Do Ants Migrate?
Migration is a behavior found only in a handful of ants. While many ant colonies may move out and transfer nests at some point, most of them don’t make a defining characteristic of migratory behavior, the return journey. As such, most ants technically emigrate and not migrate.
In this article, we’ll define migration and look at how it’s used in the context of ants. We’ll also look into migratory behavior in ants and some examples of migratory species.
What Is Migration?
Migration refers to the regular or seasonal movement of an animal population from one place to another. It’s a natural behavior usually caused by seasonal changes and other factors such as food availability, competition, presence of predators, and mating opportunities. In general, animals migrate to take advantage of more favorable conditions.
One key factor in migration is the return journey. This makes it different from emigration wherein animals leave their homes and travel to find more suitable places to live.
Migratory Animals
Migratory behavior can be found in many animals including birds, fishes, mammals, reptiles, amphibians, and insects. The following are some examples of migration in animals:
- The Atlantic salmon begins its life in the river and migrates to the ocean. When it’s time to reproduce, it heads back to the river it was born in to lay eggs and begin the cycle all over again.
- Humpback whales migrate for food. During summer they travel thousands of kilometers to feed near the polar ice. When it’s winter, they head back to warmer waters to mate and have their young.
- In insects, migration is mostly found in locusts and butterflies which migrate from breeding areas to feeding areas to hibernation sites. For instance, monarch butterflies are known to migrate long distances southward to avoid the cold winter. In spring they head back towards the north, laying eggs along the way. With that, the returning members don’t only include the original members that overwintered, but also successive generations that developed throughout the journey.
Migration In Ants
With ants, the term migration has been used to describe the nomadic behavior shown by army or driver ants. Yet, while this behavior is characterized by the constant movement from one site to another to search for food, it doesn’t feature a return journey. So by definition, these ants don’t actually migrate but emigrate instead.
This is just one case in which the term migration is used incorrectly in the strictest sense. Many, including scientists, have somewhat overused the word migration to the point of using it to describe emigration as well.
Truth is, migratory behavior is rare in ants, and only a few species engage in true back-and-forth seasonal movement. One example is conducted by colonies of the weaver ant Polyrhachis simplex. During winter, these ants nest on streamside cliffs which provide higher temperatures during the daytime. By spring however, the ants move back to small trees by the edge of the stream as the temperatures in the cliffs become intolerably hot.
Tapinoma sessile, is another species of ants that exhibit migratory behavior. These ants practice seasonal polydomy to have access to multiple food sources. Every winter, they return and stay in a single nest to overwinter. Come spring they then spread out and form multiple nests to tap into multiple food sources.
Lastly, the soil nesting species Formica japonica have been discovered to migrate within their vertical nests according to seasonal changes in temperature.
It’s worth noting that the distance migratory ants travel is relatively short compared to other animals. This may be due to physical limitations or the fact that traveling long distances may put them at great risk. Even so, the regularity of the behavior is enough to define it as migration.
Related Questions
Do Ants Relocate?
Yes they do. For the colony to grow successfully, ants may relocate to find nesting sites with ideal temperatures, better access to food, and less competition. Examples of ant relocation can be seen in army ants and the migratory ants discussed.
Where Do Ants Go In The Winter?
Most ants don’t migrate but they do make it a point to seek out warmer places in the winter. These places include deeper ground and under tree barks or rocks that serve as heat collectors. Sometimes they may even seek refuge in our homes and spend the cold hidden in our walls or underneath our floors.
Do Ants Hibernate?
Ants do not technically “hibernate” but they do enter a similar state called diapause and become dormant for a duration of around three to four months.
Summary
Migratory behavior is quite rare in ants. Most ant movement to new feeding grounds or nests don’t usually feature a return journey and is thus technically, in the strictest sense, emigration, not migration.
Only a few ant species engage in true back-and-forth seasonal movement. These species include the Polyrhachis simplex, Tapinoma sessile, and Formica japonica, all of which have shown to migrate depending on seasonal changes in temperature.
