NO. 7 PROTECTIVE ADAPTATIONS McATEE 79 



rhopala vittata taken by a starling ; 47 Donacia by a red-winged black- 

 bird; 50 of Systena sp. by a Baird's sparrow; 50 of Disonycha 

 caroUniana by a horned lark ; 58 of Myochvous dcnticollis by a house 

 wren; 212 Donacia siibtills by a Franklin's gull; 250 Colaspls 

 hrunnca by a nighthawk ; and about 300 Epitrix ciicinncris by each of 

 five individual tree swallows. 



Bruchidae spend so much of their lives within seeds that they are 

 little exposed to attack by birds ; an advantage which probably is 

 compensated for by their being devoured with the seeds by some birds 

 and other seed-eating animals. However, this is a sul)ject that has 

 scarcely been investigated. Our 47 records represent nine or more 

 species of bruchids and were distributed among 29 species of birds. 

 Expectations based on availability of free bruchids probably are 

 satisfied. 



The great series or subnrder of beetles known as the weevils or 

 Rhynchophora, for the most part, are said to be cryptically colored, 

 resembling seeds, luids, bark, bits of earth, bird droppings, etc. 

 Wallace adds : " One of the characters by which some beetles are 

 protected is excessive hardness of the elytra and integuments. Several 

 genera of weevils (Curcvilionidae) are thus saved from attack and 

 these are often mimicked by species of softer and more eatable 

 groups." (Darwinism, p. 260, 1896.) However, it should be pointed 

 out at once that those who predicate hardness as a defense against 

 predators do so without due reflection upon the digestive powers of 

 animals. 



Recall the fragmentation and gulping down of bones by dogs; the 

 swallowing of snails, shells and all, by squirrels ; while reptiles, am- 

 phibians, birds of prey, and predatory mammals either swallow their 

 vertebrate prey whole or in large pieces, the bones included ; waterfowl 

 and shorebirds habitually take shellfish entire, including such hard- 

 shelled forms as clams and oysters ; gallinaceous birds are provided 

 with gizzards which grind up the hardest seeds ; and finches and 

 numerous other birds are just as effectively equipped if on a smaller 

 scale. Not only do birds with gizzards grind up their food materials, 

 but the grit and pebbles they swallow are in most cases gradually 

 ground down and pass out through the intestines in the form of fine 

 sand. Most predators, in fact, have either a powerful mechanical or 

 a resistless chemical digestion that as a rule is fully competent to dis- 

 pose of anything entrusted to it. With such digestive powers at tlie 

 service of predators, it is extremely unlikely that hardness in the 

 degree possessed by weevils is any bar to their being eaten ; moreover 

 being jointed, weevils are thoroughlv susceptible to chemical digestion. 

 6 



