Vol. 5, pp. 96-102

Asiatic Herpetological Research

December 1993

Notes on a Collection of Squamate Reptiles from Eastern Mindanao,
Philippine Islands Part 2: Serpentes

Brian E. Smith
Museum of Natural History. Louisiana State University, Baton Rouge. Louisiana 70803-3216.

Present Address:

Department of Biology. University of Texas at Arlington. Uta Box 19498, Arlington. Texas 76019-0498

Abstract. -A systematic collection of the herpetofauna occurring in the Diuata Range of eastern
Mindanao, Philippine Islands, with incidental collections from the Mount Apo Range, was made from
April-September 1982. This paper completes taxonomic and ecological notes that were taken on thesquamates of this region. Although conclusions about the effect of habitat alteration on snake populations
are necessarily tentative due to sampling difficulties, some comments on apparent and potential shifts inpopulation size and habitat use of the more common snake species are made.

Key words:

Reptilia, Squamata, Serpentes, Philippines, taxonomy, ecology

Introduction
Except for reviews by Taylor (1922) and
Leviton (1959) and biogeographic works
by Brown and Alcala (1970), Leviton(1963a, 1970) and Wiister and Thorpe(1989, 1990, 1991a), very little is known
about the ecology and distribution ofPhilippine snakes. This paper describes
ecological and distributional data taken on
the snakes of an area in eastern Mindanao,
Philippine Islands, that I visited from AprilSeptember 1982. An earlier paper on the
lizards of this area describes the sites andmethodologies I used during this study.
Scalation data taken on snakes included

prasina favors open areas, as does Mabuya.
A female was taken on April 6 on a road inearly second-growth habitat near site 1.
inFive oviducal eggs (22.8-31.1
in
were
found
this
length)specimen.

mm

Specimens examined:
41805.

LSUMZ 41804-—

Boiga cynodon. This snake is arboreal
by morphology, but two specimens were
captured in drift fences and one found deadon a road at site 1 They were all collected
or killed at night, and were found in both
early second-growth and primary forest
habitats. Prior studies give no elevational.

dorsal scale rows at ten ventral scutes

information (Alcala, 1986; Leviton, 1968a;

posterior to the head, mid-body, and ten
ventral scutes anterior to the anal plate;ventral scute counts; and subcaudal scaleThis data is given only when it
adds to data previously published.

Smith, 1943; Taylor, 1922); the present
specimens were found at 450-650 m. This
species is aggressive and has very large
palatine teeth which are quite effective in
defense. Taylor (1922) stated that thisSpecies Accounts

species is rare in the Philippines, but it was
the most commonly captured Boiga species

counts.

at

Family Colubridae—

Ahaetulla prasina preocularis. Two
specimens were taken, one lacking specificdata that was probably collected at or above

m given
This species has a

the upper elevational limit of 800

by Leviton (1967).

morphology typical of arboreal snakes, but
is frequently taken on the ground, where it
may descend to forage on Mabuya skinks(Leviton 1967). If Mabuya is a favored
food item, then it is highly likely that A.
1993 by Asiatic Herpetological Research

As Leviton (1968a)
cynodon has an arboreal

my study sites.

noted,

B.

morphology and diet (birds and bird eggs),
but all specimens were captured on the
ground.

Specimens examined:
41816.

LSUMZ 41814-—

This
Boiga dendrophila latifasciata.
at
was
taken
on
a
road
specimennight atabout 500 m elevation in early secondgrowth forest.

Previous reports indicate

Asiatic Herpetological Research

December 1993

that this species is acommon inhabitant oflowland swampy areas (Taylor, 1922;
1965; Tweedie, 1983), but the present
specimen was found in hilly country far
from such habitat. The stomach of thisVol. 5 p. 97

taken in grassland in an extremely large ca.
100 square km) clear-cut area. This species
is arboreal in its morphology, but these data
indicate common use of the terrestrial
microhabitat.

specimen contained bird feathers. Previous
studies found this species to also eat batsand lizards (Alcala, 1986; Leviton, 1968a;

Specimens examined:
41800.

Taylor, 1922).

—

Specimen examined:

LSUMZ 41812.

—

Calamaria gervaisi. This burrowing
species was common in primary forest, but
was rarely found in early second-growthforest. One specimen was collected 20 cm
underground when digging a pit-can hole.
Four adults were taken in a single pit-can
during four days in April. The significanceof this aggregration is unknown. A female
collected April 10 contained one egg 3.4

mm in length.

