You have other birds that are helpless when they hatch.

其他鸟在孵化破壳时很无助。

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Then they nail on battens to hold the hatch coverings firmly in place.

VOA: special.2011.03.06

"They fly to it thinking they can lay their eggs there and it will be a good place for their eggs to hatch out and eat the rotting meat, but they get tricked into just pollinating the flower."

VOA: standard.2010.07.30

It's sprayed on chicks as they hatch, and costs less than a cent per bird.

FORBES: Yes, there is a pulse

They hatch only in moving water because they rely on the current to bring them food.

NPR: Waging a One-Woman War Against Black Flies

The farmers then collect the eggs and when they hatch, the caterpillars that emerge are placed on new plants, which must be regularly replaced to satisfy their voracious appetites.

CNN: Butterfly farmers help protect threatened forests