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A few hundred species migrate long distances, in some cases of thousands of kilometres. About 120 species of fish, including several species of salmon, migrate between saltwater and freshwater (they are 'diadromous'). [23] [24] Forage fish such as herring and capelin migrate around substantial parts of the North Atlantic ocean.
Of course, in the southern hemisphere, the directions are reversed, but there is less land area in the far south to support long-distance migration. [ 19 ] The primary motivation for migration appears to be food; for example, some hummingbirds choose not to migrate if fed through the winter. [ 20 ]
Shaders are most commonly used to produce lit and shadowed areas in the rendering of 3D models. Another use of shaders is for special effects, even on 2D images, (e.g., a photo from a webcam). The unaltered, unshaded image is on the left, and the same image has a shader applied on the right.
The mallard has hybridised with more than 40 species in the wild, and an additional 20 species in captivity, [13] though fertile hybrids typically have two Anas parents. [14] Mallards and their domestic conspecifics are fully interfertile; many wild mallard populations in North America contain significant amounts of domestic mallard DNA. [15] [16]
The set of APIs used to compile, link, and pass parameters to GLSL programs are specified in three OpenGL extensions, and became part of core OpenGL as of OpenGL Version 2.0. The API was expanded with geometry shaders in OpenGL 3.2, tessellation shaders in OpenGL 4.0 and compute shaders in OpenGL 4.3. These OpenGL APIs are found in the extensions:
Most hummingbirds migrate in the winter to Central America or Mexico, but some hummingbirds spend the winter on the Gulf Coast and may be found in South Texas and South Louisiana during mild winters.
By the time they are ready to migrate, they are often so heavy they can barely fly. The timing of migration appears to be triggered by day-length only. This is why it is OK to keep feeders out ...
Got hummingbirds in your yard? Learn everything you wanted to know about how they survive and where they go when the weather turns cold.