Ground foraging behaviour of Malayan giant squirrel (Ratufa bicolor)

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CURRENT SCIEN CE, VOL. 110, NO. 12, 25 JUN E 2016 2223
shaped by the mate selection. Therefore,
such high average energy input in AC2 is
likely to be an indication that it is a
breeding call. While low average energy
input per unit time in AC1 is likel y to be
for a function with lower priority, such
as territory call.
Interestingly, AC2 matches with the
description of breeding call of I. chirava-
si given by Gaitonde and Giri10, for
which they have assigned functions to
this call as associated behaviour such as
approach of female leading to amplexus
and egg laying. Whereas they have men-
tioned that the calling males exhibit call s
similar to AC1 with associated behaviour
like vicinity of another male. However,
they have not pr ovided any analysis for
the calls. Although we could not assign
functions to calls AC1 and AC2 based on
our field observations, we suggest that
AC1 is a territorial call, whereas AC2 is
a breeding call based on the energy
expenditure and suggestions made by
Gaitonde and Giri10.
Call analysis for Indirana species
provided by earlier workers is either
qualitati ve10 or with limited analysis13–15,
making it difficult to use them for com-
pilations. Nevertheless, superficially, the
spectral characteristi cs of the territory
calls of various species of Indirana are
similar, as also suggested by Kuramoto
and Dubois15, making territory calls of
limited value for taxonomy and identifi-
cation. However, the pattern of breeding
calls and energy input may be different
for different species. Further studies on
the breeding calls of other species of In-
dirana could provide important insight
into the ecology and evolution of species
belonging to this endemic genus.
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ACKNOWLEDGEMENTS. We thank the
Head, D epartment of Zoology and Biodiversity
and the Pri ncipal, MES’ Aba sahe b Ga rware
College, Pune as well as the Indian Institute
of Scien ce Edu cation and Research, Pune, for
providing infrastructural faciliti es. N.M. is
supported by IN SPIRE student fellows hip.
N.D. is supported by INSPIRE facu lty fello w-
ship. We also thank Nikhil Dandekar, Sanjay
Khata wkar, Deepa k Moda k, Satish Pande a nd
Anish Par deshi for help during field work;
Rajgopal Pati l and Pra sad Kulk arni for help in
analysis. N.M. thank s the Raven Pro team for
providing a free copy of R aven Pro 1.4 soft-
ware, and to Jonathan Micancin, Blackburn
College, Carlinville, Illinois, for his guidance
in call analysis.
Receiv ed 18 Ja nuary 2016; revised accepted
18 March 2016
NIKHIL MODAK1
NEELESH DAHAN UKAR2 ,3
HEMAN T OGALE4
ANAND PADHYE1, 5,*
1Department of Biodiversity, and
5Department of Zool ogy,
MES’ Abasahab Garware College,
Karve Road,
Pune 411 004, India
2Indian Institute of Science Education
and Research,
G1 Block, Dr Homi Bhabha Road,
Pashan, Pune 411 008, India
3Systematics, Ecology and Conservation
Laboratory, Zoo Outreach
Organization (ZOO),
96 Kumudham Nagar,
Vilankurichi Road,
Coimbatore 641 035, India
4Whistling Woods,
Ambol 416 510, India
*For correspondence.
e-mail: anand.padhye@mesagc.org
Ground foraging behaviour of Malayan giant squirrel (Ratufa bicolor)
Giant squirrels are considered an
important component of forested ecosys-
tems, and are advocated as indicators of
forest health1. The Malayan giant squir-
rel (MGS; Ratufa bicolor), one of the
four giant tree squirrels in the Oriental
region (the other three being R. affinis,
R. indica and R. macroura), is found in
the Malayan region, North East India and
Myanmar. It is listed as Near Threatened
(NT) by IUCN, in Appendix II of CITES
and Schedule II of Indian Wildlife (Pro-
tection) Act 1972. Some ecological
informati on on the MGS exists from few
studies 2,3.
There has been unanimity about the
obligate arboreal nature of giant squirrels
(genus Ratufa) that occupy an ecological
niche in the highest levels of primary
rainforest. Moore4 stressed the need of
detailed observation and reporting of any
ground foraging behaviour of Oriental
giant squirrels. Of late, recent squirrel
studies in the tropics report some inci-
dents of giant squirrels coming down to
the ground across their distributional
range5– 13. We describe here ground

