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| [Note Guidelines] Photographer's Note |
Another day, another queue at the feeder. Today was an awful day in Auckland. The wind was blowing and the rain was heavy, but the visitors to my garden were many. Yes, another image of a Silvereye. These little birds were making happy sound and eating well on such a terrible day. Thanks for looking.
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with around 5,093 species, it is roughly twice as diverse as the largest of the mammal orders, the Rodentia.
The names "passerines" and "Passeriformes" are derived from Passer domesticus, the scientific name of the type species – the House Sparrow – and ultimately from the Latin term passer for true sparrows and similar small birds.
Origin and evolution The evolutionary history of and relationships among the passerine families remained rather mysterious until around the end of the 20th century. Many passerine families were grouped together on the basis of morphological similarities that, it is now believed, are the result of convergent evolution, not a close genetic relationship. For example, the "wrens" of the northern hemisphere, those of Australia, and those of New Zealand look very similar and behave in similar ways, and yet belong to three far-flung branches of the passerine family tree; they are as unrelated as it is possible to be while remaining Passeriformes.
Much research remains to be done, but advances in molecular biology and improved paleobiogeographical data are gradually revealing a clearer picture of passerine origins and evolution. It is now thought that the first passerines evolved in Gondwana at some time in the Paleogene, maybe around the Late Paleocene some 60–55 million years ago (mya). The initial split was between the Tyranni, the songbirds, the Eurylaimides and the New Zealand "wrens", which must have diverged during a short period of time (some million years at most). The Passeriformes apparently evolved out of a fairly close-knit clade of "near passerines" which contains such birds as the Piciformes, Coraciiformes, and Cuculiformes.
A little later, a great radiation of forms took place out of Australia-New Guinea: the Passeri or songbirds. A major branch of the Passeri, "Parvorder Passerida", emerged either as the sister group to the basal lineages and corvoids ("Parvorder Corvida"), or more likely as a subgroup of it, and expanded deep into Eurasia and Africa, where there was a further explosive radiation of new lineages. This eventually led to three major passeridan lineages comprising about 4,000 species, which in addition to the corvoidan clade and numerous minor lineages make up songbird diversity today. There has been extensive biogeographical mixing, with northern forms returning to the south, southern forms moving north, and so on.
IMAGE INFORMATION
Camera: Canon 20D
Time of day: 13:29 p.m.
Date: 22nd June 2008
Weather conditions: Cloudy
Lens: Canon 100-400mm L IS
Filter: Hoya 77mm UV
Shutter Speed: 1/100
F-Stop: F/6.3
Focal Length: 400mm
ISO: 200
Support: Hand Held
Original file type: Digital Raw |
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