{{Short description|Genus of marsupials}} {{Automatic taxobox | image = Agile Antechinus (Antechinus agilis) on cloth, close-up from front.jpg | display_parents = 2 | taxon = Antechinus | authority = Macleay, 1841 | type_species = ''Antechinus stuartii'' | type_species_authority = Macleay, 1841 | subdivision_ranks = Species | subdivision = *''A. adustus'' *''A. agilis'' *''A. argentus'' *''A. arktos'' *''A. bellus'' *''A. flavipes'' *''A. godmani'' *''A. leo'' *''A. mimetes'' *''A. minimus'' *''A. mysticus'' *''A. stuartii'' *''A. subtropicus'' *''A. swainsonii'' *''A. vandycki'' }} [[File:Yellow-footed Antechinus (Antechinus flavipes) (17067818099).jpg|thumb|right|In central Victoria]]
'''''Antechinus''''' ({{IPAc-en|æ|n|t|ɪ|ˈ|k|aɪ|n|ə|s}}, 'ant-echinus') is a genus of small dasyurid marsupial endemic to Australia. They resemble mice with the bristly fur of shrews.
==Names== They are also sometimes called 'broad-footed marsupial mice', 'pouched mice', or 'Antechinus shrews'. However, the majority of those common names are considered either regional or archaic; the modern common name for the animal is antechinus.
==Description== ''Antechinus'' have short fur and are generally greyish or brownish in colour, varying with species.<ref name=":123" /> The fur is dense and generally soft. Their tails are thin and tapering and range from slightly shorter to slightly longer than body length.<ref name=":123" /> Their heads are conical in shape and ears are small to medium in size.<ref name=":123" /> Some species have a relatively long, narrow snout that gives them a shrew-like appearance.<ref name=":123" /> Species vary from {{Convert|12-31|cm|abbr=on}} in length and weigh {{Convert|16–170|g|abbr=on}} when fully grown.<ref name=":123" /> ''A. agilis'' is the smallest known species, and ''A. swainsonii'' the largest.
Sexual dimorphism occurs in most species for both weight and skeletal measurements, with males being typically larger and heavier.<ref name=":0" />
Most species nest communally in tree-hollows.<ref name=":123" /> They primarily inhabit all forests, woodlands and rainforest as well as heaths and grasslands in some species.<ref name=":123" /> The majority of ''Antechinus'' species are located on the eastern coast of Australia along the Great Dividing Range.<ref name=":123" /> There is a population of ''A. flavipes'' in south west Western Australia.<ref name=":182" /> ''A. bellus'' lives in northern Australia around the Gulf of Carpentaria.<ref name=":182" />
==Taxonomy== There are currently 15 recognised species of ''Antechinus'' with a number of subspecies.<ref name=":182">{{Cite journal|last1=Mutton|first1=Thomas Y|last2=Phillips|first2=Matthew J|last3=Fuller|first3=Susan J|last4=Bryant|first4=Litticia M|last5=Baker|first5=Andrew M|date=2019-04-27|title=Systematics, biogeography and ancestral state of the Australian marsupial genus Antechinus (Dasyuromorphia: Dasyuridae)|journal=Zoological Journal of the Linnean Society|volume=186|issue=2|pages=553–568|doi=10.1093/zoolinnean/zly062|issn=0024-4082|doi-access=free}}</ref> A few species of New Guinean ''Antechinus'' were recognised, but they have been reclassified into the genus ''Murexia''.<ref>{{Cite journal|last1=Grossek|first1=G. L.|last2=Woolley|first2=P. A.|last3=Menzies|first3=J. I. |date=2010|title=The diet of some New Guinean dasyurid marsupials |journal=Australian Mammalogy |volume=32 |issue=2 |pages=145 |doi=10.1071/am10002 |issn=0310-0049}}</ref> The interspecific relations of the genus ''Antechinus'' are still under review.<ref name=":182" /> The currently accepted phylogeny is the presence of four clades within the ''Antechinus'' genus.