Among many birds the males at mating time fall into a state of sexual frenzy, but not the females.  “I cannot call to mind a single case,” states an authority on birds (H.E.  Howard, Zooelogist, 1902, p. 146), “where I have seen anything approaching frenzy in the female of any species while mating.”

Another great authority on birds, a very patient and skillful observer, Mr. Edmund Selous, remarks, however, in describing the courting habits of the ruffs and reeves (Machetes pugnax) that, notwithstanding the passivity of the females beforehand, their movements during and after coitus show that they derive at least as much pleasure as the males. (E.  Selous, “Selection in Birds,” Zooelogist, Feb. and May, 1907.)

The same observer, after speaking of the great beauty of the male eider duck, continues:  “These glorified males—­there were a dozen of these, perhaps, to some six or seven females—­swam closely about the latter, but more in attendance upon them than as actively pursuing them, for the females seemed themselves almost as active agents in the sport of being wooed as were their lovers in wooing them.  The male bird first dipped down his head till his beak just touched the water, then raised it again in a constrained and tense manner,—­the curious rigid action so frequent in the nuptial antics of birds,—­at the same time uttering his strange haunting note.  The air became filled with it; every moment one or other of the birds—­sometimes several together—­with upturned bill would softly laugh or exclaim, and while the males did this, the females, turning excitedly, and with little eager demonstrations from one to another of them, kept lowering and extending forward the head and neck in the direction of each in turn....  I noticed that a female would often approach a male bird with her head and neck laid flat along the water as though in a very ‘coming on’ disposition, and that the male bird declined her advances.  This, taken in conjunction with the actions of the female when courted by the male, appears to me to raise a doubt as to the universal application of the law that throughout nature the male, in courtship, is eager, and the female coy.  Here, to all appearances, courtship was proceeding, and the birds had not yet mated.  The female eider ducks, however,—­at any rate, some of them,—­appeared to be anything but coy.” (Bird Watching, pp. 144-146.)

Among moor-hens and great-crested grebes sometimes what Selous terms “functional hermaphroditism” occurs and the females play the part of the male toward their male companions, and then repeat the sexual act with a reversion to the normal order, the whole to the satisfaction of both parties. (E.  Selous, Zooelogist, 1902, p. 196.)

It is not only among birds that the female sometimes takes the active part, but also among mammals.  Among white rats, for instance,