She sees the Sparrow's nest and thinks, 'Ah, hah! that bird is smaller than I am, and cannot push my egg out; I will leave it there!' This she does very quickly, and slips away again.
[Illustration: Cowbird] "When the Sparrow comes home she may wonder at the strange egg, and perhaps be able to push it out of the nest; but more likely she takes no notice of it, as it is so much like her own, and lets it stay.

If she does this, that egg is only the beginning of trouble.

It is larger than her own, so it gets more warmth and hatches more quickly.

Then the young Cowbird grows so fast that it squeezes the little Sparrows dreadfully, sometimes quite out of the nest, and eats so much that they are half or wholly starved.

The poor Sparrow and her mate must sometimes think what a big child it is; but they feed it kindly until it can fly--sometimes even after it leaves the nest.