7 2 HULL SCIENTIFIC AND FIELD NATURALISTS CLUB. 



they are suddenly startled up a regular shower of eggs is 

 rolled down the cliff. A visit to the cliff-foot during the 

 season reveals hundreds of empty egg-shells wasted on the 

 beach. If the bird is leaving its egg of its own accord it 

 often is seen to push the egg away before taking to flight, 

 but if angered or alarmed it is my firm belief that many birds 

 kick their eggs down the cliff to prevent the intruders getting 

 them. I have stood on a ledge watching a bird which 

 deliberately kicked its egg down several minutes before 

 leaving the rock itself, and still sat looking at me. Many 

 eggs are laid at sea and trawled up or washed up in Filey 

 Bay. No egg, except that of the Jack Snipe, bears so large 

 a proportion to the size of the bird as that of the Guillemot, 

 actually averaging, as it does, ^ of the weight of its parent,* 

 or, in the case of a double-yoked egg, considerably more. 



It is astonishing that amongst all the eggs, which so 

 much resemble each other, the parent can find its own 

 again, especially as in wet weather the ground colour is quite 

 lost in mud and the birds' excrement. Some writers affirm 

 that they do not always find their own again. I have seen 

 dirty eggs on the ledges, cold and deserted, but whether they 

 have been lost by the parent, or the bird has been shot, it is 

 difficult to say. When frightened off the egg the bird makes 

 a long stay away, at least half-an-hour, but if a young one is 

 on the ledge she is soon back. It is believed that the rock 

 at this season retains enough heat to preserve the vitality of 

 the egg. Taking all things into consideration, I should say 

 few birds are so careless of the safety of their eggs as the 

 Guillemots. The bird will sometimes be found sitting on a 

 ledge just wide enough to hold bird and egg, and occasionally 

 with water continually dripping upon her. 



The peculiar pear-shape of the Guillimot's egg, in con- 

 junction with its position upon the rock ledges, lends itself 

 to the belief that it has been evolved by the operation of the 

 law of the survival of the fittest, as it would obviously be 

 a protection against the destruction of the egg by the agency 

 of wind. Upon this point, however, there is room for con- 

 troversy, as an examination of the actual conditions now 

 prevailing leaves a doubt whether this abnormal shape could 

 have been so developed, (i) The parent bird leaves the egg 

 in all sorts of positions, as often as not with the small end 

 pointing seawards, and this at the extreme edge of the ledge, 

 and sometimes on a dangerously narrow ledge, sloping 



'* The average weight of a bird is 2 lbs., and of an egg \ lb. 



