Great blue herons (Ardea herodias) are probably the most iconic wading birds of North America. Small stagnant bodies of water attract year-round residents, with breeding pairs maintaining stable nest sites and foraging patterns. The heron pictured in flight here is an individual my mom and I have reliably seen over the past few years, usually found standing in one of two spots along the lake shore. Heron populations along coastlines or more prolific wetland habitats often reside in large colony aggregations (which I recently learned is called a “heronry”), benefitting from their larger numbers in reliably finding food resources. For instance, herons in larger colonies are more likely to change their foraging path day by day, following conspecifics to locations that have greater abundances of fish.
Bald eagles (Haliaeetus leucocephalus) are a major predator of blue heron eggs, nestlings, and fledglings, but interestingly some heron populations have been documented to nest associatively with eagles. Nesting eagles are thought to exclude other foreign eagles through territorial interactions, yielding a lesser overall probability that a heron nest becomes predated upon. However, this nesting tactic is a double-edged sword— a heron would not want to nest too closely to resident eagle nests, but at the same time nest close enough that it lies within the extent of the eagle’s territorial range. Herons that manage to straddle this fine line achieve higher rates of reproductive success, evading resident eagle predation and limiting visibility to foreign eagles.