Bahía de los Ángeles Islands: Beetles, Plants, and the 2027 El Niño Pulse

The islands of Bahía de los Ángeles, some of the driest in North America (~65 mm of rain a year), are a natural experiment in how a desert ecosystem runs on pulses of rain and marine subsidies such as seabird guano, carrion, and shore drift. Dr. Gary Polis and Dr. Francisco Sánchez-Piñero began sampling these islands in 1996, and every summer since, except 2002 and 2020, we have counted the tenebrionid beetles that anchor the detritus food web, and recorded everything other arthropod we catch, building one of the longest records of its kind. It shows rain acts on two clocks, with plant cover responding the same year and at 3 to 5 year lags, beetles dipping two years after rain and rising at three, and seabird islands responding differently from the rest. Because the original study caught only 1998, a very strong and very wet El Niño, and not every El Niño brings rain here, 2027 lets us separate strength from rain, and starts a recovery sequence. Plant surveys on 12 islands and drone imagery of two (Cerraja and Llave), last flown in 2018, will add vegetation and small biznaga cacti. The record is also a replicable baseline for CONANP, so we will hire local boats, add a community member or CONANP staff member to the crew, invite local children to trap on the mainland, share all data and a local beetle guide with CONANP, and present results in Bahía de los Ángeles, in Spanish, before publishing them.