Herons--Ecology.

Little Blue Herons, Snowy Egrets, and Tricolored Herons that nest in the
Everglades have declined sharply over the past decade, due in part to food resource
limitations. Here, I examined the diet of small herons to determine how prey
characteristics affected the fitness of small herons in the highly modified Florida
Everglades. Analysis of these diet differences showed birds nesting in 2017, a
hydrologically dryer-than average year, and a more taxonomically varied diet were
associated with nest success and improved body condition of nestlings. Over half (51%)
of the fish biomass Little Blue Herons consumed were non-native species, compared to
14% and 19% non-native fish biomass consumed by Snowy Egrets and Tricolored
Herons, respectively. Surprisingly, <7% of fish biomass available in the Everglades were
comprised of non-native fish species, suggesting that small herons, and Little Blue
Herons in particular, may be using alternative foraging habitats, to supplement their
dietary needs.

Avian reproductive success varies depending on environmental conditions,
degree of predation, location, and food availability. I examined food availability and
nesting habitat of wading birds in South Florida. Evaluating prey availability and prey
used by two small heron species demonstrated the ability for small herons to maintain
consistent diets through fluctuating environmental conditions, within and across different
wetland types. Small herons may be able to cope with environmental changes by altering
foraging locations and strategies. Regarding nesting habitat, man-made sites may
provide habitat comparable to natural sites, at least in the short-term. The nest’s position
can influence its susceptibility to increased temperatures and predators, particularly for.
Climatic conditions such as rainfall can also impact nesting success by altering foraging
conditions and fish behavior. Understanding the effects of hydrologic regimes on biota
can have practical applications since ecosystems around the world share similar problems with competing demands for resources, and there is a concern for how use can affect the
quality of the resource.