Crepuscular animal

Crepuscular animals are those that are active primarily during twilight (that is, the periods of dawn and dusk).[1] This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylight or the hours of darkness, respectively. The term is not precise, however, as some crepuscular animals may also be active on a moonlit night or during an overcast day. The term matutinal is used for animals that are active only before sunrise, and vespertine for those active only after sunset.

The time of day an animal is active depends on a number of factors. Predators need to link their activities to times of day at which their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature at midday may be too high or at night too low.[2] Some creatures may adjust their activities depending on local competition. Therefore, for many varied reasons, crepuscular activity may best meet an animal's requirements by compromise.

Photuris lucicrescens
An adult firefly (Photuris lucicrescens) or "lightning bug" – a crepuscular beetle

Etymology and usage

The word crepuscular derives from the Latin crepusculum ("twilight").[3] Its sense accordingly differs from diurnal and nocturnal behavior, which respectively peak during hours of daylight and darkness. The distinction is not absolute however, because crepuscular animals may also be active on a bright moonlit night or on a dull day. Some animals casually described as nocturnal are in fact crepuscular.[2]

Special classes of crepuscular behaviour include matutinal (or "matinal") and vespertine, denoting species active only in the dawn or only in the dusk, respectively. Those that are active during both morning and evening twilight are said to have a bimodal activity pattern.

Adaptive relevance

Fireflies at twilight, long exposure

The various patterns of activity are thought to be mainly antipredator adaptations, though some could equally well be predatory adaptations. Many predators forage most intensively at night, whereas others are active at midday and see best in full sun. Thus, the crepuscular habit may both reduce predation pressure, thereby increasing the crepuscular populations, and in consequence offer better foraging opportunities to predators that increasingly focus their attention on crepuscular prey until a new balance is struck. Such shifting states of balance are often found in ecology.

Some predatory species adjust their habits in response to competition from other predators. For example, the subspecies of short-eared owl that lives on the Galápagos Islands is normally active during the day, but on islands like Santa Cruz that are home to the Galapagos hawk, the owl is crepuscular.[4][5]

Apart from the relevance to predation, crepuscular activity in hot regions also may be the most effective way of avoiding heat stress while capitalizing on available light.

Occurrence of crepuscular behaviour

Ocelots are active at night, especially during dawn and dusk.

Many familiar mammal species are crepuscular, including some bats,[2] hamsters, housecats, stray dogs,[6] rabbits,[2] ferrets,[7] guinea pigs and rats.[8] Other crepuscular mammals include jaguars, ocelots, bobcats, strepsirrhines, red pandas, bears,[9] deer,[2][10] moose, sitatunga, capybaras, chinchillas, the common mouse, skunks, squirrels, Australian wombats, wallabies, quolls, possums[2] and marsupial gliders, tenrecs, spotted hyenas, and African wild dogs.

Snakes and lizards, especially those in desert environments, may be crepuscular.[2]

Crepuscular birds include the common nighthawk, barn owl,[11] owlet-nightjar, chimney swift, American woodcock, spotted crake, and white-breasted waterhen.[12]

Many moths, beetles, flies, and other insects are crepuscular and vespertine.

See also


  1. ^ "Glossary". North American Mammals. SmithsonianNational Museum of Natural History. Retrieved July 16, 2017.
  2. ^ a b c d e f g "Crepuscular". Macmillan Science Library: Animal Sciences. Macmillan Reference USA. 2001–2006. Retrieved 2011-07-11.
  3. ^ Winn, Philip (2001). Dictionary of Biological Psychology. Taylor & Francis. ISBN 0-415-13606-7.
  4. ^ Frederick, Prince (2006-04-15). "Night herons in the day!". Metro Plus Chennai. The Hindu. Retrieved 15 January 2012.
  5. ^ Merck, John. "The community of terrestrial animals". Field Studies II: The Natural History of the Galápagos Islands. University of Maryland Department of Geology. Retrieved 15 January 2012.
  6. ^ The Ecology of Stray Dogs: A Study of Free-Ranging Urban Animals – Alan M. Beck – Google Books. Retrieved 2012-04-13.
  7. ^ Williams, David L. (2012). Ophthalmology of Exotic Pets. John Wiley & Sons. p. 73. Retrieved 2017-06-23.
  8. ^ Williams, David L. (2012). Ophthalmology of Exotic Pets. John Wiley & Sons. p. 88. Retrieved 2017-06-23.
  9. ^ Schaul, Jordan Carlton (April 6, 2011). "The Kodiak Cubs Meet Their Neighbors, The American Black Bears". National Geographic Voices. National Geographic Society. Retrieved July 15, 2017.
  10. ^ "White-Tailed Deer". Animals. National Geographic Partners, LLC. Retrieved July 15, 2017.
  11. ^ Audubon, John J. (1827–1838). "Plate 171: Barn Owl". Birds of America.
  12. ^ Boyes, Steve (October 7, 2012). "Top 25 Wild Bird Photographs of the Week #23". National Geographic Voices. National Geographic Society. Retrieved July 15, 2017.
Fox hunting

