There are a lot of trails throughout the park however, in the past, most of the habitat was a bit of a monoculture of mostly dense cedar trees. Recent ice storms--and the resulting tree/limb damage--may have changed that. 

Be sure to walk the woodland edges and, in particular, bird the thicket of trees in the middle of the main circle between the in- and out- driveways. The human/bird interface, in this case, may prove productive.

There are Civilian Conservation Corps structures further west from the headquarters building which provides a "bird's eye" view (from on top) of the surrounding trees and makes for a fun exploration with the possibility of seeing birds from above.

Walking the park and grounds does not cost anything. The entrance fee is to take the tour of the cave which is very enjoyable and especially well worth it in the heat of the summer when the cave is a nice, cool 68 degrees!!

According to the official website: Due to the historic nature of Longhorn Cavern State Park, our visitor facilities and cavern walkways are not wheelchair accessible. 

However, from a birding standpoint, it might be possible to use a wheelchair or scooter around the parking lot and along some of the paths, just not down into the cave. 

Please send an edit suggestion if you use a wheelchair or scooter and can provide any specific suggestions for improvement about accessibility at this park.