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Like many precocial hatchlings, domestic chickens are already covered with a coat of downy feathers when they hatch. The word down comes from the Old Norse word dúnn, which had the same meaning as its modern equivalent. [1] The down feather is considered to be the most "straightforward" of all feather types. [2]
Newly hatched chicks have downy feathers that do not become waterproof until the chicks grow into juveniles. [20] The juvenile plumage, attained by thirty days after a chick hatches, is dark brown or gray above and white below. These feathers are mainly needed to protect the chicks from the strong sun rather than keep them warm.
Confuciusornithidae contains four genera, possessing both shafted and non-shafted (downy) feathers. Some specimens probably referable to this clade represents one of the earliest known fossil evidence of primary feather moulting. [1] They are also noted for their distinctive pair of ribbon-like tail feathers of disputed function.
A typical vaned feather features a main shaft called the quill with an upper section called the rachis. Fused to the rachis are a series of branches, or barbs ; the barbs in turn have barbules branching off them, and they in turn branch yet again with a series of growths called barbicels , some of which have minute hooks called hooklets for ...
They are born downy and by 10 days old they are able to regulate their own temperature. [19] Except in times of food shortage there is at least one parent present at all times, and both parents are present 10–30% of the time. [46] Both parents alternate between brooding the chick or foraging for food. Adults feeding chick, Lundy
A similar edible tunicate in the Mediterranean is Microcosmus sabatieri, also called a sea violet or sea fig. [11] There are concerns about the safety of eating P. chilensis, given its high concentration of vanadium, with up to 1.9 mg/kg found in dry blood plasma. [12] Vanadium is a heavy metal, considered toxic at any more than incidental ...
In more mixed eastern and southern habitats, the diversity of large predators is higher and the crowned eagle, despite its great power, is not assured at the top of the avian food chain. Amongst the more formidable raptors, the martial, the Verreaux's, and the crowned eagles, may live on the same hillside and all hunt hyraxes .
The tail feathers are white with characteristic black markings, which form an inverted black "T" pattern that resembles the tail of the western black-eared wheatear. This 14 centimetres (5.5 in) bird nests in open, stony, sparsely vegetated regions, laying four to six eggs in a hole, under a stone or in a rock crevice.