Fox hunting is an activity involving the tracking, chase and, if caught, the killing of a fox, traditionally a red fox, by trained foxhounds or other scent hounds, and a group of unarmed followers led by a "master of foxhounds" ("master of hounds"), who follow the hounds on foot or on horseback.Fox hunting with hounds, as a formalised activity, originated in England in the sixteenth century, in a form very similar to that practised until February 2005, when a law banning the activity in England and Wales came into force. A ban on hunting in Scotland had been passed in 2002, but it continues to be within the law in Northern Ireland and several other countries, including Australia, Canada, France, Ireland and the United States. In Australia, the term also refers to the hunting of foxes with firearms, similar to deer hunting. In much of the world, hunting in general is understood to relate to any game animals or weapons (e.g., deer hunting with bow and arrow); in Britain and Ireland, "hunting" without qualification implies fox hunting (or other forms of hunting with hounds—beagling, drag hunting, hunting the clean boot, mink hunting, or stag hunting), as described here.The sport is controversial, particularly in the UK. Proponents of fox hunting view it as an important part of rural culture, and useful for reasons of conservation and pest control, while opponents argue that it is cruel and unnecessary.

Gekko athymus

Gekko athymus, also known as the Brown's gecko or smooth-scaled narrow-disked gecko, is a species of gecko. The species is endemic to the island of Palawan in the Philippines. It is a rare, crepuscular animal that has only been found in intact primary forest.

Reeves's muntjac

Reeves's muntjac (Muntiacus reevesi; Chinese: 山羌), also known as Chinese muntjac, is a muntjac species found widely in southeastern China (from Gansu to Yunnan) and Taiwan. It has also been introduced in Belgium, the Netherlands, the United Kingdom (south England, the Midlands, east Wales), Ireland, and Japan. It takes its name from John Reeves, an employee of the British East India Company in the 19th century.

Solomon Islands skink

The Solomon Islands skink (Corucia zebrata), also known as prehensile-tailed skink, monkey-tailed skink, giant skink, zebra skink, and monkey skink, is an arboreal species of skink endemic to the Solomon Islands archipelago. It is the largest known extant species of skink.

The Solomon Islands skink is completely herbivorous, eating many different fruits and vegetables including the pothos plant. It is one of the few species of reptile known to function within a social group or circulus. Both male and female specimens are known to be territorial and often hostile towards members not a part of their family group.

Corucia is a monotypic genus, containing a single species. However, in 1997 it was determined that there are two subspecies of the Solomon Islands skink: the common monkey-tailed skink (Corucia zebrata zebrata) and the northern monkey-tailed skink (Corucia zebrata alfredschmidti). Among other variances, the northern skink is smaller and has darker eyes with a black sclera.

Extensive logging is a serious threat to the survival of this species. Consumption for food by indigenous Solomon Islanders and excessive pet trade exports have affected wild populations. Export of this species from the Solomon Islands is now restricted and the animal is protected under CITES appendix II.

Thorold's deer

Thorold's deer (Cervus albirostris) is a threatened species of deer found in grassland, shrubland, and forest at high altitudes in the eastern Tibetan Plateau. It is also known as the white-lipped deer (Baichunlu, 白唇鹿, in Simplified Chinese, ཤྭ་བ་མཆུ་དཀར།་ in Standard Tibetan) for the white patches around its muzzle.This deer fills an ecological niche similar to the Tibetan red deer (shou, the subspecies wallichi of the red deer species group). It was first scientifically described by Nikolai Przhevalsky in 1883, and the first specimens were procured by G. W. Thorold, after whom the species is named. As of early 2011, more than 100 Thorold's deer are kept in ISIS-registered zoos, and in 1998 it was estimated that about 7000 remain in the wild.

Internal rhythms
External cycles
See also

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