Na­ture’s Notebook

Lit­tle Blue Heron

Bonita & Estero Magazine - - DEPARTMENTS - BY WIL­LIAM R. C OX

There are 60 to 65 species of herons rec­og­nized world­wide, 20 of which are in North Amer­ica. They are di­vided into three groups: bit­terns; herons and egrets; and night herons. Florida has two species of bit­terns, eight species of herons and egrets, and two species of night herons.

The lit­tle blue heron (Egretta caerulea) is listed by the Florida Fish and Wildlife Con­ser­va­tion Com­mis­sion (FWC) as a Species of Spe­cial Con­cern. It is com­mon and wide­spread through­out most of Florida but is some­what rare in parts of the Pan­han­dle. Its pop­u­la­tion de­clined dur­ing the 19th and 20th cen­turies as a re­sult of both hu­man-in­duced and nat­u­ral im­pacts to sea­sonal wa­ter lev­els at its wet­land breed­ing colonies and foraging sites. It may also be im­pacted by pol­lu­tants as it for­ages at sites de­vel­oped by hu­mans such as drainage ditches, canals, fish ponds and im­pound­ments.

It can be ob­served foraging and nest­ing in both fresh­wa­ter and salt­wa­ter shal­low en­vi­ron­ments, though it prefers fresh­wa­ter wet­lands over salt­wa­ter wet­lands. It is com­mon on Sani­bel and Cap­tiva is­lands, as well as in south Florida.

The lit­tle blue heron is medium size at 25-29 inches in to­tal length with a wing­spread of 40 inches. Breed­ing adults are slate blue with a shaggy ma­roon head. The dis­tal third of the bill is black with the rest of the bill and or­bital skin cobalt blue (dark gray, in non­breed­ing plumage); the iris is gray­ish-green (pale yel­low, non­breed­ing); the legs are black (gray­ish green, non­breed­ing). Its long lance­o­late plumes are prom­i­nent from the head crest to the back dur­ing the breed­ing sea­son.

The lit­tle blue heron is unique among North Amer­ica’s herons and egrets in hav­ing a white phase dur­ing its im­ma­ture and ju­ve­nile stages. Dur­ing its molt­ing plumage tran­si­tion, the slate blue feath­ers of the adult are filled in grad­u­ally, and this stage of de­vel­op­ment is known as “cal­ico” or “pied.” It ac­quires its full adult plumage at 2 years of age. It be­gins breed­ing at 1112 months. The breed­ing sub-adult ob­tains the cobalt blue on the bill and or­bital skin, but its legs re­main yel­low-green.

When in its white phase, the lit­tle blue heron can be con­fused with four other herons and egrets ex­cept for sub­tle dif­fer­ences. The snowy egret (E. thula) has yel­low feet (golden

The slate blue feath­ers of the adult fill in grad­u­ally on the ju­ve­nile lit­tle blue heron.

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