Capture rates of birds in the high Andes of Ecuador

There is a long history of using birds as indicators of pervasive
environmental threats. In the High Andes, birds face potential threats
from global climate change and from the impacts of land use changes
associated with logging, grazing, fire, and agricultural expansion. We use
an 11-year constant effort, avian mist netting data set from two protected
areas in the High Andes of Azuay province, Ecuador, to explore how
environmental change is affecting resident bird species in high-elevation
habitats. We estimated a statistically significant mean decrease of 2.8%
in capture rate across years for the full species assemblage and across
all habitats. Species-specific capture rates across habitats declined for
29 of the 38 species that met our inclusion criteria. When species were
grouped by diet, body size, primary habitat occupied, or habitat breadth,
capture rates did not change differently among ecological groups of birds.
Although we cannot identify the mechanisms behind the decline, the broad
nature of the decline suggests that human-induced environmental changes,
including warming, altered rainfall patterns, and intensification of land
use, could be acting in combination, resulting in a decline in the
populations of many bird species in the region’s protected areas. This
study highlights how events occurring outside of protected areas may
affect resident bird species in these high-elevation habitats.