<ref name=":182" /><ref>{{Cite journal |last1=Baker |first1=Andrew |last2=Mutton |first2=T. |last3=Mason |first3=E. |last4=Gray |first4=E. |date=2015 |title=A taxonomic assessment of the Australian Dusky Antechinus Complex: a new species, the Tasman Peninsula Dusky Antechinus (Antechinus vandycki sp. nov.) and an elevation to species of the Mainland Dusky Antechinus (Antechinus swainsonii mimetes (Thomas))|journal=Memoirs of the Queensland Museum – Nature |volume=59 |pages=75–126 |doi=10.17082/j.2204-1478.59.2015.2014-10 |issn=0079-8835 |doi-access=free|url=https://www.biodiversitylibrary.org/partpdf/306755 }}</ref> Generally, the clades are formed by species with similar geographic distributions.<ref name=":182" />
Clade 1 (dusky antechinus)
*''A. arktos'' (black-tailed antechinus) *''A. mimetes'' <small>(</small>mainland dusky antechinus)<ref name="Australian Dusky Antechinus Complex 1478">{{Cite journal|last1=Baker|last2=Mutton|last3=Mason|last4=Gray|year=2015|title=A taxonomic assessment of the Australian Dusky Antechinus Complex: a new species, the Tasman Peninsula Dusky Antechinus (Antechinus vandycki sp. nov.) and an elevation to species of the Mainland Dusky Antechinus (Antechinus swainsonii mimetes (Thomas))|journal=Memoirs of the Queensland Museum|volume=59|pages=75–126|doi=10.17082/j.2204-1478.59.2015.2014-10|doi-access=free|url=https://www.biodiversitylibrary.org/partpdf/306755}}</ref> *''A. minimus'' (swamp antechinus) *''A. swainsonii'' (Tasmanian dusky antechinus) *''A. vandycki'' (Tasman Peninsula dusky antechinus)<ref name="Australian Dusky Antechinus Complex 1478"/>
Clade 2
*''A. godmani'' (Atherton antechinus)
Clade 3 (brown antechinus)
*''A. agilis'' (agile antechinus) *''A. stuartii'' (brown antechinus) *''A. subtropicus'' (subtropical antechinus)
Clade 4
*''A. argentus'' (silver-headed antechinus)<ref>{{cite journal|author=Andrew M Baker, Thomas Y Mutton & Harry B Hines|year=2013|title=A new dasyurid marsupial from Kroombit Tops, south-east Queensland, Australia: the silver-headed antechinus, ''Antechinus argentus'' sp. nov. (Marsupialia: Dasyuridae)|journal=Zootaxa|volume=3746|issue=2|pages=201–239|doi=10.11646/zootaxa.3746.2.1|pmid=25113476}}</ref> *''A. adustus'' (rusty antechinus) *''A. bellus'' (fawn antechinus) *''A. flavipes'' (yellow-footed antechinus) *''A. leo'' (cinnamon antechinus) *''A. mysticus'' (buff-footed antechinus)<ref>Baker, A.M.; Mutton, T.Y.; Dyck, S. van 2012: A new dasyurid marsupial from eastern Queensland, Australia: the buff-footed Antechinus, ''Antechinus mysticus'' sp. nov. (Marsupialia: Dasyuridae). ''Zootaxa'', ('''3515'''): 1-37. [http://mapress.com/zootaxa/2012/f/z03515p037f.pdf Preview]</ref>
== Diet == [[File:Beutelgilbmaus brehm.png|thumb|Illustration from Brehms Tierleben, showing an unknown species of ''Antechinus'']] ''Antechinus'' are mainly insectivorous, but the exact composition of their diet can vary by species and habitat.<ref name=":132">{{Cite journal|last=Hall|first=S|date=1980|title=The Diets of Two Coexisting Species of Antechinus (Marsupialia: Dasyuridae).|journal=Wildlife Research|volume=7|issue=3|pages=365|doi=10.1071/wr9800365|bibcode=1980WildR...7..365H|issn=1035-3712}}</ref><ref name=":142">{{Cite journal|last=Green|first=K|date=1989|title=Altitudinal and Seasonal Differences in the Diets of Antechinus-Swainsonii and Antechinus-Stuartii (Marsupialia, Dasyuridae) in Relation to the Availability of Prey in the Snowy Mountains|journal=Wildlife Research|volume=16|issue=6|pages=581|doi=10.1071/wr9890581|bibcode=1989WildR..16..581G|issn=1035-3712}}</ref> ''Antechinus'' mainly eat beetles, insect larvae and spiders.<ref name=":132" /><ref name=":152">{{Cite journal|last1=Allison|first1=Louise M.|last2=Gibson|first2=Lesley A.