Many animals are marked with conspicuous circular features often called ＇eyespots＇, which intimidate predators, preventing or halting an attack. It has long been assumed that eyespots work by mimicking the eyes of l...Many animals are marked with conspicuous circular features often called ＇eyespots＇, which intimidate predators, preventing or halting an attack. It has long been assumed that eyespots work by mimicking the eyes of larger animals, but recent experiments have indicated that conspicuousness and contrast is important in eyespot function, and not eye mimicry. We undertake two further experiments to distinguish between the conspicuousness and mimicry hypotheses, by using artificial prey presented to wild avian predators in the field. In experiment 1, we test if eyespot effectiveness depends on the marking shape （bar or circle） and arrangement （eye-like and non-eye-like positions）. We find no difference between shapes or arrangement; all spots were equally effective in scaring birds. In experiment 2, we test if the often yellow and black colors of eyespots mimic the eyes of birds of prey. We find no effect of shape, and no advantage to yellow and black spots over non-eye-like but equally conspicuous colors. The consistent finding is that eyespot function lies in being a conspicuous signal to predators, and not necessarily due to eye mimicry [ Current Zoology 55 （5） ： 319 - 326, 2009].展开更多
The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessin...The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessing highly detectable external coloration are unknown. We tested whether variation in the degree of plumage vividness in birds explained variation in flight-initiation distance. After controlling for body mass, the distance at which the experimental approach began, and phylogenetic relatedness, plumage vividness was not a predictor of FID. Contrary to the expectation that vividness affects risk, and therefore risk assess- ment, these results suggest that birds do not compensate for greater visual conspicuousness by fleeing sooner from approaching threats [Current Zoology 61 （4）： 773-780, 2015].展开更多
This year, I’m told, was a bit different:in the interest of not insulting millions of struggling Americans, Santa andhis reindeer touched down very lightly in the United States last month. New Year’sEve,
基金supported by a Research Fellowship from Girton College,Cambridge,and a Royal Society Research Grantby an Association for the Study of Animal Behaviour Undergraduate Project Scholarship+1 种基金by a Nuffield Undergraduate Science Bursaryby a Department of Zoology J Arthur Ramsay Trust Fund
文摘Many animals are marked with conspicuous circular features often called ＇eyespots＇, which intimidate predators, preventing or halting an attack. It has long been assumed that eyespots work by mimicking the eyes of larger animals, but recent experiments have indicated that conspicuousness and contrast is important in eyespot function, and not eye mimicry. We undertake two further experiments to distinguish between the conspicuousness and mimicry hypotheses, by using artificial prey presented to wild avian predators in the field. In experiment 1, we test if eyespot effectiveness depends on the marking shape （bar or circle） and arrangement （eye-like and non-eye-like positions）. We find no difference between shapes or arrangement; all spots were equally effective in scaring birds. In experiment 2, we test if the often yellow and black colors of eyespots mimic the eyes of birds of prey. We find no effect of shape, and no advantage to yellow and black spots over non-eye-like but equally conspicuous colors. The consistent finding is that eyespot function lies in being a conspicuous signal to predators, and not necessarily due to eye mimicry [ Current Zoology 55 （5） ： 319 - 326, 2009].
基金We thank Kate Rose for help managing data, the survey participants for judging vividness, C. East- wood for his intellectual contributions, and Bill Cooper and one anonymous reviewer for their constructive comments on a previous version of this MS. NMH was supported by the UC Regents Special Fellowship. JPD was supported by a National Science Foundation （NSF） Graduate Research Fellowship and a fellowship from the UCLA Graduate Division during the course of this study. DTB is supported by NSF-DEB-1119660.
文摘The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessing highly detectable external coloration are unknown. We tested whether variation in the degree of plumage vividness in birds explained variation in flight-initiation distance. After controlling for body mass, the distance at which the experimental approach began, and phylogenetic relatedness, plumage vividness was not a predictor of FID. Contrary to the expectation that vividness affects risk, and therefore risk assess- ment, these results suggest that birds do not compensate for greater visual conspicuousness by fleeing sooner from approaching threats [Current Zoology 61 （4）： 773-780, 2015].
文摘This year, I’m told, was a bit different:in the interest of not insulting millions of struggling Americans, Santa andhis reindeer touched down very lightly in the United States last month. New Year’sEve,
