I899-J PATTEN:— Nest of Little Tern. 191 



To arrive at any conclusions as to its formation, it is 

 necessary to visit as large a colony of terns as possible. 

 Observations made on one or two nests afford us little help, as 

 they are liable to variation. 



A pair of powerful field-glasses or a binocular telescope are 

 also essential, so that the nests and their occupants may be 

 investigated at a distance. Approaching too close frightens 

 the birds ; often indeed the slightest provocation induces the 

 whole colony to rise 1 from their breeding haunts and so pre- 

 vent the observer from seeing the birds at work. 



We are fortunate enough in having two colonies not far 

 from Dublin city. One at Kilcool, Co. Wicklow, on the sea 

 beach ; and the other at the far end of the Dollymount Strand, 

 or North Bull, Dublin. The nature of the ground differs 

 somewhat in the two localities, and -correlated with this fact, 

 the nests are often correspondingly modified. At Kilcool 

 gravel predominates on the beach ; at Dollymount sand and 

 shingle {broke?i shells). I^et us describe a nest found in the 

 latter locality as our type. 



In the unfinished state it is seen to consist of a depression 

 some 5 cm. (2 inches) deep. Viewed from above, the outline 

 is almost circular, with a diameter at its widest part of 6 to 7J 

 cm. or nearly 2\ to 3 inches. No shells or pebbles are 

 contained in the cavity, which at this stage is entirely lined 

 with sand. Outside, shingles are scattered somewhat abund- 

 antly. (Fig. i,4). 



When seen in vertical section the depression is somewhat 

 conical or V-shaped, the edges sloping at a definite angle, and 

 the deepest part or centre being quite narrow. 



In section we might represent the appearance diagram-- 

 matically somewhat as in fig. 1 (see next page). 



The question now arises — how is this V-shaped depression 

 excavated? By the feet or the beak ? Or both? Simply to 

 say that a hole is scratched in the sand affords us no clue as to 

 its formation. The answer is not so easy as one might be 

 inclined to anticipate. As far as direct observation goes I 

 canuot positively assert that I have ever seen the bird using 



1 Though easily startled from their nests, the Little Terns are fierce and 

 courageous, and when they see their eggs or young actually being 

 plundered, they will boldly fly in the face of their assailants. 



A 2 



