FAMILY: Least Weasel Short-tailed Weasel Long-tailed Weasel American Mink Mustelidae Mustela nivalis Mustela erminea Mustela frenata Neovison vison Also M. (Putorius) nigripes (Previously M. rixosa) (Previously M. (Lutreola) vison) (Black-footed Ferret) Length, total 6 ¾ – 9 ¾” 7 ½ – 13 ½ “ 11 – 22 “ 19 ⅜ – 22” Length, head+body 5 ⅞–7 ¼ “1; 5–10”2 5 ⅞–11“1; 7–13”2 7 ⅞–15 ⅝ “1; 9–10”2 13 ⅛–14 ⅜ “1; 14–22”2 Length, tail ⅞– 1 ¼” 1 ⅝– 3 ½ “ 3 ⅛ – 6 ⅜ “ 6 ¼ – 7 ⅝ “ tail, relative to body 10– 15% ~ 25% 50 – 100% 38 - 50% Weight 28 – 84 g 45 – 182 g 85 – 267 g 700 – 1,600 g (smaller in northern parts ♂ (<9.8”) larger than ♀ ♂ 2x size of ♀ ♂ 2x size of ♀ Weight varies with season of range) (<8.8”) 푥̅ = ♀ 111g; ♂ 195g; juv ♂ 162 g ♂ 2x larger than ♀ Physical Description Tiny. Dark brown above, Dark brown above, white Brown above, white to deep yellow Lustrous chocolate brown to white below. Tail very short below; brown tail with black tip. below. Brown tail with black tip. black fur, white spotting on and all brown. Feet white. Feet white. Turns white in Feet brown-ish. Tail often equal to chin and throat. Tail long and Turns white in winter in the winter w/black tail tip in the head+body length. somewhat bushy. northern part of range. northern part of range. Turns white in winter w/black tail (note: no white underparts) Often has an individually No chest markings. tip in northern part of range. No color change to white. distinct brown spot on chest Some individuals have spot/s on Semi-aquatic; incompletely at 18 days which disappears chest developing at 35 days. SW US adapted to aquatic life after 4 months of age. and FL may have lt. facial markings. (between polecat and otter) Breeding Mates year round with no Mates in June-July with delayed Mates mid-summer with delayed Mates January – April, with a delayed implantation; young implantation. Young are born implantation; young are born the short delayed (8-45d) born after 푥̅=35-day following April after 27-day following spring after 23-24 day implantation. *shorter gestation. active gestation active gestation. gestation in warmer ♂ and ♀ are sexually mature ♂ are sexually mature at 14 mo ♂ mature during 2nd summer; ♀ at months*Mink are not at 3-4 months although they and ♀ at 2-5 mo; ♀ is often bred 3-4 months. monogamous, and littermates seldom breed until > 10 mo by same male breeding with her may have different fathers. mother, giving birth the ♂ mature @ 18 mo; ♀ at 1 year following spring. Litter, size & description Up to 3 litters per year of 1- 1 litter of 4-9 young (푥̅ =6); born Litter size 푥̅=6-7 but wide range (<4 Litter of 1 – 10 (푥̅ =3-5) born Larger litters are more 6+ young (푥̅=4-5); usually in late spring; blind with fine to >9). Born blind and nearly naked blind and [nearly] naked in fur- common in the northern born in early spring and mid- hair. Mane present at birth and in late spring. lined nest in April or May. part of range. summer, often in abandoned continues to develop as fur A male often eventually lives burrows of another animal. comes in (14 days). with one female and helps Documented births (in the Male and female may care for with the young. wild) in every month. the young. Weight at birth 푥̅ =1.4 g 푥̅ =1.7 g ~3 g 6 or 8-10 g 1 | 2/16/2019 | Peggy Popp | 608 - 620- 8 7 5 4 | [email protected] | 2019 NWRA Symposium FAMILY: Least Weasel Short-tailed Weasel Long-tailed Weasel Mink Mustelidae Mustela nivalis Mustela erminea Mustela frenata Neovison vison Also M. (Putorius) nigripes (Previously M. rixosa) (Previously M. (Lutreola) vison) (Black-footed Ferret) Hair appears @ 4 days covered with fine Fine white hair within first day. Born with a few sparse long white Fine, silver-white hair within white hair.4 hairs on back and head. >1 day first day. covered with fine white hair.4 Begins to crawl 4 days “early” 14 days (♂), 14-21 days (♀) Brown dorsal fur appears 18 days 21 days 28-35 days Brown by 2-3 weeks; water- Hair comes in fast; at 18 days @7 days demarcation apparent; @ 3 weeks dark line of demarcation proofing present @ ~8 weeks has brown/white coloring. @14-21 days heavy mane and tail tip is black. contrasts with “scantily white @ 5 weeks brown top and bottom furred animal”4 light (white – yellow/tan) Ears open 21-28 days4 35 days4 28 days4 25-35 days Often concurrent with Quiets down after ears open :-) eyes opening Eyes open 26-30 days4 35 days (blue at first) 4 35-37 days4 25-35 days 36-41 day, ♀ before ♂5 Black tail tip appears N/A 45 days (in England)4 21 days4 N/A Weaning @14 days begins to suck and Consumes meat at 