Encompassing 2,500 acres, this bird reserve is at the endpoint of the 1,700 square mile Tijuana River watershed. One quarter of this watershed lies in the US, and three quarters in Mexico. The US portion begins at Imperial Beach, and continues to the Mexican border eight miles to the south. More than 370 species of birds have been documented in this reserve. I found a lone tree at estuary’s beginning, surrounded by flowers. The marshy estuary appears as a carpet of green, extending to the hills of Mexico in the background. I waited for a cyclist to enter my frame, bringing a sense of scale to this 24mm wideangle image.