Monday, October 5, 2009

Owl Communication Signals


When I think of most of nocturnal animal’s communication methods, I find myself exploring various auditory signals. This makes the most sense due to the limited light during the night but a great number of nocturnal animals rely on chemical, visual, tactile and even electrical communication modalities. Many nocturnal birds use visual and vocal signaling simultaneously in communication. A recent study reveals that Eagle Owls (Bubo Bubo), in Spain, use a white feathered badge on their throats and vocal choruses to communicate during the times of limited light. They now know that the contrast of feathering is more important than color variations. When the owl makes a call the white feathers, on the throat, flare up and inflate during the call. Following the call they then deflate. These owls only perform this display of feathers and calls during the dawn and dust hours, when they can transmit these visual signals without predator detection. Researchers say that the ambient lighting during these times of the day provides the best contrast for the communication. At night the feather display would be deemed a failed communication because of the darkness of the night. The researchers hypothesize that the calls may be used in attaching female owls but this is not the case because individuals retreat to their roosts during the times of this display. Most of the other hypothesis’ that have been presented have been disproved because of the timing (dawn and dusk) of these signals. The hypothesis to avoid predation can also be disproved because the owl is one of top predators in that food web. Further research is being conducted to determine the purpose and intent of these signals
One thing is for certain these modalities have coevolved to most effectively communicate with other individuals of the same species or other species in the forest. The communication of nocturnal animals is quite intriguing due to the limited light in the environment. The Eagle Owl, from the European forests, has evolved to communicate in these conditions by expressing visual signals and auditory signals during times of the night with the most available light.
Emerson Martin (1)

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