Editing Nocturnality

{{Short description|Behavior characterized by activity during the night and sleeping during the day}}
{{About|the animal behavior of nocturnality|other uses|Nocturnal (disambiguation)}}
{{Redirect|Nocturnal animals|the film directed by Tom Ford|Nocturnal Animals}}
{{More citations needed|date=May 2012}}
[[File:Owl at Night.jpg|thumb|right|[[Owl|Owls]] are well known for being nocturnal, but some owls are active during the day.]]
{{wiktionary|nocturnal}}
'''Nocturnality''' is a [[ethology|behavior in some non-human animals]] characterized by being active during the [[night]] and sleeping during the [[day]]. The common adjective is "'''nocturnal'''", versus [[diurnality|diurnal]] meaning the opposite.

Nocturnal creatures generally have highly developed senses of [[hearing (sense)|hearing]], [[olfaction|smell]], and specially adapted [[eyesight]].<ref>{{cite journal | last1 = Agee    | first1 = H. R. | last2 = Orona | first2 = E. | year = 1988 | title = Studies of the neural basis of evasive flight behavior in response to acoustic stimulation in Heliothis zea (Lepidoptera: Noctuidae): organization of the tympanic nerves | url =http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1106&context=entomologyother | journal = Annals of the Entomological Society of America | volume = 81 | issue = 6| pages = 977–985 | doi=10.1093/aesa/81.6.977}}</ref> Some animals, such as [[cat]]s and [[ferret]]s, have eyes that can adapt to both low-level and bright day levels of illumination (see [[metaturnal]]). Others, such as [[bushbaby|bushbabies]] and (some) [[bat]]s, can function only at night. Many nocturnal creatures including [[tarsier|tarsiers]] and some [[owl|owls]] have large eyes in comparison with their body size to compensate for the lower light levels at night. More specifically, they have been found to have a larger [[cornea]] relative to their eye size than diurnal creatures to increase their {{Noredirect|Contrast (vision)|visual sensitivity}}: in the low-light conditions.<ref name="HallEtAl">{{cite journal|last1=Hall |first1=M. I. |last2=Kamilar |first2=J. M. |last3=Kirk |first3=E. C. |year=2012 |title=Eye shape and the nocturnal bottleneck of mammals |journal=Proceedings of the Royal Society B: Biological Sciences |volume=279 |number=1749 |pages=4962–4968 |doi=10.1098/rspb.2012.2258 |pmid=23097513 |pmc=3497252}}</ref> Nocturnality helps [[wasps]], such as ''[[Apoica flavissima]]'', avoid hunting in intense sunlight.

[[Diurnality|Diurnal]] animals, including [[human]]s (except for [[night owl (person)|night owls]]), [[squirrel]]s and songbirds, are active during the daytime. [[Crepuscular]] species, such as [[rabbit]]s, [[skunk]]s, [[tiger]]s and [[hyena]]s, are often erroneously referred to as nocturnal. [[Cathemeral]] species, such as [[Eupleridae|fossa]]s and [[lion]]s, are active both in the day and at night.

