Carrying capacity is the largest population an environment can sustain. Explore how limited food, nesting sites, space and other resources restrict population growth and create competition near that limit.
In 1789 Gilbert White, a naturalist, observed eight breeding pairs of swifts (Apus apus) in the English village of Selborne. On average, each pair of swifts produces two offspring per year. This would allow the population to rise to 1030 swifts over 200 years. A bird survey carried out in 1983 revealed only 12 breeding pairs in this village.
What could have prevented the numbers rising to 1030 ?
I. The number of nesting sites remained the same.
II. The food supply of the swifts remained constant.
III. Predatory birds in the area were exterminated.
I only
I and II only
II and III only
I, II and III
B