Bay Area Fog

The role of birds in the transmission of mammal-associated pathogens

Immature California Scrub Jay (Aphelocoma californica) in the middle of moulting

The transmission of pathogens between wildlife populations and humans is increasingly prevalent in the Anthropocene. Understanding the relationship between changing faunal assemblages and disease regulation is therefore increasingly important as defaunation progresses globally. Previous research has demonstrated that the exclusion of large-bodied mammals can dramatically influence infection prevalence in some species. This is due, in part, to the release and proliferation of smaller species (such as rodents) which often carry high ectoparasite loads, important vectors of infectious disease. However, very little is known about the role that birds play in regulating ecosystem-wide disease transmission. Birds share several ectoparasites with mammals, are often immune to mammal-associated pathogens, and can dramatically increase the potential dispersal distance of many diseases.

In North America, one of the most common zoonotic pathogens is Borrelia spp. which can cause Lyme Disease. This project is examining the relationship between the composition of mammal communities and the prevalence of Borrelia infection in wild bird populations. In collaboration with Dr. Andrea Swei, Dr. Ravinder Sehgal, and Wilmer Amaya-Mejia at San Francisco State University, we are currently surveying birds at nine sites around the Bay Area in California which represent different conditions of large and small mammal abundance.