Editing Beaver (section)

===Family life===
The core of beaver social organization is the family, which is composed of an adult male and an adult female in a [[Pair bond|monogamous pair]] and their offspring.<ref name="MacDonald"/><ref name=Pelagic/> Beaver families can have as many as ten members; groups about this size require multiple lodges.{{sfn|Müller-Schwarze|Sun|2003|pp=30–31}} [[Mutual grooming]] and play fighting maintain bonds between family members, and aggression between them is uncommon.<ref name=Pelagic/>

Adult beavers mate with their partners, though partner replacement appears to be common. A beaver that loses its partner will wait for another one to come by. [[Estrus]] cycles begin in late December and peak in mid-January. Females may have two to four estrus cycles per season, each lasting 12–24 hours. The pair typically mate in the water and to a lesser extent in the lodge, for half a minute to three minutes.{{sfn|Müller-Schwarze|Sun|2003|pp=80, 85}}

Up to four young, or kits, are born in spring and summer, after a three or four-month [[gestation]].<ref name="Pelagic" />{{sfn|Müller-Schwarze|Sun|2003|p=80}} Newborn beavers are [[precocial]] with a full fur coat, and can open their eyes within days of birth.<ref name="JohnHopkins" /><ref name="Pelagic" /> Their mother is the primary caretaker, while their father maintains the territory.<ref name="MacDonald" /> Older siblings from a previous litter also play a role.{{sfn|Müller-Schwarze|Sun|2003|pp=32–33}}

After they are born, the kits spend their first one to two months in the lodge. Kits suckle for as long as three months, but can eat solid food within their second week and rely on their parents and older siblings to bring it to them. Eventually, beaver kits explore outside the lodge and forage on their own, but may follow an older relative and hold onto their backs.<ref name="Pelagic" /> After their first year, young beavers help their families with construction.<ref name="MacDonald" /> Beavers sexually mature around 1.5–3 years.<ref name="JohnHopkins" /> They become independent at two years old, but remain with their parents for an extra year or more during times of food shortage, high population density, or drought.{{sfn|Müller-Schwarze|Sun|2003|pp=332–333, 100–101}}<ref>{{cite journal|last1=Mayer|first1=M|last2=Zedrosser|first2=A|last3=Rosell|first3=F|year=2017|title=When to leave: the timing of natal dispersal in a large, monogamous rodent, the Eurasian beaver|journal=Animal Behaviour|volume=123|pages=375–382|doi=10.1016/j.anbehav.2016.11.020|s2cid=53183887}}</ref>