ACOUSTICALLY GUIDED BEHAVIOR IN LONG-EARE D OWLS DURING EARLY ONTOGENY - ACOUSTIC AFFERENTATION IN FEEDING-BEHAVIOR

Feeding behaviour of nestlings of long-eared owls (Asio otus) is manif ested as a complex of two components, i. e., the vocal reaction (utter ing of begging calls) and specific motor response. Exposure to the app opriate acoustic signals resulted in an increase in the number of begg ing calls and approaching reaction to the source of acoustic signals. The range of monotonal signals effective for eliciting feeding behavio ur was 0.2-1.5 kHz; the most effective were the tones of 0.3-0.7 kHz. The approaching reaction to acoustic signals was rather weak up to the 5th day after hatching, clearly pronounced in the 6-11th days, and la ter on was abruptly substituted for the response of following the visu al stimulus provoked by the acoustic stimulation. Specific acoustic af ferentation is the sole stimulus for begging in nestlings up to 11 day s of age, and it remains a triggering stimulus for feeding behaviour i n owl nestlings throughout the period of artificial feeding under labo ratory conditions (up to the 40th day after hatching).