The Elephant in the Room: Methods, challenges and concerns in the monitoring of Asian elephant populations

Abstract

Increasing anthropogenic pressures has led to the fragmentation of Asian
elephant habitats, affecting their numbers, demography and ranging patterns across their
range. Baseline information on the demography and population dynamics of free-ranging
Asian elephants is often unavailable. Population monitoring at the landscape level has
many constraints, including those of visibility, habitat, terrain and field logistics, among
several others. While knowing elephant numbers may be important for managing local
populations, demographic parameters and distribution patterns are perhaps more crucial
to ascertain long-term trends for conservation.

Full text

39
Introduction
The Asian elephant (Elephas maximus) is
classied as endangered by the IUCN (Choudhury
et al. 2008). Persistent poaching across several
landscapes contributes to selective removal
of males (Blake & Hedges 2004) while recent
reports of poaching for skin suggests additional
emerging threats. Asian elephant landscapes
are increasingly encroached upon, leading
to extensive habitat loss and fragmentation
(Leimgruber et al. 2003). Habitat availability for
the species has, in fact, almost halved over the
past few decades (Choudhury et al. 2008).
In highly populated countries like India and Sri
Lanka, around 60–70% of elephants share space
with humans, mostly in modied landscapes
(Madhusudan et al. 2015; Fernando et al. in press).
This has resulted in increased encounters and
interactions, most of which tends to be negative.
Thus, conservation efforts need to extend beyond
protected areas and into human-dominated
landscapes that are increasingly becoming
critically important for the conservation of Asian
elephants (Madhusudan et al. 2015).
Despite decades of research on Asian elephants,
information on their distribution, numbers,
demography and behaviour remain unavailable
across most landscapes (Blake & Hedges 2004;
Gray et al. 2014; Madhusudan et al. 2015).
Such information is, however, vital for the long-
term conservation of the species, especially
in two of its major strongholds: India and Sri
Lanka (de Silva et al. 2011; Jathanna et al.
2015). The paucity of information is primarily
due to visibility constraints in most Asian
elephant landscapes, which, unlike the African
savannahs, are often densely vegetated with
deciduous to evergreen forests. Problems in
detectability can signicantly downgrade density
estimates (Karanth & Nichols 1998) and affect
observational studies on elephant populations.
As conservation interventions depend heavily
on effective monitoring techniques, there is an
urgent need to develop reliable techniques and
evaluate their applicability across landscapes
and vegetation types. Although population-
monitoring techniques have improved in recent
years, there continues to be a reliance on a few
direct methods and on dung counts, primarily
© 2020 The Authors - Open Access Manuscript Editor: Prithiviraj Fernando
Review article Gajah 52 (2020) 39-47
The Elephant in the Room: Methods, Challenges and Concerns in the Monitoring
of Asian Elephant Populations
Sreedhar Vijayakrishnan1, 2,3*, Mavatur Ananda Kumar2 and Anindya Sinha1,4,5,6
1National Institute of Advanced Studies, Bangalore, Karnataka, India
2Nature Conservation Foundation, Mysuru, Karnataka, India
3Manipal Academy of Higher Education, Manipal, Karnataka, India
4Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
5Cotton University, Guwahati, Assam, India
6Centre for Wildlife Studies, Bangalore, Karnataka, India
*Corresponding author’s e-mail: sreedhar@ncf-india.org
Abstract. Increasing anthropogenic pressures has led to the fragmentation of Asian
elephant habitats, affecting their numbers, demography and ranging patterns across their
range. Baseline information on the demography and population dynamics of free-ranging
Asian elephants is often unavailable. Population monitoring at the landscape level has
many constraints, including those of visibility, habitat, terrain and eld logistics, among
several others. While knowing elephant numbers may be important for managing local
populations, demographic parameters and distribution patterns are perhaps more crucial
to ascertain long-term trends for conservation.

