Extreme environmental conditions lead to a collapsed avian soundscapes;
an agent-based model
Abstract
Climate change is increasing aridity in grassland and desert habitats
across the southwestern United States, reducing available resources and
drastically changing the breeding habitat of many bird species.
Increases in aridity reduce sound propagation distances, potentially
impacting habitat soundscapes, and leading to a breakdown of the avian
soundscapes in the form of loss of vocal culture, reduced mating
opportunities, and local population extinctions. We developed an
agent-based model to examine how changes in aridity will affect both
sound propagation and the ability of territorial birds to audibly
contact their neighbors. We simulated vocal signal attenuation under a
variety of environmental scenarios for the south central semi-arid
prairies of the United States, ranging from contemporary weather
conditions to predicted extremes under climate change. We also simulated
how changes in physiological conditions, mainly evaporative water loss
(EWL), would affect singing behavior. Under extreme climate change
conditions, we found significantly fewer individuals successfully
contacted all adjacent neighbors than did individuals in either the
contemporary or mean climate change conditions. We also found that at
higher sound frequencies and higher EWL, fewer individuals were able to
successfully contact all of their neighbors, particularly in the extreme
and extreme climate change conditions. These results indicate that
climate change-mediated aridification may disrupt the avian soundscape,
such that vocal communication no longer effectively functions for mate
attraction or territorial defense. As climate change progresses
increased aridity in current grasslands may favor shifts toward low
frequency songs, colonial resource use, and altered songbird community
compositions.