Urbanization alters the influence of weather and primary productivity on avian populations in the Seattle metropolitan area

Abstract

Two novel, abiotic challenges that affect primary productivity, and the biodiversity dependent upon it, are urbanization and climate change. Increased levels of urbanization cause an inversely proportional decrease in primary productivity, while climate change promises concurrent changes in temperature and precipitation. Although the effects of climate change are difficult to predict, the effects of El Niño years in the Pacific Northwest are similar to the changes currently predicted with climate change and may provide an insights into the long-term changes. To this end, I utilized a 250m resolution Normalized Difference Vegetation Index product from the MODIS satellite as an estimate of primary productivity and the Oceanic Niño Index as a way to estimate the strength of the El Niño -Southern Oscillation. Both variables were correlated with ten years of bird richness and relative abundance data to understand how the influence of primary productivity and weather changes with the stage of urbanization. Primary productivity was found to exert a strong influence on bird populations in landscapes undergoing active development, and much less in areas of established housing development or forested reserves. Relative to primary productivity, weather was much less influential on bird populations at actively changing sites, and more influential than productivity in forest reserves. Birds in established developments are the least influenced by weather, perhaps because anthropogenic subsidies are provided and harsh weather is buffered. This indicates that once the landscaping becomes mature, housing developments are not strongly influenced by primary productivity or weather; thus, developers should be encouraged to minimize the loss of vegetation during development and home owners should attempt to quickly achieve mature landscaping that preferably provides food and shelter for wildlife.