Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 August 2023 | 15(8): 23763-23770
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8250.15.8.23763-23770
#8250 | Received 01
November 2022 | Final received 20 June 2023 | Finally accepted 04 August 2023
Communal
egg-laying by the Frontier Bow-fingered Gecko Altiphylax
stoliczkai (Steindachner,
1867) in Ladakh, India
Dimpi A. Patel 1
, Chinnasamy
Ramesh 2, Sunetro Ghosal 3 &
Pankaj Raina 4
1,2,4 Department of Wildlife
Protection, Leh, Ladakh
(UT) 194101, India.
1,3 Wildlife Institute of India, Chandrabani, Dehradun, Uttrakhand
248001, India.
1 dmp8266@gmail.com (corresponding
author), 2 ramesh.czoo@gmail.com, 3 sunetro@stawa.org, 4
pankaj.acf@live.com
Editor: S.R. Ganesh, Kalinga Foundation, Agumbe, Karnataka, India. Date
of publication: 26 August 2023 (online & print)
Citation: Patel, D.A., C. Ramesh, S. Ghosal & P. Raina (2023). Communal
egg-laying by the Frontier Bow-fingered Gecko Altiphylax
stoliczkai (Steindachner,
1867) in Ladakh, India. Journal of Threatened Taxa 15(8):
23763–23770. https://doi.org/10.11609/jott.8250.15.8.23763-23770
Copyright: © Patel et al. 2023. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: This research project (NMHS/MG-2017/458)
been funded under the National Mission on Himalayan Studies (NMHS), Ministry of Environment, Forest, and Climate Change, Government of India NMHS and implemented by the Department of Wildlife Protection, Leh.
Competing interests: The authors declare no competing interests.
Author details: Dimpi Patel is a
researcher with an interest in herpetofauna and currently pursuing her doctoral research on herpetofauna in the Trans Himalayan region of Ladakh from Wildlife Institute of India. Chinnaswamy Ramesh, PhD is a scientist at Wildlife Institute of India with an interest in ecology, human-wildlife interactions, invasive species, climate change, biodiversity conservation, and marine research. Sunetro Ghosal, PhD
is an independent researcher with an interest in human-wildlife interactions. Pankaj Raina is currently serving as Wildlife Warden, Leh, UT Ladakh and is pursing his doctoral research on snow leopard ecology from Wildlife Institute of India.
Author contributions: DP—carried out the fieldwork, analysed the data, wrote the paper, coordinated with co-authors, and edited the manuscript. CR—provided comments, inputs, and feedback on the manuscript. SG—provided comments, inputs, feedback on the manuscript, helped with the analysis, and edited the manuscript. PR—provided
support and resources for fieldwork and provided feedback on the manuscript.
Acknowledgements: This research was supported by
the Ministry of Environment, Forest and Climate Change, Government of India
under the project National Mission for Himalayan Studies (project ID
NMHS/2016-17/MG13/06) and implemented by the Department of Wildlife Protection,
Leh. We express our deepest gratitude to the dean and
the director of the Wildlife Institute of India, Dehradun for their support. We
would like to extend our gratitude to Mr Hussain Saifee
Reshamwala for his valuable support in establishing
the three egg-laying sites and for his active involvement in the fieldwork and
Mr M. Akram for the help they provided in the
fieldwork. Anchal Bhasin
for her help in updating the map.
Abstract: Communal egg-laying behaviour in the Frontier Bow-fingered Gecko Altiphylax stoliczkai
was investigated within Ladakh’s Indian trans
Himalayan region during the summer of 2019. The findings present the first
documented evidence of communal egg-laying in the species. Distinct egg-laying
sites were identified with crevices containing between four and 10 eggs.
Confirmation of species identity was achieved through post-hatching visual
identification and genetic tests. Contrary to prevailing notions of one to two
eggs per female gekkonid, the observation suggests that communal egg-laying
involves multiple females. This behaviour attributes
to the unique environmental challenges of high-altitude mountainous terrain,
proposing significant reproductive benefits for the species.
Keywords: Adaptation, agama, Baltistan
Gecko, behaviour, cold-desert, ectotherm,
high-altitude specialist, mountain herpetofauna, oviposition, trans Himalaya.
