| Ruby-throated hummingbirds and monarch butterflies are both migrating _____
right now. The two species are similar in many ways! Both species
eat _____.
Both species _____ in areas south of the United
States border. Both begin to arrive in the United States during
the month of _____. Both species migrate north
to their breeding grounds in the _____ (N, S, E, W) region of
North America. Both species move north as their _____
becomes ready to support their needs for food, water, shelter, space.
What
makes the migrations different? As this week's migration maps show,
_____ are migrating north more quickly. Why? Is
it because _____ can fly so much faster? (They
have been clocked flying 60 miles per hour.) Is it because they
can fly over _____, and cross the _____
of Mexico in only 20 hours?
Hummingbirds
have several adaptations that allow them to migrate where spring
temperatures are too _____ for monarchs. All birds
are _____-blooded. All insects are _____-blooded.
How does this difference affect their migrations? Monarchs are paralyzed
by _____ temperatures; they cannot _____unless
their flight muscles are at least 60 degrees F. Cold temperatures
do not keep hummingbirds from _____.
Hummingbirds
have more than one source of _____. They can eat
insects and sometimes even eat _____ that drips
from tree holes drilled by other birds. This means hummingbirds
can move ahead of the blooming _____ and still
find food. Monarchs must wait for _____ to bloom
or they will not have food.
The
hummingbird's _____ cycle also gives hummingbirds
an advantage. The monarch's _____ cycle causes
a delay. The generation of monarchs who begin the migration from
Mexico lay _____ as they travel. Those adult butterflies
are at the end of their life cycle. Their offspring must complete
the migration but they need _____ to grow. The hummingbirds can complete the entire spring migration
in one _____. |
