BIRDS OF THE PAST WETMORB 379 



That this destruction is the usual course when birds die will be 

 attested by field naturalists when they reflect upon the hundreds and 

 thousands of living birds that are seen and the relatively small num- 

 ber of instances in which remains of dead birds are encountered. 

 Armies of predatory or scavenger creatures, many of them unnoticed 

 by the average individual, destroy the carcasses immediately upon 

 death. 



The bones that in past ages througli) fortuitous chance have 

 escaped this destruction are frequently of little moment to the 

 paleontologist. Bones of the toes, ends of the ulna, broken bits of 

 the coracoid, or fragments and slivers from the shafts of long bones, 

 all of which are common as fossils, ordinarily offer no distinctive 

 characters, and, in the main, should be disregarded by the careful 

 student. Unfortunately through the enthusiasm of early workers 

 in the science these have served frequently as the basis of descrip- 

 tion for names that are now stumbling blocks in modern i^aleonto- 

 logical studies. 



In work in the field I have been interested in observing the skeletal 

 remains of birds, and have found that chance to-day seems to favor 

 the preservation of exactly the same type of fragments as those found 

 among Tertiary fossils. The body of a duck or a heron is eaten by 

 some coyote or vulture which tears out the breast and the viscera, 

 destroying part of the sternum, breaks the skull to obtain the brain, 

 and mangles the wings and thighs. The remaining portions dry 

 somewhat, and the flesh is removed either fresh or dried by the work 

 of insects. The broken skeleton that remains is light, and unless 

 anchored by vegetation, blows about with the wind or is swept by 

 running water. Bit by bit it falls apart and is scattered over the 

 space of several square feet. Occasional bones are buried, usually 

 in such a way that they may be subject to decay, or, less often, where 

 they may be preserved. Even where vertebrate scavengers are not 

 active, delicate portions and many of the more sturdy bones 

 disappear. 



Imperfect preservation is common where predatory enemies are 

 absent. On the islets in the Hawaiian Bird Reservation thousands 

 upon thousands of birds of moderate size live without interference 

 from the usual enemies that prey upon birds in continental areas. It 

 might be expected that here complete skeletons would be preserved 

 in large quantity since there is the usual regular mortality among the 

 assemblage. I found, however, that even here the carcasses disin- 

 tegrated, while the thinner parts of skulls, sterna, and pelves, under 

 the combined effect of sun, rain, and wind-blown sand, were corroded 

 away, and the firmer bones were scattered by violent gales. On 

 Laysan Island many found a resting place in the concentrated salme 

 waters of a shallow, central lagoon, and here on investigation I found 



