Birds do not have the ability to count, so adding a similarly aged chick to their nest is not alarming to the parents.

• A. True
• B. False
• C. Depends on species
• D. Not enough data

Answer: (A)

Bird parents don’t tally nestlings the way we count objects. They respond to cues from each chick—begging calls, size and age, and general health—rather than keeping an exact numerical count of how many mouths need feeding. When a chick of similar age appears, its begging and hunger cues signal the parents to feed it, so the presence of one more nestling is unlikely to provoke alarm or aggression simply because it’s another chick. Some species may reject or ignore chicks that are much younger, older, or otherwise deviate significantly, especially if resources are tight, but with a similarly aged chick, acceptance is common. In practice, this is why adding a nestling of comparable age to a nest is typically not alarming to the parents.