucidate cause and effect.Īlvarez F (1993) Alertness signalling in 2 rail species. Our work suggests that although heavier individuals may have impaired escape performance they appear to show behavioural compensation by allocating more attention to anti-predator behaviour and by modifying their interscan intervals, resulting in faster response times to a ground predator. In addition, individuals in experiment 1 that head turned more while scanning were slower to respond to the stalking cat model. In contrast to a previous study, both experiments found individuals with a higher intake rate were not faster at responding to the cat model. Heavier individuals also had shorter interscan intervals. Both experiments show evidence suggesting heavier individuals (which previous literature has linked to impaired flight performance) responded more quickly to the model cat. In experiment 2, we used a camouflaged cat model simulating an ambush predator. In experiment 1, we observed chaffinch responses to a moving cat model, simulating a stalking predator. We used laboratory trials of wild caught chaffinches ( Fringilla coelebs) to determine how between individual differences in chaffinch behaviour and state correlate with latency to react to a ground predator model (domestic cat), thus providing a comparison with previous work in the same model system using aerial predator models. We suggest that birds of different individual state might also differ in their speed of response dependent upon predator type. Theory predicts that different vigilance patterns are optimal for the detection of different predator types. “There are multiple forces that push the eye to evolve in multiple ways.The relationship between body mass and reactions speed in response to a predatory threat is poorly understood. Additionally, many predators and prey animals, including most birds – which were excluded from the study’s analysis – have circular pupils.īut evolution is complex, and the new hypotheses about the advantages of pupil shape only address one aspect of the evolution of vision, Banks says. Counterexamples exist of predators without slit pupils and herbivores with them, he says. But vision scientist Ronald Kröger of Lund University in Sweden warns against assuming that an animal’s habits caused the evolution of a certain pupil shape. These visual benefits could explain why predators and prey evolved their pupil shapes, Banks’ team says. These benefits could help grazing prey spot – and flee from – an approaching slit-eyed hunter. But rectangular pupils probably have their own advantages, the authors report, including better panoramic vision and shielding of potentially blinding overhead light. The authors don’t think these pupils help with depth perception. ![]() Many herbivores, like horses and deer, have horizontal, rectangular pupils, rather than vertical slits. A predator might use this increased blurriness to help triangulate distances while stalking prey. BETTER BLUR A vertically stretched pupil, like those seen in many predators, perceives far-off horizontal objects as blurrier than vertical objects near the same location. A predator that must pounce on its dinner needs to be able to accurately judge distances, he says. ![]() The benefits of this mix of visual cues make good sense, says Michael Land, a neurobiologist at the University of Sussex in Brighton, England. A stalking predator might rely upon an object’s fuzziness to judge its location. That makes blur a good estimate of distance, says study author Martin Banks, a vision scientist at the University of California, Berkeley. This rapidly blurring vision should make it easy to detect even subtle changes in distance, the researchers say. Horizontal shapes are clear over a more limited distance, quickly going out of focus as an object moves farther away. Through these narrow slits, vertical objects appear sharp over great distances, the scientists report. Prey animals may gain different visual advantages from pupil shapes that provide panoramic views.Ĭats, foxes and many other predators that ambush prey have vertical pupils. Out-of-focus areas created by vertically elongated pupils help predators triangulate the distance to objects, scientists propose August 7 in Science Advances. But visual fuzziness might actually help some animals catch dinner. Blurry vision sounds like a reason to visit an eye doctor.
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