Predator–induced take–off strategy in great tits (Parus major)

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Abstract
When birds are attacked by predators the initial take–off is crucial for survival. The strategy in the initial phase of predator evasion is probably affected by factors such as body mass and presence of cover and conspecifics, but it may also be a response to the character of the predator's attack. In choosing an angle of flight, birds face a trade–off between climbing from the ground and accelerating across the ground. This is, to our knowledge, the first study investigating whether the attack trajectory of a raptor affects the take–off strategy of the prey bird. First–year male great tits (Parus major) adjusted take–off angle to a model predator's angle of attack. Birds attacked from a steep angle took off at a lower angle than birds attacked from a low angle. We also compared take–offs at dawn and dusk but could not find any measurable effect of the diurnal body mass gain (on average 7.9%) in the great tits on either flight velocity or angle of ascent.