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Mexican Grizzly Bear

By: Staff

Updated on: 05/04/2022

The Mexican grizzly bear is an extinct subspecies of Brown bear (Ursus arctos). Some accounts suggest that they were found in large numbers in the early 1900’s in its native range. It was one of the biggest and largest mammals found in Mexico. In 1982, the IUCN (The International Union for Conservation of Nature) released a paper declaring that the Mexican grizzly bear is extinct.

Scientific Classification

Species:U. arctos
Scientific name:Ursus arctos nelsoni

Quick Facts

Other name:Silver Bear, or ‘el oso plateado’ (meaning the silver one), pissini (in the Opatas language)
Size:6 feet in length
Weight:650 to 800 pounds
Diet:Plants, fruits and insects (and small mammals and carrions rarely).
Lifespan:20 to 25 years.
Habitat:Mountainous pine forests and the temperate grasslands.


Mexican Grizzly Bear
Mexican Grizzly Bear

Ursus arctos nelson was smaller than its counterparts found in America and Canada. Instead of golden brown color, Mexican grizzlies had silver fur varying to grayish-white. Some specimens were reddish and yellowish brown. Longest furs were present on the flanks and throat, while the fur was not dense in the belly and underparts.


The Mexican grizzly bear was found in parts of the United States and Mexico. In Mexico, they inhabited the states of Baja, Sonora and Chihuahua. In the United States, they were found in the New Mexico and Arizona.


They were known to be trapped, poisoned and shot by the farmers. Their native range in Mexico decreased to just three isolated mountain ranges – Cerro Campana, Santa Clara and Sierra del Nido. The Mexican grizzly bears became rare by the 1930s. Just 30 specimens were left by the 1960s. It is believed that by 1964, no population of this subspecies were left.

Their population in the Southwestern United States vanished by 1930.

Sightings and Search efforts

Mexican Grizzly Bear Pictures
Mexican Grizzly Bear Pictures

The last confirmed sighting came from Sierra del Nido Mountains (central Chihuahua) in Mexico in the late 1950s. In 1964, there was an unconfirmed report of grizzly bear poisonings in the same region.

Unconfirmed sighting reports came in till 1968. After reports of some surviving individuals in a ranch in Sonora state in 1968, Dr. Carl B. Koford, an American biologist, conducted a three-month-long research that ended in vain.

Some experts still believe that this Ursus arctos subspecies is perhaps only extirpated.

Interesting Facts

  • Females gave birth to one to three cubs in every three years.
  • The first Europeans came in contact with the Mexican grizzly bear were the explorers in the sixteenth century – when Francisco Vásquez de Coronado started his journey in 1540 to find the Seven Cities of Gold.
  • Farmers and ranchers considered Mexican Grizzlies as pests as this mammal killed their cattle from time to time. In the 1960s, a Mexican rancher reportedly started a campaign to eradicate this species for killing his cattle.

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