1162 The Zoologist— April, 1868. 



introduce one and another egg into the nests of some other warblers, 

 if haply by good chance it can do so. 



Thus then it comes to pass that there are, and according to the 

 nature of circumstances there must be, proportionally many ex- 

 ceptions of the rule. 



Thus, too, it comes to pass that by far the greatest number of 

 cuckoo's eggs bear the type of the eggs of Calamoherpe arundinacea, 

 Sylvia cinerea, Motacilla alba (and perhaps, in certain other localities, 

 of Anthus pratensis, Emberiza miliaria, and others), and that on that 

 account eggs of such colour form (he most frequent exceptions ; 

 that is to say, are the most frequently found in the nests of other 

 species. 



Since then, as has already been observed, just those species, even 

 in all parts, but more especially in suitable localities, are rich in indi- 

 viduals, and live very near together, and thus, either occasionally 

 or always, offer a favourable opportunity for the hatching of the 

 cuckoo's eggs; so, on the one hand, the motive for the local pre- 

 vailing colour is evident; on the other hand, the frequent occurrence 

 of such colouring in other nests is accounted for; the latter, inasmuch 

 as some birds (Calamoherpe arundinacea, for example), on account of 

 their late period of breeding, can hardly ever receive the first eggs of 

 the cuckoo, which are laid towards the begiuning of May.* On the 

 contrary, the rarer colourings will appear as exceptions still more 

 rarely, although the birds for whose nests they are designed breed 

 less abundantly, and so their nests are more difficult to be found by 

 the cuckoo; but it appears that, on this account, so much the more 

 determined is she in seeking for such nests, and she searches so as to 

 find and to make use of them, as, for example, those of the redstart 

 ["rothschwanz "] and the wren ["zaunkonig"], even on the hayrick 

 and in the charcoal -burner's hut, quite renouncing her usual timidity. 

 Does her instinct possibly tell her that eggs of such striking contrast 

 are in especial jeopardy ? Besides these very circumstances seem in 

 general to require larger districts for those kinds of pairs, and at the 

 same time to require and account for the frequent excursions of the 

 hen bird in the neighbouring districts, in her search for those 



* But bow much the more true is tbis in regard to nearly all tbe others. I would 

 investigate all, in order, if possible, to prove these views by means of more numerous 

 facts. The Badetzer pond, already mentioned, offers abundant opportunities to this 

 end. Many observers may have similar opportunities : let them, on all sides, be taken 

 advantage of. 



