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Roosting patterns of the Edible-Nest Swiftlet ( Aerodramus fuciphagus ) of the Andaman Islands: effects of lunar phase and breeding chronology


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Environmental conditions and biological rhythms can affect the behavioural routines of animals. However, the effect of lunar phase on individual roosting behaviour remains uninvestigated in most species. Here, we monitored the effect of lunar phase, sunset time, temperature, humidity and the breeding chronology on the roosting patterns of the Edible-Nest Swiftlet (Aerodramus fuciphagus) of the Andaman Islands, across breeding stages. Counts revealed that more than 98% of the population returned to the roosting caves during peak roosting hours, i.e. 1700–2000h. The proportion of birds roosting in caves was highest during the ‘new moon’ phase and when birds were at the nest-building and fledging stage of their breeding cycle. We confirmed that the variation in the roosting behaviour of the Edible-Nest Swiftlet is linked both to the stages in the breeding cycle and to the lunar phase. We hypothesise that the cause for the lunarphilic roosting pattern is an anti-predator strategy. Feeding habits and food requirements during different breeding stages are presumed to influence the roosting pattern of the species. An improved understanding of the association of the behaviour, physiology and the environmental conditions which influence these traits can only help us improve conservation outcomes for this economically important species.
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Roosting patterns of the Edible-Nest Swiftlet
(Aerodramus fuciphagus) of the Andaman Islands:
effects of lunar phase and breeding chronology
Akshaya Mohan Mane & Shirish S. Manchi
To cite this article: Akshaya Mohan Mane & Shirish S. Manchi (2017): Roosting patterns of the
Edible-Nest Swiftlet (Aerodramus fuciphagus) of the Andaman Islands: effects of lunar phase and
breeding chronology, Emu - Austral Ornithology
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Roosting patterns of the Edible-Nest Swiftlet (Aerodramus fuciphagus) of the
Andaman Islands: effects of lunar phase and breeding chronology
Akshaya Mohan Mane
and Shirish S. Manchi
Division of Conservation Ecology, Sálim Ali Centre for Ornithology and Natural History, Coimbatore, Tamil Nadu, India;
Department of
Zoology, Bharathiyar University, Coimbatore, Tamil Nadu, India
Environmental conditions and biological rhythms can affect the behavioural routines of animals.
However, the effect of lunar phase on individual roosting behaviour remains uninvestigated in most
species. Here, we monitored the effect of lunar phase, sunset time, temperature, humidity and the
breeding chronology on the roosting patterns of the Edible-Nest Swiftlet (Aerodramus fuciphagus)of
the Andaman Islands, across breeding stages. Counts revealed that more than 98% of the population
returned to the roosting caves during peak roosting hours, i.e. 17002000h. The proportion of birds
roosting in caves was highest during the new moonphase and when birds were at the nest-building
and fledging stage of their breeding cycle. We confirmed that the variation in the roosting behaviour
of the Edible-Nest Swiftlet is linked both to the stages in the breeding cycle and to the lunar phase.
We hypothesise that the cause for the lunarphilic roosting pattern is an anti-predator strategy.
Feeding habits and food requirements during different breeding stages are presumed to influence
the roosting pattern of the species. An improved understanding of the association of the behaviour,
physiology and the environmental conditions which influence these traits can only help us improve
conservation outcomes for this economically important species.
Received 15 July 2016
Accepted 21 May 2017
Roosting; behavioural
ecology; environment;
habitat; movement
Both abiotic and biotic factors affect the roosting and
foraging habits of animals (Anthony et al.1981;Bakken
and Lee 1992;KlompandFurness1992; Rahman et al.
2004;Langet al.2006;Cozziet al.2012; Lillywhite and
Brischoux 2012). Of several abiotic factors, the effect of
moonlight is known to alter animal behaviour, often
driven by predator activity (Trillmich and Mohren
1981; Gursky 2003;Langet al.2006). Animals that are
active under moonlight are known as lunarphilic animals
(Brigham and Barclay 1992;Gursky2003;Ramenofsky
et al.2008), whereas lunarphobic animals restrict their
activity under moonlight (Morrison 1978;Usmanet al.
1980; Trillmich and Mohren 1981; Nelson 1989;Börk
2006;Langet al.2006).
Many studies (Nelson 1989; Mougeoto and
Bretagnolle 2000; Powell et al.2008) focus on changes
in foraging and predatorprey interactions of different
taxa in moonlit or dark nights. For instance, Common
Poorwills (Phalaenoptilus nuttallii) in southern Arizona
are comparatively more vocal andforage less during a full
moon than a new moon (Woods and Brigham 2008).
Studies on Freckled Nightjars (Caprimulgus tristigma)
in South Africa have demonstrated more intense foraging
activity on moonlit nights and their heterothermic nature
during dark nights (Smit et al.2011). At the same time,
studies of colonial seabirds have shown a decrease in food
delivery and feeding frequency to chicks on full moon
nights, in order to reduce predation risk (Klomp and
Furness 1992; Bourgeoisa et al.2007; Riou and Hamer
2008). All the studies mentioned are related to nocturnal
birds, since we failed to find literature concerning the
diurnal foraging bird.
