Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Darwin's finches combat introduced nest parasites with fumigated cotton.

Abstract

Introduced parasites are a threat to biodiversity when naïve hosts lack effective defenses against such parasites. Several parasites have recently colonized the Galápagos Islands, threatening native bird populations. For example, the introduced parasitic nest fly Philornis downsi (Diptera: Muscidae) has been implicated in the decline of endangered species of Darwin's finches, such as the mangrove finch (Camarhynchus heliobates). Here, we show that Darwin's finches can be encouraged to 'self-fumigate' nests with cotton fibers that have been treated with permethrin. Nests with permethrin-treated cotton had significantly fewer P. downsi than control nests, and nests containing at least one gram of cotton were virtually parasite-free. Nests directly fumigated with permethrin had fewer parasites and fledged more offspring than nests treated with water.