„Though I know something about British birds I should have been lost and confused among American birds, of which unhappily I know little or nothing. Colonel Roosevelt not only knew more about American birds than I did about British birds, but he knew about British birds also. What he had lacked was an opportunity of hearing their songs, and you cannot get a knowledge of the songs of birds in any other way than by listening to them.
We began our walk, and when a song was heard I told him the name of the bird. I noticed that as soon as I mentioned the name it was unnecessary to tell him more. He knew what the bird was like. It was not necessary for him to see it. He knew the kind of bird it was, its habits and appearance. He just wanted to complete his knowledge by hearing the song. He had, too, a very trained ear for bird songs, which cannot be acquired without having spent much time in listening to them. How he had found time in that busy life to acquire this knowledge so thoroughly it is almost impossible to imagine, but there the knowledge and training undoubtedly were. He had one of the most perfectly trained ears for bird songs that I have ever known, so that if three or four birds were singing together he would pick out their songs, distinguish each, and ask to be told each separate name; and when farther on we heard any bird for a second time, he would remember the song from the first telling and be able to name the bird himself.“
— Edward Grey, 1st Viscount Grey of Fallodon British Liberal statesman 1862 - 1933