To prevent overgrown nails in pet birds, you can provide various perches of different diameters and materials for your bird to stand on. This will help naturally wear down their nails as they grip onto the perches. Regularly trimming your bird's nails or seeking professional help from a veterinarian or a bird groomer can also help prevent overgrown nails. Additionally, providing toys and activities that encourage your bird to climb and play can also help keep their nails at a healthy length.