The formula to calculate the human equivalent age of a bird is:
\[ H = B \times C \]
Where:
Let's say the bird age (B) is 5 years and the conversion factor (C) is 4. Using the formula:
\[ H = 5 \times 4 \]
We get:
\[ H = 20\, \text{years} \]
So, the human equivalent age of a 5-year-old bird is 20 years.