It's a common misconception that birds give milk to their young. Birds do not produce milk similar to that of mammals. Only three species of birds, namely pigeons, flamingos, and penguins, can produce a type of milk-like substance. This crop of milk is used to feed their babies during the initial stages of hatching. It's important to note that this bird milk is entirely different from mammal milk in terms of its composition and production. So, while some birds do produce a milk-like substance, it's not the same as mammal milk.