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We are grateful to Dr. Brigham for providing the following instructions.
A commonly used "rule" for working with flying animals is to keep the mass of the transmitter AND adhesive below 5% of body mass. This means that the smallest tag currently produced by Holohil (0.35g - LB-2N) should not be attached to bats weighing less than 7.0g. This rule may be bent (slightly) for the purpose of finding roost sites as there is little question that bats can carry heavier loads. However, for studies of roost preference, foraging behaviour, etc. it is my opinion that the 5% rule should be used. See Aldridge and Brigham, 1988 J. Mammalogy. It is important to emphasize that the rule represents a maximum transmitter load and in reality the smaller the transmitter, the less likely it is that an animal's behaviour will be affected.
Transmitters should be attached to the area between the shoulder blades so that the bats cannot use their hind feet to pull off the tag. The adhesive I find works best is Skin-Bond® (see note below). For bats with short fur (e.g., Eptesicus), transmitters seem to remain attached best if the fur is not clipped. The length of the fur, rate of growth, oiliness and even geographic location all seem to contribute to successful attachment. I suggest that at the beginning of a study, attach several tags with and without clipping fur to see what works best.
When applying the adhesive use a very thin layer on both the transmitter and the bat. Remember that adhesive also contributes to the mass of the transmitter package. Let stand for about 5 minutes until the glue bubbles, then affix the tag and hold it for a further 5 minutes. Frost the fur around the edge of the transmitter. At this point the initial setting of the glue will have occurred. It is now important to prevent the bat from scratching at and potentially loosening the tag before the glue fully sets. I recommend holding the bat for another 10 - 30 minutes to make sure that the glue has set completely before releasing the animal.