==Origins==
[[File:Kiwi bird in Christchurch, New Zealand, 2002-01-01.jpg|thumb|The [[kiwi (bird)|kiwi]] is a family of nocturnal birds endemic to New Zealand.]]
While it is difficult to say which came first, nocturnality or diurnality, a hypothesis in [[evolutionary biology]], the [[nocturnal bottleneck]] theory, postulates that in the [[Mesozoic]], many ancestors of modern-day [[mammal]]s evolved nocturnal characteristics in order to avoid contact with the numerous diurnal predators.<ref>{{Cite journal|last1=Gerkema|first1=Menno P.|last2=Davies|first2=Wayne I. L.|last3=Foster|first3=Russell G.|last4=Menaker|first4=Michael|last5=Hut|first5=Roelof A.|date=2013-08-22|title=The nocturnal bottleneck and the evolution of activity patterns in mammals|journal=Proceedings of the Royal Society B: Biological Sciences|language=en|volume=280|issue=1765|pages=20130508|doi=10.1098/rspb.2013.0508|issn=0962-8452|pmc=3712437|pmid=23825205}}</ref> A recent study attempts to answer the question as to why so many modern day mammals retain these nocturnal characteristics even though they are not active at night. The leading answer is that the high [[visual acuity]] that comes with diurnal characteristics is not needed anymore due to the evolution of compensatory sensory systems, such as a heightened sense of smell and more astute auditory systems.<ref name=":0">{{Cite journal|last1=Torres|first1=Christopher R.|last2=Clarke|first2=Julia A.|date=2018-11-07|title=Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions|journal=Proc. R. Soc. B|language=en|volume=285|issue=1890|pages=20181540|doi=10.1098/rspb.2018.1540|issn=0962-8452|pmid=30381378|pmc=6235046}}</ref>  In a recent study, recently extinct [[elephant bird]]s and modern day nocturnal [[kiwi bird]] skulls were examined to recreate their likely brain and skull formation. They indicated that [[olfactory bulb]]s were much larger in comparison to their [[optic tectum|optic lobes]], indicating they both have a common ancestor who evolved to function as a nocturnal species, decreasing their eyesight in favor of a better sense of smell.<ref name=":0" /> The anomaly to this theory were [[Simian|anthropoids]], who appeared to have the most divergence from nocturnality of all organisms examined. While most mammals did not exhibit the morphological characteristics expected of a nocturnal creature, reptiles and birds fit in perfectly. A larger [[cornea]] and [[pupil]] correlated well with whether these two classes of organisms were nocturnal or not.<ref name="HallEtAl" />

==Advantages==

===Resource competition===
[[File:Honey Badger (Mellivora capensis) (17425848662).jpg|thumb|The [[honey badger]], a nocturnal animal.]]
Being active at night is a form of [[niche differentiation]], where a species' niche is partitioned not by the amount of resources but by the amount of time (i.e. temporal division of the [[ecological niche]]). [[Hawk|Hawks]] and [[owl|owls]] can hunt the same field or meadow for the same rodents without conflict because hawks are diurnal and owls are nocturnal.<ref>{{Cite web |date=2023-08-19 |title=Are All Owls Nocturnal? All the Best FACTS Here! |url=https://birdsatfirstsight.com/are-all-owls-nocturnal/ |access-date=2023-09-14 |website=Birds At First Sight |language=en-US}}</ref> This means they are not in competition for each other's prey. Another niche that being nocturnal lessens competition within is [[pollination]] - nocturnal pollinators such as moths, beetles, thrips, and bats have a lower risk of being seen by predators, and the plants evolved temporal scent production and ambient heat to attract nocturnal pollination. <ref>{{cite journal |title=Nocturnal pollination: an overlooked ecosystem service vulnerable to environmental change |journal=Emerging Topics in Life Sciences |date=2020-06-01 |last1=Macgregor |first1=Callum J. |last2=Scott-Brown |first2=Alison S. |volume=4 |issue=1 |pages=19–32 |doi=10.1042/ETLS20190134 |pmid=32478390 |pmc=7326339 |url=https://portlandpress.com/emergtoplifesci/article/4/1/19/225093/Nocturnal-pollination-an-overlooked-ecosystem |accessdate=2021-08-28 }}</ref> Like with predators hunting the same prey, some plants such as apples can be pollinated both during the day and at night. <ref>{{cite journal |title=Nocturnal Pollinators Significantly Contribute to Apple Production |journal=Journal of Economic Entomology |date=2021-07-02 |last1=Robertson |first1=Stephen |last2=Dowling |first2=Ashley |last3=Wiedenmann |first3=Robert |last4=Joshi |first4=Neelendra |last5=Westerman |first5=Erica |volume=114 |issue=5 |pages=2155–2161 |doi=10.1093/jee/toab145 |pmid=34293132 |doi-access=free }}</ref>
===Predation===
[[File:Bat flying at night.png|thumb|Echolocating [[bats]] adjust their vocalization to catch insects against a changing environmental background.]]
Nocturnality is a form of [[crypsis]], an adaptation to avoid or enhance [[predation]]. Although lions are [[Cathemerality|cathemeral]], and may be active at any time of day or night, they prefer to hunt at night because many of their prey species ([[zebra]], [[antelope]], impala, [[wildebeest]], etc.) have poor [[night vision]]. Many species of small rodents, such as the [[Large Japanese field mouse|Large Japanese Field Mouse]], are active at night because most of the dozen or so [[birds of prey]] that hunt them are diurnal. There are many diurnal species that exhibit some nocturnal behaviors. For example, many [[seabird]]s and [[sea turtle]]s only gather at breeding sites or colonies at night to reduce the risk of predation to themselves and/or their offspring. Nocturnal species take advantage of the night time to prey on species that are used to avoiding diurnal predators. Some nocturnal fish species will use the moonlight to prey on zooplankton species that come to the surface at night.<ref name=":1">{{Cite journal|last1=Longcore|first1=Travis|last2=Rich|first2=Catherine|date=May 2004|title=Ecological light pollution|journal=Frontiers in Ecology and the Environment|language=en|volume=2|issue=4|pages=191–198|doi=10.1890/1540-9295(2004)002[0191:elp]2.0.co;2|s2cid=33259398|issn=1540-9295|doi-access=}}</ref> Some species have developed unique adaptations that allow them to hunt in the dark. Bats are famous for using [[Animal echolocation|echolocation]] to hunt down their prey, using sonar sounds to capture them in the dark.

