34 Iowa Ornitholoc4ist. 



Poplar), all nests which I have exauiined having one or more green sprigs. 

 These sprigs must be renewed almos* daily as they almost always appear fresh, 

 withered or dead leaves being rarely found in the nest. This eccentricity seems 

 also to be shared by the Swainson's Hawk ( Biiteo suHiiiisoiii ). 



THE AFFINITIES OF THE MNIOTILTID/E. 



BY MORTON E, PECK. 



Paper read before the Second Congres.s of I. O. A. 



TO arrive at even an approximately correct conclusion as to all the relation- 

 ship, near and remote, of any group of vertebrates, there is needed, not 

 only a thorough examination of the life history and external ordinal family, 

 generic and specific characters of every genetically related family, but also a 

 careful anatomical survey of these families. The most important data for .such 

 conclusions are obtained from those aberrant or generalized types which unite 

 some important features of two or more divergent groups. These so-called con- 

 nective types are such as have preserved, in a more or less modified condition, 

 some important structural points derived from remote ancestors less highly 

 specialized than their living decendents. Among mammals .such forms are the 

 Lemurs of Africa and the curious Mouse Deer of Borneo. Among birds the 

 Secretary Birds of Africa and the anomalous Hoazin of South America come 

 under this catagory. 



As we proceed to the more specialized forms, the affinities become more in- 

 tricate and puzzling within a limited sphere. With the generalized types, the 

 case is different. They are usually found to connect two or three very widely 

 seperated groups, but with no other evident connections. For example, the 

 Secretary Bird is between the raptorial and wading birds, being placed 

 doubtfully with the former. Beyond these two families it seems to possess no 

 near relationships. 



As we are to deal with one of the most higlily specialized families of birds, 

 and therefore one presenting the most numerous affinities and in the most 

 varying degrees, it is unnecessary to say that no full treatment of the subject 

 will be attempted ; anatomical points will not be touched upon, and only the 

 more salient external features briefly reviewed. 



The Mniotiltidie, or American Wood Warblers, are a well-defined family of 

 small passerine birds, divided usually into eighteen genera, which comprise 

 about one hundred and twenty species, though the exact number is not yet 

 fully determined. Most of the species are elegantly formed and highly colored, 

 graceful and active in movement, but rather weak in structure. The individ- 

 uals are usually abundant, but a number of species are extremely rare. 

 Geogi-aphically they are principally confined to North America, with but few 

 distinctive South American forms. The most typical genera are those 

 migrating a(-ross the United States. 