|last3=Aberton|first3=John G.|date=2006|title=Dietary strategy of the swamp antechinus (Antechinus minimus maritimus) (Marsupialia:Dasyuridae) in coastal and inland heathland habitats|journal=Wildlife Research|volume=33|issue=1|pages=67|doi=10.1071/wr05038|bibcode=2006WildR..33...67A |issn=1035-3712}}</ref> Amphipods, millipedes and centipedes are also quite common in their diets.<ref name=":132" /><ref name=":152" /> It has been found that after a fire, ants make up the majority of their diet—this is thought to be because ants are the only insect present in any number after the fire.<ref name=":113">{{Cite journal|last1=Matthews|first1=Jaya K.|last2=Stawski|first2=Clare|last3=Körtner|first3=Gerhard|last4=Parker|first4=Cassandra A.|last5=Geiser|first5=Fritz|date=2016-10-12|title=Torpor and basking after a severe wildfire: mammalian survival strategies in a scorched landscape|journal=Journal of Comparative Physiology B|volume=187|issue=2|pages=385–393|doi=10.1007/s00360-016-1039-4|pmid=27734149|s2cid=13226464|issn=0174-1578}}</ref> It has been reported that ''Antechinus'' also eat vertebrates, mainly small reptiles, such as skinks, or mammals, such as feathertail gliders.<ref name=":123">{{Cite book|last1=Baker|first1=Andrew|last2=Dickman|first2=Chris|date=2018|title=Secret Lives of Carnivorous Marsupials|doi=10.1071/9781486305155|isbn=9781486305155}}</ref><ref name=":162">{{Cite journal|last1=Lunney|first1=Daniel|last2=Matthews|first2=Alison|last3=Grigg|first3=Jan|date=2001|title=The diet of Antechinus agilis and A. swainsonii in unlogged and regenerating sites in Mumbulla State Forest, south-eastern New South Wales|journal=Wildlife Research|volume=28|issue=5|pages=459|doi=10.1071/wr00015|bibcode=2001WildR..28..459L |issn=1035-3712}}</ref> This is likely to occur most commonly when the ''Antechinus'' are food stressed.<ref name=":162" /> The remains of plants have been found in ''Antechinus'' stool, likely accidentally ingested while searching for other food.<ref name=":152" /> Studies on ''Antechinus'' diet usually use faecal samples which may be unreliable in detecting soft bodied prey.<ref name=":132" /><ref name=":152" />
''Antechinus'' are usually classified as dietary generalists as they eat a wide variety of invertebrates as well as some vertebrates.<ref name=":123" /><ref name=":152" /><ref>{{Cite journal|last1=Mason|first1=Eugene D.|last2=Burwell|first2=Chris J.|last3=Baker|first3=Andrew M.|date=2015|title=Prey of the silver-headed antechinus (Antechinus argentus), a new species of Australian dasyurid marsupial|journal=Australian Mammalogy|volume=37|issue=2|pages=164|doi=10.1071/am14036|issn=0310-0049}}</ref> They are also classified as opportunists because they feed on most of the prey available to them<ref name=":123" /><ref name=":162" /><ref>{{Cite journal|last1=Fox|first1=BJ|last2=Archer|first2=E|date=1984|title=The Diets of Sminthopsis Murina and Antechinus Stuartii (Marsupialia: Dasyuridae) in Sympatry.|journal=Wildlife Research|volume=11|issue=2|pages=235|doi=10.1071/wr9840235|bibcode=1984WildR..11..235F |issn=1035-3712}}</ref> However, they do show preference for some prey, i.e. beetles, spiders and larvae, especially when they are not food stressed.<ref name=":132" /><ref name=":162" />
The microhabitat and foraging techniques vary between species.<ref name=":142" /> Smaller species, such as ''A. stuartii,'' are scansorial and mainly hunt in trees.<ref name=":162" /> They have been observed jumping between branches to catch flying insects.<ref name=":172">{{Citation|last=Dickman|first=Chris R.|chapter=Use of trees by ground-dwelling mammals: implications for management|date=1991|pages=125–136|publisher=Royal Zoological Society of New South Wales|isbn=0959995153|doi=10.7882/rzsnsw.1991.012|title=Conservation of Australia's Forest Fauna}}</ref> The larger species of ''Antechinus'', such as ''A. swainsonii,'' are completely ground dwelling and forage in the leaf litter.<ref name=":162" /><ref name=":172" />