Edible-Nest Swiftlets of the genus Aerodramus are
exceptional among birds which frequently occupy caves
as colonial roosting and breeding sites (Lim and
Cranbrook 2002). In flight in darkness, within the roost-
ing cave or outside, all swiftlets of genus Aerodramus and
one species of Collocalia utter audible frequency sounds
(from 1.5 kHz to 10 kHz), described as echo clicks
(Medway 1967; Griffin and Suthers 1970; Medway and
Pye 1977;Priceet al.2004; Thomassen 2005). As the
echolocation ability of the Edible-Nest Swiftlet is not as
developed as that of bats (Chiroptera), Edible-Nest
Swiftlets apparently echolocate only for navigation in
the darkness (Medway 1967;Langham1980;Collins
CONTACT Shirish S. Manchi
Supplemental data for this article can be accessed here.
© 2017 BirdLife Australia
and Murphy 1994), within or outside their roosting caves
(Medway 1967;WaughandHails1983; Chantler 2000;
Manchi and Sankaran 2010). However, their roosting
behaviour isthought to vary in relation to breeding stages
(Nguyen et al.2002;Manchi2009).
The economic importance of Edible-Nest Swiftlet
nests for human nest consumption has resulted in
the detailed investigation of the breeding biology and
habitat use among members of the group in different
places within their distribution (Medway 1962a,
1962b;Nguyen1992; Lim and Cranbrook 2002;
Manchi and Sankaran 2010; Manchi and Mane
2012). Moonlight controls the plasma melatonin
levels (Tarlow et al.2003) and also affects sexual
signalling and territorial displays (York et al.2014)
in some birds. Overall, these studies have highlighted
the effects of moonlight on the physiology and activ-
ity pattern of birds. This is the first document sub-
sequent to the natural history observations by
Medway (1962b) on the temporal roosting patterns
of the Edible-Nest Swiftlet (Aerodramus fuciphagus)
in its wild population in caves in Sarawak. The pre-
sent study documents the temporal roosting pattern
of Edible-Nest Swiftlets (Aerodramus fuciphagus
inexpectatus) (Birdlife International 2014)inrelation
to lunar phases and with stages in the breeding cycle.
Material and methods
The Edible-Nest Swiftlet of the Andaman and Nicobar
Islands (hereinafter A&N Is) is the nominate subspecies
of the Grey-rumped Swiftlet (Aerodramus inexpectatus). It
is the westernmost representative of the species, which is
distributed eastwards in the Oriental region through the
coasts and islands of Myanmar, Thailand, Vietnam,
Malaysia to Kalimantan, Indonesia (Nguyen 1992;
Nguyen et al.2002; Cranbrook et al.2013). Observations
by Lim and Cranbrook (2002) have shown that related
species of Aerodramus swiftlets are monogamous and
have strong nest site fidelity.
Study area
We studied the Edible-Nest Swiftlets occupying (120
known) caves in a complex of more than 175 limestone
caves spread within 0.77 km
(12°07N, 92°47E) on
Baratang Island of the A&N Is in the Bay of Bengal,
India (Manchi and Mane 2012). The area is formally
protected as Baratang Reserve Forest, which contains
virgin evergreen, mixed-evergreen and mangrove forests
(Manchi and Mane 2012).
Data collection and analyses
The narrow openings of most of the caves and the
relatively small size of the swiftlet populations within
them made population estimates easily achievable. We
estimated numbers using the audible rattling echo
clicks and visual sightings of the movements of the
Edible-Nest Swiftlet at the cave openings. Birds enter-
ing into and exiting from the cave were counted
visually during light hours. We made 24 h counts at
the entrances of six accessible caves during the breeding
season from January to May 2013. We collected data for
over 1169 h, covering 32 full moon nights (when >98%
of the moons disc is illuminated) and 49 new moon
nights (the moons disc is <3% illuminated when it
crosses the local meridian). Observations were divided
into 10-min slots. We followed Indian Standard Time
(IST) for data collection and interpretation. To avoid
any potential bias linked to rain and cloudy weather, we
collected data only during clear weather conditions. We
estimated the breeding populations using the nest count
method (Sankaran 2001; Manchi and Sankaran 2014).
We also recorded environmental temperature, humidity
and sunset time on each observation day. Following
Manchi (2009), breeding chronology/seasonality data
were collected from the accessible nests in 10 different
caves (six caves selected for roost counts along with
four other caves). Though the Edible-Nest Swiftlet
breeds between December and August in Baratang,
our observations were restricted to the period January
to May, as the data gathering was hampered by nest
harvesting after the first brood. Our team visited a
sample of selected nests each day to assess the breeding
stage. We numbered all the selected caves and nests for
their individual identification. Along with nest identity
number, we also noted the number of eggs and chicks
in the nest for each date. We followed 148 nests over
140 days (20 720 observations of nests during different
breeding stages). As observed in the earlier studies
(Medway 1962b), while there might be traffic in and
out during the day, most birds returned to the caves to
roost between 1700 and 2000h (Figure 1). We recog-
nised this period as Peak Roosting Hours (PRH) and
used this for analyses.
