Crepuscular
From Wikipedia, the free encyclopedia
- For the atmospheric optical effect, see crepuscular rays.
Crepuscular is a term used to describe animals that are primarily active during the twilight. The word derives from the Middle English and French word crepuscule, meaning "twilight". Crepuscular is thus in contrast with diurnal and nocturnal. Crepuscular animals may also be active on a bright moonlit night. Many animals that are casually described as nocturnal are in fact crepuscular. Within the definition of crepuscular are the terms matinal (or "matutinal") and vespertine, denoting animals active in the morning (dawn) and evening (dusk) respectively.
The patterns of activity are thought to represent a response to selection from predators. Many predators forage most intensely at night, while others are active at mid-day and see best in full sun. Thus the crepuscular habit may reduce predation. Additionally, in hot areas, it may be a way of avoiding thermal stress while capitalizing on available light.
Crepuscular mammals include the cat, dog, deer, rabbit, chinchilla, ferret, guinea pig, hamster, common mouse, rat, and capybara. Crepuscular birds include the common nighthawk and spotted crake. Another well known crepuscular animal is the moose, which often comes out in early morning hours or late evening hours.
Some species have different habits in the absence of predators. For example, the short-eared owl is diurnal on those of the Galápagos Islands that do not have buzzard species, but crepuscular on the others.
Many moths, beetles, flies, and other insects are crepuscular as well.
The novelist Julian Barnes admits being obsessed with the word 'crepuscular' in his collected articles for the New Yorker magazine, and his character Oliver Russell displays a similar fault in Barnes' novels Talking It Over and Love, etc. Barnes uses the word as a metaphor to describe the habits of the character Stuart Hughes. He once worked for the Oxford English Dictionary as a lexicographer, and perhaps would have discovered such a rarely-used word whilst he was there.
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