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Show CHAP. VII. INSTINCT. 216 I · t d der a hen. t IS no Young pheasants, th oug h rea.re e ubnu t fear only of d ogs that chi.c kens have 1o s t al. l 1eatrh, danger-chuckle, t h ey and cats, for if the he_n lfive~un; turkeys) from under will run (more espeCia y Y. the surrounding grass or her, and conceal .th~mseli~~n~f done for the instinctive thickets; and this IS ev ! wild ground-birds, their ll . as we see In purpose of a owmg, B t this instinct retained by our mother to fly away. u 1 under domestication, for b me use ess f chickens has eco lmost lost by disuse the power o the mother-hen has a flight. 1 d that domestic instincts have Hence, w. e dm anyd cnoanteu rual ~'In s ti·ncts have been lost par.t ly been acqurre a selecting and accumulating by habit, and partly by mat~ s peculiar mental habits . · e genera wn , dunng . succeshsiiv hat first appeare d from what we must and actw. ns, w c call an acCI· a ent . In some cases .c om-in our Ignorance h fficed to produce such Inhe-pulsory habit· alone .asi:uother cases compulsory habit rited mental c?ang:~d all has been the result of selech. a s done nodth binogth, meth oa · lly and unconsciously ; but ICa d tion, pursue b bl habit and selection have acte in most cases, pro a Y' together. b t derstand how instincts in a We shall, perhaps, bes un odified by selection, by state of nature have ecome.l;n lect only three, out of considering a fe.w casesh J :aves~ discuss in my future the several whiCh I. s ~ h" h 1 ads the cuckoo to k 1 the mst1nct w IC e . wor ,-name Y.' h birds' nests; the slave-makmg lay her eggs ~ ot er. nd the comb-making power of instinct of certain ants ' a . t' cts have generally, the hive-bee: these two latter IUS ~n l' ts as the roost and most justly, been ranked by na ura IS wonderful of all known insti~ct~ that the more immeIt is now commonly admitte k ' instinct is, that diate and final cause of the. cue oo s C_HAP. VII. OF THE CUCKOO. 217 she lays her eggs, not daily, but at intervals of two or three days; so that, if she were to make her own nest and sit on her own eggs, those first laid would have to be left for some time unincubated, or there would be eggs and young birds of different ages in the same nest. If this were the case, the process of laying and hatching might be inconveniently long, more especially as she has to migrate at a very early period; and the first hatched young would probably have to be fed by the male alone. But the American cuckoo is in this predicament ; for she makes her own nest and has eggs and young successively hatched, all at the same time. It has been asserted that the American cuckoo occasionally lays her eggs in other birds' nests; but I hear on the high authority of Dr. Brewer, that this is a mistake. Nevertheless, I could give several instances of various birds which have been kno"rn occasionally to lay their eggs in other birds' nests. Now let us suppose that the ancient progenitor of our European cuckoo had the habits of the American cuckoo ; but that occasionally she laid an egg in another bird's nest. If the old bird profited by this occasional habit, or if the young were made more vigorous by advantage having been taken of the mistaken maternal instinct of another bird, than by their own mother's care, encumbered as she can hardly fail to be by having eggs and young of different ages at the same time ; then the old birds or the fostered young would gain an advantage. And analogy would lead me to believe, that the young thus reared would be apt to follow by inheritance the occasional and aberrant habit of their mother and in their turn would be apt to lay their eggs in other birds' nests, an~ thus be successful in rearing their young. By a continued process of this nature, I believe that the strange instinct of our cuckoo could be, and has been, L |