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Post by Gorilla king on Sept 4, 2021 18:20:57 GMT -5
WEST MEXICO BLACK BEAR (URSUS AMERICANUS MACHETES)
Accepted scientific name: Ursus americanus machetes (Elliot, 1903)
Description: One of the three subspecies found in Mexico (see map). A medium sized bear, typically around 90 cm at the shoulder.
Range: Found in north central Mexico, mainly in the Sierra Nevada Occidental range. This subspecies of black bear is thought to be geographically distinguished from the Olympic black bear (Ursus americanus altifrontalis) by the crest of the Klamath Mountains in the north of California.
Habitat: The high plateau of the Sierra Nevada Occidental averages 2,250 metres in elevation. The plateau is cut by deep valleys and canyons and consists of large areas of oak and pine forest.
Status: Mexican black bear subspecies are the only American black bears classified as endangered. Information on black bears in Mexico in general is very sparse and there have been no recent population surveys.
Life span: Not known but 20 to 25 years in the wild is the norm for Ursus americanus.
Food: Information on the subspecies is sketchy but it seems likely that acorns and pine nuts will form a significant part of the bears’ diet along with roots, bulbs, berries and grasses where found. Fish may also be taken along with small mammals and reptiles. There are anecdotal reports of predation on cattle.
Behaviour: There have been no recent studies of the bear and little information is available regarding behaviour.
Threats: Increasing human population and resultant loss of habitat. There is little real protection for bears. Whilst hunting ceased in 1985 poaching continues.
www.bearconservation.org.uk/west-mexico-black-bear/
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Post by Gorilla king on Sept 5, 2021 8:00:33 GMT -5
MEXICAN BLACK BEAR (URSUS AMERICANUS EREMICUS)
Accepted scientific name: Ursus americanus eremicus (Clinton Hart Merriam, 1904)
Description: Medium sized black bear, adult males weighing around 90 to 180 kg and adult females around 45 to 110 kg.
Range: Exact range in Mexico is poorly defined but recorded in the states of Sonora, Chihuahua, Coahuila, Nuevo León, Zacatecas and Durango. Chiso Mountains in Texas, USA (including within the Big Bend National Park).
Habitat: Low elevation desert scrub and in juniper, piñon pine, madrone, oak, and persimmon woodlands in mountainous areas and their foothills.
Status: There is strong evidence that Mexican black bears are increasing in numbers and, as a result, dispersing northwards into Texas in the Hill Country and along the Rio Grande; nevertheless numbers remain small. Mexico has listed black bears as in danger of extinction and the bears are listed as endangered in Texas.
Life span: No definite data but presumed to be around 20 years in the wild.Food: Pine nuts, nuts, berries, acorns, prickly pear fruit, sotol (Dasylirion wheeleri), yucca, roots, inner pulp of trees, insects and small mammals.
Behaviour: Mating occurs in June and July with birth taking place in January or February in the winter den. Due to the relatively mild climate and availability of food Mexican black bears do not hibernate as such but will come and go to and from winter dens or nests for three or four months between mid-December and mid- April. Litters are typically of two or three cubs and they will remain with their mother for around 18 months, during which time she will not become pregnant again.
Threats: Historically black bears in México have been severely affected by habitat loss, poaching, and illegal trade in body parts and skins. In recent times attitudes towards black bears seem to have improved but poaching remains an issue and climate change could threaten some of the plants and insects which make up the bears’ diet.
www.bearconservation.org.uk/mexican-black-bear/
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Post by Gorilla king on Sept 5, 2021 8:10:00 GMT -5
NEW MEXICO BLACK BEAR (URSUS AMERICANUS AMBLYCEPS)
Accepted scientific name: Ursus americanus amblyceps ( Baird, 1859)
Description: Medium sized black bear, adult males weighing between around 90 and 180 kg and adult females between around 45 and 114 kg. Length of adult bears averages around 170 cm for males and 150 cms for females.
Range: Southwest USA in Colorado, New Mexico, Texas, eastern Arizona and southeastern Utah. Also in the extreme north of Mexico (see map below).
