ON MR. SELOUS' THEORY OF THE ORIGIN OF
NESTS.
By H.E. Howard, F.Z.S.
In his article on the Great Crested Grebe in this Journal (1901, p. 339), Mr. Selous made reference to "one of two rival Wheatears catching up a piece of grass in the midst of violently excited movements," adding that he would recur to the explanation of this habit. I therefore looked forward with much interest to his explanation of a habit which I admit had puzzled me for some years, and which, taking his observations in conjunction with my own, I now feel sure is probably—if we only knew it—to be found amongst the majority of species. I therefore think it best to put my own observations on record, as they appear to me to very much strengthen the foundation on which his theory of the origin of nests is built—a theory which, to my mind, now that I look back upon the same, to me, unintelligible sexual movements which I have from time to time observed, appears to be placed outside the category of a provisional hypothesis.
In an article on the Grasshopper-Warbler (Zool. 1901, p. 61), I described the male of this species picking up a dead leaf, and following the female with it in his bill, while mating. But this only very tamely describes what really happens, and if it had not been for Mr. Selous I should still have been satisfied with the conclusion I then arrived at, viz. that it was an outward sign of the one absorbing picture in the bird's mind—the construction of its nest. Sexual frenzy precisely describes the condition of the males of the above species at this time—that is to say, during the week or so they are mating—and in every case where I have closely followed their movements at this period, they have performed the same curious ceremony, usually in the midst of intensely excited and nervous actions. These movements are characterized, as a rule, in the following way: The male walks—you might almost say struts—along in front of the female,
