Crows are members of the Corvidae family, which also includes ravens, magpies, and blue jays. Loud, rambunctious, and very intelligent, crows are most often associated with a long history of fear and loathing. They are considered pests by farmers trying to protect their crops and seedlings. Many people fear them simply because of their black feathers, which are often associating them with death.
Modern Infrared Search and Track systems can search, track and target an enemy aircraft while having a better ability to differentiate discreet aircraft in formations and intermediate ranges than many traditional fighter radar systems fielded today.
They detect heat as it moves through their field of view. When the heat level changes in an area the detector assumes this is motion. If you put it behind glass, especially energy efficient glass, this will greatly reduce the amount of infrared that gets through to the sensor and in most cases will not trip the sensor.