96 The Wilson Bulletin.— No 44. 



variation of the eggs in the nests containing but two eggs was 

 so great that it was rarely possible to tell whether the nests 

 of five belonged to two or to but one bird. That point can be 

 settled only after careful study with the birds under close 

 scrutiny. 



Over 20 young birds unable to fly were counted on the three 

 islands, but they were not considered in making an estimate 

 of the population of the islands. (il8 nests were actually 

 found, thus arguing a population of 1,236 old birds. It is 

 almost certain that many nests were overlooked, and it is not 

 likely that many nests were counted twice. Probably an esti- 

 mate of 1,500 old birds would be far within the facts. Thus 

 it would appear that the rate of increase since 1896 has been 

 enormous. On the two smaller islands the Roseates have more 

 than held their own, while on the large island the Common 

 Terns have come in hordes to possess it. 



While there were more eggs than young birds and empty 

 nests on the beach levels of the large island, on the upper levels 

 the empty nests and young predominated. Apparently the first 

 comers built their nests on the uplands by preference, while 

 the later comers were either forced to occupy the lower levels 

 or chose to do so. A little more care was manifest in the se- 

 lection of a nesting site and in the construction of the nests on 

 the uplands than on the beach. One might argue from this 

 that the upland breeding birds were the more experienced, and 

 therefore probably the older birds, but systematic study will 

 be needed to prove it. The number of eggs in a nest also ap- 

 peared to average larger on the uplands than on the beach 

 levels. 



It is common knowledge that tern eggs are protectively 

 colored to simulate pebbles on the beach. Nests made of sea 

 weed scattered among the pebbles were hard to see, because 

 the color of the sea weed resembled the stones and the eggs. 

 On the upper levels, however, and on the light colored sands 

 among the grass, and where the nests were made of light col- 

 ored fine grass, the eggs were easily detected by their bold 

 blotches. They would have been less conspicuous little end up, 

 but tradition forbade such an arrangement. Why tradition 

 should permit the use of nonprotective nest material and not 

 also furnish a degree of protection in either color or position 



