PREFACE 



Oknituoloov is the sciencci of birds (dr., opi't6'os, ornilhos^ of :i bird ; Aoyos, logos^ 

 :i discourse), tiiid to become an expert ornithologist re(|uires yeai'S of hard work, com- 

 bined with a love for the study itself; but there are many students of nature who 

 would like to know the l)irds about them, but do not have the time nor desire to go 

 deeply into the subject. To meet such a want, the present "keys" have been {pre- 

 pared, in which the species are grouped according to size, and it is believed they will 

 enable the novice to accurately identify any of our birds. 



Careful comparison of large series of birds has shown that while ndult birds of 

 the same species differ considera])ly in length, tiie wing ineasure is very constant, the 

 variation in a large number of si)ecimens being so small that, allowing for possible 

 extremes, we may safely arrange our birds in groups according to length of wing. 

 A Song Sparrow may vary slightly in size, but the largest Song Sparrow is never as 

 large as the smallest adult Robin, and vice versa. By grouping the various birds from 

 the Humming IJird to tiie Eagle and All):itross, according to the lengtli of wing (allow- 

 ing, of course, for unusual extremes), the identification of any species then becomes a 

 comparatively simple matter, as usually the birds contained in each group are so few 

 in numljer that characteristic differences in each species are easily indicated. 



Let us. for example, assume we have a l)ird before us wliich we wish to identify; 

 we first should lind out to which fuuiily it belongs, 'rurning to the Key to Families, 

 page 10, we tiud this an easy matter (as the families are few and the illustrated ditTer- 

 cnees iu the bills and feet very characteristic), we discover our bird to be a duck. 

 Having ascertained the family to which our bird belongs, we turn to the Key to 

 Species. We have, of course, measured the wing and found il to I>e r).;U) inches long, 

 measured from tiie cari)us (bend of wing) to tip. (See illustiiitiou, •' How to Meiisure 

 a Bird," on p:ige s.) 



We now turn to the Ducks, ami discover they are divided into siilifiimilies, tiie 

 \\\i\ :ind Sea Ducks liMviug :i tl:ip oi- lohe on thi' hind toe, ;inil the fresh-water ducks, 

 or River ;ind I'ond I)u<'ks, have no large ll:ip on tiie iiiiid tot'. Our liird has a Map on 

 its iiind toe, and is evidently a salt-water duck, l»elonging to tin' sulifamily Fiiligu/inir. 

 This subfamily, we find, contains two sections. Section 1 having the tail feathers 



Ciii) 



