つばめが！ - Swallows are...

日本人が大好きなつばめ。
子育てに熱心でいつも仲良くペアでいるイメージの鳥。
そんな思い入れが見事に覆されたのが、 この会。
8/31のLife Science Barのお題は、「ツバメは真面目に浮気する？」

最初から衝撃な「一夫多妻制の鳥の90％は浮気する」という事実からスタート。

ツバメの50ペアを調査したところ、
30％の巣に「つがい外子」が発見されたそうです。
そこにはかれらの「良質な遺伝子を残す」ための本能ゆえのたくましい戦略が。
まあ、つばめにかぎらず、鳥は浮気する（真面目に）訳です。
ちなみにあの夫婦仲睦ましい表現の代表格のオシドリだって、同じだそうです。。。

I joined a session at my favorite Science Bar on Aug 31.
We Japanese love swallows from old times as mascots in spring and we are happy to see they raise baby birds earnestly in pairs at close unity under the eaves.
But our special feeling toward them was diminished thanks to this session.
The topic for that day was “Swallows are cheating each other?” and the presenter started with the shocking fact; the parentage of this behavior (EPC=extra-pair copulation) can reach to 90%.

The researcher has surveyed 50 swallow pairs and found extra-pair youngs (EPY) at 30% of their nests.
   
They are seriously doing this to leave good genes through EPY by instinct in a strategic way.
Well, not only swallows but both male & female of all sorts of bird are having EPC each other - seriously.
Either “Oshidori; mandarin ducks” do. (So-called “lovebird” in Japan. They are often referred in the speech at wedding parties...)