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Evaluation of three elevated mist-net systems for sampling birds

1993; Association of Field Ornithologists; Volume: 64; Issue: 2 Linguagem: Inglês

1557-9263

J. Michael Meyers, Keith L. Pardieck,

Wildlife-Road Interactions and Conservation

-Three light-weight, low-canopy mist-net systems were developed and tested in dry tropical scrub, mangrove and forest habitats. One plastic (polyvinyl chloride) and two aluminum pole systems (with and without pulleys) were used to support mist nets to heights of up to 7.3 m. Although the aluminum telescoping-pole system (without pulleys) was expensive initially ($79-141/unit [US]), its use reduced capture of nontarget species and may have increased capture of target species when compared with ground-level netting. In one year, its use also reduced labor costs by $756, which completely offset the higher cost of the aluminum telescoping-pole system when compared to the plastic-pole system ($19/ unit). Unlike the plastic-pole system, the aluminum telescoping-pole system was adjustable to any height within its range of 1.8 to 7.3 m, was 1.5 m higher, was more efficient to operate in the field, and was easily moved to new locations. For capture of psittacines, the pulleys of the aluminum telescoping-pole system were not necessary, but their use may assist in efficiently retrieving large numbers of birds from the nets. The aluminum telescopingpole system was efficient in capturing psittacines, columbids, passerines and possibly chiropterans in habitats with canopies <10 m or in the forest subcanopy. EVALUACION DE TRES SISTEMAS DE REDES ORNITOLOGICAS ELEVADAS PARA MUESTREAR AVES Sinopsis.-Se desarrollaron tres sistemas livianos para el uso de redes ornitologicas a nivel del dosel. Estos fueron probados en bosques de matorral seco, manglar y habiticulo arboreo tropical. Los sistemas permiten que se eleven ls redes hasta una altura de 7.3 m. Uno de los sistemas estA compuesto (nicamente de tubos plAsticos (polivinyl cloride) mientras que los otros dos sistemas consisten en tubos telesc6picos de aluminio (con o sin poleas). A pesar que el sistema de tubos telesc6picos de aluminio (sin poleas) inicialmente fue mAs costoso ($79-141/unidad [US]), su uso redujo la captura de especies no deseadas y puede haber aumentado la captura de las especies deseadas, cuando se compara este sistema con los terrestres. En un afio, el uso de estos sistemas permiti6 una reducci6n de $756 en gastos de labor, lo que minimiza el alto costo de los tubos telescopicos comparado con el sistema de tubos plasticos ($19/unidad). A diferencia de los tubos pla'sticos, el sistema de tubos telesc6picos de aluminio es ajustable a cualquier altura dentro de su margen de 1.8 a 7.3 m, fue 1.5 m mas alto, es mas eficiente de operar y fue mais facil de mover a una nueva localidad. Para la captura de psittAcidos, el uso de poleas con los tubos telescopicos no fue necesario, pero puede ser eficiente al remover cantidades grandes de ayes. El sistema de tubos telescopicos (sin poleas) fue eficiente en la captura de psittacidos, columbidos, pasarinos y posiblemente chiropterados en habitaculos con doseles <10 m o en el subdosel del bosque. Mist-netting has been proven an effective method for the capture of birds since it was first introduced from Japan by Austin (1947). Although originally thought to be nonselective (Austin 1947, Low 1957), slight changes in net mesh size affect the efficiency with which certain species