i8 ANNALS OF SCOTTISH NATURAL HISTORY 



occasional notes of their arrival and departure. In this 

 paper I will try to give a short account of my observations. 

 To make the paper more easily followed I will divide the 

 birds of Sule Skerry into six classes: I. Residents; 2. 

 Regular Summer Visitors ; 3. Regular Winter Visitors ; 

 4. Occasional Summer Visitors ; 5. Occasional Winter 

 Visitors ; 6. Rare Visitors. 



I. RESIDENTERS. Shag or Green Cormorant (Phala- 

 crocorax graculus], Great Black-backed Gull (Larus jnarinus), 

 Herring Gull (L. argentatns), and Rock Pipit (Anthus 

 obscurus). In this class the Shags come first in point of 

 numbers. They seem to find an abundant supply of food 

 in the vicinity, for they are continually to be seen, no matter 

 what the weather may be. In fine weather they devote all 

 their energies to fishing a short distance from the land, and 

 when the sea is wild and stormy in winter they take refuge 

 on the rocks, seeking some sheltered nook when the storm 

 is more than usually severe. In December they don their 

 breeding plumage, when the ornamental crest on the head 

 first makes its appearance. In February, if the weather is 

 anything moderate, they begin nest-building, a piece of work 

 they go about in a very business-like way, but very often 

 their labour is in vain. Instinct guides the lower animals in 

 a wonderful manner, but I have frequently thought that a 

 wee bit of reason in the Shag's head would often have saved 

 him an immense lot of labour. Occasionally in February 

 there are a few days of quiet weather, and whenever that is 

 the case they begin nest-building, which nests, without 

 exception, are all washed away by the first heavy sea. 

 There is always a lot of withered grass on the island, which 

 is considered the best material for nest building ; and when 

 the work is begun no time is lost. One bird builds, and 

 the other acts as carrier. It is a common thing to see them 

 stealing from one another, an occurrence which causes a 

 big row. When the one engaged building is busy at work, 

 and its mate away in search of more material, I have often 

 seen a " carrier " from another nest approach in a suspicious 

 manner which is understood by the bird approached, for it 

 at once puts itself on the defensive, and uses very threatening 



