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PACIFIC SCIENCE, Vol. XXI, July 1967 
by Smith and Grant (1961), undoubtedly in- 
troduced by this method of egg transport. Today 
the species is found throughout the islands, 
from remote forests to the downtown areas of 
the largest cities. It is the most frequently ob- 
served lizard and is well represented in collec- 
tions because of its gregarious habits, little fear 
of humans, and population concentration in 
areas inhabited by people. This common gecko 
apparently has adapted itself with great success 
to living in close association with humans. It is 
a common observation that these geckos occur 
in greater numbers in well populated areas than 
in more remote sections. Of a series of 21 indi- 
viduals collected in a transect from an uninhab- 
ited area into a city, 10 were collected in a pop- 
ulous section, 5 from the fringe area, and 6 
from the uninhabited area. In making this tran- 
sect an attempt was made to maintain a con- 
stant unit of effort in each of the three habitats 
during the collections. The great number of 
numerous species of nocturnal insects attracted 
by the electric lights of the city probably is re- 
sponsible, in large part, for the large gecko 
population in the city. This does not explain, 
however, the abundance of geckos in or near 
man-made structures that were remote from any 
lighted areas. In nonurban areas, they are defi- 
nitely associated with open forests rather than 
with densely forested areas. 
Observations of several individuals indicate 
that L. lugubris is rather sedentary and that the 
home range usually does not exceed an area of 
6 or 8 ft in diameter. However, these lizards 
periodically migrate from one area to another. 
These movements are not a coordinated group 
effort, but appear to be a simultaneous evacua- 
tion of the normal home ranges of many indi- 
viduals. During these periods, individual geckos 
have been seen moving across walls, down tree 
trunks, over sidewalks, etc. Such periods of ex- 
cessive activity have not been correlated with 
season, rainfall, temperature, or other factors. 
L. lugubris is active from shortly before dark 
until sunrise. Although highly gregarious, they 
show some aggression toward each other. A 
chirping noise is utilized in social behavior and 
a squeaking occurs during painful or aggressive 
encounters. Tail-waving has been observed in 
social interactions. The females are slightly 
larger than the males. The mean snout-vent 
length of 26 females was 41.69 mm, ranging 
from 33.0 to 46.7 mm. The mean snout-vent 
length of 7 males was 35.96 mm, ranging from 
32.2 to 42.4 mm. 
Tree Gecko (Hemiphyllodactylus typus typus) 
No significant changes have appeared in the 
density and distribution of this species since 
1943; it remains rather rare. Of 161 geckos 
collected in Kailua on Oahu, only 5 were of this 
species; 4 of them were collected on the sides 
of buildings in the city and 1 from under the 
bark on a tree. They are extremely agile and 
wary lizards and it is much easier to collect 
them from the sides of buildings than from 
tree trunks. Hence we do not believe that our 
larger collection from the city buildings neces- 
sarily implies a larger population there. 
H. typus typus is not a gregarious species; 
only 1 individual was collected from a well- 
lighted building which supported over 80 other 
geckos. On a darkened building about 30 ft 
away, 2 other individuals were collected about 
10 ft apart. The only lizard found in close 
association with the tree gecko was the house 
gecko. 
House Gecko (Hemidactylus frenatus) 
This species is the latest addition to the her- 
petofauna of the Hawaiian Islands (Hunsaker, 
1966). It was first observed in June 1951 in 
the city of Kailua, about 20 miles north of 
Honolulu. It is well established at the present 
time and appears to be rapidly replacing both 
Hemidactylus garnoti and Lepidodactylus lugu- 
bris in the cities on Oahu. H. frenatus can be 
identified easily by the series of enlarged scales 
which encircle the tail, exhibiting concentric 
circles of short spines (Fig. 1). These circles 
are separated by normal scales. This species has 
a cylindrical tail and lacks the lateral folds and | 
loose femoral skin of H. garnoti. H. frenatus is 
very similar to the fox gecko in size and color, 
but it is much more aggressive. Not uncom- 
monly it attempted to bite the collector. 
Mixed colonies of H. garnoti and H. frenatus 
are rare. Apparently the new immigrant is much 
more successful a competitor than are the other 
species of geckos. This factor, and its greater 
aggressiveness, apparently are responsible for its 
rapid replacement of the fox gecko in urban 