The efficiency of ''Antechinus'' hunting increases with their age as they learn which prey are the best to eat.<ref name=":123" /> ''Antechinus'' have been observed scraping slugs on rocks and other objects to remove the mucus and make them more palatable.<ref name=":123" />
==Reproduction== ''Antechinus'' have an extremely unusual reproductive system. The females are synchronously monoestrous with mating occurring over a short three-week period.<ref name=":0">{{Cite journal |last=Marlow |first=B.J. |date=1961 |title=Reproductive Behaviour of the Marsupial Mouse, antechinus flavipes (Waterhouse) (Marsupialia) and the development of the Pouch young |journal=Australian Journal of Zoology |volume=9 |issue=2 |pages=203 |doi=10.1071/zo9610203 |issn=0004-959X}}</ref><ref name=":1">{{Cite journal |last1=McAllan |first1=Bronwyn M. |last2=Dickman |first2=Christopher R |last3=Crowther |first3=Mathew S. |date=2006-02-24 |title=Photoperiod as a reproductive cue in the marsupial genus Antechinus: ecological and evolutionary consequences |journal=Biological Journal of the Linnean Society |volume=87 |issue=3 |pages=365–379 |doi=10.1111/j.1095-8312.2006.00571.x |issn=0024-4066|doi-access=free}}</ref> The males experience mass mortality after mating, with male survival only observed in very rare cases.<ref name=":1" /> Females often mate twice or, in some cases, three times during their lives.<ref name=":6">{{Cite journal |last1=Cockburn |first1=Andrew |last2=Lee |first2=Anthony K. |last3=Martin|first3=Roger W. |date=1983 |title=Macrogeographic Variation in Litter Size in Antechinus (Marsupialia: Dasyuridae) |journal=Evolution |volume=37 |issue=1 |pages=86–95 |doi=10.2307/2408177 |issn=0014-3820 |jstor=2408177 |pmid=28568025}}</ref> The gestation period varies by species between 25 and 35 days.<ref name=":1" /> The offspring are independent after about 90–100 days, depending on the species.<ref name=":0" /> That development period is rather long compared with other, similarly sized marsupials.<ref name=":0" />
===Timing of the breeding season=== The timing of the breeding season differs between species and also with the location of populations.<ref name=":1" /><ref name=":3">{{Cite journal |last1=Cockburn |first1=Andrew |last2=Scott |first2=Michelle P. |last3=Scotts |first3=David J. |date=1985 |title=Inbreeding avoidance and male-biased natal dispersal in Antechinus spp. (Marsupialia: Dasyuridae) |journal=Animal Behaviour |volume=33 |issue=3 |pages=908–915 |doi=10.1016/s0003-3472(85)80025-7 |s2cid=53206203 |issn=0003-3472}}</ref> The breeding season is in winter or early spring of the Southern Hemisphere, from July to September.<ref name=":2">{{Cite journal |last=Dickman |first=Chris R. |date=1985 |title=Effects of photoperiod and endogenous control on timing of reproduction in the marsupial genus Antechinus |journal=Journal of Zoology |volume=206 |issue=4 |pages=509–524 |doi=10.1111/j.1469-7998.1985.tb03555.x |issn=0952-8369}}</ref> The timing of the breeding season changes very little at the same location between different years.<ref name=":2" /> The rate of change of photoperiod, the length of daylight, determines the commencement of the breeding season.<ref name=":1" /> Different species respond to different critical rates of change, for example 80% of ''A. stuartii'' ovulate when the photoperiod is increasing by a rate of 97-117s/day.<ref name=":1" /> The critical rate also varies by location within species.
