76 BULLETIN 196, UNITED STATES NATIONAL MUSEUM 



observer and becoming alarmed. Again, Miss Averil Morley (1938, 

 vol. 2) has seen a male with head sunk between the shoulders and the 

 feathers of shoulders, neck, breast, etc., puffed out so that the yellow 

 bill appeared to form a conspicuous center to a round black shield, 

 and bowing by both sexes also occurs. Other variations have been 

 observed, but the cases described serve to illustrate the general type 

 of display behavior and to emphasize how far from stereotyped the 

 posturings are in spite of the fact that certain features tend to recur. 



Nesting. — Some account of the territorial behavior of the blackbird 

 has been given under the section "territory." The nest is usually 

 built in hedges or bushes or brambles, or in ivy on trees, walls, or 

 buildings. It may also be situated low down in a tree or, less fre- 

 quently, at a fair height, though a record of one 30 feet up in a tree is 

 exceptional. Not rarely it is built on banks or on the ground in woods, 

 in quarries or among rocks, and on islands with no trees and not much 

 cover such situations may be normal. Occasional sites are the insides 

 of barns and outbuildings, hollows in trees, and so on. The nest is 

 normally built by the hen, though the cock frequently escorts her and 

 sometimes assists by bringing material. Exceptionally he may even 

 work some of the material into the nest. It is a solidly constructed 

 cup of dry grasses, straws, rootlets, and moss solidified with mud and 

 with a solid mud liuing, but unlike that of its relative the song thrush 

 the mud is concealed by an inner lining of fine dry grass and rootlets. 



Eggs. — The ground-color of the eggs is a pale bluish green or green- 

 ish blue closely freckled all over with reddish brown. Coarser spots 

 or markings of the same color may also be present and in some eggs 

 the markings may be concentrated in a cap or zone at the broad end. 

 Not rarely a blackish streak is present. Varieties with a clear blue 

 ground color, sometimes without markings, occur and a rare eryth- 

 ristic variety is white with red-brown spots (Jourdain, 1938, vol. 2). 

 Jourdain gives the measurements of 100 British eggs as: Average, 

 29.4 by 21.5 millimeters; maximum, 35 by 21.5 and 34 by 24; minimum, 

 24.2 by 19 millimeters. Niethammer's (1937) average for 56 German 

 eggs agrees closely with the above, namely 29.1 by 21.7 millimeters. 

 As two or three broods are normally reared, and exceptionally even 

 four, eggs may be found over a considerable period. In England 

 some nests with eggs are regularly to be found in March and even in 

 February, but laying is not general until April and the egg season 

 extends to July. Exceptionally eggs have been recorded in January 

 and December. In central Europe, according to Niethammer, the 

 normal egg season begins in April, and eggs even in the last half of 

 March are considered exceptional. The normal clutch in England 

 is four or five, but often there are only three, rarely six, while seven, 



