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There are lots of herons and egrets around the world; about sixty species or so. They are capable of flying long distances and have established populations on many islands and all of the continents excepting Antarctica. In doing this they have developed (evolved) populations that are somewhat dissimilar from the original birds. For instance there are about thirty populations (sub-species) of what we usually call the Green Heron (also called Striated Heron). These populations probably could inter-breed if they had the opportunity; but on each island, in each separate location, they develop traits best suited to local survival.
The larger taxonomic group of long-legged wading birds will contain not only herons, egrets, but also night-herons, tiger-herons, and bitterns. The next taxonomic level will draw in other long-legged birds of the wetlands (mostly). Scattered around the world there are also flamingoes, storks, ibis’, shoebills, and hammerkop. All of these are recognizable as wetland or grassland birds but they are not all closely related. As a matter of fact the storks are genetically closest to New World vultures than they are to herons and egrets. There is a lot more to decipher here – genetics have not opened as many doors as it has created questions — pretty cool. Adaptation and environmental pressure have caused many crooked paths for evolution to follow.
Here are three of the four Night-Herons of the world – enjoy.
The Black-crowned Night-Heron (BCNH) is the most common of the Night-Heron group in the northeastern part of the US. We also get Yellow-crowned Night-Herons (YCNH) but not very often as nesting birds. The Yellow-crowns usually arrive in mid or late summer after the nesting colonies to the south break up and the birds disperse. The above is a Black -crowned Night-Heron showing the nuptial plume that adults get in breeding season. This is a common and widespread species.Another of the Night-Heron group is the Nankeen Night-Heron of the south Pacific. They are found in Australia, New Zealand, many of the Pacific island groups and on up into the Philippines. This one was photographed in Australia where they are widespread and found everywhere but the far western part of the country.However, today’s bird of the day is the Yellow-crowned Night-Heron. There is a pair that is sort of nest-building in the area. They are probably a little late in getting started, likely young birds, and they may not nest successfully. But who knows! There was an old-time Massachusetts State Ornithologist named Archie Hagar and in his retirement years we used to chat a bit – he told me that there had been a pulse of nesting YCNC when the green crab (Carcinus maenas) population bloomed. The YCNH are crab eaters and that relationship makes sense. When there are small numbers of breeding pairs there may be no relationship between crab numbers (a population explosion that is) and birds; but YCNH are dependent on crabs of one type or another as their primary and nearly sole food source. Like all predators they will take other foods (insects, lizards, small fish, and so on) but they really depend on crustaceans as the predominant food. The green crab is native to the European and north African coasts but has been spread around the world in ships ballast over the last few centuries. It was first seen in Massachusetts in 1833.Here is one of the local YCNH returning to, what might be, the nesting platform with a stick that looks like something pruned and left on the ground. They will make a nest woven of sticks and looking a bit scraggily in the first year. The birds often return to the same site and the same nest year after year, enlarging the nest each year. The male starts the nest but soon both sexes are actively building. They may start nests in several locations but soon focus their energy on one site. It takes three years for a YCNH to develop adult plumage – but they may still not get the breeding stuff right for another year or two.
On The Road With DEC 