Without conducting an extensive study on squirrel behavior, it is difficult to make definitive claims about their road-crossing habits. However, based on personal observations and anecdotal evidence, it seems that squirrels do not cross roads more frequently when cars are present compared to when they are not. This assumption can be attributed to our cognitive biases, which lead us to perceive instances of squirrels crossing in front of cars as the norm due to our focused attention on such scenarios.

In my locality, New York City, where there is a sizable squirrel population and heavy traffic, the number of squished squirrel carcasses caused by cars is relatively low. While occasional sightings of flattened pigeons and other birds can be attributed to unfortunate incidents or weaker individuals, the scarcity of squirrel casualties suggests that they are capable of adapting and learning to navigate their urban environment.

Although no specific studies on squirrel road-crossing mortality rates exist, examples from England indicate that squirrels are indeed capable of learning and adapting to busy roads. Rope bridges were set up over roads where dead squirrels were commonly found, and the squirrels quickly learned to use these bridges to avoid cars. Additionally, in Aberdeen, it was observed that squirrels infrequently crossed busy roads, further supporting the notion of their intelligence and adaptability.

While these observations and studies provide some insights, a comprehensive study would be necessary to determine the precise behavior and road-crossing patterns of squirrels.