December 2012 Bird Photo of the Month

Tricolored Heron (Egretta tricolor) with chicks on nest © Lisa Willnow
Sony DSC-H5, 32 mm lens, ISO 400, 1/250 @ f/4

A bird species may look very different depending upon lighting (dusk, cloudy, full sun), age (hatchling, juvenile, adult), behavior, whether it is in normal or breeding plumage, and if the feathers are wet, dry, or worn.  Lisa Willnow, in May, from a boardwalk, photographed this breeding Tricolored Heron actively fluffing its feathers.  This bird looks very different from the dark slate-blue, thin long-necked heron with characteristic white belly we usually notice foraging along edges of ditches and ponds.

In February-March, in preparation for courtship, Tricolored Herons dramatically change color: brown eyes and yellow legs become deep red, and yellow bills turn brilliantly blue. The intense blue on bill and face results when the heron rubs them in the oil from the uropygial gland at the base of their tail.  The oil is used for preening the feathers but, during the breeding season, a hormone is added.  The striking colors combined with rufous-tinged back plumes and white head plumes signal each bird’s readiness to mate.  The highly colored male began a nest, attracted, and selected a similarly colorful female and they produced these three young.  Because mating ended about a month before the photo was taken, this adult’s blue bill and facial color have paled.

About 10 days old, the three nestlings with their unruly down feathers and oversized bills will continue growing rapidly.  In 30 days they will leave the nest and their dependency on parental feeding ends. They will have grown beautiful juvenile chestnut-colored feathers on the head and neck, with slate back, white under-parts and frontal neck stripe.  Parental duties completed by June, the adults molt into normal plumage of plain slate blue feathers with yellow legs, facial skin, and lower bill. Watch in February when the molt intensifies colors for courtship.  The cycle begins again.

Juanita Baker, Coordinator
Florida Bird Photo of the Month
Pelican Island Audubon

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