Assuming Reynolds' mum doesn't accidently suffocate them how is she going to know, for example, how to check whether their feathers are developing properly or whether they're developing metabolic bone disease due to dietary deficiency, which nestlings can suffer even with the best care? Rearing baby birds is difficult, pigeons even more so. Gf is sick of people bringing her half-dead, unreleasable birds which people thought would be "a good project for the children".