40
owing to the unavailability of trained personnel
and logistical constraints associated with other
techniques, described later in this paper. Moreover,
while these traditional methods are usually
applicable across a wide range of landscapes,
newer methods, such as photographic cataloguing
that effectively estimates numbers of elephants
(Goswami et al. 2019), or alternate approaches,
such as assessing elephant distribution through
questionnaire surveys (Fernando et al. in press),
may have wider applications.
In this perspective paper, we outline some of
the more important challenges that confront
the currently employed elephant population
evaluation techniques. We believe that acknow-
ledging some of these constraints may allow for
more effectively designed population-monitoring
exercises, which could contribute to informed
decisions on the management and conservation
of elephant populations in the future.
Censusing elephants
The counting of elephants is an exercise widely
prioritised across elephant range states. Routine
population monitoring, however, is limited by the
feasibility of large-scale surveys and methodolo-
gical sampling constraints in obtaining reliably
comprehensive estimates. Depending on whether
the counts are made based on direct sightings
of the animals and recording their numbers
or estimating the same from animal signs,
population estimation techniques have been
classied as direct and indirect respectively. The
direct methods that have been improvised and
implemented for elephant population monitoring
include line-transect surveys (Jathanna et al.
2003; Kumara et al. 2012), total block counts,
waterhole counts, simultaneous observer counts
(foot counts) and vehicle road counts while
the indirect sign-based abundance estimations
include dung counts (Kumaraguru et al. 2010;
Baskaran et al. 2013) and DNA-based capture-
recapture surveys (Chakraborty et al. 2014; Gray
et al. 2014).
Direct sighting methods
The direct methods commonly deployed include
line-transect surveys, block counts, waterhole
counts, and photographic cataloguing-based
capture-recapture surveys. These are primarily
adopted in areas where vegetation is relatively
sparse, allowing better sighting of animals. Most
direct sighting techniques are labour-intensive,
however, and require trained personnel. Some
of the more commonly adopted direct survey
methods are discussed here.
Line transects
Line-transect surveys continue to be one of the
most widely accepted and reliable methods for
population monitoring of elephants across their
range (Varman & Sukumar 1995; Buckland et
al. 2001; Kumara et al. 2012). Synchronised
elephant surveys, carried out at the national level
by the Project Elephant in India, for instance,
rely primarily on this technique (MoEF & CC
2017). Line-transect surveys involve two or more
surveyors walking along paths of xed length,
recording species sightings, along with other
parameters, such as sighting angle and distance,
to arrive at the perpendicular distance of the
animal from the surveyor (Varman & Sukumar
1995; Kumara et al. 2012).
Although the method provides reliable estimates
of distribution and population characteristics
(Jathanna et al. 2015), it requires the involvement
of large groups of trained volunteers to ensure
large spatial coverage. The management and
coordination of high numbers of volunteers could,
however, pose logistic difculties. While this
particular method is fairly robust, it is difcult
to execute in undulating and hilly terrains or
in habitats with closed vegetation, where the
laying of linear transects is a challenge. Poor
visibility and detection problems could further
bias estimates. To arrive at robust estimates, a
minimum of 60–80 detections is usually required
(Buckland et al. 2001) and this may be difcult
to achieve in many tropical habitats, especially
evergreen forests with dense vegetation and low
densities of elephants.
Block counts
In the block-count method, surveyors typically

