Answer:
<em><u>Instinctive</u></em>
Explanation:
The question precises that it is a baby bird and such behaviour are being acquired from birth they are not being learned. Similarly a human mother doesn't teach her baby her to suck her nipples, it is "in born".
Youngest to Oldest
Shale with ammonite
Limestone with unknown fossil
Basalt
Sandstone with trilobite
