Contact rates with nesting birds before and after invasive snake removal: estimating the effects of trap-based control

Contact rates with nesting birds before and after invasive snake removal: estimating the effects of trap-based control

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Invasive predators are responsible for almost 60% of all vertebrate extinctions worldwide with the most vulnerable faunas occurring on islands.The brown treesnake (Boiga irregularis) is a notorious invasive predator that caused the extirpation or extinction of most native forest birds on Guam.The success of avian reintroduction efforts on Guam will depend on whether snake-control techniques sufficiently reduce roneverhart.com contact rates between brown treesnakes and reintroduced birds.

Mouse-lure traps can successfully reduce brown treesnake populations at local scales.Over a 22-week period both with and without active snake removal, we evaluated snake-trap contact rates for mouse- and bird-lure traps.Bird-lure traps served as a proxy for reintroduced nesting birds.

Overall, mouse-lure traps caught more snakes per trap night than did bird-lure traps.However, cameras revealed that bird-lure traps had a snake contact rate almost 15 times greater than the number of successfully captured snakes.Snakes that entered bird-lure traps tended to be larger and in better body condition and were mostly captured in bird-lure traps, lightemupsequences.com despite numerous adjacent mouse-lure traps.

Traps placed along grid edges caught more snakes than interior traps, suggesting continuous immigration into the trapping grid within which bird-lure traps were located.Contact between snakes and bird-lure traps was equivalent before and after snake removal, suggesting mouse-lure traps did not adequately reduce the density of snakes that posed a risk to birds, at least at the timescale of this project.This study provides evidence that some snakes exhibit prey selectivity for live birds over live mouse lures.

Reliance on a single control tool and lure may be inadequate for support of avian reintroductions and could lead to unintended harvest-driven trait changes of this invasive predator.