Students' Questions and Experts' Answers
Contributed by Ornithology Expert Laura Erickson
Where do orioles live in winter?
A. The winter ranges are in American tropics and Southern Mexico southward.
Winter habitat is often in a nest overhanging the city.
Q. Where do orioles live in summer?
A. The summer range is in Canada and central U.S, and also east of
the Mississippi River. Summer habitat is often in American Elm trees.
Orioles breed in open woods, elms, and shaded trees.
What does "neotropical migrants" mean?
A. Birds that breed in North America and spend the winter south of
the U.S. border are known as "neotropical migrants." Neotropical
means the tropics of the "New World." Orioles are just one of
more than 300 kinds of neotropical migrants.
When the time comes to migrate and an oriole has eggs that haven't hatched
yet, what do the orioles do? Do they leave their eggs or do they stay
with them and not migrate that year?
A. Fortunately, most birds lay their last clutch of eggs in time to
raise their young before it comes time to migrate. The instinct to migrate
is very strong in most birds. If fall has arrived and a bird, such as
an oriole, is still sitting on eggs, the birds will abandon the nest.
In fall and winter, there would not be enough food and temperatures would
be too cold for the young to survive, and it would also be tough for the
Q. How long does it take the average oriole to
get ready to migrate?
A. It takes 2-3 weeks for an oriole or other songbird to prepare for
Q. How do orioles prepare for migration?
A. First, they molt, or shed worn feathers and grow new ones. Second,
they feed and grow fat. Fat is the birds' main source of energy during
migration. Many songbirds almost double their body weight before migration!
How long does it take the average oriole to migrate?
A. It takes 2 or 3 weeks for an oriole to prepare itself for migration.
You also know that they stop along the way. If they did not use up a lot
of their fat the night before, they may only stop for a day. If they encountered
head winds or bad weather, they will use up more fat and may stopover
for several days. On average, an oriole probably travels about 150 miles
each night, flying at about 20 miles per hour. If the weather is good,
and they do not stop for long, it would take an oriole about 2-3 weeks
to complete its migration, depending on where it started from in the fall,
or where it is going in the spring.
How do birds have the energy to fly the long distances of migration?
A. Many migrants do a LOT of eating. They use up some of their fat
as they fly, so they stop each morning (remember that songbirds migrate
at night) and feed some more to replenish the fat they lost the night
Q. What do orioles feed on?
A. They feed on insects, flower nectar, and fruits. At backyard feeders,
they eat sugar water, mealworms, and bits of fruit.
Do orioles establish territories while in the tropics?
A. No. They associate with other orioles in flocks. Orioles don't
sing very often in the tropics, either.
Q. Why are oriole flocks in the tropics so large?
A. The flocks are so large because the habitat is so concentrated
and full of food, and the birds are not fighting to establish individual
territories in the winter. Also, the wintering areas are fairly small.
All of the Orioles that summer in the U.S. and Canada are stuffed into
a few small parts of Mexico. A flock of a hundred orioles is pretty amazing,
but it happens all the time in Mexico.
What habitat do orioles prefer in winter?
Orioles winter in mixed feeding flocks concentrated in two kinds of
habitat; coastal brush and flowering trees. Think of a tree with 30 orioles
in it or a small patch of cattails with hundreds of orioles.
Q. Does leaf-out have anything to do with the
timing of spring migration?
A. Scientists wonder, too! When leaves emerge, so do lots of insects.
Some scientists think that songbirds may fuel their migration by following
the leaf-out, and eating the millions of insects available at that time.
How do orioles know when it's time to leave the tropics and return north
A. Their internal rhythms, the length of daylight, and the position
of the sun in the tropical sky all tell them it's time to go north.
Q. Do orioles migrate during the day or at
A. Most of them fly at night and land to rest and feed during the
Why do orioles migrate at night?
A. Many reasons! The Oriole's predator, the hawk, can't fly at night.
Also the winds die down so flying is smoother. The temperatures are cooler
so the exercising birds don't overheat. Seeing the stars helps them navigate.
They can fuel up during the day for their night flights.
Q. How do birds sense whether good or bad migration
conditions might be coming?
A. Birds have internal barometers and can actually feel changes in
air pressure in their inner ear. When air pressure goes down, they feed
a lot more, as if anticipating a storm.
Why do orioles fly over the Gulf of Mexico instead of going around it?
A. The answer is that it is shorter. Birds can reach their breeding
grounds quickly and get the best territory. Many of them don't make it.
Despite the danger, it offers the best chance for them to reproduce.
Q. How long does it take birds to cross the
Gulf of Mexico?
A. Since there is no place for them to land, they must cross it non-stop.
Under good conditions, the trip across the Gulf of Mexico takes 18 hours.
It can take 24 hours to cross with headwinds or bad weather.
Q. Why do orioles push northward during a single
week in late April/early May, when hummingbirds move northward so gradually,
for 8-10 weeks from March to mid-May?
A. Hummingbirds can eat a wide variety of tiny flying insects swarming
about the tips of newly budding branches, and the sap from sapsucker borings.
So even if the weather is unpredictable, they can count on plenty of food
when they first arrive. Orioles require much larger insects, such as caterpillars,
which don't hatch until buds emerge. So orioles must wait until leaf-out.
By then, their hormones are urging them forward so they can set up their
territories and start nesting, so they move north FAST!
Do ALL orioles migrate in the fall?
A. As it happens, some orioles don't leave the U.S. in the fall at
all. During this century, as people have begun feeding birds, the migration
patterns of many species have changed. Orioles are an example of a species
that has expanded its winter range.
Q. When did people first notice wintering orioles
that didn't go south?
A. Noel Warner of Tallahassee, Florida says, "The phenomena of
wintering orioles on the lower coastal plain was first noticed in the
late 1940s. By the 1960's there were quite a few people feeding them.
They are here every winter, but unless you feed them they are rare, scattered,
and seldom seen. The orioles arrive in the neighborhood in mid-October,
but will not come to the feeders until it becomes cold, usually after
the first good freeze."
How is migration affected by weather?
A. Birds want to fly with tailwinds and avoid headwinds. This means
that for a few days after a cold front passes through in the spring, birds
will be forced to land because it is too difficult for them to fly. This
is when bird watchers and researchers see lots of birds. This is especially
true along the Gulf coast because the birds have made a 500 mile non-stop
flight and are already low on energy. As the high pressure center moves
east, the winds start coming from the south, which is good for flying.
The birds are able fly much farther with the tailwinds and therefore do
Q. What is a "fallout?"
A. When massive numbers of migrating birds land at one time to bad
weather, it's known as a "fallout." Accurate timing is critical
when songbirds cross the Gulf of Mexico. When there's a fallout on the
Texas coast we know many other birds will not cross the 500 miles of open
water successfully. And, although those that arrive may stay for only
a few hours each year, their lives may depend on the coastal woodlands
habitat for food and rest. Read more!
What are some dangers faced by neotropical migratory songbirds?
A. These frequent fliers face many obstacles in the air, ranging from
cold fronts and northwinds to rainstorms. Besides all the obstacles in
the air, neotropical migrants also need to be careful when they are on
the ground, especially during the breeding season. Natural predators such
as snakes, raccoons and even other birds would love to feed on a nestful
of eggs or baby birds during the nesting season. Another huge threat is
cats that roam outdoors and prey on birds.