Journey North Oriole Migration

Frequently Asked Questions
Students' Questions and Experts' Answers
Contributed by Ornithology Expert Laura Erickson

Ecology

Q. 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.

Q. 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.

Q. 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 parents.

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 migration.

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!

Q. 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.

Q. 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 before.

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.

Q. 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.

Q. What habitat do orioles prefer in winter?

A. 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.

Q. How do orioles know when it's time to leave the tropics and return north in spring?

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 night?

A. Most of them fly at night and land to rest and feed during the day.

Q. 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.

Q. 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!

Q. 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."

Q. 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 not land.

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!

Q. 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.