Black Bear Population in Maderas del Carmen: Ecological Importance and Transboundary Conservation

The American black bear ( Ursus americanus eremicus ) is the largest terrestrial carnivore in Mexico and a keystone species in the mountain ecosystems of the northern part of the country. In the Sierra Maderas del Carmen region of Coahuila , one of the most important and ecologically functional populations of this species is found, notable not only for its stability but also for its fundamental role in biological connectivity processes on a continental scale.

Image by: Ing. Hugo Sotelo Gallardo, PhD.

A Highly Complex Ecosystem: The "Sky Island"

The Sierra del Carmen is a physiographic unit of high structural complexity within the Sierra Madre Oriental. It is characterized by steep altitudinal gradients ranging from 560 to over 2,700 meters above sea level , resulting in a remarkable heterogeneity of habitats. This topographic and climatic diversity favors the availability of food resources, shelter, and natural corridors, conditions that have allowed for the maintenance of one of the densest and best-preserved black bear populations in the country.

Ecological Functions: Umbrella Species and Regulator

From a scientific and ecological perspective, the black bear fulfills critical functions for the health of the forest:

• Umbrella Species: Requiring large areas of continuous habitat with low disturbance to survive, its protection indirectly guarantees the conservation of hundreds of other species that share its environment.

• Seed Disperser: Actively contributes to plant regeneration and the maintenance of ecosystem structure.

• Integrity Indicator: Its presence is an indicator of healthy and intact ecological systems.

• Trophic Regulator: Its omnivorous diet and opportunistic behavior position it as a regulator that influences multiple levels of the food chain.

The El Carmen–Big Bend Binational Corridor

One of the most important aspects of the resident population in Maderas del Carmen is its role within the binational ecological corridor known as the El Carmen–Big Bend complex . This connectivity has allowed for gene flow and the natural dispersal of individuals northward, facilitating the recolonization of West Texas , particularly in Big Bend National Park, where the species had been extirpated in the mid-20th century.

Conservation Status and Management Success

Unlike other populations in Mexico listed as endangered, the populations in northern Coahuila, including Maderas del Carmen, have a more favorable status. Under the NOM-059-SEMARNAT standard , these populations are considered to be in the Special Protection category due to their stability and recovery trend.

This phenomenon is the result of decades of coordinated efforts in habitat protection and management between institutions and civil organizations, consolidating the reserve as one of the main bastions of conservation of the species in North America.

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Selected references

• Delgadillo Villalobos, JA (2001). Nutritional ecology of the black bear in the Sierra Maderas del Carmen, Coahuila. UANL.

• Doan-Crider, DL, & Moctezuma, O. (2014). Conservation of the black bear in Mexico.

• NOM-059-SEMARNAT-2010.