| Autor: |
Andelt, William F., Hopper, Stuart N. |
| Zdroj: |
Progressive Fish-Culturist; Oct1996, Vol. 58 Issue 4, p258-262, 5p |
| Abstrakt: |
We evaluated the effectiveness of using alarm-distress calls of the black-crowned night heron Nycticorax nycticorax and the great blue heron Ardea herodias for frightening these piscivorous bird species from a rearing unit for rainbow trout Oncorhynchus mykiss. Heron alarm–distress calls reduced black-crowned night heron numbers 48% during the 11-d treatment period, compared with the pretreatment period, but did not affect the number of great blue herons. The number of black-crowned night herons using the rearing unit and the proportion that remained immediately after the broadcast of alarm–distress calls increased from nights 1 through 11 of the treatment period, which indicates that this predator quickly habituated to the calls. We did not find any differences between the proportions of black-crowned night herons and great blue herons that remained on the rearing unit immediately after playing calls of the respective species. Alarm–distress calls were mostly ineffective in reducing heron predation on rainbow trout fingerlings. [ABSTRACT FROM PUBLISHER] |
| Databáze: |
Complementary Index |
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