LSUMZ 41798-

Segmented worms were

found in the stomachs of two specimens.

Specimens examined:
41778.

LSUMZ 41769-

Dryphiops philippina. This specimen
was collected by a native near Mount
Talomo and is the first specimen of thisspecies collected on Mindanao. The ventral
scute count of this specimen is 172,
increasing the known variation of 177-188
Previous
reported by Leviton (1964a).
specimens were taken near sea level(Leviton, 1964a), but this specimen may
have been collected as high as ca. 1000 m.
This species was previously known only
from Luzon, Negros, and Sibuyan (Leviton
1964a). Subsequent investigations should
discover it on other large islands in thePhilippine archipelago.

Specimen examined:—

LSUMZ 41790.

—

One
Cyclocorus nuchalis taylori:.
in
was
found
in
leaf
litterthespecimen

This
Elaphe erythrura erythrura.
isacommonspeciesground-dwelling

primary forest, the other was caught in afence in early second-growth forest.
One specimen had eaten a juvenile Mabuya
Leviton (1965) foundmulticarinata.
specimens of the skink genera Mabuya andSphenomorphus in stomachs of the C.
nuchalis he examined.

diurnal inhabitant of all forest situations.

drift

Specimens examined:
41797.

LSUMZ 41796-—

Dendrelaphis caudolineatus terrificus.
Leviton (1968b) gave an elevational rangeof 0-35 m for this species, but I collected
specimens of this snake from 100-1000 m.
Also, I did not note any particularassociation with water, as did Alcala(1986). Although thought to be primarily
arboreal (Leviton, 1968b), all the
specimens I collected were taken on the
One specimen had eaten aground.
terrestrial skink,

Sphenomorphus coxi.

a typical, heavy-bodied, mammal-eating
constrictor that opportunistically takes other
prey.

It is

also a common food item of thePhilippine Eagle (Pithecophaga jefferyi)
and the Philippine Serpent-Eagle (Spilornis
Alcala (1986) reports anholospilus).
altitudinal range to 500 m, but I took
specimens up to 1065 m. I collected young
snakes August 1 and September 8 (twosnakes). These specimens measured 465,
383, and 409 SVL, respectively. The twolargest of this group were identified as
young males. Leviton (1977) stated thatyear-old young probably measure 400

mm

SVL.

A

specimen examined by Leviton (1968b)
also contained a terrestrial skink, Mabuya
species.

It

feeds on lizards, birds, and mammals(Alcala, 1986; Leviton, 1977; Taylor,
1922).
My specimens commonly had
mammals or mammal remains in theirstomachs, and I consider this species to be

One specimen that I collected wasSpecimens examined:
41811.

LSUMZ 41807-

Asiatic Herpetological ResearchVol. 5 p. 98—

December 1993

Oligodon maculatus. This is only thefifth known specimen of this species.
Taylor (1922) took two specimens beneath
sod and trash piles at Bunawan, Agusan, in
the Agusan Valley of Mindanao. A third

frogs and snakes are also taken (Greene,
1989; Leviton, 1983). Greene (1989) did
not report insects as a food item in thespecimen was taken in northern Surigao

Specimens examined:
41789.

Province (Taylor, 1925).

A fourth was

specimens he examined.

LSUMZ 41779-

collected on Mount Todaya in the Mount

Apo Range (Leviton, 1962). My specimen
was taken during daylight in the forest floor
litter on Mount Talomo, Mount Apo Range,
at about 1000 m elevation. Alcala (1986)
reports two specimens from 400 and 850 m
elevation, but gives no further information.
Including my data, an altitudinal range of

400-1000 m is indicated. This species isknown only from eastern Mindanao.

