Ursus arctos ssp. nelsoni (Mexican Grizzly Bear)

[peej]

Does any one have any information on this animal.I can not seem to find any info at all.

[Peter]

Yes, I have at home! The Doomsday Book of Animals has a fantastic image of this bear and information. The first I've found. I will post the information this evening or tomorrow!

....or someone must be faster than me! ;D

[Melly]

The last bears were killed by farmers in 1964 who wanted protect their herds.

[sebbe67]

The Mexican grizzly bear was the largest animal native to Mexico. They could weigh as much as 318kg and often measure 183cm from nose to tail the mexican grizzly was the smallest of the four subspecies of american brown bear.

Beacuse it was so distinctive coloured it was often called silver bear (el oso plateado in mexico). The mexican grizzly was the first one to cime into contact with europeans. It was recorded as early as 1540. But the first specimens wasent collected until 1899 in Chihuahua. By the 1930 the Mexican grizzly had been hunted, trapped and poisoned to such extent that it vanished from Arizona, New Mexico, Southern California and southern Texas. In Mexico it could only be found in the state of Chihuahua in the isolated mountain islands of Cerro compano, Santa Clara and Sierro del Nido. By 1960 not more than 30 bears survived and even though a few private citizens attempted to protect this last handful of Mexican bears others deliberately set out to kill them. From 1961 to 1964 ranchers in this region engaged in an intensive campaign of poisoning, trapping and hunting on the surviving population. In 1968 Dr Carl Koford made a three month survey of the territory and reported that he could not find any evidence that a single bear survived this onslaught. Despite one notable claim to the contrary it is now obvious that the ranchers campaign achieved its goal- by 1964 the Mexican grizzly bear ( Silver grizzly bear) was extinct.

[Peter]

Have you all noticed that the IUCN Red List has made some changed on its species information pages. They have now included databases and image search engines, by direct link!

IUCN Red List: www.redlist.org/search/details.php?species=22825

This subspecies is still recognised by the IUCN and listed as extinct. However not everyone does, like ITIS:

Found this:
Name Used in Concept Reference: Ursus arctos
Taxonomic Comments: GENERAL: Recent genetic studies of brown bears indicate that the traditional morphology-based taxonomy of brown bears is highly discordant with bear phylogeny as indicated by geographic patterns of mtDNA variation. Based on recent and permafrost-preserved Pleistocene material, there is no genetic (mtDNA) support for the validity of any of the commonly recognized North American subspecies (e.g., horribilis, middendorffi), and North American brown bears do not represent a distinct lineage with respect to brown bears in Northern Asia and Europe (Waits et al. 1998, Leonard et al. 2000, Barnes et al. 2002). If a subspecific name is to be applied to North American brown bears, it should be Ursus arctos arctos, a taxon whose range encompasses both North America and parts of Eurasia. This name has been adopted for North American brown bears by ITIS (http://www.itis.usda.gov/index.html), which lists U. a. horribilis and U. a. nelsoni as invalid because they are junior synonyms of U. a. arctos.

SPECIFICS: Based on electrophoretic data indicating that the Kodiak Island population is reproductively isolated from the mainland Alaska population, Allendorf et al. (1992) concluded that the Kodiak Island population may warrent subspecific recognition (i.e., as subspecies middendorffi). However, subsequent studies have revealed that the mtDNA sequence observed in all individuals from Kodiak Island is identical to sequences observed in brown bears from many regions in mainland Alaska and from northern Asia and Europe (Waits et al. 1998). MtDNA data also provide no support for a distinct taxonomic group on the Kenai Peninsula; all sequences from individuals sampled in this region group with other mainland Alaska bears. Cronin et al. (1991) also found that the two morphological forms of U. arctos, grizzly and coastal brown bears, do not cluster as distinct mtDNA lineages. Waits et al. (1998) suggested that the morphological differences used to define brown bear subspecies may represent phenotypic plasticity in differing environments rather than long-term genetic isolation.

Recent studies of mtDNA from permafrost-preserved material indicate that the Beringian brown bear population of 36,000 years ago included mtDNA sequences from three clades now restricted to local regions in North America (Leonard et al. 2000). Thus the geographical partitioning of mtDNA haplotypes in extant North American populations is a relatively recent event (a consequence of founder effects and lineage partitioning) rather than evidence of long history of isolation. Waits et al. (1998) had suggested that the North American clades of brown bears likely are evolutionarily significant units that should be managed separately for conservation, but the genetic data from the perma-frost preserved material raise doubts about this (Leonard et al. 2000).

Bears from Yellowstone National Park have less allozyme variation than do all other North American populations except for the Kodiak Island population. There are significant genetic differences between Cabinet-Yaak-Selkirk and Northern Continental Divide Ecosystem bears, but not between Yellowstone and Northern Continental Divide populations (Allendorf et al. 1992).

Western and eastern populations of brown bears in Europe comprise two distinct lineages that diverged about 850,000 years ago (Dorozynski, 1994, Science 263:175).

Various kinds of evidence (fossils, protein, mitochondrial DNA) indicate that the brown bear and polar bear are sister taxa, more closely related to each other than either is to the black bear (see Shields and Kocher 1991, Cronin et al. 1991). In fact, recent mtDNA data indicate that the brown bear is paraphyletic with respect to the polar bear (i.e., brown bears from certain areas are genetically more closely related to the polar bear than they are to other brown bears) (e.g, Waits et al. 1998, Barnes et al. 2002, and other sources cited therein).

Source: www.natureserve.org/explorer/servlet/NatureServe?searchName=Ursus+arctos

[Melly]

Here is another pic of the Mexican Grizzly

planet-mammiferes.org/sespece.php?indice=Ursus+arctos+nelsoni

[another specialist]

image found by melanie

MEXICAN SILVER GRIZZLY
The last Mexican Silver Grizzly was killed in 1964 by ranchers protecting their herds.

[Melanie]

In 1969 some people claimed that some bears survived on a farm on the headwaters of Rio Yaqui, Sonora. But also this report remained unconfirmed.

[another specialist]

What was your source Melanie?

[Melanie]

'Atlas of World Wildlife' by Sir Julian Huxley, 1973. A very successful book in the 1970s.

[another specialist]

thanks melanie

[another specialist]

wontolla.homepage.t-online.de/wontolla/aliens.htm

[sebbe67]

[another specialist]

from the doomsday day book by david day also called the encyclopedia of vanished species depending on what edition you look for.

[peej2]

How many extinct species are in this book? Are they just mammals or are there reptiles and birds as well?

[sebbe67]

The book cover birds, mammals, reptiles, frogs, fishes and a few plants.

[another specialist]

peej2 said:

How many extinct species are in this book? Are they just mammals or are there reptiles and birds as well?

It has subspecies aswell but is a bit out dated now but a good reference book anyway

[Bhagatí]

from: www.naturalia.org.mx/conservaccion/extincion.htm
www.naturalia.org.mx/conservaccion/extincion.gif

[another specialist]

baghira said:

from: www.naturalia.org.mx/conservaccion/extincion.htm
www.naturalia.org.mx/conservaccion/extincion.gif

This images i would say don't show the Mexican grizzly bear.

The images are to recent as the last Mexican Silver Grizzly was killed in 1964 by ranchers protecting their herds.

[Bhagatí]

I'm understand.
Only is just for information.