Disentangling island insect community connections after the loss of a top predator

Biological invasions are one of the greatest threats to biodiversity today. Species diversity determines interactions within food-webs and ecosystem processes and is therefore a key factor for the stability of ecosystems. Islands are powerful study systems for species additions and removals as they often support unique biodiversity, and are particularly susceptible to invasions. The island of Guam was invaded by the brown tree snake (Boiga irregularis) after WWII and decimated the native bird community. The native birds were the top predators on the island, and without them, spider abundance has increased, in a pattern called meso-predator release. Predation is an important source of mortality for herbivorous insects, but attack rates and predator identities are poorly known, especially in the tropics. A few places on Guam still have some insectivorous forest birds, providing the opportunity for comparisons. This summer, we surveyed invertebrates across areas with birds and without birds using beating sheets.  We expected to see significant differences in insect composition and predation risk in areas with birds and without birds. Understanding the food-web shifts on islands due to the brown tree snake invasion is crucial in restoring the native bird community, preserving native insects, preventing invasive arthropods from establishing, and preventing other islands from experiencing irreversible biological losses.