Leviton (1962) stated that this species has
17 dorsal scale rows throughout; myspecimen reduces to 15 in the posterior
third of the body. Leviton also noted thatthe loreal may be present or absent; in my
specimen it is absent. This specimen also
differs from the ones analyzed by Leviton
in having one instead of two preoculars.
My specimen also has fewer scutes thanspecies is aleaf-litter herpetofauna in all habitat types
I
did not find it to beinvestigated.
associated with water, as reported by Alcala(1986). These are small inoffensive snakes
which usually attempt to conceal
themselves rather than flee or bite when

captured. I collected gravid females June
17 (three eggs, 9.9-10.5
in length) and30 (one egg, 9.0 mm), and July 8 (threeeggs, 5.3-7.6 mm) and 23 (two eggs, 9.09.2 mm).
Juveniles 135-235
SVL
were collected April 7, 11, and 12, May 18mmmm

and 23, June 14, and July 8. The gradually
increasing SVL of these specimens indicatethat they could be the members of a single
cohort.
Leviton (1970) indicated two

LSUMZ 41806.

modestum. — T h efrog eggs, as also reported by Leviton(1970).

156-164. The specimen I collected is male.
The stomach was empty.

Specimen examined:

specimen taken was a gravid female witheight eggs measuring 18.9-26.1 mm inlength. This specimen was collected on aroad at about 400 m elevation in latesecond-growth forest. There is no further
data to add to that given by Leviton(1964b).

Specimens examined:
41768.
Stegonotus muelleri.

LSUMZ 41803.

Psammodynastes pulverulentus.
a

—This

common and aggressive rear-fanged

colubrid of the forest floor litter. It is
diurnal and was taken in all habitat types.
Juveniles 190 and 197
SVL weremmcollected May 3 and May 23 at site 1. I
found insects, a lizard tail, and a snake{Calamaria gervaisi) in the stomachs of thespecimens I examined. This species is
primarily

known as a lizard feeder, but

LSUMZ 41749-—This

is the eighth

known specimen of this species, and only
the second taken on Mindanao (Leviton
1959).

Specimen examined:

is

—This

common diurnal member of thehatching seasons in the Mount Apo Range,
during June- July and October-November.
My observations within the Diuata Range
indicate that the hatching season here could
occur as early as March, but data arescanty. Specimens had eaten frogs andthose examined by Leviton, increasing the

known variability in ventral scute counts to

Oxyrhabdium

Rhabdophis auriculata auriculata.

Virtually no ecological data areThis specimen was found deadon a logging road in early second-growthforest at about 590 m elevation. Leviton(1959) found three adult Rana limnocharisin the stomach of a large adult; the present
available.

The
specimen's stomach was empty.
I
collected
is
male.
Its
ventralspecimenscute count is higher than that given formales by Leviton (1959), thereby
increasing the range of this measurement to217-236.

Asiatic Herpetological Research

December 1993

Specimen examined:

LSUMZ 41 802.

found in primary forest, and residents told
me that they never saw individuals of thisdendrophiops—
were collected
Specimens
dendrophiops.
Tropidonophis

during the day in all habitats, but always
near swift-flowing streams. The altitudinalrange given by Alcala (1986) extends to700 m; one individual I collected was taken
at 900 m. Juveniles were collected April 18
SVL),SVL), May 21 (242
(161

mm

mm

and June 24 (308 mm SVL) at site 1.
These could be members of a single cohortborn in March or April. One specimen wascollected in a pit-can eating a frog. Taylor(1922) also reported frogs as common fooditems of this species. Alcala (1986) refers
to this species as Natrix

dendrophiops.
Malnate and Underwood (1988) haverecently assigned this species to the genus
Tropidonophis

LSUMZ 41791-

Specimens examined:
41795.

Vol. 5 p. 99

species in the forest.

It islikely that theconversion of much of the Philippines into
altered habitat has resulted in an increased
abundance of this highly venomous snake.
I saw or collected this species from sea

m1000
elevation.
Despite its
toxic
venom
(Minton 1967), thehighlylocal residents believed that this snake
brought luck, and individuals found underlevel toand around houses were invariably leftI
alive.
actively sought out reports ofenvenomation resulting from bites of N.
samarensis, but received no such reports,
and was told by locals that bites of thisspecies were seldom problematical. This is
in contrast to conclusions reached by Reyes

and Lamana (1955). This is a spitting
cobra, and there is at least one report of an
accurate strike in the eyes resulting in agreat deal of pain but no serious after-

Wallach,personalI
handled many
specimens, but never saw one exude any
Thisappreciable quantity of venom.

effects(Vancommunication).
Family Elapidae

Maticora intestinalis philippina.

—Onespecimen was taken in a pit-can at site 2 inlate second-growth forest at 400 m
elevation.

This snake is thought to be rarein the Philippines (Alcala, 1986; Taylor,

1922).

