( 278 ) THE COURTSHIP OF THE COMMON GULL.

BY MAUD D. HAVILAHD.

(PLATE 17.) ON May 9th, 1913, I found a colony of about twenty pairs of Common Gulls (Larus c. camts) nesting on a small island in a freshwater loch in the Outer Hebrides. The islet was occupied also by about the same number of pairs of Black-headed Gulls (Larus ridibundus) and in many cases the nests were side by side. Later on, however, I noticed that the Common Gulls were fond of building in long, thick heather, while for the most part the Black-headed Gulls preferred more open situations near the water's edge. On May 9th, a few nests contained eggs, but the greater number of the birds were courting. The mating of the Common Gull, like that of most other species, can be divided into two parts : (a) the challenging of the cock bird to his peers, and (b) the actual wooing of the female. So far as I could ascertain, however, it would be difficult to draw an arbitrary distinction between the performances in this case. Judging from the procedure of a dozen birds, which from their behaviour I took to be males, the sequence was as follows : The bird stood upon some prominent perch and called vociferously for some minutes. I do not know whether the coloration of the inside of the mouth plays any part in sexual selection in this species, but the bill is often opened to an extent quite dispropor­ tionate to the volume of sound emitted. This is shown in fig. 1. Sometimes the bird broke off here; if not he went on to utter a deep rasping note, which was given as if with great effort. The bill was nearly closed, and the head and neck were stretched out stiffly (fig. 2). It seemed to me that although far less noisy than the previous performance this was more of a challenge. In three British Birds, Vol. VII., PI. 17.

Fig. 1. COMMON GULL: TO SHOW ATTITUDE ONE.

Fig. 2 COMMON GULL: TO SHOW ATTITUDE TWO.

(Photographed by Miss M. D. Haviland.) VOL. VII.] COURTSHIP OF COMMON GULL. 279 cases the result was that the bird on the stone was swooped at and buffeted by another, but I only once saw a bird struck while behaving as in fig. 1. The third performance took place upon the ground, among the long grass and raspberry canes which grew upon the island. Two male birds walked side by side,

Fig. 3. COMMON GULL: TO SHOW ATTITUDES ONE AND THESE. (Photographed hy MIBS M. D. HaYiland.) as closely as though they had been coupled together, with their heads drawn in, as shown in the bird in the foreground of fig. 3. The leg was bent until the tarsus was almost on the ground, the whole body was stiffened, and the bird uttered a curious guttural note. While walking thus, the Gulls followed certain definite tracks or runs in the herbage, but whether these runs were made by these repeated promenades, or whether they simply chose them as the easiest places to walk in, I cannot say. I twice saw the male bird assume this attitude before another bird which subsequently proved to be a female, but I never saw a female act thus. 280 BRITISH BIRDS. [VOL. VH. I repeatedly saw the cock birds go through a fourth performance, but was never near enough to photograph them in the act. It invariably preceded the successful consummation of the courtship : I never saw it on any other occasion. The male bird, crouching in front of the female, jerked his head upwards spasmodically, while he uttered a high-pitched note, something like the creaking of a gate-hinge, only more musical.* The hen birds treated the cocks with great indifference, but I never saw them refuse a male bird which had been through the performance just described. I am inclined to think that there must be a fifth phase of courtship between those which I have here designated three and four, but if there was I did not distinguish it. The coarting only went on in the forenoon. Later, the birds scattered over the loch to sun themselves and fish. The Common Gull is a confirmed egg-stealer, and I several times saw birds smash and suck the eggs of some of the Black-headed Gulls round them. The Common Gull was not very abundant in the district. Besides the colony described above, we only found one small breeding-station among some sand- dunes four miles higher up the coast. There was, however, a great colony of Herring- and Lesser Black- backed Gulls on one island in one of the inland lochs, and amongst these I distinguished some Common Gulls. I was not able to land upon this island, however, and elsewhere the Common Gull was not nearly so abundant a breeding species as the Herring-Gull.

* I have seen a young Herring-Gull go through an almost simila* performance in the late summer when begging for food from an adult.