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Trapping, measurements, radio tracking and field surveys. Trapping - Harp Traps. Harp traps are designed to catch flying bats without damaging their wings.
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Trapping - Harp Traps • Harp traps are designed to catch flying bats without damaging their wings. • They consist of a frame that supports two rows of fine thread, and a catching bag at the base. If a bat detects the first row and swerves to pass through, it collides with the second row and tumbles into the collecting bag.
Trapping - Mist Nets • 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 mesh suspended between two poles, resembling an oversized volleyball net. • When properly deployed, the nets are virtually invisible.
Monitoring and Measurements • Traps are checked after the evening peak activity and bats are collected • Processing of most bats are done in the forests, however selected species will be taken back to base for further processing • If kept over night, released at first light and species trapped during dawn peak activity processed
Monitoring and Measurements • Measurements taken once a bat has been trapped: • Forearm length • Age • Sex • Species • Weight • Location • If the individual has been caught before, we can then work out how far the bat has traveled since we last caught it, and how much older it is
Radio Tracking • By attaching a small electronic device to an individual animal, movement throughout its environment can be accurately tracked and monitored. • There are a number of different tracking techniques, but each involves the transmission of an electronic signal from an attached device – either via satellite, high frequency radio waves, or the mobile telephone network.
Radio Tracking cont. • In this study, radio tracking will be used to identify roosts. • The spatial co-ordinates are recorded and then then the roost is characterised in terms of its physical characteristics • Roost type • Diameter at breast height • Height of roost opening • Vegetation cover • Distance to trail, water etc • The roost is monitored daily to see if the bat switches roosts
Field Surveys • Field surveys are essential to identify the habitats present in a study area and to record the locations of habitats • Habitat surveys are done in 50x50m plots. • Each tree over 5m is assigned to a size class.