Editing Stoat (section)

===Reproduction and development===
[[File:Mustela.erminea.young.jpg|thumb|Young stoat]]
In the Northern Hemisphere, mating occurs in the April–July period. In spring, the male's [[testes]] are enlarged, a process accompanied by an increase of [[testosterone]] concentration in the [[Blood plasma|plasma]]. [[Spermatogenesis]] occurs in December, and the males are fertile from May to August, after which the testes regress.<ref>Gulamhusein, A. P., and W. H. Tam. "[https://rep.bioscientifica.com/downloadpdf/journals/rep/41/2/jrf_41_2_006.pdf Reproduction in the male stoat, Mustela erminea] {{Webarchive|url=https://web.archive.org/web/20220806231104/https://rep.bioscientifica.com/downloadpdf/journals/rep/41/2/jrf_41_2_006.pdf |date=2022-08-06 }}." Reproduction 41.2 (1974): 303–312.</ref> Female stoats are usually only [[Estrous cycle|in heat]] for a brief period, which is triggered by changes in day length.<ref name="k215">{{Harvnb|King|Powell|2007|pp=215}}</ref> [[Copulation (zoology)|Copulation]] can last as long as 1 hour.<ref>Amstislavsky, Sergei, and Yulia Ternovskaya. "[https://web.archive.org/web/20171117174933/https://pdfs.semanticscholar.org/f3b8/69a6701e7bb11035119faf36745f0bd0fafc.pdf Reproduction in mustelids]." Animal Reproduction Science 60 (2000): 571–581.</ref> Stoats are not [[Monogamy in animals|monogamous]], with litters often being of mixed paternity. Stoats undergo [[embryonic diapause]], meaning that the embryo does not immediately implant in the uterus after fertilization, but rather lies dormant for a period of nine to ten months.<ref name="k209">{{Harvnb|King|Powell|2007|pp=209–210}}</ref> The [[gestation period]] is therefore variable but typically around 300 days, and after mating in the summer, the offspring will not be born until the following spring – adult female stoats spend almost all their lives either pregnant or in heat.<ref name="k215"/> Females can reabsorb embryos and in the event of a severe winter they may reabsorb their entire litter.<ref name="k255">{{Harvnb|King|Powell|2007|pp=255}}</ref> Males play no part in rearing the young, which are born blind, deaf, toothless and covered in fine white or pinkish down. The [[milk teeth]] erupt after three weeks, and solid food is eaten after four weeks. The eyes open after five to six weeks, with the black tail-tip appearing a week later. [[Lactation]] ends after 12 weeks. Prior to the age of five to seven weeks, kits have poor [[thermoregulation]], so they huddle for warmth when the mother is absent. Males become sexually mature at 10–11 months, while females are sexually mature at the age of 2–3 weeks whilst still blind, deaf and hairless, and are usually mated with adult males before being [[weaning|weaned]].<ref name="h464">{{Harvnb|Harris|Yalden|2008|pp=464–465}}</ref>