FLORIDO: They try to sing higher. Some birds change the frequency of their songs, others change individual notes. (SOUNDBITE OF BIRD TWEETING).
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.
Read More at Source.