I'm sorry that you were not aware that many of the residents of the salt marsh are birds. We often see dolphins, crabs and salt marsh turtles and occasionally visitors like seals, otters, or coyotes so I'm not sure that I would want to state that we would only encounter birds. This is what we currently say in the ad.
Observe a variety of bird species and marine life.
And of course we do spend a great deal of time in the salt marsh which is certainly one of the less explored nature preserves by most people. I'm glad that you were able to get out and see this much less accessible area even though it's wasn't what you were expecting.