Statistical approach
For analysing time-series of count data collected from
various caves, we used generalised linear models
(GLM) with a Poisson error distribution and log link
function (Gregory and Strien 2010) to test the effects of
environmental and biological factors on the birdsarri-
val patterns at the roost sites. Since the data collected
were from various caves with different population sizes,
we counted the total number of birds roosting inside
the caves from a 24 h count and calculated the percen-
tage of birds entering at each hour. The proportion of
birds coming to roost or leaving a roost every hour was
calculated using the formula (100 × t)/T(where tis the
number of birds coming to roost or leaving a roost in a
particular hour and Tis the maximum number of birds
estimated roosting in a particular cave). We then com-
pared the proportion of birds entering during PRH
with the explanatory variables (i.e. the effect of lunar
illumination, breeding stages, time of sunset, environ-
mental temperature and humidity) (Table 1: online
supplementary material). We used the best-fit model
(Burnham and Anderson 2002; Mazerolle 2006)to
evaluate the impact of environmental and biological
factors on the roosting behaviour of the Edible-Nest
Swiftlet. In order to rank the models, the Akaike infor-
mation criterion (AIC
) corrected for small sample
sizes, ΔAIC
(the difference in AIC
between each
candidate model and the model with the lowest AIC
value) and Akaike weights (w
) were used (Burnham
and Anderson 2002). We started with a global model,
using all variables and selected those models with
below 4.00. By comparing the support for each
model, we excluded those with little support (ΔAIC
4.00). We then conducted model averaging by selecting
Figure 1. Mean percentage bird activity at the openings of different roosting and breeding caves at Baratang, Andaman Islands,
India. A53, B27, B30, B45, B59 and C12 are the identification codes assigned for different caves. Positive values represent the
percentage of birds entering the caves and negative values represent the percentage of birds leaving the caves. For the box-plots,
boxes indicate interquartile ranges and the line inside the box shows the median. Limits of the whiskers represent minimum and
maximum values of the data.
Table 1. Selection table for fits of the 15 competing general-
ised linear models
Models KAIC
Cum. w
MP*BS 7 568.35 0.00 0.73 0.73 276.41
MP*BS+SST 8 570.45 2.10 0.26 0.99 276.22
BS*MP+SST*Hum*Temp 14 577.18 8.83 0.01 1.00 271.41
8 618.79 50.44 0.00 1.00 300.40
MP+BS+SST+Temp 7 631.37 63.01 0.00 1.00 307.92
MP+BS*SST 7 635.97 67.62 0.00 1.00 310.22
MP+BS 5 637.90 69.55 0.00 1.00 313.55
MP+BS+SST 6 639.85 71.50 0.00 1.00 313.36
BS*SST 6 672.36 104.01 0.00 1.00 329.61
BS 4 674.67 106.32 0.00 1.00 333.07
BS+SST 5 676.92 108.57 0.00 1.00 333.06
MP+BS*SST 2 684.63 116.28 0.00 1.00 340.24
SST+Temp+Hum 4 703.37 135.02 0.00 1.00 347.42
SST 2 729.28 160.93 0.00 1.00 362.56
Birds ~1 1 750.55 182.19 0.00 1.00 374.25
MP = lunar/moon phase, BS = breeding stage, SST = first bird arrival with
respect to sunset time, Temp = temperature, Hum = humidity. K=number
of parameters, AIC
= Akaike information criterion, ΔAIC
= delta information
criterion. Model probabilities: Akaike weights (w
), cumulative weight (Cum.
) and the log-likelihood (LL) for different models fitted to count observa-
tions (N= 81) of the Edible-Nest Swiftletfrom caves at Baratang Islands, A&N
Is, from January to May 2013. The largest w
is shown in bold.
best-fit models. All models were implemented using
the package AICcmodavg (2.04) for Model Selection
and Multimodel Inference Based on (Q)AIC(c) and
Model Averaging (Mazerolle 2006).
The PRH were further classified into three time classes
(Table 1: online supplementary material). We used these
time classes to understand the temporal variation, if any, in
the roosting pattern across the days of observation.
ANOVA was used to determine the temporal variation in
roosting behaviour. Tukeys honest significance test was
performed to check the pair-wise difference of time classes
holding roosting population (Zar 2008). Further, we tested
and proportion of roosting birds by performing the
Wilcoxon signed rank test, with continuity correction.
We analysed 43 observations using the KruskalWallis
test with continuity correlation to examine the variations
in Edible-Nest Swiftletsroosting behaviour after sunset
with breeding stage. We classified the breeding stages fol-
lowing Manchis(2009)method(Table 2:onlinesupple-
mentary material). We used the KruskalWallis rank sum
test on 81 observations (28 observations during nest build-
ing, 25 during incubation, 24 during nestling and 4 during
fledging) to examine the variation in the proportion of
birds roosting in PRH during different breeding stages.
