Swallows in France: understanding their presence and the effects of climate change

A symbol of the return of warmer days, swallows are among the most beloved birds in France. Every spring, their arrival marks the beginning of a new breeding season.

However, behind this familiar presence lie significant changes related to environmental transformations and climate change.

Through available ornithological data, let's discover how swallows occupy French territory and why some now remain in France during winter.

Two main species of swallows present in France

During the breeding period, between spring and late summer, swallows occupy almost all of France.

The two main species observed are:

• the Barn Swallow;
• the House Martin.

Even though they are present throughout mainland France, their habits and habitats differ.

The Barn Swallow: the bird of the countryside

The Barn Swallow is strongly linked to rural areas.

It generally builds its nest:

• in barns;
• stables;
• open garages;
• farm buildings.

This species seeks open spaces rich in flying insects to feed its young.

Illustration: Barn Swallow in a barn

Presence throughout the territory

During the summer, the Barn Swallow can be observed almost everywhere in France.

The only less frequented areas remain very high mountainous altitudes where conditions are less favorable.

The House Martin: a more urban species

Unlike its rustic cousin, the House Martin adapts very well to villages and towns.

It builds its nests in colonies:

• under roof overhangs;
• on exterior facades;
• under cornices.

Its recognizable mud nests are often installed high up on buildings.

Illustration: House Martin colonies on a facade

House Martin nests under a roof overhang.

Source: Wild Cookham

A species dependent on insects

Like all swallows, the House Martin is entirely dependent on flying insects to survive and feed its young.

The scarcity of insects linked to pesticides and urbanization now poses a significant threat to the species.

100% summer occupation of French territory

If the presence of swallows between April and September were mapped, mainland France would appear almost entirely occupied.

This distribution is explained by the abundance of insects during the warm season.

The countryside, villages, wetlands, and even cities then offer favorable conditions for reproduction.

Winter observations: an increasingly visible phenomenon

Traditionally, swallows migrate to Africa in the autumn.

However, climate change is gradually altering their migratory behavior.

Some Barn Swallows now remain in France during winter.

Illustration: Map of winter Barn Swallow observations

Winter observations of the Barn Swallow in mainland France.

Source: Post-Ornithos

More favorable regions in winter

Winter observations are mainly concentrated:

• on the Atlantic coast;
• the Channel coast;
• the Mediterranean rim.

These regions benefit from milder winters, still allowing for the presence of a small quantity of insects.

This evolution is a concrete indicator of the effects of global warming on migratory behaviors.

Why are swallows threatened?

Despite their widespread summer presence, swallow populations have experienced a significant decline for several decades.

The main causes are:

• the disappearance of insects;
• the use of pesticides;
• the destruction of nests;
• building renovation;
• the artificialization of environments.

Extreme climatic events can also weaken populations during migrations.

How to protect swallows?

A few simple actions can encourage their presence:

• preserve existing nests;
• avoid destruction during the breeding period;
• install anti-soiling boards;
• reduce the use of pesticides;
• promote biodiversity in gardens.

It is important to remember that swallows and their nests are protected by law in France.

Conclusion

Swallows still occupy all of French territory during the warm season. The Barn Swallow remains strongly linked to rural areas, while the House Martin has adapted to urban environments. However, increasingly frequent winter observations show that migratory behaviors are evolving due to climate change.

Fragile but essential to the balance of ecosystems, swallows play a valuable role in insect regulation.

Preserving their habitats and promoting biodiversity is now a major challenge to ensure their survival in the coming decades.