The steep sloped canyons, closed canopy woodlands of oak and Ashe juniper, and meandering creeks found in the Bull Creek area represent exceptional habitat for the endangered golden-cheeked warbler. This migratory songbird breeds nowhere else in the world but Central Texas. The Bull Creek Preserve*, purchased by the City of Austin in the 1990s, protects a portion of that habitat amid the expansion of urban life.

*The Bull Creek Preserve is not to be confused with the adjacent St. Edwards Park, Bull Creek Greenbelt or Bull Creek District Park, all of which are managed by the City's Parks and Recreation Department and have different rules for access.

For this reason, entry into the Bull Creek Preserve during the golden-cheeked warbler breeding season requires an Entry Permit from March 1 until July 31. During this period, warblers are arriving, setting up territories, selecting mates, building nests and raising young. A limited number of Entry Permits are issued each year through the City of Austin's Balcones Canyonlands Preserve (BCP) program with a two-fold purpose; to create an educated user group accessing the Bull Creek Preserve and limit the amount of disturbance to the endangered birds during nesting season. Hiking within the Preserve without an Entry Permit between March 1 and July 31 is unauthorized access and is considered trespassing, enforceable to the full extent of the law.

During the restricted period, each individual in 9th grade or older hiking in the Bull Creek Preserve must possess their own Entry Permit. Younger children may hike with an adult who has an Entry Permit, but the Preserve's rule is still in effect that groups are allowed of three or less individuals. Permits, once earned, are valid for three years. An Entry Permit to the Bull Creek Preserve does not authorize an individual to lead groups there, nor does it authorize access into any other BCP property, City-owned or otherwise. Those interested in leading group hikes should contact outreach staff via email or at (512) 972-1687.

Registration for the Entry Permit course begins in January of each year with the last permits issued by the end of February, weather permitting. Registration is on a first-come, first-served basis. If you would like to be notified when registration is beginning for the next course cycle, please send your name, email address and a phone number (in case your email address changes) to the coordinator for the course at 972-1687 or via email.