41
walk in a zigzag manner and record all elephant
sightings within a sampling unit, called a block;
these are often dened and demarcated a priori
by the surveyors themselves. While the method
assumes perfect detectability, not all individuals
within a block get detected during surveys,
thereby violating its underlying assumption
(Jathanna et al. 2015). This method is logistically
convenient, especially for government forest
departments, owing to their familiarity with
an area but such surveys in habitats, without
systematic stratication, could signicantly bias
estimates (Kumara et al. 2012). For instance,
blocks may not even spatially cover the different
habitat types across particular landscapes, owing
to improper placement of the sampling units.
Waterhole counts
Waterhole counts, where surveyors remain
stationary near water bodies counting all
elephants that visit the area, reect an inherent
bias in its sampling approach. Many dry habitats
across elephant ranges are today dotted with
numerous human-made water sources, leading to
enhanced congregations of elephants (Dzinotizei
et al. 2019) and enhanced estimates of their
densities. Moreover, waterhole counts are often
practised in areas where natural water sources,
such as streams, are aplenty and elephants do
not necessarily frequent waterholes. In fact,
elephants are known to preferentially use natural
water bodies, such as streams or rivers, in dry
forests (Pastorini et al. 2010; Lakshminarayanan
et al. 2015) or dry streambeds to access subsoil
moisture (Sukumar 1989). The failure to take
these behavioural strategies into account while
planning surveys thus leads to the appearance of
systematic biases in waterhole counts.
Photo-based capture-mark-recapture surveys
Photographing elephants to build a database and
assessing their population size through capture-
recapture techniques have increasingly gained
momentum in recent years (Goswami et al.
2007, 2019; de Silva et al. 2011). This method
helps obtain robust estimates, provided there
is adequate spatial coverage of the landscape
and the various assumptions of the capture-
recapture models are veried and accounted
for. Considering the large-scale distribution of
elephants in closed habitats across tropical Asia,
however, the applicability of this method is
restricted only to certain areas, where individual
elephants can be conveniently photographed,
within typically expansive elephant habitats.
Indirect counting methods
In the wake of difculties encountered with direct
sighting-based methods, indirect sign-based
surveys have often been adopted to estimate
elephant counts. The most widely used of these
methods include dung count surveys, DNA-
based capture-recapture techniques and camera-
trap-based monitoring exercises.
Dung count surveys
Dung surveys are one of the most commonly
adopted techniques across tropical Asia,
typically in areas constrained by direct visibility
of elephants and characterised by low-density
populations. Dung-based density estimates rely
primarily on three components: dung encounter
rates, defecation rates and dung decay rates. Dung
encounter rates are primarily determined by dung
deposition rates and the disintegration of dung
piles. A range of abiotic and biotic factors, such
as temperature, rainfall, humidity, shade, animal
activity and various anthropogenic disturbances
inuence dung encounter rates (Dawson 1993;
Barnes 2001; Nchanji & Plumptre 2001; Breuer
& Hockemba 2007; Pastorini et al. 2007;
Baskaran et al. 2013). Single-site estimations of
dung decay rates, used in population estimations,
can affect density estimates (Nchanji & Plumptre
2001), warranting site-specic assessments.
Additionally, the standardisation of the method
by using defecation rates of captive elephants
rather than from those in the eld could inuence
the nal estimates. Similarly, dung production,
defecation rates and dung decay characteristics in
a particular landscape are all strongly dependent
on seasonality, type of diet, representative age
classes of the elephants, their overall health
as well as on certain abiotic factors, such as
water availability in the area (Nchanji et al.
2008). Theuerkauf & Gula (2010) discuss how

