219 
peckers. It is characteristically a bird of the orchard and with a little 
encouragement will build in birdhouses in the garden where its gentle 
ways, pretty murmuring notes, and brilliant coloration make it quite 
an acquisition. 
Economic Status. The Bluebird feeds mainly upon insects and is, 
therefore, highly beneficial. Weed seeds form an important part of 
its food and it eats some soft fruit, but practically no cultivated kinds 
aga Hence the Bluebird can be regarded as a consistently useful 
ird. 
GLOSSARY. 
Albinism. The occasional and erratic occurrence of white specimens, either pure or 
partial, complete or in irregular spots, in species that normally are not white. It is nothing 
more than a freak caused by a deficiency of colouring matter in the plumage (p. 7). 
Axillars or Axillaries. A fan-shaped group of feathers under the wing closing the 
space between the innermost flight feathers and the body when in flight. 
Bars. In descriptions of bird coloration, bars designate lines drawn across the body 
and not parallel with the shafts of the feathers (see stripes). 
‘ Cere. A wax-like appearing swelling about the base of the upper mandible, present 
in some species, especially the Hawks. See Figure 33a and b, page 23. 
Coverts. The feathers covering the bases of the larger flight and tail feathers. There 
are upper and under wing coverts and upper and under tail coverts. The upper wing 
coverts are divided into greater and lesser coverts, the former being the largest line imme- 
diately next to the flight shafts and resembling them to some degree in texture (Figure 1 
p. 18). 
Crepuscular. Pertaining to twilight. 
Crown. The top of the head from the forehead to near the base of the skull. 
Culmen. This may be called the ridge line of the bill. Viewed sideways, the line 
forming the top outline of the bill from the spring of the first forehead feathers to the tip is 
the culmen line. It is measured in a straight line, as with dividers, not following the curves 
as with a tape line (Figure 1, p. 18). 
Dichromatism. The normal occurrence of two different colorations in the same 
species due to neither sex, season, nor age and only partly hereditary. Both colorations 
may occur in the same brood though the tendency is for like to produce like and one form 
may predominate in any given locality (see p. 7). 
Emarginate. When applied to the shape of feathers indicates that more or less of one 
web is cut away as if a shaving had been removed with a jack-knife. 
Extralimital. In describing distribution refers to the subject occurring without 
the geographical bounds of the area under discussicn. 
Family. In zoological classification is one of the larger groups of animals having 
enough mutual resemblance to be classed together and apart from all other forms. It is 
the next larger group to a genus and next smaller to an order or suborder. For example, 
all the Ducks, Geese, and Swans belong to the same family, Anatide (see p. 5). 
Flanks. Thesides of the body, below or under the closed wing. They are often 
covered by a loose group of feathers that may be laid at will either over or under the shafts 
of the closed wing (Figure 1, p. 18). 
Genus (plural, genera). In zoological classification is one of the smaller groups of 
animals having enough resemblance to be classed together and apart from all other groups 
of like rank. It is a subdivision of a family or subfamily and next above a species. A 
genus is, therefore, a group of species, and a group of genera is a family (see p. 5). 
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