The most reasonable inference about the relationship between wading bird reproductive success and water depth in the Everglades, based on the information provided, is:
Water depth likely affects wading birds’ access to food and thus affects wading birds’ reproductive success.
This response is supported by the observation that fewer wading bird nests were observed in dry years than in wet years, indicating that water depth (and consequently food availability) likely plays a significant role in the reproductive success of these birds.