Research

Ecosystem (dis)services provided by wild birds on organic farms

American goldfinch_full belly

bird box at say hay

Recently, birds and other wildlife have been blamed for outbreaks of food-borne disease in humans. In response, many growers in the United States have been pressured to clear natural vegetation from their farms. However, the costs and benefits of birds associated with natural vegetation on farms are largely uncertain. The Avian Biodiversity: Impacts, Risks, and Descriptive Survey (A-BIRDS) project aims to determing the net impacts of birds on organic farms, using DNA diet analysis and pathogen testing of bird poop samples collected at organic farms across California, Oregon, and Washington State.

 

Causes of decline in endangered Tasmanian songbirds

Shot_By_Angi_Pardalotes-063

forty-spotted pardalote in net Forty-spotted pardalotes are endangered habitat specialists native to Tasmanian, Australia. While this species occupies < 50 km2, and has experienced 60%  population decline within the past 20 years, drivers of decline are uncertain. Passeromyia longicornis, a native fly parasite, is likely a major threat to forty-spotted pardalotes, within their remaining habitat. This parasites kills 81% of all nestlings, and is the largest known source of mortality for the species (Edworthy 2016, AJZ). Other threats include competition for nest hollows with striated pardalotes (Edworthy 2016, Condor), extreme diet specialization on a sugary sap-like excretion produced by white gum trees (Case and Edworthy 2016, Ibis), and loss of this critical habitat.

 

Long-term survival and characteristics of tree cavities used by bird and mammal communities

mountain bluebirds and tree cavity tree cavity survival figure

Tree cavities are a shared resource for more than 30 species of birds and mammals in interior BC. During my MSc with Kathy Martin at UBC, I studied factors influencing persistence of tree cavities in both mature forest and forests harvested with retention of aspen trees (the primary cavity tree). I also studied changes in tree cavity characteristics over time, which affect their likelihood of use by species including bluebirds, woodpeckers, ducks, and squirrels.