The most reasonable inference about the relationship between wading bird reproductive success and water depth in the Everglades, based on the provided information, is:
Water depth likely affects wading birds’ access to food and thus affects wading birds’ reproductive success.
This conclusion is drawn from the observation that fewer nests were counted in dry years, suggesting that lower water levels may reduce the availability of fish, which are the primary food source for wading birds, ultimately affecting their reproductive success.