From Route 202 or from Route 523, go south to Route 29. Take Route 29 north along the Delaware River through Stockton about 6 miles to Bull's Island Recreation Area on the left. Park in the day-use lot. Late April and first half of May are good for migrants; the island is good in June for breeding specialties such as Yellow-throated Warbler (arrival about Apr. 20), Cerulean Warbler, Acadian Flycatcher, Cliff Swallow (on the footbridge to Pennsylvania), Warbling Vireo and Bank and Rough-winged Swallow. April 28 to May 1 is especially good if birds are on time because the foliage is not yet full. Ceruleans are very high in the sycamores. Check the southern tip of the island for Map Turtle.
If you camp there, you can drive into the north end, and you can get some of these birds from your campsite. If you are not camping, you cannot drive into the north end where the campground is located.
The southern end of the island is a State Natural Area that can be birded from the canal towpath. On a good warbler flight day, the island can be pretty busy. If you go in May, you can finish off the day with a quick trip over to Orchard Road, Linvale via Routes 518 east and 31 north; then right at the white church on Linvale Road to Orchard Road. There you can pick up grassland birds such as Upland Sandpiper, Grasshopper and Savannah sparrows, Bobolink and Meadowlark.