We used the statistical programming language R 3.2.3
with R-Studio as an interface (R-Studio Team 2015)for
data analyses.
The roosting patterns of the Edible-Nest Swiftlet
Most of the Edible-Nest Swiftlet populations
(mean = 77.48 ± 18.67% SD) left the roost sites between
0400 and 0700h in the morning. In the evening, more than
their roost sites within PRH (Figure 1). The first bird
returned to the roost site at 1719 ± 0.01 h SD, and the
the total birds observed entering) in 14 counts which
returned after PRH up to 2350h. The numbers of birds
returning during three time classes of PRH varied signifi-
cantly (F=86.05,df=2,P= 0.000). Time class 17001800h
had the highest proportion (mean = 48.06 ± 19.40% SD) of
birds returned followed by time class 18001900h
(mean = 44.06 ± 17.32% SD) and time class 19002000h
(mean = 07.30 ± 09.82% SD). The variation between
classes 17001800h and 18001900h was not significant,
indicating that the PRH are essentially from 1700 to 1900h.
Modelling responses to biological and
environmental factors
The best-fit models depicted that the timing of the
return to roost by these Edible-Nest Swiftlets was influ-
enced by several variables (Table 1). The moon phase
and breeding stage were estimated to be the most
significant predictors in the first best-fit model
(Figure 2). Further, the second best-fit model with the
lowest AIC
also included the sunset time as one of the
significant variables, affecting the roosting decisions of
the individuals (Table 1). According to the models,
temperature and humidity do not affect the timing of
roosting behaviour of the Edible-Nest Swiftlet.
Effect of lunar phase
The new moon phase was the factor with the highest
coefficient (0.665) in the average model fits (Table 2).
This supports the conclusion that fewer birds returned
to roost during PRH on full moon nights than new moon
nights (Z = 10.063, n=81,P< 0.0001). Furthermore, the
first bird returned earlier to roost during new moon
nights (mean = 1720 ± 0.01 h SD) compared to full
moon nights (mean = 1717 ± 0.01 h SD), (Z = 7.851,
P< 0.0001). The last bird returned to roost significantly
later during a full moon night (mean = 1935 ± 0.04 h SD)
(Z = 7.428, P< 0.0001) than on a new moon night
(mean = 1925 ± 0.03 h SD), after excluding the single
event of six late arriving birds at 2350h on the same full
moon night. Moreover, there was a significant difference
(W=127.5,P< 0.02) in the proportion of birds returning
during PRH to roost on new moon nights
(mean = 87.91 ± 12.14% SD) compared to full moon
nights (mean = 70.10 ± 17.14% SD).
Effect of sunset time
Although some Edible-Nest Swiftlets returned to their
roosting caves before sunset, most (mean = 92.68 ± 9.03%
SD) of the individuals returned to their roosting caves only
after sunset (Z = 2.160, P< 0.05). However, the variation in
sunset timing did not significantly affect the proportion of
birds arriving for roosting within PRH (χ
= 4.876, df = 3,
Table 2. Model-averaged parameter estimates from best-fit
models from Table 1
Birds encountered Estimate SE Adjusted SE zvalue Pr(>|z|)
(Intercept) 0.750 0.053 0.054 13.903 <2e-16*
NM 0.665 0.065 0.066 10.011 <2e-16*
Incb 0.450 0.068 0.069 06.519 <2e-16*
Nest 0.617 0.073 0.074 08.373 <2e-16*
NM:Incb 0.719 0.088 0.090 08.030 <2e-16*
NM:Nest 0.565 0.086 0.087 06.471 <2e-16*
* Significance P< 0.001.
NM = new moon, Incb = incubation, Nest = nest building, SE = standard
P= 0.181) or the timing of the first bird arriving to roost
= 4.645, df = 3, P= 0.2). Nevertheless, the frequency of
the first bird returning before sunset was higher (64.03%)
than after sunset (35.07%). Among the breeding stages, the
proportion of birds returning after sunset differed signifi-
cantly (χ
= 8.742, df = 3, P< 0.05): a higher proportion of
birds returning after sunset during the stage of nest build-
ing and fledging (94.43 ± 07.03% SD, n=22and
92.58 ± 10.47% SD, n= 2, respectively), as compared
with incubation (mean = 85.94 ± 05.87% SD, n=8)and
nestling stages (mean = 88.72 ± 12.54% SD, n=11).
