THE LITTLE-GULL 153 



Sandman and Henrici found the nests floating on the surface of the 

 water or partly supported by the growing clumps of Phragmites and 

 water-aloe (Stmtiotes), while the principal materials used were the 

 stalks of Sdrpus lacustns. Owing to the situation of the nests, a very 

 slight rise in the water-level is enough to submerge them, and this has 

 been observed to happen both in Denmark and also in Esthonia. 

 Russow states that on visiting a colony after a disaster of this kind 

 about a week later, he found the birds busily building much more 

 substantial structures, which had a foundation about six inches 

 deep. 1 He also noticed that in Esthonia many nests were built 

 on the masses of dead reeds crushed down by snow and ice in 

 the winter. 



In the artless nest the eggs, usually two, or more typically three, 

 in number, are laid in the latter half of May and early in June. 

 Christensen found clutches highly incubated in Denmark on May 15, 

 1904, but on Karlo full clutches were first found by Sandman between 

 June 7th and 10th. Russow says that four eggs have exceptionally 

 been found in one nest. 2 They bear a strong resemblance to those of 

 the common-tern, but do not show the traces of " run " colour, due to 

 rotation in the oviduct, and are a rather fuller and more rounded 

 oval in shape, though distinctly pointed at the small end. There is 

 generally also a tendency to an oily gloss, which is absent from the 

 tern's eggs, and the greenish olive ground is also characteristic of the 

 gull's eggs. As the two species are very often found breeding together, 

 careful identification is always necessary. Exceptionally, blue eggs 

 have occurred, as in so many other species of gulls. 



The average size of 97 eggs is 1-63x1 -18 in. [41 -5x301 mm.]. 

 When incubation has begun the birds cease to fly up and down the 

 lake with continuous cries. At daybreak the non-incubating birds go 

 away to feed, and do not return till nearly midday, when they are met 

 by their mates, who change places with them. We still lack information 



1 Die Ornis Ehst-, lAv- und Curland's, p. 194. 



2 One instance of five eggs in a nest has been recorded (W. Meves). 



VOL. III. 



