The common raven (Corvus corax) is a resident species across the western U.S. However, over the last several decades, raven numbers have increased dramatically across the western U.S., primarily due to human activities.
The raven is considered a subsidized predator, which is a predatory species whose population increases and benefits from resource subsidies (e.g., food, water, and nesting opportunities) that humans inadvertently provide. Ravens proliferate near garbage dumps, sewage ponds, agricultural areas, and along roads, all of which provide unnaturally abundant food, water, perches, and nest sites.
Predation by subsidized predators such as the raven can drive rare, native prey populations to endangerment and extinction because human derived resources protect the predator from prey population fluctuations, allowing the predator population to remain high even as natural prey becomes increasingly rare.
Ravens are known to prey on eggs and young of several threatened and endangered species, including the Mojave desert tortoise (Gopherus agassizii). In particular, the raven has been implicated as a significant threat to Mojave desert tortoise survival and management in the western Mojave Desert, with estimated mortality in localized areas ranging from 9 to 72 percent.
Other wildlife taxa in the western Mojave Desert that are known or likely to be directly impacted by increased raven populations include the Inyo California towhee (Melozone crissalis eremophila), golden eagle (Aquila chrysaetos), burrowing owl (Athene cunicularia), greater sage-grouse (Centrocercus urophasianus), Gunnison sage-grouse (C. minimus), western snowy plover (Charadrius nivosus nivosus), greater sandhill crane (Antigone canadensis tabida), marbled murrelet (Brachyramphus marmoratus), California least tern (Sternula antillarum browni), California condor (Gymnogyps californianus), and San Clemente loggerhead shrike (Lanius ludovicianus mearnsi) as well as multiple small mammals and reptiles.
Adult ravens can reach up over 2 feet in length and weigh between over 3 pounds. They build large nests that are typically 2 to 4 feet across and 1.5 to 2 feet tall from the base to the top of the rim.
This raven display was designed and constructed by GSRC Senior Ecologist Sean Graham with help from Rick Mignano, a wooden duck carver, and will be used by the Navy for environmental education and outreach. The display consists of a wood carved raven and seven eggs, a nest constructed from local materials commonly used by ravens during nesting, and a display stand constructed to resemble a power pole representing an abundant nest site subsidy.
