Skip to content
NatureHQ

Claim check

Is migration purely instinctive?

MisleadingThe words are defensible; the impression they create is not.

What is inherited is a direction and roughly how long to fly — a rule, not a route. Displace a first-year bird and it flies that rule into the wrong continent, while an adult beside it corrects. And in some species the route is not inherited at all, but learned from older birds.

The claim as it circulates

“Migration is pure instinct — birds are born knowing the route and simply follow it.”

Where you may have met it: School material on instinct versus learning; Documentary narration; Popular writing about animal behaviour

Taking it apart

What was claimed
That migratory routes are innate: a young bird carries knowledge of where to go and how to get there, and learning plays no part.
What was actually observed
Hand-raised blackcaps orient in their own population’s direction without ever seeing an adult migrate, and hybrids of two populations orient between the two parental directions. Eleven thousand starlings displaced from the Netherlands to Switzerland split by age: adults reached the normal wintering area, first-year birds continued on their original bearing and wintered in the wrong place. White-crowned sparrows flown across the United States produced the same split. In reintroduced whooping cranes, route accuracy improved with age and improved far more when an older bird was in the group.
What the evidence supports
That an inherited component is real and specific — a bearing and a duration, heritable and quantitative. And that it is not sufficient: correcting for displacement requires experience, and in socially migrating species the route itself can be cultural.
What it does not support
It does not support routes being inherited, and it does not support a single answer across species. A songbird migrating alone in its first autumn and a crane travelling with its family are solving the problem in different ways, and describing both as instinct hides the difference that matters — including what happens to a population when the experienced individuals are lost.

How we know

Cross-breeding two populations that fly in different directions

Is a migratory direction inherited — and if so, inherited as what?

Blackcaps from an Austrian population that migrates south-east and a German population that migrates south-west were bred together in captivity. Their offspring were hand-raised without ever seeing an adult migrate or experiencing a migration, then tested in orientation cages during the migratory season, and their preferred headings compared with those of hand-raised birds from each parent population.

What happened

Birds from each parent population oriented in their population’s direction. The hybrids oriented between the two, on an intermediate bearing that neither parent population uses.

What it shows

That migratory direction is inherited, and inherited as a quantitative bearing rather than as a choice between two routes. An intermediate heading is what you get from a continuously varying trait, and it is not what you would get if the birds inherited a route or copied a parent.

What it does not show

It does not show that the *route* is inherited. What the hybrids carry is a compass bearing, and in the wild that bearing would take them into the Alps rather than along either parent’s route — which is why the two populations are separated by a migratory divide in the first place. Nor does it establish anything about how these birds would behave with a season’s experience behind them.

The controls — what makes this evidence rather than a story
  • Hand-raising from the nest, so no bird could have learned a direction from another.
  • Both parent populations raised and tested identically alongside the hybrids.
  • Testing in cages that exclude landscape cues, leaving the birds’ own preference as the measurement.

From Inheritance of migratory direction in a bird species: a cross-breeding experiment with SE- and SW-migrating blackcaps (Sylvia atricapilla)

How we know

Moving eleven thousand starlings to see what they would do

Is migration one ability or several? Specifically: does a bird know where it is, or only which way to fly?

Starlings were trapped in the Netherlands during autumn migration, ringed, transported several hundred kilometres south to Switzerland, and released — a place none of them had any business being. The crucial element is that recoveries were analysed separately by age. Juveniles had never migrated; adults had made the journey at least once. If migration were a single inherited programme, both groups should behave identically.

What happened

Juveniles continued on the original compass heading from the displaced release point and were recovered in Spain, well outside the species’ normal wintering range. Adults changed heading and were recovered in their usual wintering areas in northern France and Britain.

What it shows

That "migration instinct" is at least two capabilities. A young bird inherits a direction and roughly how long to hold it, which works from the place it was born and fails predictably from anywhere else. An experienced bird knows its position relative to a goal — true navigation — and that is learned rather than inherited.

What it does not show

It does not reveal what the adults use to work out where they are; the map component is demonstrated here and identified nowhere. Recovery data are also biased by where people are and how likely they are to report a ring, which distorts distributions in ways that cannot be fully corrected. And displacement is a severe manipulation — the birds arrive in poor condition in an unfamiliar place, and motivation cannot be measured.

The controls — what makes this evidence rather than a story
  • Age determined from plumage at ringing, so the two groups are separated before anyone knows what will happen.
  • A very large sample — more than eleven thousand birds — because recovery rates for ringed birds are low and the result depends on the shape of a distribution.
  • Birds trapped mid-migration rather than at the breeding site, so all were already in migratory condition.
  • Recoveries reported independently by finders across several countries, with no involvement from the experimenters in where birds turned up.

