No one will be surprised at my keeping specially in mind that endlessly melancholy cry of the cuckoo in the darkness. How lonely and empty our German woodlands would seem without the cuckoo and the cuckoo cry! As a matter of fact the African primeval forest _never_ hears the same cry that has become so clear to ourselves. Our cuckoo, migrating in a few days all the way from the north to the equator, flies in restless haste through wood and plain, but _he is silent_. His cry is heard only in our country at home. But in the East Africa district of Pori, amongst many other cries those of two species of cuckoo are heard in rivalry. These are the sickle cuckoo--the “Tipi-tipi” of the Swahili--a reddish-brown fellow that flutters in heavy flight everywhere about the bush, the reedy bogs and hill-slopes; and the solitary cuckoo (_Cuculus solitarius_, Step.), about whose cry I was for a long time mistaken. The unceasing, low cry of the former, the sickle cuckoo, if it is heard even a few times, can never again be forgotten. It sounds like--“Dut-dút--dududu--dut-dút.” One hears it by day and also in the darkest night, contrasting strongly with the sharply defined, clear note of our European cuckoo, though the latter listens in silence to the cry of his cousins all through the winter under the equator. This cry seems to me, with its low, dull, softly prolonged tones--so different from the louder cry of its northern relative--to be quite in keeping with its mysterious tropical home. For the sickle cuckoo knows all its deepest mysteries, and no bird ranges so unweariedly through the densest thickets and over the most inaccessible regions. In the most hidden, solitary, and unknown spots[42] it would come fluttering up from the ground at my feet, often startling me. It seemed to me as if the bird wanted to call my attention to newly discovered mysteries, as its “Dut-dút--dududu--dut-dút” came sounding to me, now here, now there, low, soft and melodious, by day under the brooding noonday heat, and just the same in the midnight hours. At night, too, he is seconded, as I have already mentioned, by his more timid cousin, with an ever repeated “Kí-kü-kü--kí-kü-kü,” that resounds monotonously in the distance. There is a strange charm in continually hearing these voices again and again, without knowing the little singers; and a triumph at last in making out which they are.