I was reading about the reasons for the disappearance of song birds in Germany. The spread of scientific forestry, horticulture, and agriculture, have cut them off from their nesting places and their food supply. More and more, with modern methods, we are doing away with hollow trees, waste lands, brushwood, fallen leaves. I felt sore at heart. I was not thinking so much about the loss of pleasure for human beings, but I was so much distressed at the idea of the stealthy and inexorable destruction of these defenceless little creatures, that the tears came into my eyes.
Letter from Rosa Luxemburg to Sophie Liebknecht, 2 May 1917 (http://tiny.cc/TfMi5).