Hundreds of pheasant chicks have been stolen from a breeder in Hampshire.
About 800 three-week-old birds were taken from brooder units in Colemore, near Alton, between 2200 BST on Wednesday and 0700 BST on Thursday.
Officers said lighting and heating equipment needed to care for the birds had not been stolen, causing concern for their welfare.
Police are appealing for information and have urged breeders to check their security.
Pc Lee Coleshill, from Hampshire Constabulary's Country Watch team, said: "Birds of this age are very vulnerable and if they are not cared for correctly they will die.
"They need suitable lighting and heating equipment which wasn't stolen, which could either mean the thief already has the necessary items needed, has an outlet for the chicks or has stolen them without realising what is needed.
"It is likely the thief did know what they were doing as to catch and handle the chicks would require some degree of confidence and knowledge of the task, so it is unlikely this has been an opportunistic burglary."