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MEASUREMENT AND WEIGHT- Editorial Comment

Editorial Comment

(Editorial Overview Text Replicated on Overall Species page - Ursus americanus - American black bear)

LENGTH
Adult: 
Black bears measure about 1.2 - 1.9 m, with males typically larger than females, averaging 1.57 and 1.43 m respectively.
Newborns: Newborn cubs measure about 199 mm.

HEIGHT 
Adults and sub-adults: Black bears are about 0.7 - 1.05 m at the shoulder (2.3 - 3.4 ft).
Juveniles: --

WEIGHT
Adult: 
Male black bears may weigh 60 - 225 kg usually, but reach or pass 300 kg in some areas where they feed on corn. Females may weigh 40 - 150 kg usually but can exceed 180 kg.
Newborns: Cubs weigh about 250 - 360 g.

GROWTH RATE: The growth rate of cubs is affected by their mother's size. One study found wild cubs to gain about 500 g in their first month and 2.5 kg in the first 12 weeks. Zoo data showed cubs to average 1.8 kg at a month old, 3.5 kg at two months and 10 kg at three months. Females reach full skeletal growth by four to five years, males by six or seven years. Weight gain continues for two or three years after skeletal growth has stopped. 

(References are available in detailed literature reports below)

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Length

Adult

SUMMARY: Black bears measure about 1.2 - 1.9 m, with males typically larger than females, averaging 1.57 and 1.43 m respectively.
  • Head and body length 1.5 - 1.8 m. (B147)
  • Head and body length 1.2 - 1.9 m (4.0 - 6.2 ft). (B285.w4)
  • Typically, males are 10% longer than females. (D245)
  • 1.3 - 1.8 m (4 - 6 ft). (B144)
  • Total length:
  • 137 - 188 cm ( four feet six inches to six feet two inches). (B180)
  • Males 1.57 +/- 0.18 m (D245)
  • Females 1.43 +/- 0.14 m (D245)

Neonate / Young

SUMMARY: Newborn cubs measure about 199 mm.
  • Mean crown-rump length 199 mm (data from five cubs). (J348.70.w1)

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Height

Adult

SUMMARY: Black bears are about 0.7 - 1.05 m at the shoulder (2.3 - 3.4 ft).
  • Up to 0.91 m. (B147)
  • 0.7 - 1.0 m (2.3 - 3.3 ft). (B285.w4)
  • 90 - 105 cm (3 ft to 3ft 5 inches). (B180)
  • 0.8 - 0.95 m (2.5 - 3 ft). (B144)

[Height = highest point measured]

Neonate / Young

  • --

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Weight

Adult

SUMMARY: Male black bears may weigh 60 - 225 kg usually, but reach or pass 300 kg in some areas where they feed on corn. Females may weigh 40 - 150 kg usually but can exceed 180 kg. 
  • 92 - 267 kg (203 - 587 lb). (B180)
  • 120 -150 kg (264 - 330 lb). (B144)
  • During late summer and fall, when food is plentiful, adult females and subadults may gain 0.2 kg (0.5 lb) per day, while adult males can gain 0.7 - 0.9 kg (1.5 - 2.0 lb) per day and exceptionally 1.4 kg (3 lb) in a day. (B406.35.w35)
  • Males 
    • 115 - 270 kg. (B147)
    • Usually 60 - 225 kg (130 - 500 lb); up to 300 kg (650 lb) or even heavier in some areas where they eat corn. (B285.w4)
    • Average 86.0 kg (for 30 bears in California); 67.3 kg (for 201 bears in Tennessee and North Carolina). (D245)
    • In Washington, a study found mean mass of 43 adult male bears (four years old or more) was 110.9 +/- 38.9 kg (mean +/- SD). (J332.84.w1)
    • Average 60-140 kg but some individuals exceeding 250 - 300 kg. (B442.8.w8)
  • Females
    • 92 - 140 kg. (B147)
    • Usually 40 - 150 kg (90 - 330 lb) but can reach over 180 kg (400 lb). (B285.w4)
    • Average 58.0 kg (for 11 bears in California); 50.1 kg (for 352 bears in Tennessee and North Carolina). (D245)
    • In Washington, a study found mean mass of 35 adult female bears was 67.3 +/- 13.7 kg (mean +/- SD). (J332.84.w1)
    • Average 40 - 70 kg. (B442.8.w8)
  • A study of adult females during hibernation and lactation found that body mass was 105 +/- 18 kg; bears lost weight over hibernation, maintained body weight in summer and gained weight in fall (autumn). For non-lactating bears, mass loss during lactation averaged varied, being as little as 70 g/day in small individuals. In lactating females, mass loss in the den was 45% higher than for non-lactating individuals of the same mass. (J30.73.w3)

