Friday, December 9, 2016

URSP Student Jonathan Clark Examines How Urban Noise Affects Grassland Bird Species

For some reason, I’ve always had a fascination with birds. The closest thing I have to a logical justification for this is that they are the sole, living descendants of dinosaurs, which is pretty dang cool…

Over the summer I collected data on a group of birds that have it particularly bad in North America right now, species that require grassland habitats. My team looked at the community composition and territorial behaviors of grassland birds in Northern Virginia, and how these were affected by the amount of ambient noise from human development, such as roads.

We presented the initial results on the measures of community composition, including species richness and the abundance of key species, earlier this year. We found that overall these measures were negatively associated with sound level, suggesting these species fare better in habitats that are less noisy.

We've spent this fall analyzing the slightly more complicated spatial and behavioral data collected on our two focus species, the Eastern Meadowlark and Grasshopper Sparrow. So far, our analysis has suggested these species are less capable of defending a large territory when it's loud then when it's quiet, as one might suspect since songbirds defend their territories with vocal signals.

We've been able to determine these trends of territory size by using programs such as Google Earth and R to analyze the spatial data that was collected by intense observation in the field. Our analysis still has a ways to go before we can concretely say that sound level is the sole cause of this trend, but we're currently working through our statistics and are hope to publish our results soon.

Overall, we believe that sound pollution in urban areas makes communication more difficult for grassland bird species and likely affects their reproductive behaviors. When planning conservation actions to protect these species, it's important to consider how these species are affected by urban noise.