''Antechinus'' live in the relatively stable environments along the east coast of Australia.<ref name=":1" /> Responding to the photoperiod, rather than temperature or rainfall, allows ''Antechinus'' to have young developing before the seasonal increase of food experienced, rather than waiting for the increase of food and possibly missing the window of opportunity. The timing of mating ensures that the offspring are weaning when there is a large amount of food available in the environment.<ref name=":2" /> The timing of the increase in food changes throughout the different ranges of the various species of ''Antechinus'', a reason for different species having different mating seasons.<ref name=":1" />
Many species of ''Antechinus'' occur sympatrically.<ref name=":1" /> Whenever two or more species of ''Antechinus'' occur together, the critical rate of change of photoperiod which triggers ovulation differs between the species.<ref name=":1" /><ref>{{Cite journal|last1=McAllan|first1=B. M.|last2=Dickman|first2=C. R.|date=1986|title=The role of photoperiod in the timing of reproduction in the Dasyurid Marsupial Antechinus stuartii|journal=Oecologia|volume=68|issue=2|pages=259–264|doi=10.1007/bf00384797|pmid=28310137|bibcode=1986Oecol..68..259M|s2cid=23924636|issn=0029-8549}}</ref> This reproductive isolation may have led to sympatric speciation.<ref name=":1" /> There is a possible genetic link that would allow for the selection of specific responses to different rates of change of photoperiod.<ref name=":1" /> The slightly different timings of reproduction by these sympatric species may also mean that they can take advantage of different increases of food in the spring and summer.<ref name=":1" /> Larger species of ''Antechinus'' usually mate first, meaning that the smaller species may have evolved later mating times to reduce competition and capitalise on later increases in food.<ref name=":1" />
''A. swainsonii'' and ''A. minimums'' occur in Tasmania and their reliance on the rate of change of the photoperiod for reproduction is less certain.<ref name=":1" /> That is because in higher latitudes the photoperiod changes much faster. Animals that mate when the photoperiod is changing by 35-90s/day would only have two or three days in Tasmania, compared with two weeks in New South Wales.<ref name=":1" />
Females control the synchrony of mating, with males reproductively mature and ready to mate four or five weeks before the breeding season.<ref name=":2" /><ref name=":4">{{Cite journal |last=Scott |first=M. P. |date=1986-08-08 |title=The Timing and Synchrony of Seasonal Breeding in the Marsupial, Antechinus stuartii: Interaction of Environmental and Social Cues |journal=Journal of Mammalogy |volume=67 |issue=3 |pages=551–560 |doi=10.2307/1381287 |issn=1545-1542 |jstor=1381287}}</ref> Males have been selected to be ready before the females to ensure the maximum amount of time for mating.
thumb|Pouch of agile antechinus (''A. agilis''), showing offspring inside
===Reproductive anatomy=== ''Antechinus'' do not have a complete pouch, as in other marsupials, but simply a flap of skin covering the teats.<ref name=":123" /> The number of teats in ''Antechinus'' species varies between different populations of the same species,<ref name=":0" /><ref name=":6" /> and can be anywhere from six to 13.<ref name=":6" /> Populations in which females have six teats are found in lower latitudes where the environment is more stable. In higher latitudes, there are populations with eight to 12 nipples. Odd numbers of teats only occur in transition zones and probably occur when populations with a different number of teats mate.<ref name=":6" /> The number of nipples is thought to correlate with the number of young that can be supported. In more seasonal environments, where more nipples occur, there is a larger increase in the availability of food for supporting the young.<ref name=":6" /> Females with fewer nipples are more likely to survive until the next breeding season. This is thought to be because it is less stressful to raise a smaller litter.<ref name=":6" /> The rate of survival of females to reproduce twice differs between species. The larger species, e.g. ''A. swainsonii'' are more likely to survive to reproduce for a second time.<ref name=":6" />
===Mating behaviour=== Mating is intense for ''Antechinus'' and can last up to 12 hours in some species.<ref name=":0" /><ref name=":5">{{Cite journal |last=Scott |first=M. P. |date=1987-08-28 |title=The Effect of Mating and Agonistic Experience on Adrenal Function and Mortality of Male Antechinus stuartii (Marsupialia) |journal=Journal of Mammalogy |volume=68 |issue=3 |pages=479–486 |doi=10.2307/1381584 |issn=1545-1542 |jstor=1381584}}</ref> The males mate with a number of females and the litters have a number of fathers.<ref name=":0" /> During the short breeding window, males expand their home range and are often active during night and day.<ref name=":5" />
