Addressing the raven food subsidy challenge by engaging restaurants to close their dumpsters

Ravens have benefitted from resource subsidies provided by humans so much that their population has increased by over 800% in the western Mojave desert over the last 50 years. Our food waste is an especially large subsidy. Raven predation is one of the greatest threats to desert tortoise survival in the California desert. We sought to create and evaluate a behavioral change program among restaurants in Yucca Valley and Twentynine Palms, California in the western Mojave with elevated raven populations. Half of the 60 restaurants in these two communities received an intervention encouraging them to close their dumpsters while the other half served as controls with no intervention. Treatment restaurants received two in-person visits to discuss the manifold importance of dumpster closure and laminated information signs to display and extend communication to staff. We surveyed all dumpsters for open/closed status five times before the intervention and five times again 3 months after the intervention. We found a significant increase in closure rates among treatment restaurants due to the interventions, with an average of 9.5% increase toward maximum possible lid closure. Restaurants achieving 80%+ closure received "Gold Star Awards" to further stimulate community-wide behavior change by publicly recognizing and encouraging desired behaviors. We summarize dumpster closure rates from similar interventions in nearby Joshua Tree and across the Coachella Valley to illustrate how local social norms may influence behavior.