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Comparing Two Migrations
Ruby-throated Hummingbirds and Monarch Butterflies

Comparison Chart | Journal | Answer Key
ruby map monarch map
Ruby-throated Hummingbirds Monarch Butterflies

Ruby-throated hummingbirds and monarch butterflies are both migrating north right now. The two species are similar in many ways! Both species eat nectar. Both species overwinter in areas south of the United States border. Both begin to arrive in the United States during the month of March. Both species migrate north to their breeding grounds in the eastern region of North America. Both species move north as their habitat becomes ready to support their needs for food, water, shelter, space.

What makes the migrations different? As this week's migration map shows, hummingbirds are migrating north more quickly. Why? Is it because hummingbirds can fly so much faster? (They have been clocked flying 60 miles per hour.) Is it because they can fly over water, and cross the Gulf of Mexico in only 20 hours?

Hummingbirds have several adaptations that allow them to migrate where spring temperatures are too cold for monarchs. All birds are warm-blooded. All insects are cold-blooded. How does this difference affect their migrations? Monarchs are paralyzed by cold temperatures; they cannot fly unless their flight muscles are at least 60 degrees F. Cold temperatures do not keep hummingbirds from flying.

Hummingbirds have more than one source of food. They can eat insects and sometimes even eat sap that drips from tree holes drilled by other birds. This means hummingbirds can move ahead of the blooming flowers and still find food. Monarchs must wait for flowers to bloom or they will not have food.

The hummingbird's life cycle also gives hummingbirds an advantage. The monarch's life cycle causes a delay. The generation of monarchs who begin the migration from Mexico lay eggs as they travel. Those adult butterflies are at the end of their life cycle. Their offspring must complete the migration but they need time to grow. It takes about one month for an egg to develop into an adult butterfly. The hummingbirds can complete the entire spring migration in one generation.