Introduction
Animal
aggregations have received considerable attention regarding their adaptive
value (Hamilton 1971; Treisman 1975; Turner &
Pitcher 1986; Inman & Krebs 1987). In comparison, aggregation for
egg-laying has received relatively less attention (Danchin
& Wagner 1997). Laying eggs with conspecifics is one of the oviposition
strategies used by many reptilian species. This behaviour
has been documented in many species including dinosaurs and, in contemporary
times, about 481 species of reptiles and amphibians around the world (Plummer
1981; Graves & Duvall 1995; Brown & Shine 2005; Radder
& Shine 2007; Doody et al. 2009).
The
phenomenon of communal egg-laying, observed in various reptilian species
globally, has prompted the formulation of several hypotheses to elucidate its
drivers. These hypotheses include the notion that scarcity of optimal
egg-laying sites with stable thermal and humidity conditions might influence
this behaviour. However, none of these proposed
hypotheses has achieved conclusive establishment as the definitive explanation.
Despite multiple hypotheses aiming to explain the communal egg-laying behaviour in different species, consensus remains elusive,
as underscored by the work of Doody et al. (2009).
Each species
uses specific strategies for oviposition based on a combination of biological
and environmental factors. Current literature has identified ‘adaptation’ and
‘constraint’ as two critical factors with high correlation with female lizards
laying eggs with conspecifics. In this context, the term ‘adaptation’ refers to
fitness benefits for young individuals and ‘constraint’ refers to the scarcity
of favourable environmental conditions for laying
eggs (Radder & Shine 2007). It is assumed that
high-altitude cold deserts are one such place where environmental constraints
have a significant influence on the ecology of various species, especially
ectotherms/poikilotherms (cold-blooded) animals though this has been very
poorly studied so far. Here, we elaborate on the egg-laying habits of one such high-altitude
specialist reptile – the Frontier Bow-fingered Gecko Altiphylax
stoliczkai in Ladakh,
of the western Himalaya.
The Frontier
Bow-fingered Gecko, also referred to as the Baltistan Gecko, belongs to the Gekkonidae family and thrives in high-altitude regions. Its
global presence is confined to the Palearctic zones of northern India and
Pakistan, specifically in central Asia and the trans Himalayan region within
the Altiphylax genus, as highlighted in Bauer
et al.’s (2013) work. In India, this gecko species is identified in the union
territories of Ladakh and Jammu & Kashmir,
formerly known as Jammu & Kashmir State, as documented by Smith (1935). The
measurements align with Smith’s (1935) data, indicating an average
snout-to-vent length (SVL) and tail length (TL) of approximately 50 mm. Despite
its presence, knowledge about the biology of Altiphylax
stoliczkai remains limited. Displaying nocturnal behaviour, the species seeks shelter under small rocks for
thermoregulation during daylight hours and is often found near human
settlements. Although established as oviparous based on Auffenberg
et al.’s (2004) work and Sharma’s (2002) findings, there is a notable absence
of documented proof or published records detailing its egg-laying strategy or
preferred elevation range. This study contributes significant insights,
presenting original observations from Ladakh, India,
which provide the inaugural documented evidence of communal egg-laying behaviour exhibited by the Frontier Bow-fingered Gecko.
Study area
Ladakh (32.15–34.38 °N &
75.36–78.22 °E) is located in the rain shadow region to the north of the
Himalayan ranges and the annual precipitation ranges 90–110 mm (Srivastava et
al. 2009). The elevation in the region varies, ranging from an altitude of 2,600
m to over 7,000 m. The temperature ranges from an average of -30 °C in winter
to 30 °C in the summer. The landscape in Ladakh is
undulating, arid, and resource-scarce due to the lack of precipitation, short
growing seasons and harsh, long winters. Ladakh is
included in the trans Himalayan biogeographic region (Rodgers & Panwar
1998). Most of the region is treeless except for plantations, cultivated lands
and areas along water sources (Kachroo et al. 1977;
Hartmann 1983). The herpetological diversity and richness of Ladakh are similar to neighbouring
regions of Gilgit-Baltistan (Ficetola et al. 2010)
with which it shares geographical, topographic, and climatic characteristics.
Currently, Ladakh has been documented to host four
lizard species, one snake species, and one amphibian species (Patel et al.
2023).
Materials
and Methods
A series of comprehensive
herpetological surveys were undertaken across diverse Ladakh
habitats (Image 6) between March and September 2019. A cumulative 220 h were
dedicated to surveying 150 km of randomised trails,
averaging 6 km daily. The survey hours spanned 0800–1700 h. The primary
objective centred on documenting reptile and
amphibian diversity and abundance. Captured specimens underwent manual
handling, with recorded metrics including snout-vent length (SVL) and total
length (TL).
