Of the two considerations when designing a field study, the level of information needed and the limitations imposed by the animal itself, it is the latter that usually dictates what is possible. When deciding the proper field technique, consideration has to be given to the size of the animal, its niche

A sonogram of a northern minke whale (Balaenoptera acutorostrata). (Photo by Flip Nicklin/Minden Pictures. Reproduced by permission.)

Researchers measure the head of a Tasmanian devil (Sarcophilus la-niarius) during a study in Australia. (Photo by © Penny Tweedie/Cor-bis. Reproduced by permission.)

bats, particularly bats that forage above the canopy or within complex foliage.

Direct observation is usually not possible, especially during foraging. An exception is small light tags that can be placed on bats to observe short-distance foraging. It is possible to observe maternal behavior in communal nesting species either directly or with video equipment. Radio telemetry units are just reaching the size where movements can be monitored for longer than a day, but weight is still a serious concern.

A technique with potential is using the bats' ultrasonic call to identify species and possibly individuals. Devices can record and catalog the calls to a computer where a number of call parameters can be measured. At this time, there are quantifiable means to differentiate some, but not all bat species based on call parameters. Usually the calls can be used to predict which suite of species generated the call, but not the exact species. There is individual variability in the calls and it may be possible in the future to capture calls, as one would pictures of animals with unique markings. At this time, not enough call parameters can be measured to recommend use.

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    What are limitations mammals?
    7 years ago

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