Unlike Elyria Canyon Park, Heidelberg Park is not easy access for me and I have not gone there often. Nonetheless, I am somehow still the leading eBirder for the park. Habitats are similar to Elyria Canyon, but with a denser canopy. The trail system is not as well established and foot access can be difficult seasonally given the park’s steep terrain. While signage indicates Heidelberg is a Mountains Recreation & Conservation Authority park, the park is not listed on their website. Directly across Moon Avenue from Heidelberg Park is the much smaller (and more vegetatively barren) Moon Canyon Park.
Species Accounts
Photographs
Looking north toward the San Gabriel Mountains with Heidelberg Park below from Moon Avenue. November 2019. 
View from a trail in the park southwest toward San Rafael Avenue. The majority of the trees in this photo are Southern California Black Walnut. November 2014. 
View from the trail system north toward the San Gabriel Mountains. November 2014. 
Looking south from a trail that follows the retaining wall along San Rafael Avenue. Moon Avenue is on the upper left. December 2020. 
Heidelberg Park sign at the junction of San Rafael Avenue and Moon Avenue. January 2021.