21-28 days Consumes meat at 21 days and by 35-45 days, after eyes and ears Continues limited nursing chew on pieces of mouse; and by 35 days is eating >50% 36 days are eating ½ to nearly their open and concurrent with until dispersal Eating solid food > 18 days4 BW in meat (continues to nurse own weight in meat/day.4 increased mobility. Weaning is Weaning Initiated at 32 days until dispersion)4 At 7-8 weeks the ♂ are already gradual. Young remain with and continues until 42-56 Juveniles begin hunting at 10-12 larger than their mother. their mother until the family days4. Disperse at 4 mo. weeks. disperses in early fall. First kills prey 6-7 weeks 80 days (Europe) > 56 days At 40 d mother begins training, and young are adept at 42-45d. Orphans 1st become adept at killing at 50-60 days.1 Growth complete Reaches adult length at 8-12 ♀ slows growth ≥ 8 wks.; both sexes 1 year? Weights vary with sex Disperses at 13-18 weeks weeks and adult weight at at adult size ≥ 12 wks. and season. Max heaviness 12-15 weeks. Adult male Consuming 28-38% BW/day occurs in autumn. Domestic consumes >40% BW/day mink are much larger (4-6 lbs) 2 | 2/16/2019 | Peggy Popp | 608 - 620- 8 7 5 4 | [email protected] | 2019 NWRA Symposium FAMILY: Least Weasel Short-tailed Weasel Long-tailed Weasel [Mink] Mustelidae Mustela nivalis Mustela erminea Mustela frenata Neovison vison Also M. (Putorius) nigripes (Previously M. rixosa) (Previously M. (Lutreola) vison) (Black-footed Ferret) Kills prey by =========> Grabs prey by the nape then bites through the base of the skull and/or throat area, often wrapping Biting back of the neck. Killing move is instinctive body and legs around the prey. Eats the entire animal (skin, intestines, bones, etc.). Prefers Marks hunting territory with but efficiency improves with head/brains, then inner organs and muscles, and will eat those first (which is useful to know for fetid musk > skunk but short- training/experience. medicating purposes – inject the brain of the prey food). lived. Activity Day and/or night, all Active both day and night. Most wide-spread carnivore in the Able to dive to depth > 16 feet, Killing technique is seasons. Hunts mainly on the ground but Western Hemisphere. Active both the mink is an accomplished instinctive but hunting is a Very rarely seen as they stay can climb and even pursues day and night. swimmer and spends much learned behavior. undercover. prey into the water. Hunts mainly on the ground but can time hunting in ponds and climb. streams. Adapts activity to prey. Also climbs. Vocalization Murmurs, chirps, purrs. Grunts, murmurs, hisses, Screech and squeal, rapid trill, and If angered or alarmed (or When disturbed may give a chatters, shrill (and very loud) purr when content. trapped) may hiss, snarl, or shrill squeaking call, and may alarm call. Purrs when content screech, and discharge its anal also hiss when threatened. glands. Purrs when content. Habitat Grassy and brushy fields, Varies: open woodland, brushy Varies: forested, brushy, and open Males have large home ranges The range of the male is marsh areas. Known to climb areas, grasslands, wetlands, and including farm land, preferably near that extend for a half mile or generally larger than the trees/brush/logs but active farmland. Dens may be water. Dens in abandoned burrows, more along waterways and range of the female; larger primarily underground and appropriated from chipmunks, making a nest lined with hair from overlap with the smaller home ranges in wooded under vegetation following often found in or beneath a log, prey. Will climb trees when chasing ranges of several females. environment vs open. All mouse/vole burrows. stump, roots, brush pile, or prey. Mink dens typically consist of require fresh water within their home range. - Unlikely to dig their own stone wall. Readily climbs trees - Solitary except males may assist long burrows along river tunnels unless soft substrate and other objects; will swim if with providing food for young banks, creeks, lakes, ponds, but will take abandoned necessary. Also known to (probably in exchange for breeding and marshes; holes under logs, burrow of another small inhabit human residences. rights). tree stumps, or roots; and mammal, adding mouse hair - Known to live both solitary - 2-5 favorite denning sites and 3-10 hollow trees. Dens in openings to the dried grass lining the and in a group. daytime resting places. in stream banks, 4” wide, nest. - 2-5 favorite denning sites and - Home range 2.5-12 acres in open usually appropriated from - Solitary as adults.