2 BULXjETIN 113, UNITED STATES NATIONAL MUSEUM. 



Nesting.— Yarrell (1871) says: 



The great skua arrives in tlie Shetlands about the end of April, and its nest, 

 which consists of a neatly rounded cavity in the moss and heather of the 

 highest moorlands, is prepared in the latter half of May. According to Maj. 

 Feilden, the birds appear to prepare several nests before they decide on using 

 one. There is no difficulty in finding the nests, as the parent birds at once 

 attack any intruder upon their domain v^ith fiex'ce and repeated swoops. When 

 handling the nestling the editor found their assaults were unremitting; first 

 one bird and then the other wheeling short, and coming down at full speed, 

 almost skimming the ground. At about 15 yards' distance the strong clawed 

 feet are lowered and held stiffly out, producing for the 'moment a very ungainly 

 appearance, and it seems as if the bird would strike the observer full in the 

 center of the body, but on quickly raising the hand or stick the bird rises also, 

 the whirr and vibration of its pinions being distinctly heard and felt. Its 

 ordinary flight is soaring and stately. On leaving the territory of one pair, 

 the attack is taken up by another, and so on ; for the great skuas do not nest 

 in close proximity. 



Morris (1903) writes: 



The nest of the skua is of large size, as well as somewhat carefully con- 

 structed ; tlie nsaterials used being grasses, lichens, moss, and heath. The bird 

 places it on the tops of the mountains or cliffs in the neighborhood of the sea, 

 but not on the rocks themselves. They build separately in pairs. 



Eggs. — The skua lays ordinarily two eggs, rarely three, and some- 

 times only one. These vary in shape from ovate or slightly elongated 

 ovate to short ovate. The shell is smooth, with a dull luster. The 

 ground color is " Saccardo's olive," " Isabella color," or " deep olive 

 buff." The markings are usually not profuse and consist of spots 

 and blotches, scattered irregularly over the egg, of " sepia," " bis- 

 ter," " snuff brown," or '' tawny olive." There are also usually a few 

 faint spots or blotches of pale shades of drab or gray. Rev. F. C. E.. 

 Jourdain has collected for me the measurements of 68 eggs, which 

 average 70.58 by 49.43 millimeters; the eggs showing the four ex- 

 tremes measure 76.3 by 50.4, 71.5 by 53.3, and 62 by 44.5 millimeters. 



Young. — Macgillivray (1852) quotes Captain Vetch as saying: 



The young bird is a nimble, gallant little animal, and almost as soon as 

 hatched leaves the nest. On the approach of danger he secretes himself in 

 holes or behind stones with great art, and when captured at least makes a show 

 of defense that is quite amusing. 



Plumages. — I have never seen the downy young, but Coues (1903) 

 describes it as " buffy-gray, ruddier above than below." Ridgway 

 (1887) quotes Dresser as calling it " brownish or cinnamon-gray, 

 rather darker in color on the upper parts than on the under surface of 

 the body." 



I have not been able to examine enough specimens to come to any 

 definite conclusions as to the sequence of molts and plumages. Coues 

 (1903) gives the following good description of the young of the year: 



Size much less ; bill weaker and slenderer ; cere illy developed ; striae not 

 apparent and its ridges and angles all want sharpness of definition. Wings 