Effect of breeding stage
The next most important variable entered into the model
was breeding stage (Table 1). The species had a mean nest-
building period of 61.10 ± 10.96 days SD (n=207),incu-
bation period of 22.73 ± 2.19 days SD (n=245),anda
nestling period of 36.31 ± 4.15 days SD (n=85)followed
by fledging of chicks. Among the breeding stages, the
proportion of birds returned within PRH differed signifi-
cantly (χ
= 9.162, df = 3, P< 0.05). A higher proportion of
birds returned within PRH during nest-building and fled-
ging stages (94.06 ± 07.05% SD, n= 28 and 95.80 ± 07.91%
SD, n= 4, respectively), as compared with the incubation
(mean = 71.13 ± 12.55% SD, n= 25) and nestling stages
(mean = 71.07 ± 24.77% SD, n= 24). Further, we found a
significant variation in the time of the first arrival among
different breeding stages (χ
= 15.276, df = 3, P< 0.005). In
addition, the first bird arrived significantly later during the
nest-building stage (nest building = 1724 ± 0.01 h SD;
incubation = 1714 ± 0.00 h SD; nestling = 1718 ± 0.01 h
SD; fledging = 1715 ± 0.00 h SD). The significant average
coefficient for interaction between new moon phase and
incubation stage (0.719) and new moon phase and nest-
building stage (0.565) showed that the effect of lunar
phase on the roosting behaviour of the swiftlets is signifi-
cantly influenced by the breeding stage.
As with other bird species, the Edible-Nest Swiftlet
demonstrates a rhythmic roosting pattern. The return
to roost commenced before sunset on most occasions
but, unlike most avian species, the ability to navigate in
the dark by echolocation enables Edible-Nest Swiftlets
to return to their roosting/breeding sites after sunset.
Unlike most diurnal foraging birds, including many
non-echolocating swifts and swiftlets, more than
92.68 ± 9.03% SD individuals of the Edible-Nest
Swiftlet returned to their roosting caves after sunset.
However, besides the capability of echolocation,
Medway (1962a,1962b) and Harrisson (1976) have
recorded that Black-Nest Swiftlets (Aerodramus max-
imus) and Mossy-Nest Swiftlets (Aerodramus salanga-
nus) forage by night in bright moonlight. Also,
Tarburton (1987) observed the White-rumped Swiftlet
(Aerodramus spodiopygius) returning comparatively
later to its roost sites on bright moonlit nights.
During new moon nights, most of the Edible-Nest
Swiftlets at Baratang returned to their roost sites imme-
diately after sunset. On full moon nights, some pre-
sumably foraged far from the breeding site after sunset
and returned later to the roost (Manchi and Sankaran
Figure 2. Mean percentage of birds returning to roosting and breeding caves between Peak Roosting Hours (17002000h) on new
moon night, incubation time and nest-building time at Baratang, Andaman Islands, India. Boxes indicate interquartile ranges and
the line inside the box shows the median. Limits of the whiskers represent minimum and maximum values of the data.
2010). Also, further, detailed understanding of the
foraging range and habits of this swiftlet, perhaps
through satellite tracking studies, will help explain the
delayed individuals at roost sites.
Similar to the observations of Manchi (2009)from
Chalis-ek, in the Andaman Islands, breeding chronology
affected the roosting pattern of the Edible-Nest Swiftlet
at Baratang. The food/energy requirements in different
breeding stages (Manchi 2009)mayinfluencethe
changes in the roosting patterns. The percentage of
birds roosting within PRH during incubation and nest-
building periods is significantly higher than nestling and
fledging periods. The Edible-Nest Swiftlet of the
Andaman Islands constructs its nest only during nights,
while roosting (Manchi 2009). The nest construction
period was extended (61.10 ± 10.96 days SD) in the
study area, during which individuals returned early
(after dusk) for longer roosting bouts. The birds were
also seen leaving the roost site before dawn, for foraging,
perhaps to accomplish the relatively high protein/energy
requirement during the nest-building season to produce
enough saliva in the seasonally enlarged salivary glands
(Lim and Cranbrook 2002). Like other swiftlet species
and the subspecies of Grey-rumped Swiftlet, one parent
is obliged to be at the nest during the incubation period
(Medway 1962b;LimandCranbrook2002;Nguyen
et al.2002; Manchi 2009). However, both parents endea-
vour to forage to the maximum just before roosting, and
try to return to attend the nest and eggs as quickly as
possible, whereas during the nestling and fledgling per-
iod, throughout the day, parents make multiple visits to
the nests and chicks for feeding the chicks (Manchi
2009). This also allows them to forage longer before
roosting, resulting in a comparatively smaller proportion
of birds returning to roost within the PRH. As Manchi
(2009) has described, fluctuations in the number of birds
roosting in caves during the fledging period may be
related to food availability (Manchi and Sankaran 2014).
Similarly, with the effect of lunar phase, the roosting
pattern of the Edible-Nest Swiftlet of the Andaman
Islands changes significantly during its breeding season.
When arriving at and leaving the roost, lunarphilic
Edible-Nest Swiftlets must have adapted their anti-pre-
dator (Tarburton 2009), foraging or successful breeding
strategies. At Baratang Island, owls are more active dur-
ing dawn and dusk (Mane and Manchi 2013). The arrival
of most individuals within the PRH, during darkness on
new moon nights, fits well with the hypothesis that it is
the result of the anti-predatory strategy. Also, the late
return for roosting on full moon nights compared to
new moon nights allows us to consider the Edible-Nest
Swiftlet as lunarphilic to some extent, if not completely.
The present study demonstrates that different bio-
logical and environmental factors do affect the beha-
viour of the Edible-Nest Swiftlet in the Andaman
Islands and highlights the need to conserve this fasci-
nating species, which is globally declining in the wild.
