Data Zone
| Country/Territory | Mexico |
| Area | 230,000 km2 |
| Altitude | 1200 - 3600 m |
| Priority | urgent |
| Habitat loss | major |
| Knowledge | incomplete |
The Sierra Madre Occidental is the longest continuous mountain range in Mexico, passing north to south through the states of Sonora, Chihuahua, Sinaloa, Durango, Nayarit, Zacatecas, Jalisco and Michoacán. The trans-Mexican volcanic range, which also forms part of this EBA, runs from the southern end of the Sierra Madre Occidental eastwards along the southern edge of the Mexico plateau, from the states of Michoacán and Colima in the west to Puebla in the east; it has several of the highest peaks in Mexico, such as the volcanoes of Pico de Orizaba (5,650 m), Popacatapetl (5,450 m), and Ixtaccíhuatl (5,280 m).
The Sierra Madre Occidental and the western end of the trans-Mexican range, around Sierra de Manantlán and Nevados de Colima, lie adjacent to the North-west Mexican Pacific slope (EBA 005). The southern side of the trans-Mexican volcanic range lies alongside the Balsas region (EBA 008 in part), and at its eastern end abuts the Sierra Madre Oriental (EBA 012).
The EBA is characterized by temperate forests: with increasing altitude from 1,500 to 3,000 m these are of mature pine oak, pine, and fir. The dominant species are mainly pine Pinus but also spruce Abies, firs Pseudotsuga, oaks Quercus, Arbutus and Pop
All the restricted-range species are forest birds, apart from Xenospiza baileyi, which favours marsh and bunch-grass, but is normally in areas with some pines. This species and Atlapetes virenticeps are found in both the Sierra Madre Occidental and the trans-Mexican range, whereas Rhynchopsitta pachyrhyn
Eared Quetzal Euptilotis neoxenus is not included as a restricted-range species though, like Rhyncho
Much of the main wintering area of Colima Warbler Vermivora crissalis (an endemic breeder of the Sierra Madre Oriental, EBA 010) falls within the present EBA in the centre and west of the trans-Mexican range.
| Country | IBA Name | IBA Book Code |
|---|---|---|
| Mexico | La Cima | MX013 |
| Mexico | Nevado de Colima | MX032 |
| Mexico | Sierra de Taxco - Nevado de Toluca | MX017 |
| Mexico | Sur del Valle de México | MX014 |
Several of the restricted-range species are threatened, due in part to the almost complete destruction of old-growth pine forest within the EBA. For example, old-growth clearance for timber and wood pulp threatens the survival ofRhynchopsitta pachyrhyncha by destroying food sources and nest-sites; because it is nomadic in response to variations in cone abundance, it requires substantial areas of pine in different, but adjacent, parts of its range if it is to be secure.
Lack of any extensive continuous tracts of old-growth forest has been the major cause of the now probable extinction of Campephilus imperialis, the largest woodpecker in the world (although it is officially classified as Critical). It was previously thought not to have been recorded with certainty since 1958 (Collar et al. 1992), but recent surveys have uncovered reliable reports of a pair in February 1993 and a lone individual as recently as March 1995 (Lammertink et al. 1996). However, the handful of remaining birds must be forced to wander over huge areas in the last remnants of their forest, and, with no suitable breeding area to support a viable population, the species is effectively extinct (Lammertink 1996, Lammertink et al. 1996). These same surveys also found Euptilotis neoxenus (see Restricted-range species, above) in many new localities in Durango and Nayarit, often within degraded, secondary pine forest, and the species is clearly not as threatened as was thought previously (e.g. Endangered in Collar et al. 1994).Xenospiza baileyi has been seen in recent years only in a few localities near Mexico City in the trans-Mexican range. However, at only one of these sites, El Capulín La Cima, is it regularly recorded, and there have been problems with burning and cattle-grazing of its bunch-grass habitat there (Collar et al. 1992). The species has not been seen in the Sierra Madre Occidental part of the EBA since 1951, in spite of searches in 1994 in the Sierra Huicholes near to Bolaños (Lammertink and Rojas Tomé 1995), one of only a handful of historical localities for the species from the Sierra Madre Occidental.
There are a number of protected areas in the trans-Mexican range, but, apart from La Michilía Biosphere Reserve (350 km2) in south-east Durango, there are no protected areas within the Sierra Madre Occidental, and therefore Rhynchopsitta pachy
Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Sierra Madre Occidental and trans-Mexican range. Downloaded from
https://datazone.birdlife.org/eba/factsheet/4 on 23/11/2024.