So one of the major issues with eBird is how and when hot spots were created. For Antelope Island State Park there is an overarching location for the entire park including the causeway. There is also this location which is supposed to be any location on the island. Originally there were only 3 spots for the park--one for the causeway, one for the island, and one for the ranch. But over the years, trying to be more precise with the data the various locations for the park have popped up. On the island there are now the following locations:
Visitor Center & Loop Road
Lady Finger Point
White Rock Bay
Road to Garr Ranch
Backcountry (incl. Frary Peak Trail)
These are all very specific locations, some with habitat only found at said locations, while others have overlapping habitats, and in some cases are right next to each other. Many birders who just use eBird to keep lists will create just one checklist for their entire visit to the island and put it on either the causeway, the island location, or the state park location. Some will even put it on one of the other specific locations skewing the data slightly for those spots. It is all confusing and there is no great solution for the near future. But looking at it from this perspective will hopefully help. The causeway is a very different habitat from anywhere on the island, and the birds you're going to see are very different. Separating your causeway list from the island list will help at a basic level. Keeping lists for even more specific locations will make the data even better. Birding wise, I'm not going to talk about anything else for this location, as there is lots of information on those pages I mentioned above. At a minimum if you want to use this spot try to do it separately from the causeway to help keep things clean.
In Layton, take I-15 exit 332 west bound onto Antelope Drive for about 7 miles to the entrance station to the park. After paying an entrance fee continue about 6 miles across the causeway to the island. For specific directions to locations on the island see pages for the above listed hot spots.