Superstition concerning Swallow

Both

English

Japanese

Almost all of them have no scientific basis, but some have make sense.

日本には数多くの迷信・言い伝えが存在します。

For example, it is said that “It will rain if swallows fly at low altitude.”

その多くは科学的な根拠がありませんが、筋の通ったものもあります。

As a low pressure system approaches, small bugs/flies get less able to fly at high altitude, because moisture attaches to their wings.

例えば、「ツバメが低く飛ぶと雨が降る」です。

Since these small bugs/flies are baits of swallows, when they fly at low altitude, swallows also fly low to catch them.

低気圧が近づいて湿度が高くなると、小さな虫は水分が羽に付いて体が重くなり、高く飛ぶことができなくなります。

I heard that the rain forecast based on the behavior of swallows is reliable in many cases.

小さな虫はツバメの餌であるため、虫が低く飛ぶと、ツバメもそれを追って低く飛ぶことになります。