278 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
further damage. The flickers (Colaptes), members of the woodpecker 
family, have found a less laborious method of obtaining a considerable 
portion of their food—they have learned to eat ants on the ground 
and have taken to feeding extensively on these and other insects in 
addition to what they get from the trees. The California wood- 
pecker (Balanosphyra formicivora baird2) and its relatives feed to some 
extent on acorns, which are very plentiful in many portions of their 
range, and they have adopted the practice of making holes in the 
bark of trees or in posts in which they place acorns for future use. 
Sometimes a trunk or limb of a tree or post will be studded ‘with 
hundreds of acorns, each in its own separate setting which holds it 
securely with the end of the nut projecting slightly from the hole. 
The night hawks (Chordeiles), whippoorwills (Antrostomus), swifts 
(Chaetura), swallows (Hirundo) and their relatives capture practically 
all their food in their very wide capacious mouths while flying. Some 
birds such as the tyrant flycatchers (Tyrannidae) and a few others 
have the habit of sitting on a perch that gives a good view of sur- 
rounding territory and watching for insects. As these come within 
range, they are captured in the air in a short flight by the bird, which 
then returns to its perch to watch for more. The hummingbirds 
(Trochilidae), as is well known, have a very long beak and tongue 
which they extend into flowers to feed on the nectar and insects that 
they find there. Other small birds known as honey creepers (Co- 
erebidae and Melithreptidae) have a long, sickle-shaped beak which 
they use in obtaining insects, nectar, and fruit pulp and juices. 
Feeding habits among the mammals also vary widely. The langur 
and colobus monkeys (Presbytis and Colobus) feed mainly on the 
leaves of certain trees. Many of the bats, particularly the small ones 
(Microchiroptera), feed almost exclusively on insects that they cap- 
ture in flight. Some forms are carnivorous, killing other bats and 
small birds and perhaps small mammals. Vampire and false vampire 
bats (Desmodus and Diaemus) lap blood that they obtain from warm- 
blooded animals by cutting off a very thin layer of the skin with their 
razorlike incisor teeth. Other very large bats with a wingspread of 
as much as 4 feet, which inhabit the Tropics, are known as fruit bats 
(Pteropus and related genera) because they feed largely on fruit. 
These bats frequently travel in considerable flocks and move to 
various regions from time to time to find food. 
Most rodents eat mainly plant food such as seeds or nuts, leaves, 
stems, or roots of plants; many, however, also eat some insects and 
small amounts of meat. A few have developed highly specialized 
feeding habits together with specialized teeth and shape of jaws. 
These include the fish-eating rat of South America (Icthyomys) and 
an insectivorous type (Rhynchomys) from Luzon Island in the Philip- 
pines. Nothing has been recorded regarding the habits of this animal, 
