Biology Regents Practice Exam

The action that would not be considered a reason for the decline in monarch butterfly populations is habitat preservation. Preserving habitats is beneficial for monarch butterflies as it helps maintain the ecosystems they rely on for breeding and feeding. Monarchs depend on specific plants, particularly milkweed, for laying their eggs, and they need diverse flowering plants for nectar. When habitats are preserved, these crucial resources remain available, supporting healthy populations.

In contrast, illegal deforestation, extreme temperature changes, and decreasing food supplies all contribute negatively to the monarch's survival. Deforestation reduces the available habitat and food sources, while extreme temperature fluctuations can disrupt migration patterns and breeding success. Decreasing food supplies, whether from habitat loss or environmental changes, further diminishes the number of butterflies that can thrive, leading to population declines.