Reproduction and development The long-tailed weasel mates in July–August, with implantation of the fertilised egg on the uterine wall being delayed until about March. The
gestation period lasts 10 months, with actual embryonic development taking place only during the last four weeks of this period, an adaptation to timing births for spring, when small mammals are abundant. Litter size generally consists of 5–8 kits, which are born in April–May. The kits are born partially naked, blind and weighing , about the same weight of a
hummingbird. The long-tailed weasel's
growth rate is rapid, as by the age of three weeks, the kits are well furred, can crawl outside the nest and eat meat. At this time, the kits weigh . At five weeks of age, the kits' eyes open, and the young become physically active and vocal.
Weaning begins at this stage, with the kits emerging from the nest and accompanying the mother in hunting trips a week later. The kits are fully grown by autumn, at which time the family disbands. The females are able to breed at 3–4 months of age, while males become sexually mature at 15–18 months.
Defense The enemies of the long-tailed weasel are usually
coyotes,
foxes,
wildcats,
wolves, and the
Canadian lynx. The weasel will give off its musky odor, however, this is not primarily used when encountering other creatures. When leaving an area they were just in, they will leave their odor behind. This is done by the weasels taking themselves and hauling their bodies across surfaces they just interacted with. The long-tailed weasel does this to "discourage predators" from coming back to the area, possibly indicating that the weasel considers this a safe haven for return.
Tree-climbing is another type of defense mechanism that long-tailed weasels utilize against predators on the ground. When the long-tailed weasel becomes more white in the
winter, this defense mechanism is especially used. The black-tipped tail distracts predators from the rest of the body, as it is more visible to the eye of a predator. This causes the visibility of the actual weasel to be rather difficult and makes the predator attack the tail instead of the weasel. The weasel is allowed to escape the predator because of this.
Diet The long-tailed weasel is a fearless and aggressive hunter which may attack animals far larger than itself. When stalking, it waves its head from side to side in order to pick up the scent of its prey. It hunts small prey, such as
mice, by rushing at them and killing them with one bite to the head. With large prey, such as
rabbits, the long-tailed weasel strikes quickly, taking its prey off guard. It grabs the nearest part of the animal and climbs upon its body, maintaining its hold with its feet. The long-tailed weasel then manoeuvres itself to inflict a lethal bite to the neck.The long-tailed weasel is an
obligate carnivore which prefers its prey to be fresh or alive, eating only the carrion stored within its burrows.
Rodents are almost exclusively taken when they are available. Its primary prey consists of
mice,
rats,
squirrels,
chipmunks,
shrews,
moles and rabbits. Occasionally, it may eat small
birds, bird eggs,
reptiles,
amphibians,
fish,
earthworms and some
insects. The species has also been observed to take
bats from nursery colonies. It occasionally
surplus kills, usually in spring when the kits are being fed, and again in autumn. Some of the surplus kills may be
cached, but are usually left uneaten. Kits in captivity eat from a quarter to half of their body weight in 24 hours, while adults eat only one fifth to one third. After killing its prey, the long-tailed weasel laps up the blood, but does not suck it, as is popularly believed. With small prey, also the fur, feathers, flesh and bones are consumed, but only some flesh is eaten from large prey. When stealing eggs, the long-tailed weasel removes each egg from its nest one at a time, then carries it in its mouth to a safe location where it bites off the top and licks out the contents or if they have babies in the den they may hold it in their mouth all the way back to them. ==Subspecies==