habit, behavior pattern

I observe their behavior.

私は習性を観察します

I observe the birds' behavior.

私は鳥の習性を観察します

I observe the birds' behavior in the forest.

私は森で鳥の習性を観察します

I observe the birds' behavior in the forest at dawn.

私は早朝、森で鳥の習性を観察します

I observe the birds' behavior in the forest with the researchers at dawn.

私は研究員たちと早朝、森で鳥の習性を観察します