Males disperse from the nests once they are physiologically independent. Mothers initiate that dispersal but are tolerant of unrelated males in the nest. Inbreeding avoidance is likely to explain that behaviour.<ref name=":3" />
=== Male semelparity=== {{Main|Semelparity and iteroparity}} Male die-off occurs because of an increase in free corticosteroids in the blood,<ref name=":5" /> which causes a suppression of the immune system and internal hemorrhaging and which result in male mortality.<ref name=":5" /><ref>{{Cite journal |last1=McDonald |first1=I.R. |last2=Lee |first2=A.K. |last3=Bradley |first3=A.J. |last4=Than |first4=K.A.|date=1981 |title=Endocrine changes in dasyurid marsupials with differing mortality patterns|journal=General and Comparative Endocrinology |volume=44 |issue=3 |pages=292–301 |doi=10.1016/0016-6480(81)90004-6 |pmid=7286612 |issn=0016-6480}}</ref><ref>{{Cite journal |last1=Bradley |first1=A. J. |last2=McDonald |first2=I. R. |last3=Lee |first3=A. K. |date=1975 |journal=Journal of Endocrinology |volume=66 |issue=2 |pages=281–282 |doi=10.1677/joe.0.0660281 |issn=0022-0795 |title=Effect of Exogenous Cortisol on Mortality of a Dasyurid Marsupial |pmid=1165455}}</ref> An increase in free corticosteroids is thought to allow males to utilise their reserve energy and maximise their reproductive effort, even though the increase usually proves fatal.<ref name=":5" /> If there were no male die-off, there would still only be a small likelihood of males surviving to the next mating period.<ref name=":1" /> Thus, it is far better for the males to invest heavily in one breeding season than attempt to survive to the next one.
There are a few possible evolutionary advantages to the evolution of synchronous mating. It may ensure that as many matings as possible occur during the mating period. It also ensures that males can focus all their effort into one short breeding season. Another possible advantage of synchronous mating is to overwhelm predators with large numbers of offspring after weaning.<ref name=":4" />
== Torpor == Torpor is periodic lowering of body temperature and metabolic rate to reduce energy consumption.<ref name=":7">{{Cite journal|last1=Geiser|first1=Fritz|last2=Körtner|first2=Gerhard|date=2010|title=Hibernation and daily torpor in Australian mammals|journal=Australian Zoologist|volume=35|issue=2|pages=204–215|doi=10.7882/az.2010.009|issn=0067-2238|doi-access=free|hdl=10072/37379|hdl-access=free}}</ref> Many marsupials undergo torpor as well as some birds and placental mammals.<ref name=":7" /> There are two types of torpor: hibernation which is long term (weeks or months) and daily torpor which is usually only a few hours.<ref name=":7" /> Daily torpor involves a less extreme lowering of body temperature and metabolic rate than hibernation. ''Antechinus'' undergo daily torpor.<ref>{{Cite journal|last=Wallis|first=Robert L.|date=1976|title=Torpor in the dasyurid marsupial Antechinus stuartii|journal=Comparative Biochemistry and Physiology Part A: Physiology|volume=53|issue=4|pages=319–322|doi=10.1016/s0300-9629(76)80147-8|pmid=3311|issn=0300-9629}}</ref>
Unlike hibernation, daily torpor is not simply reliant on ambient air temperatures.<ref name=":82">{{Cite journal|last=Geiser|first=Fritz|date=1988|title=Daily torpor and thermoregulation in antechinus (Marsupialia): influence of body mass, season, development, reproduction, and sex|journal=Oecologia|volume=77|issue=3|pages=395–399|doi=10.1007/bf00378050|pmid=28311957|bibcode=1988Oecol..77..395G|s2cid=21801223|issn=0029-8549}}</ref> ''Antechinus'' can move into torpor on summer days with temperatures in the range of {{Convert|25-30|C}}.<ref name=":82" /> This is called spontaneous torpor. Induced torpor occurs when food and water are restricted – this is most easily observed in a laboratory environment as restriction of food in the wild is hard to determine.<ref name=":7" /> Torpor of ''Antechinus'' in the wild is likely to be the result of a combination of factors.<ref name=":82" />
''Antechinus'' are small mammals and thus have a high surface/volume ratio which results in high heat loss.<ref name=":82" /> They also have a high metabolic rate and normothermic temperatures of around {{Convert|35|°C}}.<ref name=":92">{{Cite journal|last=Geiser|first=F|date=1994|title=Hibernation and Daily Torpor in Marsupials - a Review|journal=Australian Journal of Zoology|volume=42|issue=1|pages=1|doi=10.1071/zo9940001|s2cid=84914662|issn=0004-959X}}</ref> Going into torpor allows them to greatly reduce metabolic rates, sometimes up to 80%<ref name=":7" /> This reduces both the food and water requirements of the animal.