Neonate / Young 

SUMMARY: Cubs weigh about 250 - 360 g.
  • About 225 - 330 g. (B147)
  • Just over 200 g (7 oz). (B180)
  • 350 - 400 g ( 12.5 - 14 oz). (B144)
  • The weight and growth rate of cubs is affected by the mother's size. (D245)
  • Weights of 265 to 362 g (9.3 - 12.7 oz) were recorded for four cubs born at Copenhagen Zoo. (B288.w11)
  • Zoo data: 250 - 350 g. (D247.6.w6)
  • Newborn black bears weighed about 3.7 g per kg of maternal body mass (3.0 - 5.0 g/kg) with a total litter mass averaging 12 g/kg. Individual cubs weighed 325 - 432 g at 0 to 2 days. (J348.70.w1)
  • 200 - 300 g (0.4 - 0.7 lb) at birth. (B406.35.w35)
  • Four cubs born at Copenhagen zoo weighed 340g, 362 g, 275 g and 265 g at birth. (J339.20.w1)

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Growth Rate

SUMMARY: The growth rate of cubs is affected by their mother's size and by food availability. One study found wild cubs to gain about 500 g in their first month and 2.5 kg in the first 12 weeks. Zoo data showed cubs to average 1.8 kg at a month old, 3.5 kg at two months and 10 kg at three months. Females reach full skeletal growth by four to five years, males by six or seven years. Weight gain continues for two or three years after skeletal growth has stopped. 
  • The individual cub growth rate (birth to weaning) is 77.0 g/day, with a litter growth rate of 192.5 g/day. (P17.57.w2)
  • Black bear cubs gained about 500g in their first month and 2.5 kg over their first 12 weeks. (J348.70.w1)
  • Zoo data: Average weight at one month 1.8 kg, at two months 3.5 kg and at three months 10.0 kg. (D247.6.w6)
  • The weight and growth rate of cubs is affected by the mother's size. (D245)
  • Females reach adult size at three to four years, males not until five years. (D245)
  • Black bear cubs reached a crown-rump length of 268 mm (mean) by one month. (J348.70.w1)
  • By six weeks old cubs may weigh as much as 4 kg ( nine pounds); by nine months they may reach 30 kg (100 lb). (B406.35.w35)
  • A study of three sets of mother-reared twins found a growth rate of 49 +/- 9 g/day during the hibernation period, to give cubs weighing 2.6 +/- 0.5 kg by the time of den emergence, followed by increased growth rate, reaching a maximum of 351 +/- 107 g/day. Pre-hibernation mass of the cubs was 51 kg. During maternal hibernation, cubs gained 0.7 +/- 0.1 kg for every 1.0 kg of mass loss by their dam over the normal hibernating loss. (J30.73.w3)
  • In northeastern Minnesota, it was noted that yearlings making use of garbage dumps gained weight faster than those not using this resource: six bears using the dump averaged 41.9 kg by fall (autumn), while seven bears eating only natural foods averaged 36.2 kg. (D248.w7)
  • Four black bear cubs hand-reared at Copenhagen zoo, using cream as a milk replacer, weighed 1.0 - 1.2 kg at 28 days, 2.5 - 3.75 kg at 60 days and 4.5 - 5.0 kg at 90 days. (J339.20.w1)
  • Females reach full skeletal growth by four to five years, males by six or seven years. Weight gain continues for two or three years after skeletal growth has stopped. (B442.8.w8)

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Authors & Referees

Authors

Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)

Referee

David L. Garshelis (V.w98)

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