Yes it´s true. They only spend one hour and a half per evening shooting doves and I think each one shot between 500 and 600 shotshells per evening so I guess that if you want to spent the whole day there you can shoot more than 2000 per day.
Doves are considered pest and you can shoot them year round. Some farmers put poison on their crops to stop them and also to stop parrots, they are also considered a pest.
L