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separates a cane field from a waste grassland. 
Throughout the area from which rodents were 
trapped, large Java plum trees ( Eugenia cu- 
mini) and kukui trees ( Aleurites moluccana ) 
form a forest- like overstory. In the understory 
there are ti plants ( Taetsia fruticosa ), coffee 
shrubs ( Coffea sp.), and a restricted variety of 
other species. The floor of this gulch is formed 
of large exposed boulders and is subject to 
occasional, torrential runoff. 
Thick stands of false ironwood ( Casuarina 
sp.) predominate in the gulch near Waipio 
Valley. Scattered growths of kukui and guava 
( Psidium guajava) trees, and of ti, as well as 
patches of palm grass ( Setaria palmifolia ) and 
panicum grasses ( Panicum purpurascens, P. 
maximum) are found along the slopes. The 
floor of this short gulch is not eroded and is 
densely matted with honohono {Commelina 
mtdiflora) , panicum, and palm grasses. 
Areas of Human Habitation 
In residential areas, consisting mainly of rural 
villages, traps were placed in or about houses, 
storage sheds, garages, stone fences, hedges, 
orchards, pig and cattle pens, and chicken 
coops. 
METHODS AND PROCEDURES 
The stomachs of rodents caught by snap-traps 
were removed in the laboratory and preserved 
in 70% isopropyl alcohol. Contents were 
weighed to the nearest O.lg on a triple beam 
balance, and then sorted and spread evenly in 
a petri dish. A grid of 1 cm 2 units, drawn on 
a card, was placed beneath the dish to aid in 
estimating the percentages of different items 
found in the stomach. Weights and percentages 
of these items were the only quantitative mea- 
surements taken. 
Examination of the food materials was made 
with the aid of a dissecting microscope. Items 
not easily distinguished were placed on a piece 
of cheesecloth and washed with a jet of water. 
Hulls of certain grass seeds and stalks were 
washed and dried to make identification possi- 
ble. Identifications were frequently made by 
direct comparison with sample items gathered 
from the various trapping areas. (A check list of 
botanical names of plants used by rodents as 
food will be found at the end of this article.) 
PACIFIC SCIENCE, Vol. XX, July 1966 
Because coconut was used as bait in snap- 
traps, stomachs of rodents which had fed ex- 
clusively on coconut were not included in the 
tabulations. Rodents caught in a 3. 5 -acre tract 
of waste grassland adjacent to a sugar cane field 
were treated as being caught in the cane field, 
because stomach examinations showed contents 
similar to rats caught in cane fields and also 
because of the small sample size of rats captured 
in the grassland. 
Trapping was conducted once a month for a 
four-day period from July 1963 to June 1964. 
RESULTS 
Cane Fields (see Table 1) 
Rattus norvegicus: Only one specimen was 
obtained from the cane fields; insect fragments 
were the only dietary item. This animal was not 
included in Table 1. 
Rattus exulans: The principal food of cane 
field R. exulans was sugar cane, which occurred 
in 68.2% of the rats and amounted to 67.2% 
of the food materials. Foods of secondary im- 
portance were seeds and stalks of grasses, found 
in 21.3% of the animals and constituting 
15.1% of the volume. Insects, including adults, 
larvae, and egg masses, contributed 6.0% to 
the food materials. 
In most cases, identification of these insects 
was possible only as ground-inhabiting Coleop- 
tera or Orthoptera because the hard chitinous 
exoskeleton was masticated into fine fragments 
beyond exact recognition. However, the larvae 
of craneflies (Tipulidae) and small moths 
(Tineidae), and the adults of the sugar cane 
mealy bug ( Saccharicoccus sacchari) and of the 
sugar cane weevil ( Rhabdoscelus obscurus), 
and the eggs of the mealy bug were identified 
below the ordinal level. Larvae and egg masses 
were often found mixed with other food items, 
but no relationship between these insects and 
any particular food item was found. 
The pulp and seeds of guava fruits were 
utilized by 4.8% of the animals and formed 
3.5% of the volume. Other food materials in- 
cluded kukui nuts, animal flesh, earthworms, 
slugs, and materials which could not be identi- 
fied. These items amounted to 8.1% of the 
volume. 
