把啄木鸟和信鸽交配能得到什么？一种送信时能敲门的鸟。
对于信鸽而言，自然界的指南针（来自太阳能和磁场方面的）经常不如它们掌握的人类交通路线知识更重要。
一个普通的鸟不会迁徙，但是非常擅长找到自己的回家的路，这就是家鸽。
1·For instance, if a homing pigeon is to navigate with its Sun compass, its clock must be properly set by cues provided by the daylight/darkness cycle.
例如，如果一只信鸽要用它的太阳罗盘进行导航，它必须根据日光/黑暗的循环所提供的线索正确设置时间。
2·While my gait is small and bandied, I have always had a homing pigeon’s sense of direction, and for all its twists and turns, Rome had long been mapped inside my head.
我的步伐很小，走路还摇摇晃晃的，尽管如此，我的方向感跟信鸽一样好，罗马地图已深深印在我脑海里，犄角旮旯我也一清二楚。
3·Cambridge had called; he had responded like a homing pigeon.
剑桥发出了召唤，他象一只归来的信鸽似的作出响应。