科研之友
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摘要
Aposematism and crypticity are viewed as mutually exclusive antipredator defense strategies with skunks being a classic example of the former. Skunks can spray noxious anal secretions and many species (Conepatus and Mephitis spp.) have bold blocks of white fur on black pelage, but spotted skunks (Spilogale sp.) have white spots and lines on a black coat suggesting an additional function. We tested the possibility that spotted skunks are conspicuous at close range but cryptic at a distance. Using quantitative measures of colouration extracted from photographs of taxidermied western spotted skunk, bobcat and striped skunk mounts taken at 5 m, we found that spotted skunk colouration was significantly more conspicuous than the cryptic bobcat but not than the striped skunk. Differences between mount and background colouration were significantly greater for spotted skunks than for bobcats but not for striped skunks. Both sets of results indicate that spotted skunks match their background poorly when viewed close up. In poor light, human observers found it easy to see a striped skunk mount when standing 40145m away but difficult to see a bobcat mount. Spotted skunk mounts were more difficult to see than a striped skunk but easier than a bobcat mount during evening watches, and no easier to see than a bobcat during early morning watches, results of which were broadly confirmed using dyed spotted skunk mounts. Therefore naturally coloured spotted skunks are relatively cryptic under certain lighting conditions when viewed from afar by human observers. Finally, across skunk species, spottedness is associated with small size, living in closed habitats, and being arboreal, similar to some other small cryptic carnivore species. Our analyses provide preliminary support for spotted skunks being cryptic at a distance but conspicuous close up, adding to a small but growing list of species utilizing two formerly distinct antipredator defense strategies.
- 出版日期2013-4-1
