INTRODUCTION. 19 



to be less than 8^ inches we are justified in calhng the duck a teal (F or'FF). 

 The light blue shoulders are quite distinctive and our specimen may be 

 labeled Blue- winged Teal, provisionally. It remains to turn to the full 

 description of this species on a following page, confirm our diagnosis, and 

 try to decide whether this individual is male or female, adult or immature. 

 As a second example of the use of the artificial key let us take the common 

 Blue Jay. Starting with the Key to the Larger Groups, we find that our 

 specimen agrees successively with the following fines: 



AA. Not at all web-footed. 



GG. Tibia feathered down to heel joint ("knee"). 



QQ. Upper mandible without cere or soft membrane at base. 

 TT. Three toes in front. 



VV. Nail of middle toe not pectinate. 

 WW. Tail feathers not spine-tipped. 



XX. Birds more than four inches long. 



YY. Hind toe and claw more than half as 

 long as middle toe and claw. — 

 Passeres. 



This shows that our specimen belongs in the order Passeres or Perching 

 Birds, and we turn to the key to the members of that group. Here we find 

 a Key to Families, and following the same plan as with the previous key 

 we decide that our bird agrees successively with the lines: 

 2. Upper mandible imperfectly or not at all hooked, toothed, or notched 

 at tip. 



CC. Tips of folded wings not reaching to tips of middle tail feathers. 

 EE. Tail not tipped with bright yellow. 



FF. First primary about one-half the length of the longest. 

 N. Tail feathers with soft, rounded tips. 



00. Wing 5 inches or more. Family Corvidae. 



Under this heading, we find a Key to Species which gives us in regular 

 order: 



AA. Smaller birds, wing less than 10 inches, plumage not all black. 



CC. Tail moderate (about 6 inches), somewhat rounded at tip. (This 

 refers not to the tips of the individual tail feathers, but to the 

 outline of the whole end of tail.) 

 D. Head with a conspicuous crest; plumage largely blue — Blue Jay. 



Turning now to the full description of this species, and noting the 

 measurements of total length, wing, tail and bill, it is easy to confirm 

 the identification. Incidentally it may be noted that in spite of the 

 fact that the Blue Jay is conspicuously blue, the question of color is en- 

 countered but twice in the passage through the keys, once in the key to the 

 families ("tail not tipped with yellow"), and again at the end of the key 

 to species, where "plumage largely blue" is the final characteristic which 

 marks the Blue Jay, although even here it is a secondary consideration since 

 the " conspicuous crest " is of first importance. Of course it would be possible 

 to make an artificial key using color as the most important feature, which 

 would lead us more directly to the'^Blue Jay, but it would be a very diflficult 

 matter to make such a key equally good for the many other species which 



