4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



to meet the requirements of the selection theories. We further can 

 not admit what the experimenters imply, namely, that the analyses 

 of the stomach contents of birds fail to reveal the approximate num- 

 bers present of certain insects (such as butterflies) which they believe 

 are eaten to a considerable extent. This point will be discussed later. 

 So much for what has happened between the previous paper and 

 the present, which as stated, will be devoted chiefly to an exposition 

 of the animal food of nearctic birds, with special reference to the 

 so-called protective adaptations. 



PROTECTIVE ADAPTATIONS 



The characteristics of animals that are usually classed as protective 

 adaptations include resemblance to generalities or details of the en- 

 vironment, whether through color or other modification of the animal 

 itself or utilization by it of materials from the environment for 

 concealment, the possession of protective bristles, spines, hard in- 

 teguments, stings, poisonous bites, and the like, and nauseous or 

 irritating odors or tastes. There are animals with actually poisonous 

 properties among many of the phyla including species with poison 

 glands and special organs for using the poison in offense or defense, 

 among Coelenterata, Echinodermata, Arachnida, Insecta, and Pisces ; 

 others with poison glands connected with the mouth organs among 

 worms, spiders, other arachnids, mites, myriapods, chilopods, insects, 

 fishes, and reptiles ; animals with unarmed poison glands among 

 coelenterates, echinoderms, myriapods, insects, moUusks, amphibians ; 

 and others poisonous in a variety of ways so that practically all phyla 

 are represented. The colors of the animals possessing dangerous 

 qualities in many cases are said to be warning in nature, and the 

 colors of animals which resemble them but lack the disagreeable 

 qualities are termed mimetic. The subject of protective adaptations 

 has very largely become one of coloration especially as associated with 

 the qualities of animals from the supposed point of view of possible 

 predators. 



A statement of the various classes of color adaptations is here 

 quoted from Prof. E. B. Poulton, the leading advocate of the view 

 that these adaptations are really protectiA^e and that they have been 

 developed by natural selection. 



Protective arid Aggressive Reseiiiblaiicc. — By far the most widespread use 

 of colour is to assist an animal in escaping from its enemies or in capturing its 

 prey; the former is Protective, the latter Aggressive. It is probable that these 

 were the first uses to which non-significant colours were put. The resemblances 

 are of various kinds ; the commonest cases are tliose of simple concealment. 

 The animal passes undetected by resembling some common object which is of 



