PATTERNS OF COLOBATION. 613 



[E.] ON THE RELATION BETWEEN LATITUDE AND THE 

 PATTERN OF COLORATION IN OHIO BIRDS*. 



At the last meeting of the Society I expressed an opinion somewhat adverse to the 

 universal application of the laws of latitudinal variation among birds, at least to their 

 availability for the purpose of determining whether certain forms should be considered 

 species or varieties +. 



At the same meeting I expressed myself as doubtful of the correctness of the opinion 

 there advanced that white wing-bars and white tips to tail feathers should be considered 

 as simply ornamental. A few words will give my reason for dissenting from sueh a view. 

 Without attempting to show that tail spots or wing-bars are not peculiar to that sex 

 which is most highly ornamented among birds, let us first examine into the structural 

 relation of the feathers bearing these marks to the marks themselves. In the case of 

 white tail tips, I am of the opinion that the presence or absence of these spots has 

 largely to do with the form of the tail, of which there are two strongly marked types, 

 forked, and rounded. In the former th» lateral feathers are the longest, in the latter the 

 central. Among all our Ohio birds, I find none with forked tails and white tips to 

 the tail feathers, all white tail tips being combined with more or leasronnded tails. The 

 King-bird has a white tipped tail all the tips being nearly equal, while the tail as a 

 whole is nearly square. In other birds with a rounded tail and white tips the white in- 

 creases in the same or in an increasing proportion to the shortening of the lateral 

 feathers. I do not wish it to be understood that all birds with rounded tails have white- 

 tips for this is not the case, bat that there is a definite correllation between these 

 characters is evident. In the Hummingbird, the male has a forked tail of uniform color, 

 while the female has a rounded tail with white tips. 



In tail feathers then we find white tips associated with the feathers of less develop- 

 ment as to length, and I might add that in many birds the white of the tip extends 

 towards the base of the outer feathers along the outer, that is to say the shorter, web of 

 the feather. 



Id the case of wing-bars the same relation may be seen, though perhaps there are 

 more exceptions to the rule than in the case of tail-tips. Wing-bars, that is white tips 

 to the greater or lesser row of wing-coverts are in their greatest perfection in Pasaeres, 

 in which order, the coverts are not more than half as long as the secondary qnills, while 

 in all other orders, with few exceptions (e. g. Pioides), the wing-coverts are more than 

 half the secondaries. I find a single reasen, and this a negative one, to suppose that 

 wing-bars may be simply ornamental, as follows ; Most birds in the Order Passeres 

 which have wing-bars nest in trees, while in many instances the lack of wing- bars is 

 associated with the habit of ground nesting. The relations between this habit aad 

 the presence or absence of this color-mark are well seen in family Sylvioolidse, where, 

 with the exception of one or two species of Helminthophaga, all the ground nesting 



* Bead before the Columbus Society of Natural History, Aug. 29, 1874. 



+ The laws of latitudinal variation have been given on page 194-196 of this report and 

 need not be again presented here. 