In this period, 61 randomly
chosen sites were surveyed, each representing one of six distinct habitat types
classified based on topography, ecology, and local insights. These encompassed
riverine settings, rocky outcrops, plains of both sandy and rocky terrain,
agricultural lands, sand dunes, and grasslands. Survey activities spanned both
sunny and cloudy days, with limited nocturnal surveys due to logistical
constraints.
Results
During the survey, we obtained
119 sightings of Altiphylax stoliczkai in 24 of 61 sites in relatively dry areas.
The observed individuals displayed morphological characteristics consistent
with established literature. Specifically, this gecko species is medium-sized
and often exhibits a shorter tail. Its body and head show slight dorso-ventral compression, with the dorsal surface
featuring greyish colouring and dark brown wavy
cross-bars, while the ventral surface appears greyish-white. The extent of tail
swelling varies among individuals, being more prominent in recently regenerated
tails.
In addition to morphometric
measurements, a genetic analysis was performed on a tail segment collected from
one of the sites, confirming the gecko species’ identity. The corresponding
genetic sequence has been submitted to the National Centre for Biotechnology
Information (NCBI) with accession numbers MZ293046, MZ293045, MZ293047, and
MZ293044.
Since the species is nocturnal,
it was observed hiding under rocks during the day and foraging during the night
(Image 1). The survey encompassed a sample size of 119 adult A. stoliczkai individuals, yielding mean snout-vent length
(SVL) and tail length (TL) values of 51.27 ± 14.99 mm and 72.60 ± 34.65 mm,
respectively.
During the survey
in early August (1–10 August 2019), clusters of eggs were found at four sites
(Table 1). These sites were located near the villages of Ney (six eggs), and Phyang (four eggs) in Leh
District; and Chiktan (four eggs), and Wakha (10 eggs) in Kargil District,
in the Union Territory of Ladakh. The egg
measurements at the site in Ney ranged 11.7–12.87 mm in length and 8.84–9.91 in
width. Eggs measurements at the site in Phyang ranged
12.3–12.88 mm in length and 9.89–9.93 mm in width whereas at the sites in Chiktan and Wakha, they ranged
12.41–12.86 mm in length, 9.93–9.94 mm width and 11.9–12.81 mm length,
8.85–9.88 width, respectively. No adult Altiphylax
stoliczkai or hatching was observed near these
egg-laying sites during multiple visits to the same sites. In Ney, Phyang, and Chiktan- the eggs
were located beneath medium-sized boulders covered with loose soil. The Ney and
Phyang sites were relatively flat with small to
medium-sized boulders (Images 2 and 4). The site in Wakha
was located on a steep south-facing mountain slope with rocky outcrops. Here,
the soil was relatively compact and 10 eggs were
observed through a narrow fissure in a rock (Images 3 and 5). On closer
inspection, we found a broken egg. We were able to identify the premature
neonate inside of the broken egg as Altiphylax
stoliczkai by its physical features that match
with literature descriptions. We cautiously measured, and
photographed the eggs at all the sites to avoid embryo damage. Though this
species has been recorded near human settlements, all the above-mentioned sites
were at least three to four km from the nearest human habitation with minimal
disturbance and no flowing water in the immediate vicinity. Since all survey
sites were located away from human habitation, currently fewer data are
available on egg-laying behaviour near human
settlements. Common vegetation in these areas included Ephedra Ephedra gerardiana
and wormwood Artemisia spp.
Discussion
Upon the
eggs’ discovery, the identity of the species responsible was unequivocally
determined only at the Wakha site, as previously
mentioned. To establish the egg layer at the other three sites, we employed
deductive reasoning and indirect indicators. Despite the presence of Theobald’s
Toad-headed Agama Phrynocephalus theobaldi Blyth, 1863 at the Ney and Phyang sites, the viviparous nature of this species ruled
it out as the egg layer. Consequently, Altiphylax
stoliczkai emerged as the likely candidate.