===Water conservation===

Another reason for nocturnality is avoiding the heat of the day. This is especially true in [[arid]] biomes like [[desert]]s, where nocturnal behavior prevents creatures from losing precious water during the hot, dry daytime. This is an [[adaptation]] that enhances [[osmoregulation]].<ref>N.&nbsp;A.&nbsp;Campbell (1996) ''Biology'' (4th edition) Benjamin Cummings New York. {{ISBN|0-8053-1957-3}}</ref> One of the reasons that ([[cathemeral]]) lions prefer to hunt at night is to conserve water. [[Hamilton's frog]], found on Stephens and Maud islands, stays hidden for most of the day when temperatures are warmer and is mainly active at night. They will only come out during the day if there are humid and cool conditions.  

Many plant species native to arid biomes have adapted so that their flowers only open at night when the sun's intense heat cannot wither and destroy their moist, delicate blossoms. These flowers are [[pollinate]]d by bats, another creature of the night.

[[Climate change]] has led to an increasing number of diurnal species to push their activity patterns closer towards crepuscular or fully nocturnal behavior. This adaptive measure allows species to avoid the day's heat, without having to leave that particular habitat.<ref>{{Cite journal|last1=Levy|first1=Ofir|last2=Dayan|first2=Tamar|last3=Porter|first3=Warren P.|last4=Kronfeld-Schor|first4=Noga|date=2018-11-12|title=Time and ecological resilience: can diurnal animals compensate for climate change by shifting to nocturnal activity?|journal=Ecological Monographs|volume=89|pages=e01334|language=en|doi=10.1002/ecm.1334|issn=0012-9615|doi-access=free}}</ref>

== Human disturbances ==
The exponential increase in human expansion and technological advances in the last few centuries has had a major effect on nocturnal animals, as well as diurnal species. The causes of these can be traced to distinct, sometimes overlapping areas: [[light pollution]] and spatial disturbance.

