Western meadowlarks (Sturnella neglecta) incubate their eggs for 13 to 16 days. Once a nest with eggs is located, it is not long before the helpless chicks arrive. The chicks are helpless and naked with only a light covering of gray down.
Two western meadowlark hatchlings and one egg are visible in this nest, located in a pasture near our house (Lookout CA). The one baby bird appears vigorous and healthy. The second bird, at the bottom of the photograph, looks as though it might be dead, but is not. After I took the pictures and moved away from the nest entrance I could see this second chick raise its head and open its mouth. I have not been back to the nest, so do not know if the third egg hatched or was infertile.
The baby seemed to open its mouth to one of two cues. Any slight movement of the grass around the nest would cause the hatchling to open its mouth as would any little noise such as the camera snapping or my clucking. Note the spines on the inside of the mouth. I do not know their purpose, but assume, from the orientation of the spines, that they help move the food into the esophagus.
These hatchlings will grow fast. Western meadowlarks only remain in the nest 10 to 12 days before fledging (leaving the nest). Once the young meadowlarks leave the nest the parents can begin a second brood this season.