Orians GH, Christman GM (1968) A comparative study of the behavior of Red-winged, Tricolored, and Yellow-headed Blackbirds. Morton ES (1975) Ecological sources of selection on avian sounds. Marten K, Quine D, Marier P (1977) Sound transmission and its significance for animal vocalization. Marten K, Marier P (1977) Sound transmission and its significance for animal vocalization. King AP, West MJ, Eastzer DH, Staddon JER (1981) An experimental investigation of the bioacoustics of cowbird song. Ingard U (1953) A review of the influence of meteorological conditions on sound propagation. PhD dissertation, Cornell University, Ithaca, New York Howard RA Jr (1977) Habitat structure, polygyny, and the evolution of upland nesting in Red-winged Blackbirds. Henwood K, Fabrick A (1979) A quantitative analysis of the dawn chorus: temporal selection for communicatory optimization. Heinz RD, Sinnott JM, Sachs MB (1977) Auditory sensitivity of the Redwing Blackbird ( Agelaius phoeniceus) and Brown-headed Cowbird ( Molothrus ater). Brüel and Kjaer Instruments, Inc., Marlborough, Massachusetts Hassall JR, Zaveri K (1979) Acoustic noise measurements, 4th ed. J Comp Physiol Psychol 88:1–20Įhret G (1977) Comparative psychoacoustics: perspectives of peripheral sound analysis in mammals. Springer, Berlin Heidelberg New York, pp 261–288ĭooling RJ, Saunders JC (1975) Hearing in the parakeet ( Melopsittacus undulatus): absolute thresholds, critical ratios, frequency difference limens, and vocalizations. In: Popper AN, Fay RR (eds) Comparative studies of hearing in vertebrates. Z Tierpsychol 56:137–149ĭooling RJ (1980) Behavior and psychophysics of hearing in birds. Nature 222:778–780ĭabelsteen TC (1981) The sound pressure level in the dawn song of the Blackbird ( Turdus merula) and a method for adjusting the level in experimental song to the level in natural song. Behav Ecol Sociobiol 10:29–38Ĭody ML, Brown JH (1969) Song asynchrony in neighboring bird species. Anim Behav 29:641–642īrenowitz EA (1982) Long-range communication of species identity by song in the Red-winged Blackbird. Auk 98:355–360īrenowitz EA (1981b) ‘Territorial song’ as a flocking signal in Red-winged Blackbirds. J Exp Biol 78:163–166īrenowitz EA (1981a) The effect of stimulus presentation sequence on the response of Red-winged Blackbirds in playback studies. J Ornithol 120:353–389īrackenbury JH (1979) Power capabilities of the avian sound-producing system. This suggests that redwing song is adapted in its structure and amplitude at the source to communicate a male's presence throughout the extent of his neighbors' territories.īowman RI (1979) Adaptive morphology of song dialects in Darwin's finches. Maximum measurements of active space correspond closely to the maximum distances across 2 individual upland redwing territories. This distance varies with changes in ambient noise level during the day, and with relative wind direction. In the absence of wind, the maximum active space of redwing song is about 189 m for a signal SPL of 93.5 dB at 1 m. Also, redwings are able to detect differences in this ratio as small as 3 dB. Measured on a 4 kHz octave filter scale (center frequency = 4 kHz, octave pass-band = 2.83– 5.66 kHz), noise during one day ranges from 15 dB SPL (at 06∶00 h) to 36 dB SPL (at 11∶00 h), more than a 10-fold variation in ambient sound pressure.Ī 3 dB signal to noise ratio is sufficient for detection of song masked by noise in the field (Figs. The rate of attenuation varies with relative wind direction (Table 1).Īmbient noise level is relatively low in early morning, rises in late morning and afternoon as air turbulence increases, and then drops again in the evening as turbulence decreases (Table 2 and Appendix). At distances beyond about 30 m, however, excess attenuation becomes important (Fig. Maximum root-mean-square song amplitude at 1 m from a singing bird ranged from 88.5–93.5 dB SPL ( \(\bar X\)± SE = 90.8☐.21 dB SPL).Ĭlose to the source, song attenuates at a rate which closely matches that predicted by spherical spreading (6 dB/doubling of distance) alone. Song amplitude, the rate of signal attenuation, the amplitude of ambient noise, and the sensitivity of redwings to song masked by noise determine active space and were measured in the field: Active space, that distance from the source over which signal amplitude remains above the detection threshold of potential receivers, was determined for Red-winged Blackbird ( Agelaius phoeniceus) song in an upland pasture near Ithaca, New York.
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