Ten pigeons were stolen from a shed in Furnace Green.
Sussex Police said the pigeons, which were worth £400 in total, were stolen from a garden shed in Coltash Road, Crawley, on Sunday (April 13).
Sussex Police said it is thought the birds were taken some time between 10.30am and 6pm that day.
A Sussex Police spokesman said: “We’re keen to speak to anyone who was in or around Coltash Road on Sunday and could have seen someone acting suspiciously.
“Whoever took the pigeons would have needed a vehicle to transport them unless a large number of people were involved.
“If you saw or heard anything, or are offered the chance to buy racing pigeons, please contact us.”
Anyone with information should call 101 quoting serial 1273 of 13/4, email email@example.com or call the independent charity Crimestoppers anonymously on 0800 555111.