Comparing Migrations
Monarch Butterflies and Ruby-throated Hummingbirds

Fill-in-the-Blank | Answer Key
habitat hour nectar generation
food bloom delay month
flight fly flowers breeding
four life temperatures cold
north bird sap adult
can March use warm
Gulf winter eggs  

Monarch butterflies and ruby-throated hummingbirds have similar migrations even though one is a ____ and the other is a butterfly. Both species eat ____ . Both spend the _____ south of the United States border and migrate _____ in the spring. Both species begin to arrive in the United States in the month of _____, as they return to their _____ grounds in eastern North America. Both species move north as their _____ becomes ready to support their needs.

What makes their migrations different? Do differences in _____ speeds matter? Hummingbirds have been clocked flying 60 miles per _____ . They can fly across the _____ of Mexico in only 20 hours! Monarch butterflies only fly about _____ miles per hour unless the wind carries them faster.

Unlike monarchs, hummingbirds have more than one source of _____. They can eat insects and sometimes they even eat _____ that drips from holes made in trees by woodpeckers. This means some hummingbirds can migrate north before _____ bloom and still find food. Monarchs must wait for flowers to _____ or they will not have food.

The _____ cycle of each species also affects the pace of its migration. Hummingbirds can complete the entire spring migration in one _____. In contrast, the monarch's life cycle causes a _____ . The monarchs that overwintered in Mexico only live until mid-to-late April. They must lay _____ before they die. It takes about one _____ for an egg to develop into an _____ butterfly. As adults, this generation completes the migration throughout the northern breeding grounds.

Spring temperatures also affect both migrations in many ways. Because they are insects, monarchs are _____-blooded and are paralyzed by cold _____ . Monarchs cannot _____ unless their flight muscles are at least 55° F. Because they are birds, hummingbirds are _____-blooded. They _____ fly in cold temperatures. However, they must _____ much more energy to keep their bodies warm.