Lecture 27: Echolocation

What is echolocation?

the production of sounds for use in target detection

How does echolocation work?

sound waves bounce off targets and these echoes provide information to the sound producer

What are three purposes for echolocation signals?

• communication

• orientation

• locating prey

What types of information does echolocation provide?

• locating day roosts, mating sites, hibernation sites, and feeding areas

• longe-range warnings

• vocal signatures (mother-young recognition)

What are tongue clicks?

produced with tongue in two bat species (pteropodids)

What are vocal signals?

• produced in the larynx of most echolocating bats and shrews

• emitted via mouth or nose - oral or nasal emitters

Describe how the sounds generated by a hunting bat vary from searching, to approaching a prey item, to capturing the prey item- include both time and frequency in your description.

• The time and frequency when a bat is searching is low

• when they begin to approach prey the frequency and time both increase

• when they capture the prey the time increases, but the frequency decreases

What is a narrow bandwidth?

great for discriminating moving objects from stationary landscape

What is increased bandwidth?

for determining finer details, but with reduced detection distance

Name two ways in which bats avoid injuring their own hearing with their super loud calls.

• the stapedius ad tensor tympani muscles contract, which dampens sound

• the bulla and periotic bone are not directly attached to the skull, which reduced conduction

How does skull morphology differ in a mouth vs a nose emitter?

• nasal emitters have rostral part of skull rotated ventrally

• aligns nasal cavity with direction of flight

What is the type of calls in bats that forage in open habitats?

long, high-intensity, low-frequency, narrowband calls

What is the type of calls in bats that forage in edge habitats?

short, intense calls, (with a combination of broadband and narrowband)

What is the type of calls in bats that forage in closed habitats?

short, broadband, low-intensity calls

Why are bats and moths in an evolutionary arms race?

• avoidance maneuvers in moths

• bats get new frequencies, partially abandoning echolocation