We sincerely thank all the Edible-Nest Swiftlet protectors
(Rajender, Nuel, Sukra, Thomas, Ashisan, Dilbar, Birsa,
Ranjan) at Baratang for their dedicated involvement, participa-
tion in the conservation of the Edible-Nest Swiftlet and assisting
Forests and Climate Change, Government of India for the finan-
acknowledge the Department of Environment and Forests,
Andaman and Nicobar Islands for their long-term collaboration
towards executing the Edible-Nest Swiftlet research and conser-
vation programme in the area. We thank Prof. Dr K. Thiyagesan
(Ret.), AVC Collage, Mayiladuthurai for his statistical inputs. We
sincerely thank Dr Chris Bowden from the RSPB, Dr R. P. Singh
from the SACON and the Earl of Cranbrook, pioneer of swiftlet
research from Saxmundham, England for providing valuable
comments and suggestions on the draft of the manuscript. Our
sincere thanks to the reviewers, Editor Kate Buchanan, and the
concerned Associate Editor of EMU Austral Ornithology,
whose inputs and queries resulted in significant improvement
of the manuscript. We also thank all those who were involved
directly and indirectly in the documented work.
Anthony, E. L. P., Stack, M. H., and Kunz, T. H. (1981).
Night roosting and the nocturnal time budget of the little
brown bat, Myotis lucifugus: Effects of reproductive status,
prey density, and environmental conditions. Oecologia
(Berl) 51, 151156. doi:10.1007/BF00540593
Bakken, G. S., and Lee, K. F. (1992). Effects of wind and
illumination on behavior and metabolic rate of american
goldfinches (Carduelis tristis). The Auk 109, 119125.
Birdlife International. (2014). Birdlife taxonomic checklist
version 7.Available at
cies/taxonomy [Verified 4 August 2014].
Börk, K. S. (2006). Lunar phobia in the greater fishing bat
noctilio leporinus (Chiroptera: Noctilionidae). Revista de
Biología Tropical 54(4), 11171123. doi:10.15517/rbt.
Bourgeoisa, K., Dromzéeb, S., Vidala, É., and Legranda, J.
(2007). Yelkouan shearwater Pufnus yelkouan presence
and behaviour at colonies: Not only a moonlight question.
Comptes Rendus Biologies 331,8897. doi:10.1016/j.
Brigham, M. R., and Barclay, M. R. R. (1992). Lunar influ-
ence on foraging and nesting activity of common poor-
wills (Phalaenoptilus nuttallii). The Auk 109(2), 315320.
Burnham, K. P., and Anderson, D. R. (2002). Model
Selection and Multimodel Inference: A Practical
Information-Theoretic Approach,2nd edn. (Springer:
New York.)
Chantler, P. (2000). Swifts: A Guide to the Swifts and
Treeswifts of the World,2nd edn. (Yale University
Press: New Haven.)
Collins, C. T., and Murphy, R. (1994). Echolocation acuity of
the palawan Swiftlet (Aerodramus palawanensis). Avocetta
17, 157162.
Cozzi, G., Broekhuis, F., McNutt, J. W., Turnbull, L. A.,
MacDonald, D. W., and Schmidt, B. (2012). Fear of the
dark or dinner by moonlight? Reduced temporal partition-
ing among Africas large carnivores. Ecology 93, 2590
2599. doi:10.1890/12-0017.1
Cranbrook, E. O., Lim, G. W., Lim, C. K., and Rahman, M.
A. (2013). The species of white-nest swiftlets (Apodidae,
Collocaliini) of Malaysia and the origins of house-farm
birds: Morphometric and genetic evidence. Forktail 29,
Gregory, R. D., and Strien, A. V. (2010). Wild bird indica-
tors: Using composite population trends of birds as mea-
sures of environmental health. Orithology Science 9,322.
Griffin, D. R., and Suthers, R. A. (1970). Sensitivity of echo-
location in cave swiftlets. The Biological Bulletin 139, 495
501. doi:10.2307/1540368
Gursky, S. (2003). Lunar philia in a nocturnal primate.
International Journal of Primatology 24, 351367.
Harrisson, T. (1976). The food of Collocalia swiftlets (Aves,
Aposidae) at Niah cave in Borneo. Journal of Bombay
Natural History Society 71, 376393.
Klomp, N. I., and Furness, R. W. (1992). Patterns of chick
feeding in corys shearwaters and the associations with
ambient light. Colonial Waterbirds 15,95102.
Lang, A. B., Kalko, E. K. V., Römer, H., Bockholdt, C., and
Dechmann, D. K. N. (2006). Activity levels of bats and
Katydids in relation to the lunar cycle. Oecologia 146, 659
666. doi:10.1007/s00442-005-0131-3
Langham, N. (1980). Breeding biology of the edible-nest
swiftlet (Collocalia fuciphaga). Ibis 122, 447461.
Lillywhite, H. B., and Brischoux, F. (2012). Is it better in
the moonlight? Nocturnal activity of insular cotton-
mouth snakes increases with lunar light levels.
