PDF(Pubmed)
Abstract：
Flying animals have had to evolve robust and effective guidance strategies for dealing with habitat clutter. Birds and insects use optic flow expansion cues to sense and avoid obstacles, but orchid bees have also been shown to use brightness cues during gap negotiation. Such brightness cues might therefore be of general importance in structuring visually guided flight behaviours. To test the hypothesis that brightness cues also affect gap negotiation behaviours in birds, we presented captive zebra finches Taeniopygia guttata with a symmetric or asymmetric background brightness distribution on the other side of a tunnel. The background brightness conditions influenced both the birds\' decision to enter the tunnel aperture, and their flight direction upon exit. Zebra finches were more likely to initiate flight through the tunnel if they could see a bright background through it; they were also more likely to fly to the bright side upon exiting. We found no evidence of the centring response that would be expected if optic flow cues were balanced bilaterally during gap negotiation. Instead, the birds entered the tunnel by targeting a clearance of approximately one wing length from its near edge. Brightness cues therefore affect how zebra finches structure their flight when negotiating gaps in enclosed environments.
摘要：
飞行动物必须制定强大而有效的指导策略来应对栖息地的混乱。鸟类和昆虫使用光流扩展线索来感知和避开障碍物，但是兰花蜜蜂也被证明在间隙协商期间使用亮度提示。因此，这种亮度提示在构造视觉引导的飞行行为中可能具有普遍的重要性。为了检验亮度线索也会影响鸟类间隙协商行为的假设，我们在隧道的另一侧展示了圈养斑马雀Taeniopygiaguttata，背景亮度分布对称或不对称。背景亮度条件影响了鸟类进入隧道孔径的决定，和他们离开时的飞行方向。如果斑马雀能看到明亮的背景，它们更有可能在隧道中飞行；它们也更有可能在离开时飞向光明的一面。我们没有发现任何证据表明，如果在间隙谈判过程中双向平衡光流线索，则可以预期集中响应。相反，鸟类通过瞄准距隧道近边缘约一个机翼长度的间隙进入隧道。因此，亮度提示会影响斑马雀在封闭环境中协商间隙时的飞行结构。
