Mist nets are used by hunters and poachers, but also by ornithologists and chiropterologists to capture wild birds and bats for banding or other research projects. Mist nets are typically made of nylon or polyester mesh suspended between two poles, resembling a volleyball net. When properly deployed in the correct habitat, the nets are virtually invisible. Mist nets have shelves created by horizontally strung lines that create a loose, baggy pocket. When a bird or bat hits the net, it falls into this pocket, where it becomes tangled. The mesh size of the netting varies according to the size of the species targeted for capture. Mesh sizes can be measured along one side of the edge of a single mesh square, or along the diagonal of that square. Measures given here are along the diagonal. Small passerines are typically captured with 30–38 mm mesh, while larger birds, like hawks and ducks, are captured using mesh sizes of ~127 mm. Net dimensions can vary widely depending on the proposed use. Net height for avian mist netting is typically 1.2 - 2.6 m. Net width may vary from 3 to 18 m, although longer nets may also be used. A dho-gazza is a type of mist net that can be used for larger birds, such as raptors. This net lacks shelves. The purchase and use of mist nets requires permits, which vary according to a country or state's wildlife regulations. Mist net handling requires skill for optimal placement, avoiding entangling nets in vegetation, and proper storage. Bird and bat handling requires extensive training to avoid injury to the captured animals. Bat handling may be especially difficult since bats are captured at night and may bite. A 2011 research survey found mist netting to result in low rates of injury while providing high scientific value. Usage of mist nets Mist nets have been used by Japanese hunters for nearly 300 years to capture birds. They were first introduced into use for ornithology in the United States of America by Oliver L. Austin in 1947. Mist netting is a popular and important tool for monitoring species diversity, relative abundance, population size, and demography. There are two ways in which mist nets are primarily utilized: target netting of specific species or individuals, and broadcast netting of all birds within a particular area. Targeted netting is typically used for scientific studies that examine a single species.