Practice AP Environmental Science questions on resource availability, population growth, carrying capacity, density dependence, mortality, fecundity, and stability.
Chickadees are a K-selected species of bird that eat insects and spiders. Spiders consume insects, and many insects consume plants as shown in the following food chain.
Chickadee habitat includes forests and residential yards. Residential yards often contain nonnative plants, which do not naturally exist in an area, but were introduced by humans.
Scientists measured the average number of insects and spiders as related to the percentage of nonnative plants (Figure 1). The scientists also measured the chickadees' average population growth rate (Figure 2) to determine the impact of nonnative plants on chickadee populations.
Figure 1. Percentage of Nonnative Plants and Average Number of Individual Spiders and Insects
Figure 2. Chickadee Population Average Growth Rate and Percentage of Nonnative Plants
Respond to parts A, B, C, D, E, F, G, and H, and all subparts.
Scientists hypothesized that the population of chickadees would be stable or growing with fewer than 25\% nonnative plants. Describe one way that the data in Figure 2 support this hypothesis.