I have visited Rio de Los Angeles State Park regularly since it opened on Earth Day in 2007. In that time, I have observed more than 75% of the bird species ever recorded for the park, and in the process have become intimately familiar with its flora and fauna.
Measuring approximately 40 acres in extent (not including adjacent City-owned properties planned for park expansion), the park is managed jointly by the California Department of Parks & Recreation and the City of Los Angeles Department of Recreation and Parks. The natural areas of the park are a mix of riparian woodlands (associated with a maintained seasonal wetland), grasslands, and oak woodland. The habitats and wildlife here are substantively different than those found at Elyria Canyon Park less than a mile away.
Species Accounts
Photographs
Seasonal wetland at the west end of the park. A half-mile trail circles the wetland. This is breeding habitat for Least Bell’s Vireo and Yellow-breasted Chat. May 2023. 
Northeast side of wetland area looking south during the dry season. July 2017. 
Trail from parking lot to the northeast side of the wetland area, looking roughly west. May 2019. 
Off-trail in a mowed area near the recreation center. This is a good area for sparrows and warblers during migration. September 2023. 
Looking southeast with the playground on the left and soccer/football field in the distance. October 2023.