Torpor in ''Antechinus'' usually occurs during rest periods, either in the early morning after nightly foraging or the late afternoon before nightly foraging.<ref name=":7" /><ref name=":102">{{Cite journal|last1=Rojas|first1=A. Daniella|last2=Körtner|first2=Gerhard|last3=Geiser|first3=Fritz|date=2014-01-18|title=Torpor in free-ranging antechinus: does it increase fitness?|journal=Naturwissenschaften|volume=101|issue=2|pages=105–114|doi=10.1007/s00114-013-1136-0|pmid=24441710|bibcode=2014NW....101..105R|s2cid=14137977|issn=0028-1042}}</ref> However, going into torpor during the night is not uncommon.<ref name=":113" /> Torpor allows the animals to conserve energy while they are not foraging. The substantial savings in water requirements during torpor may also help ''Antechinus'' cope with droughts.<ref name=":7" />
Body mass is an important factor for the induction of torpor, with larger animals less likely to go into torpor and more likely to stay in torpor for shorter periods of time.<ref name=":82" /> This means that males go into torpor less frequently than females. Lactating females do not go into torpor.<ref name=":82" /> Torpor in ''Antechinus'' can last for one to nine hours and in extreme cases nearly 20 hours.<ref name=":7" /> The body temperatures of these animals drops significantly.<ref name=":102" /> In female ''A. flavipes'' the minimum body temperature during torpor can be around {{Convert|20|°C}}.<ref name=":92" /><ref name=":102" /> In males it is higher, around {{Convert|30|°C}}.<ref name=":92" /><ref name=":102" /> Smaller animals have a lower body temperature during torpor.<ref name=":7" />
An increase in the induction of torpor in ''Antechinus'' has been found to occur after intense bushfires.<ref name=":113" /> Intense bushfires destroy the dense undergrowth that provide ''Antechinus'' with shelter and food. After intense bush fires ''Antechinus'' were recorded as eating mainly ants, which usually form a very small part of their diet.<ref name=":113" /> Increasing the occurrences of torpor, in both males and females, is thought to help with survival after an intense bushfire by reducing the need for foraging and thus avoiding predators.<ref name=":113" /> It has been shown that smoke, ash and charcoal provide a cue for torpor induction.<ref>{{Cite journal|last1=Stawski|first1=Clare|last2=Nowack|first2=Julia|last3=Körtner|first3=Gerhard|last4=Geiser|first4=Fritz|date=2017-01-15|title=A new cue for torpor induction: charcoal, ash and smoke|journal=The Journal of Experimental Biology|volume=220|issue=2|pages=220–226|doi=10.1242/jeb.146548|pmid=28100803|issn=0022-0949|doi-access=free|bibcode=2017JExpB.220..220S |url=https://researchonline.ljmu.ac.uk/id/eprint/9175/1/A%20new%20cue%20for%20torpor%20induction%20charcoal%2C%20ash%20and%20smoke.pdf}}</ref>
Increasing body temperature after torpor is energetically costly and reduces some of the metabolic savings.<ref name=":7" /> However, animals have been observed basking to help increase their body temperature without increasing their food intake.<ref name=":113" />
Females that have survived to a second year go into torpor much more frequently than females that are in their first year, even though second-year females are larger.<ref name=":102" /> It is thought that this is because first-year females are still growing and thus need more food which requires more time spent foraging.<ref name=":102" /> Older females are also more experienced at foraging and may meet their energy requirements more efficiently.<ref name=":102" /><ref name=":123" />
