Clara Elena, Regolin Lucia, Vallortigara Giorgio, Rogers Lesley J
Centre for Neuroscience and Animal Behaviour, University of New England, Armidale, NSW 2351, Australia.
Anim Cogn. 2009 Nov;12(6):755-65. doi: 10.1007/s10071-009-0235-y. Epub 2009 May 23.
Spontaneous preferences towards possible prey have been little investigated using targets in motion. Preferences of domestic chicks (Gallus gallus) to peck at video-images of stimuli representing live insects moving along their longer body axis (i.e. "forwards") or along the shorter body axis (i.e. "sideways") were investigated. Chicks presented with both types of stimulus displayed a significant preference for pecking at stimuli moving sideways. This preference was already present on day 1 post-hatching, and it strengthened on day 6 for those chicks that had experienced pecking at live insects. Head angles used to fixate the stimuli prior to pecking were also analysed and were consistent (i.e. 30 degrees -35 degrees and 60 degrees -65 degrees ) with those reported for fixation of non-edible targets (larger stimuli at a distance). In a first control experiment the same video-presented stimuli were used but the insect's legs were removed to reduce flickering. In a second control experiment, paper-printed images of the whole insect were used. In both cases, the sideways direction of movement was clearly preferred. Overall, our data show that chicks have a spontaneous preference to peck at video-images resembling live insects moving along their shorter body axis. Sideways movement may constitute a crucial signal attracting chicks' attention and enhancing predatory responses possibly because of stronger stimulation of motion detectors.
利用运动目标对潜在猎物的自发偏好鲜有研究。本研究调查了家鸡（原鸡）对代表活昆虫的视频图像的啄食偏好，这些昆虫沿着其身体长轴（即“向前”）或短轴（即“侧向”）移动。同时呈现这两种刺激类型时，雏鸡对侧向移动的刺激表现出显著的啄食偏好。这种偏好在孵化后第1天就已存在，对于那些经历过啄食活昆虫的雏鸡，在第6天偏好增强。还分析了啄食前用于注视刺激的头部角度，这些角度与报道的注视不可食用目标（远处较大刺激）的角度一致（即30度 - 35度和60度 - 65度）。在第一个对照实验中，使用了相同的视频呈现刺激，但去除了昆虫的腿以减少闪烁。在第二个对照实验中，使用了整个昆虫的纸质印刷图像。在这两种情况下，明显更偏好侧向移动方向。总体而言，我们的数据表明，雏鸡对类似沿着其短轴移动的活昆虫的视频图像有自发的啄食偏好。侧向移动可能构成吸引雏鸡注意力并增强捕食反应的关键信号，这可能是因为对运动探测器的刺激更强。
