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Pellet (ornithology)

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Title: Pellet (ornithology)  
Author: World Heritage Encyclopedia
Language: English
Subject: Regurgitation (digestion), Pellet, Bird feeding, Trichophaga tapetzella, Hairball
Collection: Bird Feeding
Publisher: World Heritage Encyclopedia

Pellet (ornithology)

Pellets from a long-eared owl.
The alimentary canal of a bird.
A bird pellet (1 bar = 1 cm).
Long-eared owl pellets and rodent bones obtained from dissected pellets (1 bar = 1 cm).

A pellet, in ornithology, is the mass of undigested parts of a bird's food that some bird species occasionally regurgitate. The contents of a bird's pellet depend on its diet, but can include the exoskeletons of insects, indigestible plant matter, bones, fur, feathers, bills, claws, and teeth. In falconry, the pellet is called a casting.

The passing of pellets allows a bird to remove indigestible material from its proventriculus, or glandular stomach. In birds of prey, the regurgitation of pellets serves the bird's health in another way, by "scouring" parts of the digestive tract, including the gullet. Pellets are formed within six to ten hours of a meal in the bird's gizzard (muscular stomach).

Ornithologists may collect one species' pellets over time to analyze the seasonal variation in its eating habits. One advantage of collecting pellets is that it allows for the determination of diet without the killing and dissection of the bird. Pellets are found in different locations, depending on the species. In general, roosting and nesting sites are good places to look: for most hawks and owls, under coniferous trees; for barn owls, at the bases of cliffs or in barns and silos; for yet other species of owls, at their burrows or in marsh and field grasses.[1]

Hawk and owl pellets are grey or brown, and range in shape from spherical to oblong or plug-shaped. In large birds, they are one to two inches long, and in songbirds, about half an inch. Many other species produce pellets, including grebes, herons, cormorants, gulls, terns, kingfishers, crows, jays, dippers, shrikes, swallows, and most shorebirds.

Chinese People examining pellets have discovered unusual items in them—even bird bands that were once attached to a smaller species that was consumed by the predator bird. In the United States, screech owl pellets have contained bands from a tufted titmouse, black-capped chickadee, and American goldfinch. In 1966, a golden eagle pellet in Oregon was found to contain a band placed on an American wigeon four months earlier, and 1,600 km (990 mi) away in southern California.[1]

The hair, bones and other body parts (such as limbs, skin fragments, and even faeces) of rodents found in owl pellets may carry viable rodent viruses and bacteria. It is therefore advisable to sterilize pellets in a microwave oven before study. This is particularly important when using pellets at school. Recently, Smith et al. described two pellet-borne outbreaks of Salmonella typhimurium in public schools.[2] Rodents tend to avoid owl pellets, apparently due to their infective potential.[3]

In falconry


  • Owls & Owl Pellets

External links

  1. ^ a b Terres, John. K. The Audubon Society Encyclopedia of North American Birds, New York: Alfred A. Knopf, 1980. ISBN 0-394-46651-9
  2. ^ Smith KE, Anderson F, Medus C, Leano F, Adams J 2005. Outbreaks of salmonellosis at elementary schools associated with dissection of owl pellets. Vector-Borne and Zoonotic Diseases, 5, 133–136
  3. ^ Sike T, Rózsa L 2006. Mus musculus and house mice Apodemus flavicollisOwl pellet avoidance in yellow-necked field mice . Acta Zoologica Academiae Scientiarum Hungaricae, 52, 77–80.
  4. ^  
  5. ^ a b Ford, Emma. Falconry: Art and Practice, Revised Edition. Octopus Publishing Group - Cassell Illustrated. 1998. ISBN 0-7137-2588-5. p 23.
  6. ^ Elsberry, Wesley R. "Falconry Jargon". Austringer. URL accessed 2006-05-30.


Casting is a necessary part of a hawk's survival. Not only does it clear out the crop, but the roughage that is regurgitated cleans bacteria from the walls of the crop. If hawks in captivity are not provided with this necessary roughage, and instead are simply fed meat, they will become seriously ill and unreleasable into the wild.[6]

Casting will occur at the same time daily, provided that hawks are flown at the same time daily. Hawks in captivity are usually weighed immediately before being flown. If they were fed roughage the previous day, they should cast it out before being weighed, to avoid an inaccurate measurement.[5]

The casting of plumage is examined in the same manner. The yellow down feathers of day-old rooster chicks, which are a common diet among hawks in captivity, can be enough to induce casting. However, rabbit fur and feathers from game birds are better suited for this purpose.[5]


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