Similarly, the Himalayan Agama Paralaudakia
himalayana Steindachner,
1867 was observed at the Wakha and Chiktan sites It is oviparous but
the eggs of agamas are leathery and ellipsoidal in shape making them distinctly
different from the eggs of geckos. Also, most agamid species dig small burrows
to lay their eggs. The ones we observed were spherical and hard-shelled (Table
1), which is typical of eggs laid by members of the Gekkonidae
family (Andrews 2004). Further egg comparison among the three sites and the
confirmed Wakha identification showed notable
consistency. Subsequent validation occurred by revisiting the sites at least
twice after the initial discovery, culminating in hatching around mid-August
and confirming Altiphylax stoliczkai as the egg layer.
A review of
the current literature suggests that this is the first record of such an en masse, communal egg-laying strategy used by Altiphylax stoliczkai.
Auffenberg et al. (2004) allude to the possibility
that this species might be laying eggs communally based on observations of eggs
near Skardo in Baltistan but did not provide any
details or confirmation. The measurements of the three eggs collected by them
ranged 9.7–11.1 mm in length and 7.6–8.5 mm in width which is smaller than the
eggs we recorded. This difference is probably a reflection of body size as our
largest recorded adult (SVL = 59.27 mm) was larger than the largest adult (SVL
= 46.5 mm) reported from Baltistan. The species was documented within sites
positioned at altitudes ranging 3,000–4,026 m, a higher elevation than the
previously reported range of 2,300–3,700 m documented by Auffenberg
et al. (2004).
Neither the
process of egg-laying nor genetic tests to ascertain distinct female
contributors per egg-laying site were observed or conducted. Nonetheless, it is
noteworthy that the majority of gecko species tend to yield a maximum of one or
two eggs during a given time frame (Shine & Greer 1991; Doughty 1996;
Mesquita et al. 2016). Additionally, a relationship exists between the size of
a gecko and its clutch size, with the former serving as a constraining factor
on the number of eggs a female can produce (Doughty 1996).
Thus,
communal egg-laying in geckos might be a behavioural
adaptation to cope with the constraint of clutch size, as it increases female
fitness by improving the performance of hatchlings (Blouin-Demers et al. 2004; Radder & Shine 2007). Current literature correlates
this behaviour with social factors (Brown & Shine
2005; Radder & Shine 2007; Refsnider
et al. 2010), scarcity of suitable egg-laying sites (Rand & Dugan 1983) and
reduction of predation risk (Martin 1998; Spencer 2002). Of these, the scarcity
of suitable egg-laying sites is the most commonly cited factor to explain
communal egg-laying. In this regard, suitable sites provide desired thermal and
humidity conditions. This is perhaps even more important for species that do
not show post-egg-laying parental care, especially reptiles and turtles. While
this could be one of several factors, it contributes to the adoption of
communal egg-laying behaviour in certain species
(Bustard 1968; Shine & Greer 1991; Doughty 1996; Doody et al. 2009).
Most
oviparous lizards generally do not engage in parental care, and the success of
their reproduction depends primarily on choosing optimal egg-laying sites (Pike
et al. 2011). The scarcity of suitable egg-laying sites, as determined by
optimum temperatures and moisture conditions are important factors that
influence the success of the communal egg-laying strategy among reptiles and
amphibians (Graves & Duvall 1995; Rand 1967). In addition, communal
egg-laying provides many adaptive benefits including reduced predation risk.
The larger the group of eggs, the smaller the probability of predation risk
faced by each egg (Mateo & Cuadrado 2012).
Furthermore, egg-laying sites located under large boulders are assumed to have
stable conditions required for the incubation of eggs due to stable
microclimatic processes (Garcia-Roa et al. 2015).
Also, proximity with other eggs is known to alter moisture and thermal exchange
to reduce water intake and produce healthier offspring (Radder
& Shine 2007; Dees et al. 2020).
A substantial
quantity of old and new eggshells was observed at all four egg-laying sites,
implying their recurrent utilization. There were no egg-laying sites for this
or any other species nearby. Adverse climatic conditions in the region might
have incentivized individuals of this species to select previously successful
sites. This not only increases the likelihood of success but also reduces the
energy expenditure needed to locate new sites with unfamiliar microclimates
(Doody et al. 2009). Mountain herpetofauna species, in particular, could be
more susceptible to climate change impacts (Sinervo
et al. 2010). Furthermore, limited optimal egg-laying sites, harsh weather
conditions, and unpredictability could contribute to these adaptive strategies.
Ladakh’s demanding climate conditions create
challenges for ectotherms/poikilotherms reliant on external heat sources and
adaptive behaviours for temperature regulation.