=== Light pollution ===
[[File:Light Pollution (5346483205).jpg|thumb|Light pollution on a ski slope in Finland gives the area a hazy, brightened sky.]]
Light pollution is a major issue for nocturnal species, and the impact continues to increase as electricity reaches parts of the world that previously had no access.<ref>{{Cite journal|last1=Gaston|first1=Kevin J.|last2=Davies|first2=Thomas W.|last3=Bennie|first3=Jonathan|last4=Hopkins|first4=John|date=2012-11-02|title=REVIEW: Reducing the ecological consequences of night-time light pollution: options and developments|journal=Journal of Applied Ecology|language=en|volume=49|issue=6|pages=1256–1266|doi=10.1111/j.1365-2664.2012.02212.x|issn=0021-8901|pmc=3546378|pmid=23335816|bibcode=2012JApEc..49.1256G }}</ref> Species in the tropics are generally more affected by this due to the change in their relatively constant light patterns, but temperate species relying on day-night triggers for behavioral patterns are also affected as well. Many diurnal species see the benefit of a "longer day", allowing for a longer hunting period which is detrimental to their nocturnal prey trying to avoid them.<ref name=":1" />

==== Orientation ====
Light pollution can disorient species that are used to darkness, as their adaptive eyes are not as used to the artificial lighting. Insects are the most obvious example, who are attracted by the lighting and are usually killed by either the heat or electrical current.<ref name=":2">{{Cite book|title=Behavioral Approaches to Conservation in the Wild|last=Witherington|first=B.E.|publisher=Cambridge University Press|year=1997 |editor1=Clemmons, J.R. |editor2=Buchholz, R.|location=Cambridge|pages=303–328|chapter=The problem of photopollution for sea turtles and other nocturnal animals}}</ref> Some species of frogs are blinded by the quick changes in light, while nocturnal migratory birds may be disoriented, causing them to lose direction, tire out, or be captured by predators.<ref name=":1" /> Sea turtles are particularly affected by this, adding to a number of threats to the different endangered species. Adults are likely to stay away from artificially lit beaches that they might prefer to lay eggs on, as there is less cover against predators.<ref name=":1" /><ref name=":2" /> Additionally, baby sea turtles that hatch from eggs on artificially lit beaches often get lost, heading towards the light sources as opposed to the ocean.<ref name=":2" />

==== Rhythmic behaviors ====
Rhythmic behaviors are affected by light pollution both seasonally and daily patterns. Migrating birds or mammals might have issues with the timing of their movement for example.<ref name=":2" /> On a day-to-day basis, species can see significant changes in their internal temperatures, their general movement, feeding and body mass.<ref name=":3">{{Cite journal|last1=Gaynor|first1=Kaitlyn M.|last2=Hojnowski|first2=Cheryl E.|last3=Carter|first3=Neil H.|last4=Brashares|first4=Justin S.|date=2018-06-15|title=The influence of human disturbance on wildlife nocturnality|journal=Science|language=en|volume=360|issue=6394|pages=1232–1235|doi=10.1126/science.aar7121|issn=0036-8075|pmid=29903973|bibcode=2018Sci...360.1232G|s2cid=49212187|url=https://escholarship.org/content/qt87b547gj/qt87b547gj.pdf?t=pd32zi|doi-access=free}}</ref> These small scale changes can eventually lead to a population decline, as well as hurting local trophic levels and interconnecting species.<ref name=":3" /> Some typically diurnal species have even become crepuscular or nocturnal as a result of light pollution and general human disturbance.<ref name=":3" />

==== Reproduction ====
There have been documented effects of light pollution on reproductive cycles and factors in different species. It can affect [[mate choice]], migration to breeding grounds, and nest site selection.<ref name=":1" /> In male [[Northern green frog|green frogs]], artificial light causes a decrease in mate calls and continued to move around instead of waiting for a potential mate to arrive.<ref name=":5">{{Cite journal|last1=Baker|first1=B.J.|last2=Richardson|first2=J.M.L.|date=October 2006|title=The effect of artificial light on male breeding-season behaviour in green frogs, Rana clamitans melanota|journal=Canadian Journal of Zoology|volume=84|issue=10|pages=1528–1532|doi=10.1139/z06-142|bibcode=2006CaJZ...84.1528B |issn=0008-4301}}</ref> This hurts the overall [[Fitness (biology)|fitness]] of the species, which is concerning considering the overall decrease in [[amphibian]] populations.<ref name=":5" />

'''Predation'''