From Two types of orientation in migrating starlings and chaffinches, as revealed by displacement experiments

The rest of the answer

The claims underneath

Each one carries its own evidence, scope and caveats. Expand any of them to reach the studies.

A young bird inherits a direction and roughly how long to fly, not a route. Cross two populations that head different ways and the offspring head between them.

Established

Specialists would state this without hedging. Multiple independent lines of evidence agree.

Migratory direction and the amount of migratory restlessness are heritable quantitative traits: hand-raised birds express their population’s direction without exposure to it, hybrids of populations with divergent headings orient intermediately, and both traits respond rapidly to artificial selection.

Who this applies to
Established in blackcaps and related warblers; the inherited-programme model is applied more widely than it has been tested.
Studied in
Sylvia atricapilla, Sylviidae
Why we rate it this way, and what the caveats are
EstablishedHigh confidence

Hand-rearing removes the possibility of learning the direction, and the intermediate hybrid headings are a quantitative prediction that was met.

How far it can be extended

The cage-orientation and cross-breeding results are from a few species, but consistent with the age-related displacement results across many.

Caveats

  • What is inherited is a direction and a duration, which is not a route: the same programme carries a displaced bird into the wrong continent.
  • Cage restlessness is a proxy for migration, and the hybrids were never tracked on a real journey.
  • Species that learn routes socially do not fit this model at all.

Still unanswered

  • How the inherited programme and later route experience interact in a bird making its second migration.

Last reviewed 2026-09-03

The evidence (3 studies)

Carry a migrating bird a thousand kilometres sideways and what happens next depends on its age. Adults turn towards where they were going. Birds on their first migration carry on as though nothing had happened.

Established

Specialists would state this without hedging. Multiple independent lines of evidence agree.

In displacement experiments on several migratory passerines, experienced adults compensate for displacement and orient towards the normal wintering area, while first-year birds maintain the compass heading held before capture, indicating that route experience is what converts compass orientation into map-based navigation.

Who this applies to
Demonstrated in starlings, chaffinches and white-crowned sparrows; the age split is the general result.
Studied in
Passeriformes
Why we rate it this way, and what the caveats are
EstablishedHigh confidence

Two independent methods, decades apart, on different species and flyways, producing the same age split.

How far it can be extended

Reproduced with ringing recoveries in the 1950s and with radio telemetry fifty years later, in different species on different continents.

Caveats

  • Ringing recoveries depend on birds being found and reported, which varies by country and by habitat.
  • Telemetry samples are necessarily small, and follow birds for days rather than to their destination.
  • Species that migrate socially may acquire the correction differently, from companions rather than from their own experience.

Still unanswered

  • What experienced birds are actually reading to establish position, which remains unresolved for every species tested.

Last reviewed 2026-09-03

The evidence (2 studies)

In some species the route is not inherited at all — it is learned from older birds. A single experienced individual in a flock improves the whole group’s route more than any number of young ones.

Well supported

Good evidence backs this, though some details remain open.

In a reintroduced whooping crane population with known individual ages and group composition, deviation from the direct migratory route declined with age, and the presence of older individuals in a travelling group improved performance substantially more than group size did.

Who this applies to
One reintroduced population of a long-lived, socially migrating bird whose first route was human-led.Do not extend this beyond the taxa listed — the popular version over-reaches.
Studied in
Grus americana
Why we rate it this way, and what the caveats are
Well supportedHigh confidence

Eight years of tracks with known ages and companions — a record wild populations do not provide — and an effect size that separates social learning from simple maturation.

How far it can be extended

Most migratory birds travel alone on their first migration and cannot be learning the route from anybody. Social route learning is a real mechanism in some species, not the general case.

Caveats

  • A reintroduced population taught its first route behind an aircraft, which is not how a wild population acquires one.
  • Observational: nobody assigned birds to travel with or without an elder.
  • Says nothing about species that migrate alone in their first year, which is most songbirds.

Still unanswered

  • Whether wild populations of socially migrating species show the same dependence on a few experienced individuals — and what happens to a route when those individuals are lost.

Last reviewed 2026-09-03

The evidence (1 study)

Go deeper

Bird migration

Move a young bird 500 km and it flies the same heading into the wrong country. Move an adult and it corrects.

Related things people ask

Last reviewed 2026-09-03