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The role of vision in the prey-catching behaviour of Little Penguins Eudyptula minor was tested using four captive penguins in a swimming pool. A live fish was placed in the pool with a penguin at various light intensities before and after dawn and dusk. The penguins' behaviour in the morning was the same as in the evening. As the light decreased, the percentage of fish chased by the penguins decreased, and no fish were caught at a light level less than 0.01 μeinstein/m2/s (which occurs approximately 25 min before sunrise and after sunset at latitude 37dS). The time the penguins spent searching for the fish also decreased with decreasing light. The probability of a penguin pursuing a fish was found to be dependent on the amount of light, such that log,(p/1 - p) = 6.323 + 2.08 × log,(light level), where p= the probability of pursuing a fish. |
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