Leviton(1963b)gives

noecological information, and Taylor (1922)
describes an apparent anti-predator display
during which specimens exhibit aimlessthrashing motions, similar to displays
described for other New and Old World
coral snakes (Greene, 1973).
DespiteAlcala's (1986) statement that this species
is found in arboreal ferns as well as underrotten logs, I consider this species to be atypical semi-fossorial coral snake. Thisagrees with Taylor's (1922) observations.
There are no data on food habits of thisspecies;myspecimen's stomach was

empty.

Specimen examined:Najasamarensis.

diurnal species.

habitations

LSUMZ 41817.

— This

It is quite

and

early

is

an alert

common aroundisPhilippine

to eatSerpent-Eagle{Spilornis

holospilus) Two juveniles were taken withan adult male from a hole in the ground at

m

These
on Mount Talomo.
a
local
to
me
by
specimens were brought
1000

resident.

It

was not possible to ascertain

whether there was any significance to thisaggregation, but other cobras are known toguard both eggs and young (Campbell andQuinn, 1975; Tryon, 1979; Tweedie,
1983). Wiister and Thorpe (1991b) haverecently elevated Naja naja samarensis tofull species status, and I use this new
species designation in this paper.

second-growth

Contrary to Alcala (1986) andthis species was never(1922),
Taylorhabitats.

known

frogs, snakes
androdents(Gressitt,(Calamaria gervaisi),
1937; Leviton, 1964c; Taylor, 1922). A
specimen I examined contained a small
Bufo marinus (SVL 95mm), and Van
Wallach reports (personal communication)
only B. marinus in the stomachs of N.
samarensis he collected in rice paddies on
Mindanao near the city of Surigao. N.
samarensis itself is eaten by the Philippine
Eagle {Pirhecophagas jefferyi) and thespeciesSpecimens examined:
41824.

LSUMZ 41819-

Asiatic Herpetological ResearchVol. 5 p. 100

December 1993

Discussion

Acknowledgments

Unlike lizards, snakes are rarely taken insuch numbers that it is possible to gauge

This is a portion of a thesis submitted to
the graduate school of Louisiana Stateabundance

University in partial fulfillment of
requirements for the Master of Science
degree. I thank my major advisor. Dr. D.
A. Rossman, and my committee members,
Drs. J. V. Remsen, J. W. Fleeger, and W.

theirrelativein

any given

Therefore, ecological conclusions
based on studies such as this one are few
and tentative. Most of these conclusions
have already been reached in individual
species accounts.
habitat.

J.

Harmanthesis.

The pace of destruction of primary forest
in the Philippines has created a great deal of

second-growth habitats of various types.
At least one snake, Naja samarensis, hasprobably benefitted from this trend. Taylor(1922) observed this species in primary
forest, but neither I nor any other biologiststhat I worked with, nor any local residents,
ever told me of seeing this species in the
primary forest. I consider it a common
snake of second-growth and agricultural
Other species, such as Elaphe
areas.

erythrura

erythruraand Rhabdophis

auriculata auriculata appear to be common

have notin
habitatan
shift
undergone
apparent
similartoN.
samarensis.
The
preference
otherabundant
Calamaria
snake,
onlyvery
gervaisi, may be adversely affected byinallhabitats, although they

deforestation, in that it was common inprimary forest but not in second-growthhabitats.

Logging causes bothsoil

compaction from the movement of heavyequipment and soil drying from increased
insolation.

changesseems likely
would adversely
Itthat these

affectaburrowing animal such as C. gervaisi.

Snake ecology suffers from the typicalproblems inherent to studies of higher level
predators. Since they are frequently at the
top of the food chain, snakes never seem tobe very abundant.

In addition, they are

secretive by nature, making collection andobservation difficult.
If we are tounderstand the effect of habitat loss on
snake populations, it will be necessary touse novel approaches which are uniquely

designedtoovercome these

specific

for their

Drs. R. S.

comments on my
Kennedy and J. P.

O'Neill helped to arrange funding for myMembers of the Philippine Eagle
trip.
Conservation Project and local residents
assisted in the collections. The Dallas Zoo

provided an intellectually stimulating
environment in which to finish final editingof this paper. Comments by Jim Murphy,
E. D. Brodie, Jr., and J. A. Campbell
improved the final draft.
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