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Mist nets are used by ornithologists and bat biologists 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 the 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-gaza 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 to optimally place the nets, avoid entangling nets in vegetation, and properly store nets. 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 == 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. Nets deployed in this manner often use a playback of a the species' song or call, or a model of that species placed near the net to lure the targeted individuals into the net (e.g. ). Because broadcast netting captures birds indiscriminately, this technique is better suited to examining the species that occur within a specific habitat. Bird banding stations throughout the United States use this method. Typically such stations collect a set of standard measurements from each individual, including mass, wing chord, breeding status, body fat index, sex, age, and molt status. Although setting up mist nets is time consuming and requires certification, there are certain advantages to visual and aural monitoring techniques, such as sampling species that may be poorly detected in other ways. It also allows easy standardization, hands-on examination, and reduces misidentification of species. Because they allow scientists to examine species up close, mist nets are often used in mark-recapture studies over extended periods of time to detect trends in population indices (Dunn and Ralph 2004). Some uses of data collected using mist net sampling are: * Mark-recapture for population sampling * Humane capture and relocation of small birds or bats * Tagging and tracking * Testing health of bird or bat species and for ectoparasite studies * Examination of avian phenology in response to climatic and other variables * Examination of patterns of molt Because there is still debate as to whether or not these techniques provide precise data measurements, it is suggested that mist netting is used as a supplement to aural and visual methods of observation. One of the main disadvantages of mist nets is that the numbers captured may only represent a small proportion of the true population size (Dunn and Ralph 2004). Mist netting is a unique method in that it provides demographic estimates throughout all seasons, and offers valuable guides to relative abundance of certain species or birds and/or bats (Dunn and Ralph 2004). ==Example study== Mist nets can be important tools for collecting data to reveal critical ecological conditions in a variety of situations. This summarized study, "Effects of forest fragmentation on Amazonian understory bird communities" by Richard O. Bierregaard and Thomas E. Lovejoy, used mist nets to analyze the effects of forest fragmentation on understory bird communities in terra firme forest of Central Amazon. Data from intensive mist netting mark-recapture programs on understory birds from isolated forest reserves were compared to pre-isolation data from the same reserves to investigate changes related to isolation from continuous forest (Bierregard and Lovejoy 1989). Birds surveyed were from a variety of ecological guilds, including nectivores, insectivores, frugivores, obligatory army ant followers, forest edge specialists and flocking species. The periodic sampling by mist netting capture program provided the quantitative basis for this project. Reserves of varied sizes (1 and 10 hectare) within the Biological Dynamics of Forest Fragments project site were sampled with transects of tethered mist nets once every three or four weeks. Capture rates from isolated reserves were compared to pre-isolation rates to measure changes in population size and/or avian activity due to isolation (Bierregard and Lovejoy 1989). Data was analyzed in the following ways: capture rates per net hour as a function off time since isolation, percent recapture as a function of time since isolation, abundance distribution of species against the species rank by abundance, percent individuals banded according to species and feeding strategy, and finally, capture rates per net hour in isolated reserves against capture rates per net hour in continuous forests. A summary of the results and discussion as stated by Bierregaard and Lovejoy is as follows: ...changes in the understory avian community in isolated patches. Following isolation, capture rates increase significantly as birds fleeing the felled forest entered new forest fragments. Movement to and from the reserve is limited as witnessed by an increase in recapture percentages following isolation. Species of birds that are obligate army ant followers disappeared at the time the surrounding habitat was removed from 1 and 10 ha areas. The complex mixed-species of insectivorous flocks typical of Amazonian forests deteriorated within 2 years of isolation of 1 and 10 ha forest fragments. Several species of mid-story insectivores changed their foraging behavior after isolation of small forest reserves. These data were collected using mist nets. Data from mist netting efforts may be used to gain a greater understanding of ecological effects of factors impacting ecosystems, such human activities or environmental changes. This is just one example of the use of mist nets as a tool for ecological and biological sciences, as well as possible ecosystem management implications mist net data offers. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「mist net」の詳細全文を読む スポンサード リンク
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