Habitat: Mainly found in forests, particularly in mountainous areas. When habitat becomes limited or degraded, sub-adults will move to areas close to human populations, for example during drought conditions, as many as 25 sub-adult bears have wandered into Albuquerque and surrounding communities in late summer and autumn in search of food.
Status: Not in danger and numbers are closely monitored to prevent over-hunting.
Life span: In the wild 20 to 25 years,but in New Mexico in most of their range where they are hunted the average is around seven or eight years.
Food: New Mexico black bears are omnivorous. In spring they eat grasses, flowering plants, roots, insects and carrion. In summer the diet expands to include berries, fruit and honey; and in autumn acorns, pinon nuts, and juniper berries. They will also eat small rodents and occasionally prey upon livestock.
Behaviour:. Breeding usually begins when a female reaches five or six years of age. Mating takes place between mid-May and July with the cubs born in the winter den in January or February. Bears emerge from their dens in April or May. Cubs remain with their mother for around eighteen months during which time she will not become pregnant again.
Threats: Hunting, conflict with humans and poaching including for body-parts.
www.bearconservation.org.uk/new-mexico-black-bear/
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Post by Gorilla king on Sept 5, 2021 8:24:41 GMT -5
Human–black bear interactions in Northern Mexico
Abstract
In Mexico, black bear (Ursus americanus) is an endangered species. Human invasion of its habitat has provoked a change in its foraging behavior. Human–black bear interactions (HBIs) occur in a variety of locations and create conflict. Spatial information can predict the probabilities of interaction and identify environmental variables. We implemented ecological niche models to identified areas with high probability of HBI. Results indicated that the occurrence of interactions was related to submontane scrub, forest, and urban zones. Verification was carried out in the field, which confirmed the high performance and accuracy of the probability model.
www.researchgate.net/publication/340772716_Human-black_bear_interactions_in_Northern_Mexico
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Post by Gorilla king on Sept 5, 2021 8:28:10 GMT -5
Additional records of black bear (Ursus americanus) in central-eastern México
Abstract and Figures
The distribution range of the black bear (Ursus americanus) in México showed a significant reduction in the 20th century. However, growing evidence of its presence in areas outside the known range of distribution has emerged in recent years. This note documents a set of new records of black bear for the States of Guanajuato, Querétaro, and San Luis Potosí in central-eastern México. Black bears were spotted from monitoring that included camera traps, sightings, and indirect evidence (tracks and depredation events) between the years 2000 and 2019. We detected the presence of black bear through six records in the States of Guanajuato, Querétaro, and San Luis Potosí, in an area close to the southernmost distribution for this species in the American continent. Five of these observations occurred within protected natural areas. With these observations, the number of mammal species recorded in the State of Guanajuato increases to 95 and confirm the presence of black bear in the States of Querétaro and San Luis Potosí. The observations provide evidence supporting the hypothesis that black bear populations from northeastern México are moving toward central-eastern México through the Sierra Madre Oriental (SMO). The presence of black bear in central-eastern México points to the need for closer systematic monitoring of biodiversity in the SMO and protected areas of the region through monitoring and conservation programs.
www.researchgate.net/publication/349120309_Additional_records_of_black_bear_Ursus_americanus_in_central-eastern_Mexico
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Post by Gorilla king on Sept 5, 2021 8:30:40 GMT -5
Connecting mountains and desert valleys for black bears in northern Mexico
Abstract and Figures
Context Black bear connectivity studies are scarce in the southern distribution where the species is endangered. The identification of corridors is a strategy to promote conservation in human-modified landscapes. Objectives Assess and validate long-distance corridors in the southern black bear distribution using resistance models, occurrence records, and radio-telemetry of an individual that dispersed between the Sierras Madres of Mexico. Methods We acquired black bear occurrence records from several sources and telemetry records from one dispersal individual in northern Mexico. We generated ensemble habitat suitability models and resistance landscape surfaces to generate cumulative resistant kernel and least-cost paths to identify connectivity core areas and corridors of importance through Natural Protected Areas. Finally, we assessed long-distance corridors. Results We developed three habitat suitability models for black bears southern range; one matches the current distribution of the species. When including radio-tracking records, the landscape resistance is reduced to arid sites with low habitat suitability. We used least resistance connectivity surfaces to merge subpopulations within each Sierra Madre. The long-distance corridor models indicate narrow routes that require individuals with plastic behavioral dispersal capacity. Almost 20% of the connectivity core areas are within Natural Protected Areas. These are the first large-scale corridors using resistance layers in the southern black bear distribution. Conclusions Corridors can be functional for a range of temperate and dry habitat species. Landscape connectivity models should include the monitoring of dispersal individuals to identify the plasticity of organisms and the tangible barriers for them.
