What is the reason why the pigeons make a coo?

The pigeon's gurgling scream was estrus, attracting the opposite sex.Usually, they will not grine again after they succeed.They are gurgling when they are frightened. Such a pigeon who just arrives at home will appear.At this time, don't disturb them, let them raise them for a few days, and it will be better to adapt slowly.In addition, they may also grun when they are sick.