Ventilation rate (fv) in bats has been measured using various techniques. These include: holding the bats and positioning a hot-wire anemometer close to one nostril (Roberts, 1972); attaching a face mask incorporating a flow probe (Suthers et al. 1972; Thomas and Suthers, 1972; Suthers and Fattu, 1973; Thomas, 1981; Thomas et al. 1984; Carpenter, 1985,1986); using a body plethysmograph (Suthers and Fattu, 1973; Fattu and Suthers, 1981); inserting electrodes into the chest coupled to an impedance pneumograph (Studier and O’Farrell, 1972, 1976); and attaching a microphone to the abdomen (Kulzer, 1965; Schnitzler, 1968). These techniques are all invasive, raising the possibility that the values of fv recorded may deviate from those of unhindered animals. Here we describe the use of low-power Doppler radar to measure...

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