* Instinct: Kittens are born with a strong instinct to vocalize. This helps them communicate with their mother and siblings, especially when they're separated from them. They might cry out of fear or anxiety when they're picked up, as they're used to being close to their mother for warmth, comfort, and feeding.
* Discomfort: They might be uncomfortable being held or moved, especially if they're cold, hungry, or need to use the litter box.
* Searching for their mother: They might be crying because they're searching for their mother's warmth and milk.
* Seeking attention: Some kittens might cry to get attention from their humans. This is especially true if they're used to being handled frequently.
Important Note: If a newborn kitten is crying excessively, it's important to check on them to ensure they're not sick or in distress. If you're unsure, it's always best to consult with a veterinarian.