The Effects of High-Amplitude Impulsive Noise on Hatching Success: A reanalysis of the Sooty Tern Incident
BBN LABS INC CANOGA PARK CA
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In a widely cited article, Austin ET AL. 1970a, Proc. Int. Ornith. Cong. 15627 attributed a mass hatching failure among 50,000 pairs of Sooty Terns Sterna fuscata nesting on the Dry Tortugas to damage caused by sonic booms from low-flying military aircraft. Theoretically, eggshells and embryonic tissues should withstand pressures much greater than those generated by even the most intense sonic booms, so we conducted a worst case experiment to test whether impulsive noise could cause mass hatching failures. We exposed 20 chicken Gallus gallus and 20 quail Coturnix couturnix eggs to explosions of four pest-control devices mean peak flat sound pressure level 177.3 db re 20 upa mean CSEL of 139 mean frequency 620 Hz. None of these eggs showed the longitudinal cracks that had been reported on Dry Tortugas. We also exposed fertile chicken 13 and quail 8 eggs to five similar impulses and compared hatch rates with those of matched controls. The chicken eggs were exposed on Day 2 of incubation, the most sensitive phase of development the quail eggs at half-way through incubation, the time of exposure on the Dry, Tortugas. Hatch rates and weights between control and exposed embryos were not significantly different.