Journal of Zoology 286,194199. doi:10.1111/j.1469-
Lim, C. K., and Cranbrook, E. (2002). Swiftlets of Borneo:
Builders of Edible Nests.pp. 10 + 171. (Natural
History Publications (Borneo), Borneo: Kota Kinabalu,
Manchi, S. (2009). Breeding ecology of the edible-nest swift-
let (Collocalia fuciphaga) and the glossy swiftlet (Collocalia
esculenta) in the Andaman Islands, India. PhD disserta-
tion, Department of Zoology, Bharathiyar University,
Coimbatore through Sálim Ali Centre for Ornithology
and Natural History, Coimbatore. 150 pp.
Manchi, S., and Mane, A. (2012). Conservation of the edible-
nest swiftlets in the Andaman and Nicobar Islands. Sálim
Ali Centre for Ornithology and Natural History, report to
the department of environment and forest, Andaman and
Nicobar Islands, pp. 144.
Manchi, S., and Sankaran, R. (2010). Foraging habits and
habitat requirements of the edible-nest swiftlet and the
glossy swiftlet in the Andaman Islands. Wilson Journal of
Ornithology 122(2), 259272. doi:10.1676/09-144.1
Manchi, S., and Sankaran, R. (2014). Protection of the white-
nest swiftlet Aerodramus fuciphagus in the Andaman
Islands, India: An assessment. Oryx 48(2), 213217.
Mane, A. M., and Manchi, S. S. (2013). Abundance of the
potential predators around the edible-nest swiftlets breed-
ing caves at Baratang Island. In Ecosystem Services and
Functions of Birds. (Eds R. Jayapal, S. Babu, G. Quadros,
P. R. Arun, P. Pramod, H. N. Kumara, and P. A. Azeez.)
proceedings of the second international conference on
indian ornithology. pp. 4445. (Salim Ali Centre for
Ornithology and Natural History: Coimbatore, India.)
Mazerolle, M. J. (2006). Improving data analysis in herpetol-
ogy: Using Akaikes Information Criterion (AIC) to assess
the strength of biological hypotheses. Amphibia-Reptilia
27,:169180. doi:10.1163/156853806777239922
Medway, L. (1962a). The swiftlets (Collocalia) of Niah cave,
Sarawak. Part I. Breeding biology. Ibis 104,4566.
Medway, L. (1962b). The swiftlets (Collocalia) of Niah cave,
Sarawak. Part II. Ecology and the regulation of breeding.
Ibis 104, 228245. doi:10.1111/j.1474-919X.1962.tb08648.x
Medway, L. (1967). The function of echo navigation among
swiftlets. Animal Behaviour 15, 416420. doi:10.1016/
Medway, L., and Pye, J. D. (1977). Echolocation and systema-
tics of swiftlets. In Evolutionary Ecology. (Eds B.
Stonehouse and C. Perrins.) pp. 225238. (Macmillan:
Morrison, D. W. (1978). Lunar phobia in a neotropical fruit bat,
Artibevs jamaicensis (Chiroptera: Phyllostomidae). Animal
Behaviour 26,852855. doi:10.1016/0003-3472(78)90151-3
Mougeoto, F., and Bretagnolle, V. (2000). Predation risk and
moonlight avoidance in nocturnal seabirds. Journal of
Avian Biology 31, 376386. doi:10.1034/j.1600-
Nelson, D. A. (1989). Gull predation on cassins auklet varies
with the lunar cycle. The Auk 106(3), 495497.
Nguyen, Q. P. (1992). Breeding biology and moult in the
edible-nest swiftlet, Collocalia fuciphaga germane,Oustalet
1878 in Vietnam. Oiseau et Revue FrancaisedOrnithologie
62, 149161.
Nguyen, Q. P., Yen, V. Q., and Voisin, J. (2002). The White-
Nest Swiftlet and the Black-Nest Swiftlet.pp. 297. (Société
Nouvelle des Éditions Boubée: Paris.)
Powell, C., Bradley, S., and Wooller, R. (2008). Is colony
attendance by shearwaters influenced by bright moonlight
or inclement weather? Papers and Proceedings of the Royal
Society of Tasmania 142,3543.
Price, J. J., Johnson, K. P., and Clayton, D. H. (2004). The
evolution of echolocation in swiftlets. Journal of Avian
Biology 35, 135143. doi:10.1111/j.0908-8857.2004.03182.x
R Studio Team. (2015). R Studio: Integrated Development
for R.(R studio, Inc.: Boston, MA.) Available at http:// [Verified 28 November 2015].
Rahman, M. S., Kim, B.-H., Takemura, A., Park, C.-B., and
Lee, Y.-D.. (2004). Effects of moonlight exposure on
plasma melatonin rhythms in the seagrass rabbitfish,
Siganus canaliculatus.Journal of Biological Rhythms 19(4),
325334. doi:10.1177/0748730404266712
Ramenofsky, M., Agatsuma, R., and Ramfar, T. (2008).
