An Nguyen | Geology Reports

USGS2023

Suppression of invasive Brown Treesnakes and reintroduction of native avifauna on Guam

Many agencies and interest groups are committed to re-establishing components of Guam's native avifauna through the reintroduction of captive-reared birds or translocation from other islands in the Marianas if the Brown Treesnake ( Boiga irregularis ; BTS) can be eliminated. Island-wide eradication of BTS from Guam continues to appear out of reach, but with recent and future advancement in BTS suppression technology, we may soon reach a point where suppression may enable the reintroduction of some of Guam's extirpated bird species. Our simulations indicate that bird persistence in Guam's forests would only be possible at a suppression level just short of full eradication.

Bulletin of the Ecological Society of America↗

USGS2021

Distilling professional opinion to gauge vulnerability of Guam avifauna to Brown Treesnake predation

The avifauna of Guam was devastated by the introduction of the Brown Treesnake, and the restoration of native birds would need to address the problem with eradication or suppression of BTS. With eradication of the snake unlikely in the near term, and suppression capabilities limited to specific finite areas, key information for reintroductions is how low BTS abundance will likely need to be for each bird species to be re-established based on their vulnerability to BTS predation. Here, we estimate vulnerability, which can no longer be measured directly, so biologists who are familiar with one or more of seven Guam birds were surveyed to obtain their knowledge and produce quantitative vulnerability estimates. As is typical of birds adapted to islands devoid of predators, respondents judged that our focal species exhibit few predator avoidance and tolerance traits, leaving body size as the prime determinant of vulnerability. Respondent opinion also holds that any behavior that reduces the likelihood of an encounter by BTS, e.g., roosting/nesting in palm crowns, cavity nesting, and in particular urban dwelling, substantially reduces vulnerability. Our results can help inform species-specific decisions about when it may be safe to consider the release of birds on Guam depending on the relative vulnerability of each species to predation by BTS.

Guam↗