September, 1920] 



The Canadian Field-Naturalist 



103 



The results of my survey are shown m the 

 accompanying table. The figures in the three 

 columns at the right are estimates; all the other 



figures in the table are the results of actual counts. 

 The term "adult" in this table refers to all birds 

 hatched prior to 1920. 



A conservative estimate would, I believe, place 

 the fetal number of grown-up birds in the colony 

 in 1920 at not less than 1,250, made up of about 

 1,200 Great Black-backed Gulls aod 50 Herring 

 Gulls. These figures may be arrived at in either 

 of two ways. 



The total number of nests seen is 341 ; if this 

 ^vas twc-thirds of the total number present, the 

 colony contained 511 nests, which would mean 

 1,022 breeding birds. That there were enough 

 non-breeding grown-up Gulls in the colony to bring 

 the total up to 1,250 is not improbable. 



Again, the number of grown-up birds seen at the 

 colony by me was most conservatively estimated, 

 as shown by the tabulated figures, at 915 Great 

 Black-backed Gulls and 35 Herring Gulls. To 

 suppose that at least 285 of the former species and 

 15 of the latter were away from the colony, hunt- 

 ing for food, at the time of my visit seems very 

 reasonable. Not only were Gulls to be seen fiying 

 to the lake at 9.00 a.m., when I approached it, and 

 at 6.00 p.m., when I finally left its vicinity, but 

 Great Black-backed Gulls, presumably from this 

 colony, may be found daily in summer at practical- 

 ly every point along the seacoast for sixty miles 

 in either direction. 



These estimates are the best which I have been 

 able to prepare, but, if any one considers them in 

 error in any way, the actual counts and facts 

 stated above may, of course, form a basis for any 

 estimate preferred. 



When one approaches an island in the colony, 

 the Gulls able to fly gradually leave it and, for the 

 most part, circle overhead, although some alight 

 on the water not far away. The air becomes filled 

 with a pandemonium of deep cries, of which I was 



able to distinguish three kinds, a moderately loud 

 cub-cuh-cuh, cuh-cuh-cuh, a Icud, bass Ojp, Ow, 

 and a roaring rrr-rrr-rrr-rrr. Mos' of the flying 

 birds are in fully adult plumage, but some of them 

 show traces of immaturity in brown markings here 

 and there. By the time one lands on an island, 

 all the Gulls able to fly have left it, and none of 

 them re:urn until the intruder has departed. As 

 I walked over Big Gull Island, with fully six 

 hundred Great Black-backed Gulls circling above 

 me, I could not help thinking how little their fear 

 was justified by the actual locaticn of the power 

 to harm. If those hundreds of tremendous birds 

 had but realized their strength and willed to use 

 it in effective coordination against the weaponless, 

 shelterless human being intruding among their 

 homes, they could with the greatest ease and speed 

 have laid my bare skeleton to bleach upon the grass. 

 Bu' Great Black-backed Gulls are useful scaveng- 

 ers, naturally wild and shy, and I could not see that 

 any of them at any time showed even especial 

 solicitude for the particular nests or young ncai 

 which I might be. 



At the time of my visit, June 16, most of the 

 young were recently hatched, but others were in 

 the act of hatching. The newly-hatched young of 

 the Great Black-backed Gull is a wet, spine- 

 covered, ugly-looking dark object, sprawling help- 

 lessly, and uttering repeatedly a short, shrill whine. 

 Soon, however, its spines burst into gray and black 

 down, it gains the ability to walk and run about, 

 and its cry changes to a rattling eh-eh-eh. The 

 majority of the young which I saw on June 16 

 were in the downy stage. A small number showed 

 feathers of the juvenal plumage in the wings and 

 at the sides of the breast, and a very few of the 



