( 278 ) 

 THE COURTSHIP OF THP: COMMON GULL. 



BY 



MAUD D. HAVILAND. 



(Plate 17.) 



On May 9th, 1913, I found a colony of about twenty 

 pairs of Common Gulls (Lams c. caniis) nesting on a 

 small island in a freshAvater loch in the Outer Hebrides. 

 The islet Avas 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, hke that of most other 

 species, can be divided into two parts : [a) the challenging 

 of the cock bird to his peers, and (6) 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 Avas given as if with 

 great effort. The bill Avas nearly closed, and the head 

 and neck Avere stretched out stiffly (fig. 2). It seemed 

 to me that although far less noisy than the previous 

 performance this Avas more of a challenge. In three 



