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Position of the uropygial gland, indicated on a budgerigar Uropygial gland of a blue jay. The uropygial gland, informally known as the preen gland or the oil gland, is a bilobed sebaceous gland possessed by the majority of birds used to distribute the gland's oil through the plumage by means of preening.
The analysis was later generalized by Rutherford Aris for arbitrary values of the Peclet number. The dispersion process is sometimes also referred to as the Taylor-Aris dispersion . The canonical example is that of a simple diffusing species in uniform Poiseuille flow through a uniform circular pipe with no-flux boundary conditions.
When preening, a bird (such as this red lory) draws individual feathers through its beak, realigning and re-interlocking the barbules.. Preening is a maintenance behaviour found in birds that involves the use of the beak to position feathers, interlock feather barbules that have become separated, clean plumage, and keep ectoparasites in check.
Waterfowl production areas (WPAs) are a small component of the National Wildlife Refuge System. There are over 2 million acres (8,100 km 2) of this prime duck-producing land, mostly prairie potholes in the Dakotas, Minnesota, and Montana. The U.S. Fish and Wildlife Service owns, leases, or holds easements on the lands. [1]
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which includes over 170 species of waterfowl, among them the ducks, geese, and swans. Most modern species in the ...
Particle image velocimetry (PIV) is a non-intrusive optical flow measurement technique used to study fluid flow patterns and velocities. PIV has found widespread applications in various fields of science and engineering, including aerodynamics, combustion, oceanography, and biofluids.
By 2007, $827 million had been spent in Canada to purchase and enhance waterfowl habitats encompassing 4.4 million acres (18,000 km²). [5] In total, joint ventures have invested $4.5 billion to protect 15.7 million acres (64,000 km²) of such habitats. [2] The plan coordinates activities with other organizations, such as Ducks Unlimited.