A red car may resemble a food cue
One proposed explanation is that red paint catches a bird’s attention because many ripe fruits are red. Birds use visual cues when searching for food, so a red surface might briefly prompt a closer look. But a car does not smell, feel, or behave like fruit; color alone would have to do the work, and it is not clear that it does.
Attention is not the same as a target
Even if a bird notices a red car, droppings do not show that it deliberately chose the vehicle. A bird may simply be passing overhead or resting on a nearby branch. Where a car is parked, how long it stays there, and what is above it can all affect the chance of being hit.
That leaves the proposed fruit resemblance as a plausible idea, not a settled explanation. The practical twist is that a red car could draw notice without being mistaken for food—and a bird dropping on it may have had no interest in the car at all.
