Guatemala Forest; Birds of the Tropical 



Central American Lowlands 



A small segment from the upper tree-level of a great tropical forest is reproduced in 

 this exhibit. The locale is in the lowlands of eastern Guatemala, near Puerto Barrios, 

 an area supporting a rain forest characteristic of humid lowlands from southern 

 Mexico southward to the grasslands of South America. A fruit-bearing tree serves as 

 the focal point for the gathering of several species with similar food habits. Other birds 

 commonly found among the upper branches of great forest trees are also present. 



Two kinds of toucans, the short-keeled and the collared aracari, are shown in com- 

 petition for the mutual source of food. A bishop grosbeak, also a fruit-eater, is in the 

 center foreground. 



Toucans are among the most prominent and characteristic birds of the American 

 tropics. Some toucans bear a striking resemblance to some of the smaller hornbills of 

 the Old World. They are, however, more closely related to the woodpeckers than to 

 the hornbills, and occur only in the warmer parts of the western hemisphere. Perhaps 

 the most prominent physical characteristic of the toucan is its enormous bill. In many 

 forms the bill is highly colored and has the appearance of great weight. It is, on the 

 contrary, extremely light, the outer portions being very thin and filled with cellular 

 bony tissue. The tongue of a toucan is also a remarkable structure, consisting of a flat, 

 narrow plate with a series of notches along the margins. 



All toucans are forest birds and, within their range, one species or another is usually 

 found in abundance from sea level upward to an altitude of 7,000-8,000 feet in the 

 mountains. They are primarily frugivorous and, except when breeding, generally as- 

 sociate in noisy flocks that roam the forests in search of food. Berry- and fruit-bearing 

 trees invariably attract large numbers. It is not unusual to find the upper branches 

 alive with these grotesque birds. Toucans become more furtive during the breeding 

 season and the large flocks disband. From one to three eggs, usually white and some- 

 what glossy, are deposited in hollow trees. 



Scarcely less characteristic of tropical America are woodhewers, one species of 

 which can be seen ascending the bole of a tree in the left foreground. Like toucans, 

 these birds are endemic to the western hemisphere and have their center of abundance 

 in the Amazon basin. All woodhewers are relatively drab in color, and primarily 

 arboreal. The specialized feeding habits of some species have led to remarkable modi- 

 fications of the bill, which may vary from a short, sturdy structure to a slender sickle- 

 like organ. The tail, too, has become modified to serve as a support while feeding, as 

 with the woodpeckers, although otherwise the families are fundamentally distinct. 



EXPLANATION OF CHART (p. 79) ILLUSTRATING EXHIBIT OF 

 BIRDS OF GUATEMALA FOREST 



1 . Short-keeled toucan (Ramphaslos piscivorus) 4. Western barred woodhewer 



2. Collared aracari (Pteroglossus torqualus) (Dendrocolaptes certhia) 



3. Chestnut-collared woodpecker 5. Wood thrush {Hylockhla mustelina) 



{Celeus casianeus) 6, Bishop grosbeak {Caryoihraustes poliogasier) 



[781 



