Summary
Bats of the speciesNoctilio albiventris were trained to detect the presence of a target or to discriminate differences in target distance by means of echolocation. During the discrimination trials, the bats emitted pairs of pulses at a rate of 7–10/s. The first was an 8 ms constant frequency (CF) signal at about 75 kHz. This was followed after about 28 ms by a short-constant frequency/ frequency modulated (short-CF/FM) signal composed of a 6 ms CF component at about 75 kHz terminating in a 2 ms FM component sweeping downward to about 57 kHz. There was no apparent difference in the pulse structure or emission pattern used for any of the tasks. The orientation sounds of bats flying in the laboratory and hunting prey under natural conditions follow the same general pattern but differ in interesting ways.
The bats were able to discriminate a difference in target distance of 13 mm between two simultaneously presented targets and of 30 mm between single sequentially presented targets around an absolute distance of 35 cm, using a criterion of 75% correct responses.
The bats were unable to detect the presence of the target or to discriminate distance in the presence of continuous white noise of 54 dB or higher SPL. Under conditions of continuous white noise, the bats increased their pulse repetition rate and the relative proportion of CF/FM pulses.
The bats required a minimum of 1–2 successive CF/FM pulse-echo pairs for target detection and 2–3 to discriminate a 5 cm difference in distance. When the distance discrimination tasks were made more difficult by reducing the difference in distance between the two targets the bats needed to integrate information from a greater number of successive CF/FM pulse-echo pairs to make the discrimination.
Similar content being viewed by others
Abbreviations
- CF :
-
constant frequency
- FM :
-
frequency modulation
References
Airapetianz E, Konstantinov AI (1974) Echolocation in nature. Nauka Leningrad. English Translation Joint Publications Research Service No 63328, 100 North Glebe Road, Arlington, Virginia 22201
Gellerman LW (1933) Chance disorders of alternating stimuli in visual discrimination experiments. J Genet Psychol 42:205–208
Goldman LJ, Henson OW (1977) Prey recognition and selection by the constant frequency bat,Pteronotus p. parnellii. Behav Ecol Sociobiol 2:411–420
Griffin DR (1958) Listening in the dark. Yale University Press, New Haven. Dover Press, New York
Griffin DR, McCue JJG, Grinnell AD (1963) The resistance of bats to jamming. J Exp Zool 152:229–250
Griffin DR, Novick A (1955) Acoustic orientation of neotropical bats. J Exp Zool 130:251–300
Grinnell AD (1973) Neural processing mechanisms in echolocating bats, correlated with differences in emitted sounds. J Acoust Soc Am 54:147–156
Grinnell AD, Hagiwara S (1972) Adaptations of the auditory nervous system for echolocation. Studies of New Guinea bats. Z Vergl Physiol 76:41–81
Habersetzer J, Vogler B (1983) Discrimination of surface-structured targets by the echolocating batMyotis myotis during flight. J Comp Physiol 152:275–282
Hartridge H (1945) Acoustical control in the flight of bats. Nature 156:490–494
Novick A (1977) Acoustic orientation. In: Wimsatt WA (ed) Biology of bats vol III. Academic Press, New York, pp 13–281
Schnitzler HU (1968) Die Ultraschall-Ortungslaute der Hufeisen-Fledermäuse (Chiroptera-Rhinolophidae) in verschiedenen Orientierungssituationen. Z Vergl Physiol 57:376–408
Schnitzler HU (1970) Echoortung bei der FledermausChilonycteris rubiginosa. Z Vergl Physiol 68:35–38
Schnitzler HU, Flieger E (1983) Detection of oscillating target movements by echolocation in the Greater Horseshoe bat. J Comp Physiol 153:385–391
Schnitzler HU, Henson OW Jr (1980) Performance of airborne animal sonar systems: I. Microchiroptera. In: Busnel RG, Fish JF (eds) Animal sonar systems. Plenum Press, New York, pp 109–181
Schnitzler HU, Menne D, Rudi K, Heblich K (1984) The acoustical image of fluttering insects in echolocating bats. In: Huber F, Markl H (eds) Neuroethology and behavioral physiology. Roots and growing points. Springer, Berlin Heidelberg New York Tokyo, pp 235–250
Schuller G (1979) Coding of small sinusoidal frequency and amplitude modulations in the inferior colliculus of ‘CF-FM’ bat,Rhinolophus ferrumequinum. Exp Brain Res 34:117–132
Simmons JA (1968) Depth perception by sonar in the batEptesicus fuscus. PhD Thesis, Princeton University
Simmons JA (1971) Echolocation in bats; signal processing of echoes for target range. Science 171:925–928
Simmons JA (1973) The resolution of target range by echolocating bats. J Acoust Soc Am 54:157–173
Simmons JA, Howell DJ, Suga N (1975) Information content of bat sonar echoes. Am Sci 63:204–215
Simmons JA, Lavender WA, Lavender BA (1978) Adaptation of echolocation to environmental noise by the batEptesicus fuscus. Kenya National Academy for Advancement of Arts and Science, pp 97–104
Simmons JA, Vernon JA (1971) Echolocation: Discrimination of targets by the bat,Eptesicus fuscus. J Exp Zool 176:315–328
Skolnik MI (1962) Introduction to radar systems. McGraw-Hill, New York
Suthers RA (1965) Acoustic orientation by fish-catching bats. J Exp Zool 158:319–348
Suthers RA, Fattu JM (1973) Fishing behavior and acoustic orientation by the bat (Noctilio labialis). Anim Behav 21:61–66
Woodward PM (1964) Probability and information theory, with applications to radar, 2nd ed. Pergamon Press, New York
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Roverud, R.C., Grinnell, A.D. Discrimination performance and echolocation signal integration requirements for target detection and distance determination in the CF/FM bat,Noctilio albiventris . J. Comp. Physiol. 156, 447–456 (1985). https://doi.org/10.1007/BF00613969
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00613969