Mountain pigeons are four species of birds in the genusGymnophaps in the pigeon familyColumbidae. They are found on islands in eastern Indonesia and Melanesia, where they inhabit hill and montane forest. Medium-sized pigeons with long tails and wings, they are 33 to 38.5 cm (13.0 to 15.2 in) long and weigh 259 to 385 g (9.1 to 13.6 oz). They mostly have dull grey, white, or chestnut-brown plumage, their most distinctive feature being bright red skin around the eyes. Males and females mostly look alike, but the Papuan and pale mountain pigeons show slight sexual dimorphism. They are social and are usually seen in flocks of 10 to 40 birds, although some species can form flocks of more than 100. The genus was originally described by the Italian zoologist Tommaso Salvadori in 1874 and currently contains the Papuan, Seram, Buru, and pale mountain pigeons. Mountain pigeons inhabit trees and feed on a wide variety of fruit. All four species are listed as being of least concern on the IUCN Red List. (Full article...)
Bathymetry is the study of the underwater depth of sea and ocean floors, lake floors, and river floors. It has been carried out for more than 3000 years, with the first recorded evidence of measurements of water depth occurring in ancient Egypt. Bathymetric measurements are conducted with various methods, including depth sounding, sonar and lidar techniques, buoys, and satellite altimetry. However, despite modern computer-based research, the depth of the seabed of Earth remains less well measured in many locations than the topography of Mars. Bathymetry has various uses, including the production of bathymetric charts to guide vessels and identify underwater hazards, the study of marine life near the bottom of bodies of water, coastline analysis, and ocean dynamics, including predicting currents and tides. This video, created by the Scientific Visualization Studio at NASA's Goddard Space Flight Center, simulates the effect on a satellite world map of a gradual decrease in worldwide sea levels. As the sea level drops, more seabed is exposed in shades of brown, producing a bathymetric map of the world. Continental shelves appear mostly by a depth of 140 meters (460 ft), mid-ocean ridges by 3,000 meters (9,800 ft), and oceanic trenches at depths beyond 6,000 meters (20,000 ft). The video ends at a depth of 10,190 meters (33,430 ft) below sea level – the approximate depth of the Challenger Deep, the deepest known point of the seabed.
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