Which of the following is the biggest threat to the monarch butterflies’ annual migration?

• A. Loss of milkweed habitat due to agricultural practices
• B. Competition with honeybees for nectar
• C. Increased rainfall during migration
• D. Predation by birds

Answer: (A)

Verified step by step guidance

1. Understand the biology of monarch butterflies: Monarch butterflies rely on milkweed plants as their primary food source during their larval stage. Milkweed is essential for their survival and reproduction.
2. Analyze the threats listed in the problem: Loss of milkweed habitat, competition with honeybees, increased rainfall, and predation by birds. Consider which of these directly impacts the monarch butterflies' ability to complete their migration.
3. Evaluate the impact of milkweed loss: Agricultural practices, such as the use of herbicides and land development, have significantly reduced milkweed availability, which directly affects monarch populations and their ability to migrate successfully.
4. Consider the other options: Competition with honeybees for nectar is less significant because monarchs primarily rely on milkweed during their larval stage. Increased rainfall and predation by birds may affect migration but are not as critical as the loss of milkweed habitat.
5. Conclude that the biggest threat to monarch butterflies’ annual migration is the loss of milkweed habitat due to agricultural practices, as it directly impacts their survival and reproduction.