42
seasonality and rainfall can be accounted for by
extensive sampling in the dry season, although
there could well be seasonal inuences on the use
of certain habitats by elephants.
DNA-based capture-recapture surveys
DNA-based estimations of elephant population
characteristics involve dung sample collection and
individual identication in a capture-recapture
framework (Hedges et al. 2013; Chakraborty et
al. 2014; Gray et al. 2014). While this method
usually generates reliable estimates once
dedicated laboratories with skilled technicians are
able to standardise the molecular techniques, it is
largely applicable to small elephant populations
and areas with low animal densities. It is usually
difcult to implement over large areas with high
elephant densities, primarily owing to the costs
involved. The other constraints typically involve
the logistics of collection, handling and storage
of dung in the eld, which would ensure the
availability of non-degraded, uncontaminated
faecal samples for sound laboratory analyses.
Camera-trap-based monitoring
Varma et al. (2006) discuss the use of camera
traps for large-scale population monitoring of
elephants. This method has also been used to
understand crop-raiding patterns, demography
of populations in human-use areas and social
behaviour (Ranjeewa et al. 2015; Smit et al.
2019; Srinivasaiah et al. 2019). A critical aspect
of camera-trap surveys is the right placement
of the units to get usable pictures (Varma et al.
2006). This is evident from the large number of
generally uninformative elephant images that
are produced by camera traps that monitor other
sympatric species across protected areas. The
rather elaborate process involved in its execution,
its labour-intensive nature and often the low-
capture rates obtained, accompanied by the
high costs involved, could limit the application
of this method to relatively restricted areas and
small elephant populations. Camera traps can,
however, be useful in areas with extremely low
animal densities and difcult terrains (Moolman
et al. 2019).
Population monitoring: Size, structure or
dynamics?
One of the primary objectives of elephant
population estimation, routinely carried out
across range countries, is to understand how
the populations are responding to increasing
anthropogenic pressures and to understand their
changing ranging patterns (Nichols & Karanth
2012; Jathanna et al. 2015; MoEF & CC 2017).
The loss of elephants to threats such as poaching
for ivory or the recent increase in the demand for
elephant skin in southeast Asia (Sampson et al.
2018) warrant regular monitoring. Poaching for
ivory has also led to skewed sex ratios (Sukumar
et al. 1998) and increase in numbers of tuskless
males in certain populations (Sukumar 2003).
Baskaran et al. (2013) have also reported a
signicant female bias amongst individuals in
the older age classes in the Anamalai landscape
of the Western Ghats, indicating a possibly
targeted removal of males in the past, as has been
described from other landscapes as well (Kumara
et al. 2012).
In addition to population estimates, therefore, it
may also be vital to evaluate the demographic
responses of populations to various ecological
pressures, as changes in certain demographic
parameters allow for the prediction of population
uctuations, including the possibilities of
local extinction (Caswell 2000; González et
al. 2013). Although, globally, various studies
have demonstrated the behavioural plasticity
of different species populations (Hockings et
al. 2015), including those of Asian elephants
(Srinivasaiah et al. 2019), which may allow them
to successfully adapt to current anthropogenic
regimes, their long-term survival appears to be
bleak. Demographic declines have already been
documented in several taxa, ranging from insects
(Habel et al. 2019; Janzen & Hallwachs 2019),
amphibians and reptiles (Falaschi et al. 2019;
Hill et al. 2019) to birds (Lee & Bond 2015;
Haché et al. 2016) and large mammals (Hervieux
et al. 2013; Hockings et al. 2015). Such declines,
unfortunately, remain unknown for large-
bodied species like Asian elephants, in which
demographic changes can be further pronounced
due to relatively longer life-history processes.

43
Abundance estimates: Is just counting ele-
phants enough?
Issues with extrapolation
Population estimation exercises typically provide
density estimates for the sampling areas alone and
not exact numbers of elephants, which require
further extrapolation. The landscape features
and distribution patterns of elephants, however,
confound such estimations (Baskaran et al.
2013). Issues of extrapolation thus constitute an
important concern when population estimations
are conducted. Similarly, a unied approach
in estimating critically important population
parameters is still to be arrived at, although
synchronised surveys are regularly conducted
across elephant range countries. The differences
in spatial scales at which surveys are generally
executed and the varying methodologies adopted
thus often make comparative analyses difcult,
as, for example, in the case of the Anamalai
elephant populations, for which variable estim-
ates have been obtained by different studies
(Sukumar et al. 1998; Leimgruber et al. 2003;
Baskaran et al. 2013). Elephant distributions
at the landscape level often tend to be non-
uniform, especially in large, contiguous, often
heterogeneous landscapes, such as those in the
Western Ghats, with elephants not using several
of its mountainous slopes and human-populated
valleys. These problems thus need to be addressed
by conducting rigorous surveys that would rst
effectively establish the distribution patterns of
the concerned elephant populations across their
range.
Understanding ne-scale distribution patterns of
elephants
Although one of the most studied of all
mammalian species, our understanding of the
ne-scale distribution patterns of Asian elephants
still remains limited. The available information
on elephant distribution patterns across Asian
countries have predominantly been located
within protected areas, largely ignoring groups or
individuals outside parks (Baskaran et al. 2013;
Fernando & Pastorini 2011). Several recent
studies have, however, considered wide-ranging
elephant groups or individuals that often use the
matrix of human-dominated areas outside parks
while mapping their distribution (Madhusudan et
al. 2015; Fernando et al. in press). The human-
dominated Valparai plateau, which forms part
of the Anamalai Tiger Reserve in the Anamalai
hills of southern India, for example, supports
about 100–120 elephants annually (Kumar et al.
2010) but is typically ignored during the annual
population estimation exercise in the reserve;
about 5% of the resident elephant population
of the region is thus never evaluated. Mapping
such populations is nevertheless crucial, as
the prevailing human-elephant conict could
signicantly threaten the persistence of some of
these unaccounted groups in the long term. Long-
term monitoring and reliable mapping exercises
could also reveal potential range expansion or
reduction over time, as has been observed in
certain populations in Sri Lanka (Fernando et al.
in press).
Conclusions
Asian elephant populations are subject to a
wide range of inuences that threaten their very
survival across their distribution range. These
could be direct threats like poaching and conict-
related mortalities, or more indirect ones, such as
certain management measures, including drives
and captures. Indiscriminate drives, followed
by the subsequent connement of individuals in
protected areas, leading to increased competition
and eventual mortality of large numbers of
elephants, as has happened in Sri Lanka, is an
example of such persecution (Fernando 2015).
In India, population control measures, including
immunocontraception, are now being suggested
to attempt the mitigation of rapidly rising negative
interactions between elephants and humans
across their shared habitats. These practices
are reminiscent of those being implemented in
African elephant populations that are now largely
being maintained within private game reserves
with their numbers managed through selective
culling and immunocontraception (Pimm & van
Aarde 2001).
Reliable countrywide estimates should be made
available prior to consideration of such strategies.

