266 HxjxLEY, Bird-watching and Biological Science. [j^Jjy 



but the male is often distinguished by a very small patch of red 

 on the head. To correlate this with courtship-habits would in 

 itself be interesting; and still more so would be to compare the 

 courtship of the average Woodpecker with that of the Red-Headed 

 Woodpecker, where both sexes are in the first place similar, and in 

 the second place brilliantly colored. 



(5) Various similar interesting comparisons within groups can 

 be made. E. g. between the Robin and the various Thrushes; or 

 between the sexually dimorphic Ducks and the sexually similar 

 Geese and Swans. 



(6) The whole family of Grebes (Podicipidse) is one in which 

 very interesting results will be forthcoming. There is every variety 

 in the degree of ornament while the sexes are on the whole very simi- 

 lar. For instance, in the Dabchick and the Pied-billed Grebe there 

 is very little ornament, and in the Dabchick at least the mutual 

 displays are largely vocal. In the Great Crested Grebe and the 

 Horned Grebe there is a great deal of ornament accompanied, in 

 the former species at least, by elaborate mutual ceremonies. 



(7) In most sea-birds mutual courtship seems to be the rule. 

 From my own unpublished observations it seems to be at its most 

 primitive and unspecialized among the Gulls. 



Selous ('05) has some interesting notes on Guillemots, Fulmars 

 and Kittiwakes. 



The Puffin (Fratercula ardica) in which during the breeding- 

 season the bill in both sexes enlarges enormously and becomes 

 brilliantly colored, will undoubtedly furnish interesting data; I 

 recommend it to all those who love the grotesque. 



(8) Finally, the Heron family is extremely interesting. In it the 

 sexes always resemble each other; but while the Bitterns are on the 

 whole sober and unornamented, we get crests and breast-plumes in 

 such forms as the Louisiana and the Great Blue Heron, and most 

 elaborate and often exquisite ornaments in species like the Reddish 

 Egret, the Snowy Heron, and the ill-starred American Egret. I 

 have absolutely no doubt in prophesying that these latter birds will 

 show most elaborate and beautiful mutual dances and displays.^ 



1 Since the above was written, I have had the opportunity to study the courtship of the 

 Snowy Egret and Louisiana Heron on Mr. Mcllhenny's remarkable Heron-pond in Louisi- 

 ana. The results, though shortly to be published in extenso, are worth brief mention here. 