Some nocturnal predator-prey relationships are interrupted by artificial lighting. Bats that are fast-moving are often at an advantage with insects being drawn to light; they are fast enough to escape any predators also attracted to the light, leaving slow-moving bats at a disadvantage.<ref name=":1" /> Another example is [[harbor seal]]s eating juvenile [[salmon]] that moved down a river lit by nearby artificial lighting. Once the lights were turned off, predation levels decreased.<ref name=":1" /> Many diurnal prey species forced into being nocturnal are susceptible to nocturnal predators and those species with poor nocturnal eyesight often bear the brunt of the cost.<ref name=":3" />

=== Spatial disturbance ===
The increasing amount of habitat destruction worldwide as a result of human expansion has given both advantages and disadvantages to different nocturnal animals. As a result of peak human activity in the daytime, more species are likely to be active at night in order to avoid the new disturbance in their habitat.<ref name=":6">{{Cite journal|last1=Wu|first1=Yonghua|last2=Wang|first2=Haifeng|last3=Wang|first3=Haitao|last4=Feng|first4=Jiang|date=2018-01-29|title=Arms race of temporal partitioning between carnivorous and herbivorous mammals|journal=Scientific Reports|language=En|volume=8|issue=1|doi=10.1038/s41598-018-20098-6|pmid=29379083|issn=2045-2322|pmc=5789060|page=1713|bibcode=2018NatSR...8.1713W}}</ref> Carnivorous predators however are less timid of the disturbance, feeding on human waste and keeping a relatively similar spatial habitat as they did before.<ref name=":6" /> In comparison, herbivorous prey tend to stay in areas where human disturbance is low, limiting both resources and their spatial habitat. This leads to an imbalance in favor of predators, who increase in population and come out more often at night.<ref name=":6" />

==In captivity==

===Zoos===
In [[zoo]]s, nocturnal animals are usually kept in special [[Nocturnal house|night-illumination enclosures]] to invert their normal [[sleep-wake cycle]] and to keep them active during the hours when visitors will be there to see them.

===Pets===
[[Image:European hedgehog (Erinaceus europaeus).jpg|thumb|Hedgehogs are mostly nocturnal.]]
[[Hedgehog]]s and [[sugar glider]]s are just two of the many nocturnal species kept as ([[exotic pets|exotic]]) pets. Cats have adapted to domestication so that each individual, whether stray alley cat or pampered housecat, can change their activity level at will, becoming nocturnal or [[diurnality|diurnal]] in response to their environment or the routine of their owners. Cats normally demonstrate [[crepuscular]] behavior, bordering nocturnal, being most active in hunting and exploration at dusk and dawn.<ref>{{cite web|title=Nocturnal Activity in Cats|url=http://www.vcahospitals.com/main/pet-health-information/article/animal-health/nocturnal-activity-in-cats/212|publisher=VCA Antech|access-date=7 October 2012|author=Debra Horwitz|author2=Gary Landsberg|archive-url=https://web.archive.org/web/20130501063519/http://www.vcahospitals.com/main/pet-health-information/article/animal-health/nocturnal-activity-in-cats/212|archive-date=1 May 2013|url-status=dead}}</ref>

==See also==
{{commons category|Nocturnality}}
* [[Adaptation]]
* [[Antipredator adaptation]]
* [[Competitive exclusion principle]]
* [[Crepuscular]]
* [[Crypsis]]
* [[Diurnality]]
* [[List of nocturnal animals]]
* [[List of nocturnal birds]]
* [[Niche (ecology)]]
* [[Niche differentiation]]
* [[Night owl (person)]]
* [[Tapetum lucidum]]

==References==
{{reflist}}

{{Light Ethology}}
{{modelling ecosystems}}
{{Evo ecol}}

[[Category:Antipredator adaptations]] <!-- note also used by predators, so leave 'predation' category -->
[[Category:Behavioral ecology]]
[[Category:Biological interactions]]
[[Category:Chronobiology]]
[[Category:Circadian rhythm]]
[[Category:Ethology]]
[[Category:Nocturnal animals| ]]
[[Category:Predation]]
[[Category:Sleep]]