Waikiki has three distinct areas: 

Bird the switchback trail down to the preserve for a wetter, shadier coniferous forest with more douglas fir. Take an offshoot trail on the final switchback here to bird relatively lush forest where some of the springs move down the hill into the river valley below. 

Bird the riparian zone along the Little Spokane for fantastic and abundant birds, including very good birding during June, July and August. Look down the river from the bridge for ducks, especially in winter and spring. 

Bird the drier hills after the bridge on the far side of the river for a completely different habitat from the two you've encountered so far.  

Many species of sparrows can be found in the grassy/weedy floodplain on either side of the Little Spokane during fall migration.

Look for ducks and geese on the river, especially in winter and spring. 

Loads of passerines, as well as kingfishers and raptors can be found in the bushes and trees in the riparian area along the river. This is a reliable area for Bewick's wren year round. Bald eagles are also here nearly year round. Calliope hummingbirds and occasionally black chinned and rufous hummingbirds frequent this area during their breeding season. Several species of empidonax flycatchers can be found here during their breeding season. Cedar waxwings are extremely abundant along the river during the breeding season. Some warblers, particularly yellow warbler, as well as lazuli buntings also breed here, making this one of the best places to find them during the summer months. 

Both sides of the forest areas can be good for many of the birds listed above, and is also great for both ruby and golden crowned kinglets in fall, winter and spring. Resident birds such as chickadees and nuthatches are extremely abundant here.

There is only technically an entrance fee because a discover pass is required at any of the four parking spots at the actual trailhead. However, those spots are typically full anyway and most days you will end up using free street parking in the neighborhood. Beware of no parking signs!

The main switchback trail down into the natural area used to be a dirt road and has been changed to be pedestrian only. It then passes along a road and by a few private homes before going back into the natural area by forking to the right. This wide portion of the trail is extremely popular with locals for dog walking and jogging and can be very busy. It gets much quieter and much better for birding once you get across the bridge and onto the loop trail on the far side of the bridge.