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foraging of MGS in a tropical forest
fragment of Brahmaputra valley, North
East India (Figure 1), which is the west-
ern most distributional range of the spe-
cies.
As part of a larger study (October
2012 through March 2015) on resource
partitioning among sympatric arboreal
squirrels in the tropical forests of Hol-
longapar Gibbon Sanctuary (HGS) (Fig-
ure 2), we observed five focal MGS from
dawn to dusk. HGS (2640–2645N,
9423–9423E; area 20.98 km2) is situ-
ated in Jorhat district, Assam. According
to the classification scheme of Champion
and Seth14, the forest type in HGS is
Assam Plains Alluvial Semi Evergreen
Forests (1/2/2B/C), sparsely interspersed
with wet evergreen forest patches domi-
nated by Di pterocarpus macrocarpus in
the upper canopy, while Mesua ferrea
dominates the middle canopy.
We observed squirrels with equal
effort in both dry (October–March) and
wet (April–September) seasons. Obser-
vations were made using ad libitum and
scan sampling methods15 with 5 min
interval. Whenever we found squirrels
coming to the ground, we recorded the
time, distance traversed and the follow-
ing information.
(a) Distance of the squirrel from any
nearest tree.
(b) Behaviour of the squirrel (foraging,
alert, rest, play and chase). Alert be-
haviour, in the context of this study,
is any sudden abrupt motionless body
posture with raised head and emitting
alarm vocalizations due to awareness
of the presence of any thr eat.
MGS mostly foraged (98.9%) in the
canopy and sub-canopy within source
tree crowns (n = 2340 scans out of 2366
total scan observations). However,
ground foraging was seen only during 11
occasions (1.1%) throughout the study
period (n = 26 scans out of 2366 total
scan observations). The mean distance
travelled from the source tree (from
which it descended) while on the ground
was 7.7 m  6.5 SD (n = 11, range: 2–
23 m). It was observed that MGS came
down to the ground using the tree trunk
and woody climbers more in the forest
edge (n = 9) than in the interior (n = 2).
The forest edge is the ecotone between
forest and tea gardens, and forest and vil-
lage. MGS also travelled more distance
(8.3 m  7.1 SD, n = 9) in the forest edge
than the interior (5.0 m  1.4 SD, n = 2).
The mean time spent during each descent
was 16.3 min  10.2 SD (n = 11). MGS
spent more time on the ground in the
morning (0600–0900 h, 21.1 min  8.1
SD, n = 8) than in the afternoon (1300–
1500 h, 5.0 min  5.5 SD, n = 3). A no-
table change in behaviour was observed
when MGS moved beyond 5 m from the
source tree. Significant association of
foraging behaviour was seen with the
closeness from the source tree, while
frequency of alertness was more when
MGS crossed beyond 5 m distance
from the source tree (

2 = 10.9, df = 1,
P < 0.01).
The tropical belt wit h significant to-
pographic relief and forest cover serves
as a global hotspot of diversity and en-
demism for arboreal squirrels, especially
giant squirrels1. However, reports of
ground foraging behaviour by arboreal
giant squirrels are rare. This could be due
to the paucity of squirrel research in the
tropics in general and Asia in particular1.
The ground foraging of giant squirrels
was observed only 11 times during the
present study. This suggests that such
opportunistic foraging behaviour occurs
infrequently. We observed that the
ground-descending activity of MGS was
related to feeding and foraging behaviour
Figure 1. Malayan giant squirrel
foraging on the ground in Hollon gapar Gibbon Sanctuary,
Assam, India.
Figure 2. The location and study area of Hollongapar Gibbon Sanctuary. Black dots
indicate
area s where the giant squirrel descended to the gr ound.

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CURRENT SCIEN CE, VOL. 110, NO. 12, 25 JUN E 2016 2225
on fallen fruit clusters of Mesua ferrea
(flesh juicy part ingested, while seed dis-
carded) and termite hill s (top soft part),
which may be due to their ability to ex-
ploit a wider variety of food in periods of
fruit scarcity. There are reports of giant
squirrels consuming soil5,8,9 after feeding
on seeds rich in secondar y metabolites
such as Olea dioica to neutralize the
effect of the metabolites from a seasonal
cloud forest of the Western Ghats6, as
well as termites10,11 and fallen fruit clus-
ters of Zizyphus mauritiana from South
India5. Diets of giant squirrels can shi ft
to bark and leaves during fruit scarcity,
but they prefer fruits, especially seeds,
when t hey are available5. Food is usuall y
consumed within the source tree crown
itself3, as in the case of R. affinis and R.
color4. Nevertheless, such sporadic inci-
dents thr ow light upon behavioural plas-
ticity and the ability of the giant squirrels
to expand the spectrum of food items as
well as foraging height depending upon
the resource availability.
MGS could concentrate on foraging
near the source tree, as it was safer for
them to access it when in danger. There-
fore, more frequency in alertness was
seen when they were far from the source
tree. Most of the observations were re-
corded in the forest edges. This might be
due to different microclimatic condition
at the forest edges. A recent study on
arboreal squirrels shows variation in
their normal diurnal activity pattern with
changes in environmental variables1 6.
The obser vations of ground foraging be-
haviour of MGS were recorded in an area
which also supports a healthy population
of six other primate species (including
three sympatric macaque species) with
overlappi ng home ranges and showed
no aggressive interspecific interactions
among them. This supports the findings
of Sushma and Singh17, that predation of
giant squirrel by macaque species may be
a sporadic event17. Giant squirrels of the
genus Ratufa have been reported to jump
3.5 m  0.1 SE within canopy cover, but
failed to jump >5 m distance in frag-
mented habitats18. Forest fragmentation
increases edge effects and isolation, and
thus decreases the ability of arboreal ani-
mals to move widely without coming
down to the ground.
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ACKNOWLEDGEMENTS. We thank the
Principal Chief C onser vator of Forest and
Chief Wildl ife Warden of Assam for provid-
ing the necessa ry permission to carry out this
study and the Divisiona l Forest Offic ers of
Jorhat, Jorhat Forest Division and Rang e
Officers of Meleng for logi stic su ppor t. We
also thank WWF (WWF S mall Grant ) and
UGC (UGC-BSR fellowship) for financial
support. S.G. thanks Dilip Baruah and Deben
Bora h for assistance in the field.
Receiv ed 30 September 2015; revised ac-
cepted 30 Mar ch 2016
SAMRAT SENGUP TA1
HILLOLJY OTI SINGHA2 ,*
PANNA DE B2
1Department of Ecology and
Environmental Sciences, and
2Centre for Biodiversity and Natural
Resource Conservation,
Assam University,
Silchar 788 011, India
*For correspondence.
e-mail: hilloljyoti.singha@gmail.com