The brand-new ducks are 4 days old in this photo. In a process called “Imprinting” they have learned to follow their mother, even though dad and big sis duck are also present.

Imprinting is rapid learning that occurs during a brief receptive period, typically soon after birth or hatching, and establishes a long-lasting behavioral response to a specific individual or object, as attachment to parent, offspring, or site.  – source: Dictionary.com