Impacts of the Brown Tree Snake: Patterns of Decline and Species Persistence in Guam's Avifauna
Wiles GJ, Bart J, Beck RE, Aguon CF. 2003. Impacts of the Brown Tree Snake: Patterns of Decline and Species Persistence in Guam's Avifauna. Conservation Biology. 17(5):1350-1360
Predation by brown tree snakes (Boiga irregularis) devastated the avifauna of Guam in the Mariana Islands during the last half of the twentieth century, causing the extirpation or serious reduction of most of the island's 25 resident bird species. Past studies have provided qualitative descriptions of the decline of native forest birds but have not considered all species or presented quantitative analyses. We analyzed two sets of survey data gathered in northern Guam between 1976 and 1998 and reviewed unpublished sources to provide a comprehensive account ot the impact of brown tree snakes on the island's birds. Our results indicate that 22 species, including 17 of 18 native species, were severely affected by snakes. Twelve species were likely extirpated as breeding residents on the main island, 8 others experienced declines of 90% or greater throughout the island or at least in the north, and two were kept at reduced population levels during all or much of the study. The most important factor predisposing a species to coexistence with brown tree snakes was its ability to nest and roost at locations where snakes were uncommon. Large clutch size and large body size were also related to longer persistence times, although large body size appeared to delay, but not prevent, extirpation. Our results draw attention to the enormous detrimental impact that brown tree snakes are likely to have upon invading new areas. Increased containment efforts on Guam are needed to prevent further colonizations, but a variety of additional management efforts would also benefit the island's remaining bird populations.
- Type
- Journal Article
- Authors
- Wiles, Gary; Bart, Jonathan; Beck, Robert; Aguon, Celestino
- Units
- PACN , WAPA
- Keywords
- Absence (Biodiversity), Animal Studies, Aves birds, Boiga irregularis, Brown tree snake, Extinction, extirpation, Guam, Introduced Species, Invasive Species, Population Decline, Population Dynamics, Population Trend, Predation, Presence (Biodiversity), Taxa List Only