www.researchgate.net/publication/352975450_Connecting_mountains_and_desert_valleys_for_black_bears_in_northern_Mexico
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Post by Gorilla king on Sept 5, 2021 8:32:32 GMT -5
There is barely any info on Mexican black bears, that is why i decided to put all 3 subspecies in just 1 thread.
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Post by Gorilla king on Aug 7, 2022 11:27:13 GMT -5
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Post by oldindigosilverback on Aug 7, 2022 15:42:48 GMT -5
It seems that larger bears have a greater sexual dimorphism in comparison to the smaller bears. Black bears also become full grown faster than brown and polar bears.
Reason for the greater sexual demorphism between brown and polar bears compared to black bears, they former two take longer to become full grown.
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Post by arctozilla on Aug 8, 2022 3:04:23 GMT -5
Yes polar bears and brown bears attain full body weight up to 10 years of age whereas black bears up to 5 years of age.
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Post by Gorilla king on Aug 8, 2022 3:14:10 GMT -5
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Post by oldindigosilverback on Aug 8, 2022 4:36:03 GMT -5
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Post by Gorilla king on Aug 8, 2022 5:57:43 GMT -5
I know that source says 5 years, but that's just too young to be fully grown. Check this chart out, it shows skull width/age relationship, the width keeps getting larger after year #5, seems like after year 8 it gets steadier.
Reply #13:
beargorillarealm.proboards.com/post/2388/thread
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Post by Gorilla king on Nov 13, 2022 14:09:09 GMT -5
Record of american black bear (Ursus americanus) in Durango, México
Abstract
In Mexico, the American black bear (Ursus americanus) has withstood a number of anthropogenic pressures such as habitat loss, illegal poaching, poor legislation regarding conservation, management and exploitation, etc. Consequently, these have been the major causes of the decline of large carnivorous mammals in Mexico. The new technologies currently available have provided tools that facilitate their study, documenting their presence and distribution, in addition to expanding the biological and ecological information of this group of predators. During the 2009 winter season, intensive field surveys were conducted in southeastern Chihuahua and western Durango. In each area surveyed, 40 fixed monitoring stations were set, fitted with a camera trap and an scent station, distributed at distances ≥ 1 km between stations across the study areas. A total sampling effort of 2,400 days/trap resulted in one record of a juvenile American black bear (Ursus americanus; Figure 1) at Ejido “Lobos y Pescaderos”, in the municipality of Tepehuanes, Durango, in Sierra Madre Occidental, Mexico (Figure 2). This record was obtained at 2436 masl, representing the second reliable report of the presence of the American black bear at these altitudes. The photographic record currently available underscores the need to implement and intensify long-term surveys that contribute to determine the presence of American black bear in the northwestern states of Mexico, specifically in Sierra Madre Occidental in the state of Durango, in sites already identified as having temperate forests habitat conditions that are potentially suitable for the American black bear.
www.researchgate.net/publication/328023692_Record_of_american_black_bear_Ursus_americanus_in_Durango_Mexico
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Post by brobear on Nov 14, 2022 2:23:50 GMT -5
From reply #1, "Description: Medium sized black bear, adult males weighing around 90 to 180 kg and adult females around 45 to 110 kg."
Adult males; 198.42 pounds to 396.83 pounds. A black bear west of the Mississippi River pushing 400 pounds is a huge black bear.
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Post by Gorilla king on Jun 21, 2023 11:23:39 GMT -5
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Post by Gorilla king on Sept 17, 2023 8:39:09 GMT -5
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