== Threats == ''A. arktos'' and ''A. argentus'' are currently listed as endangered.<ref>{{Cite journal |last1=Baker |first1=Andrew M. |last2=Mutton |first2=Thomas Y. |last3=Hines |first3=Harry B.|date=2013-12-11|title=A new dasyurid marsupial from Kroombit Tops, south-east Queensland, Australia: the Silver-headed <em>Antechinus</em>, <em>Antechinus argentus</em> sp. nov. (Marsupialia: Dasyuridae)|journal=Zootaxa|volume=3746|issue=2|pages=201–39|doi=10.11646/zootaxa.3746.2.1|pmid=25113476|issn=1175-5334}}</ref><ref>{{Cite journal|last1=Gray|first1=Emma L.|last2=Burwell|first2=Chris J.|last3=Baker|first3=Andrew M.|date=2016|title=Benefits of being a generalist carnivore when threatened by climate change: the comparative dietary ecology of two sympatric semelparous marsupials, including a new endangered species (Antechinus arktos)|journal=Australian Journal of Zoology|volume=64|issue=4|pages=249|doi=10.1071/zo16044|s2cid=88872665|issn=0004-959X}}</ref> The main threats to those species, indeed all species of ''Antechinus'', are habitat destruction and introduced animals.<ref name=":192">{{Cite journal|last1=Stokes|first1=Vicki L|last2=Pech|first2=Roger P|last3=Banks|first3=Peter B|last4=Arthur|first4=Anthony D|date=2004|title=Foraging behaviour and habitat use by Antechinus flavipes and Sminthopsis murina (Marsupialia: Dasyuridae) in response to predation risk in eucalypt woodland|journal=Biological Conservation|volume=117|issue=3|pages=331–342|doi=10.1016/j.biocon.2003.12.012|bibcode=2004BCons.117..331S |issn=0006-3207}}</ref>
Deforestation and habitat destruction removes the complex understorey habitat which ''Antechinus'' require for protection from predators and for food.<ref name=":192" /><ref name=":20">{{Cite journal|last1=Lada|first1=Hania|last2=Mac Nally|first2=Ralph|date=2008|title=Decline and potential recovery of Yellow-footed Antechinus in parts of south-eastern Australia: A perspective with implications for management|journal=Ecological Management & Restoration|volume=9|issue=2|pages=120–125|doi=10.1111/j.1442-8903.2008.00403.x|bibcode=2008EcoMR...9..120L |issn=1442-7001}}</ref> ''Antechinus'' also nest in tree hollows, which only form in senescent trees.<ref>{{Citation|last1=Dickman|first1=Chris R.|title=Use of habitat by mammals in eastern Australian forests: are common species important in forest management?|date=2004|work=Conservation of Australia's Forest Fauna|pages=761–773|publisher=Royal Zoological Society of New South Wales|isbn=095860858X|last2=Steeves|first2=Tracey E.|doi=10.7882/fs.2004.046|doi-access=free}}</ref><ref>{{Cite journal|last1=Naylor|first1=R.|last2=Richardson|first2=S. J.|last3=McAllan|first3=B. M.|date=2008-01-22|title=Boom and bust: a review of the physiology of the marsupial genus Antechinus|journal=Journal of Comparative Physiology B|volume=178|issue=5|pages=545–562|doi=10.1007/s00360-007-0250-8|pmid=18210128|s2cid=11591839|issn=0174-1578}}</ref>
Introduced predators, especially foxes and cats, threaten ''Antechinus'' populations by predating on them.<ref name=":192" /> There is also competition between ''Antechinus'' and introduced rats and mice for habitat and food, which may be detrimental to ''Antechinus'' numbers.<ref>{{Cite journal |last1=Glen |first1=Alistair S. |last2=Dickman |first2=Chris R. |s2cid=34517892 |date=2005-04-13 |title=Complex interactions among mammalian carnivores in Australia, and their implications for wildlife management |journal=Biological Reviews |volume=80 |issue=3 |pages=387–401 |doi=10.1017/s1464793105006718 |pmid=16094805 |issn=1464-7931}}</ref> Pigs, cattle and horses trample ''Antechinus'' habitats.<ref name=":123" />
Changed fire regimes since European colonisation have resulted in more intense bushfires, which can adversely affect ''Antechinus'' populations by destroying understorey vegetation and removing their preferred food.<ref name=":113" /><ref name=":20" />
Climate change threatens several high altitude species, especially those in northern Queensland.<ref name=":123" />
== References == {{Reflist}}
{{Dasyuromorphia|D.D.}} {{Taxonbar|from=Q650656}} {{Authority control}}
Category:Dasyuromorphs Category:Marsupial genera Category:Taxa named by William Sharp Macleay