Extended periods of cold weather and intense solar radiation due to elevation
make the region unsuitable for ectotherms. The existing species have developed
energy-efficient strategies to meet nutritional needs and adjust to the
environment, potentially explaining the region’s diminished species diversity.
While these reptilian species evolve physiological adaptations over time, behavioural adjustments are less resource-intensive and
time-consuming (Hertz 1981). Communal oviposition might well represent one such
adaptation.
The precise
cues guiding individual geckos’ selection of egg-laying sites and whether this
decision-making occurs independently or collectively remain uncertain. An
intriguing possibility is that geckos acquire familiarity with these sites
through individual observation, potentially coupled with site-specific cues
such as the presence of aged eggshells and optimal microclimatic conditions.
However, a comprehensive investigation of these factors is essential for deeper
comprehension. Additionally, as mentioned earlier, another oviparous species,
the Himalayan Agama, was observed at two sites without the discovery of their
nests. This observation suggests that Altiphylax
stoliczkai and Paralaudakia
himalayana likely do not engage in site
competition due to distinct egg-laying strategies and site preferences,
presumably influenced by inherent variations in egg size and clutch size.
Communal
egg-laying behaviour has been observed in certain
species where egg-laying sites are inherited across generations. This
phenomenon, known as natal homing, has been documented in various species,
including sea turtles and snakes (Meylan et al. 1990;
Graves & Duvall 1995; Brown & Shine 2005;). For instance, in Morton
National Park, located in south-eastern Australia, a mark-recapture study
focusing on Lesueur’s Velvet Gecko Oedura lesueurii
revealed that hatchlings return to their natal nests as gravid females (Webb et
al. 2008). A similar pattern was identified among Oudri’s
Fan-footed Gecko Ptyodactylus oudrii in northern Africa, where the presence of
eggshells plays a pivotal role in selecting egg-laying sites (Mateo & Cuadrado 2012). Additionally, Pike et al.’s (2011)
experimental study involving Oedura lesueurii showcased the geckos’ reliance on both biotic
(eggshell presence) and abiotic (thermal and moisture conditions) cues when
choosing egg-laying sites. Interestingly, they showed a preference for sites
with hatched eggshells and stable, cooler temperatures over warmer
alternatives. Notably, these aspects remain unexplored in the context of Altiphylax stoliczkai,
particularly regarding its biological requirements and the environmental
constraints unique to the Ladakh region.
While these
observations are significant, they also highlight the large knowledge gap that
exists about the ecology of reptiles in cold regions such as Ladakh. The findings of this paper point to several lines
of investigation to gain further insights into various strategies employed by
ectotherms in response to various environmental challenges in Ladakh. The study findings will help design further
long-term studies to understand various behavioural
choices and this, in turn, will help develop appropriate conservation
strategies for herpetofauna in Ladakh and regions
with a similar climate.
Table 1. Details of eggs, egg-laying sites
and other lizard species recorded in the habitat along with egg clutches of Altiphylax stoliczkai
in Ladakh, India.
|
Site name, GPS, and elevation
(m) |
Habitat type |
No. of eggs (n) |
Range of egg
measurements (mm) |
Average size of
eggs (mm) |
Type of shell |
Presence of old
eggshells |
Sympatric lizards
and their reproductive strategies |
|||
|
Length |
Width |
Length |
Width |
|||||||
|
Wakha N 34.369381 E 76.382559 3396 m |
Rocky outcrop |
10 |
11.9–12.81 |
8.85–9.88 |
12.15 |
9.23 |
Spherical, hard |
Yes |
P. himalayana |
Oviparous agamid |
|
Chiktan N 34.4751306 E 76.4962916, 3337m |
Rocky outcrop |
04 |
12.41–12.86 |
9.93–9.94 |
12.63 |
9.94 |
Spherical, hard |
Yes |
P. himalayana |
Oviparous agamid |
|
Ney N 34.265275, E 77.295730 3575m |
Rocky pains |
06 |
11.7–12.87 |
8.84–9.91 |
12.16 |
9.23 |
Spherical, hard |
Yes |
P. theobaldi |
Viviparous agamid |
|
Phyang N 34.1838889, E 77.482666 3551 m |
Rocky plains |
04 |
12.3–12.88 |
9.89–9.93 |
12.59 |
9.91 |
Spherical, hard |
Yes |
P. theobaldi |
Viviparous agamid |
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