44
There is also no conclusive evidence that
increased instances of human-elephant conict
are related to an increase in elephant numbers.
Increase in conict instances is possibly more a
reection of changing distribution and ranging
patterns of the species.
Given that certain management interventions
have direct bearing on elephant populations,
their long-term monitoring becomes crucially
important, particularly to take informed
decisions in conservation policies. Our own
personal observations and a review of the
existing literature indicate that there is no single
method that can be reliably applied across
landscapes while stand-alone survey techniques
may not work as well, even at ner landscape
levels. Madhusudan et al. (2015), on the other
hand, ably demonstrate how data from various
sources, ranging from systematic surveys to
newspaper or other informal reports, can be
used to successfully map elephant distributions
over large regions. Camera-trap- or sign-based
abundance estimates and distribution mapping
could similarly be coupled with questionnaire
surveys (Fernando et al. in press), especially
outside protected areas. Different sources of
information, therefore, collectively contribute
to our knowledge of elephant populations across
large swathes of particular landscapes.
With the rapid growth of serious public interest
in the survival threats being faced by wildlife
in many habitat countries, citizen-science
initiatives need to be urgently harnessed to
acquire functional information as well as
formulate participatory conservation strategies
for many threatened taxa and their populations
(SoIB 2020). In the case of Asian elephants, such
citizen-sourced information could aid the long-
term tracking of individual elephants across local
habitats and also contribute to the building up of
behavioural databases on individual elephants
that interact with human communities over the
larger landscape.
We also strongly believe that setting up of long-
term scientic monitoring stations/groups in
critical and important areas across elephant
ranges may help better understand the structure
and dynamics of local populations in the long
term. Finally, informal observation networks can
cumulatively produce meaningful group-level
data that can be used to understand the structure
and dynamics of elephant populations across
entire landscapes (Araujo et al. 2017).
Acknowledgements
We would like to thank the Elephant Family, Oracle
India, Whitley Fund for Nature, Rohini Nilekani
Philanthropies and Arvind Datar for nancial
and logistic support. SV has been supported
by a doctoral fellowship from the National
Institute of Advanced Studies, Bangalore. The
authors wish to thank the Elephant Conservation
Group for creative discussions on conservation
issues across the elephant range countries. SV
is grateful to Ganesh Raghunathan and MAK
to his colleagues at the Nature Conservation
Foundation for useful discussions. Finally, we
acknowledge the support of the Tamil Nadu
and Kerala State Forest Departments, and the
plantation managements of Valparai for research
permits. We also acknowledge comments from
Prithiviraj Fernando in considerably improving
this manuscript.
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