A couple are devastated after vandals smashed their rare bird eggs with huge stones just days before they were due to hatch.
Steve Walker and Carole Woodhead, of Marsh Hall, Northowram, say they will offer a substantial reward to anyone with information about the attack.
The birds, a South American breed called a rhea, were nesting close to the boundary wall when the heartless vandals scared them away during the night by throwing large rocks.
Mr Walker, 48, said: “They’re gorgeous creatures, very calm and docile. That’s why it’s such an awful thing to do.”
It is suspected that local youngsters may have been responsible for the attack while jumping over hay bales in a neighbouring field.
The vandals then launched rocks at the eggs, killing eight out of the twelve baby birds. Mr Walker is uncertain whether the remaining few will hatch.
He said: “It wasn’t an accident: somebody was having a go.
“It’s heartbreaking when you lose them because you do start to get attached.”
The rheas had been keeping the eggs warm for around five weeks and Mr Walker said they had been very disturbed by the attack.
He said: “It’s not just upsetting for me and them but for the whole neighbourhood.”
The couple have kept the birds for around a year and are well-known in the village for the unusual creatures.
Mr Walker said the exotic birds, a relative of ostrich and emu, had flourished despite the colder climate.
“I’m privileged that they were settled enough to breed here.”