Literaturdatenbank
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Bowles, A. E., & Eckert, S. (1997). Desert tortoises (gopherus agassizii) lack an acoustic startle response: implications for studies of noise effects (abstract). Journal of the Acoustical Society of America, 102(5), 3176.
Added by: Admin (21 Nov 2009 11:53:06 UTC) |
| Resource type: Journal Article BibTeX citation key: Bowles1997 View all bibliographic details  |
Categories: General Keywords: akustische Kommunikation = acoustic communication, Habitat = habitat, Nordamerika = North America, Physiologie = physiology, Schildkröten = turtles + tortoises Creators: Bowles, Eckert Collection: Journal of the Acoustical Society of America |
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| Abstract |
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Testudinidae The startle reflex is little studied in nonmammalian vertebrates, but in mammals it is often characterized by increase in heart rate. Orienting can also occur, characterized by a brief decrease in heart rate. To determine whether these responses occur in a testudinate, the desert tortoise, heart rate and behavior were measured during exposures to simulated jet overflights (94.6–114.2 dB CSEL) and sonic booms (6–10.5 psf). The best sensitivities of the 14 subjects ranged from 23 dB–50 dB SPL (average 34 dB SPL at 250 Hz) measured using ABR. Initial exposure to simulated jet overflights produced a typical reptilian defensive response: freezing. Tortoises became totally immobile for periods of up to 113 min. The average heart rate showed a gradual decline (7–8%), recovering within 2–4 h. Tortoises oriented when exposed to simulated sonic booms and after repeated exposure to subsonic aircraft noise; orienting produced no detectable change in heart rate. These results suggest that (1) high-intensity transients affect desert tortoises by altering activity patterns, but do not have a direct effect on heart rate and (2) tortoises experience a physiological response that produces protracted freezing.
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