Here's why:
* Warm waters: They migrate to warmer waters, often in tropical or subtropical areas, to give birth. This is because calves are vulnerable to cold temperatures.
* Food abundance: These areas are typically where food is abundant for the mother whale to recover from the energy expenditure of pregnancy and lactation.
* Calf development: The timing allows for the calves to grow and develop before the long migration back to feeding grounds in the summer.
It's important to note that the exact timing can vary depending on the location and individual whale.