1. The problem states that the bird population is decreasing by 2% per year. 2. The decay factor represents the multiplier applied each year to the population to account for the decrease. 3. The decay factor is calculated as $1 - \text{decay rate}$. 4. Since the decay rate is 2%, convert it to decimal: $2\% = 0.02$. 5. Calculate the decay factor: $$ \text{decay factor} = 1 - 0.02 = 0.98 $$ 6. This means each year the population is multiplied by 0.98, representing a 2% decrease annually. Final answer: The decay factor is $0.98$.