Climatic flux together with anthropogenic changes in land use and land cover pose major threats to wildlife, but our understanding of their combined impacts is limited. In arid southwestern North America, ferruginous pygmy-owls (Glaucidium brasilianum) are of major conservation concern due to marked declines in abundance linked to changes in land use and land cover during the past century. We reassessed abundance trends of pygmy-owls in northern Mexico across 17 years (2000-2016), which included data gathered over four additional years since inferences were last reported.
This report summarizes my efforts to describe the distribution, abundance, habitat, and biogeographical relationships of breeding birds in montane vegetation communities in the Sky Islands and adjacent Sierra Madre Occidental of northwest Mexico. Following extensive commercial logging in the early and mid-1900s, vegetation in many Sky Islands in Mexico has matured, land uses are now limited in many ranges, and vast areas of montane forest and woodland in the region are essentially de facto wilderness, especially at higher elevations.
A young pygmy-owl perched when the mother flys up and starts ripping apart a lizard and feeding it to her young.
Resumen del Proyecto:
As initially projected, this report would have been considerably larger. Fuller discussion of the systematics of many species would have been desirable and the inclusion of life-history observations and allied subjects would have added considerably to its usefulness. In normal times this would·have been possible, for investigation to fill in the not inconsiderable gaps was definitely on schedule for. 1942 and 1943. During the enforced postponement of such plans the outlook has been altered some- what and activity for the post war years has been greatly enlarged- in prospect.
The pine-oak forests of the Sierra Madre Occidental, a mountain range in NW Mexico, have recently been recognized as an area of high endemism and biodiversity. Selective logging threatens three bird species endemic to this habitat, who depend on standing dead trees (snags). This report is based on an 11 month field survey that aimed to locate old- growth remnants and to assess the status of the endemic birds. Old-growth is defined here as a forest that has never been logged mechanically.