Environmental conditions affect the behavior of captive,
migratory white-crowned sparrows. Condor 110(4), 658
671. doi:10.1525/cond.2008.110.issue-4
Riou, S., and Hamer, K. C. (2008). Predation risk and repro-
ductive effort: Impacts of moonlight on food provisioning
and chick growth in manx shearwaters. Animal
Behaviour 76, 17431748. doi:10.1016/j.anbehav.2008.
Sankaran, R. (2001). The status and conservation of the
Edible-nest Swiftlet (Collocalia fuciphaga) in the
Andaman and Nicobar Islands. Biological Conservation
97, 283294. doi:10.1016/S0006-3207(00)00124-5
Smit, B., Boyles, J. G., Brigham, R. M., and McKechnie, A. E.
(2011). Torpor in dark Times: Patterns of heterothermy
are associated with the lunar cycle in a nocturnal bird.
Journal of Biological Rhythms 26(3), 241248. doi:10.1177/
Tarburton, M. K. (1987). The population, status and long-
evity of the white-rumped swiftlet in Fiji. Corella 11,
Tarburton, M. K. (2009). Swiftlet behaviour responses to
predators in proximity to their nests. Corella 33,99102.
Tarlow, E. M., Hau, M., Anderson, D. J., and Wikelski, M.
(2003). Diel changes in plasma melatonin and corticoster-
one concentrations in tropical Nazca boobies (Sula granti)
in relation to moon phase and age. General and
Comparative Endocrinology 133(3), 297304. doi:10.1016/
Thomassen, H. A. (2005). Swift as sound. Design and evolu-
tion of the echolocation system in Swiftlets (Apodidae:
Collocaliini). Docotral Thesis, Institute of Biology,
Faculty of Mathematics & Natural Sciences, Leiden
University, Netherlands.
Trillmich, F., and Mohren, W. (1981). Effects of the lunar
cycle on the galápagos fur seal, Arctocephalus galapagoen-
sis.Oecologia 48(1), 8592. doi:10.1007/BF00346992
Usman, K., Habersetzer, J., Subbaraj, R., Gopalkrishnaswamy,
G., and Paramanandam, K. (1980). Behaviour of bats during
alunareclipse.Behavioral Ecology and Sociobiology 7,7981.
Waugh, D. R., and Hails, C. J. (1983). Foraging ecology of a
tropical aerial feeding guild. Ibis 125, 200217.
Woods, C. P., and Brigham, R. M. (2008). Common poorwill
activity and calling behavior in relation to moonlight and
predation. The Wilson Journal of Ornithology 120(3), 505
512. doi:10.1676/06-067.1
York, J. E., Young, A. J., and Radford, A. N. (2014). Singing
in the moonlight: Dawn song performance of a diurnal
bird varies with lunar phase. Biology Letters 10(1),
20130970. doi:10.1098/rsbl.2013.0970
Zar, J. H. (2008). Biostatistical Analysis,4th edn. pp. 661
+120. (Tan Prints (1) Pvt. Ltd: India.)
... Swiftlets are known to flock near their breeding and roosting sites during dawn and dusk while leaving or returning to their roosts (Tarburton 2009;Mane & Manchi 2017). The cave-dwelling swiftlets are usually known to be vulnerable while entering and exiting the caves (Mane & Manchi 2017). ...
... Swiftlets are known to flock near their breeding and roosting sites during dawn and dusk while leaving or returning to their roosts (Tarburton 2009;Mane & Manchi 2017). The cave-dwelling swiftlets are usually known to be vulnerable while entering and exiting the caves (Mane & Manchi 2017). The present study, however, is the first to document aerial predation of swiftlets by the Besra around human-habitation. ...
... Flying in flocks equips the swiftlets to successfully evade predators. The time of arrival at the roost (Mane & Manchi 2017 and the speed used for entering the breeding/roosting sites (Tarburton 2009) are counted as the anti-predatory behaviors of the swiftlets. ...
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We report the crepuscular hunting behavior by the Besra Accipiter virgatus, on the Glossy Swiftlets Collocalia esculenta affinis and the Edible-nest Swiftlets Aerodramus fuciphagus inexpectatus in urban areas the Andaman & Nicobar Islands. Unlike other raptors in the islands, the Besra hunts at twilight often in the absence of moonlight or/and artificial light. Glossy and Edible-nest Swiftlets have been ranched in human habitations and their nests harvested for livelihood support of local communities under an ex situ conservation program. Using the focal animal sampling method, we recorded the hunting behavior of the Besra (the predator) on the swiftlets (the prey) for 40h (120 min/day for 20 days) at the ex situ swiftlet colony established in a house in the Middle Andamans. The Besra made 84 hunting attempts, with the highest success rate (15.4%) between 17.00–18.00 h. The catch rate was a mean of 4±11 (SD) per day. The maximum time that was used for attempt to kill the prey was two hours. Depredation of the Edible-nest Swiftlet by the Besra could affect ex situ conservation efforts, which can also lead to economic losses and retaliation against the raptor. Restricting perch sites for the raptor around ranching houses might reduce predation risks for the swiftlets.
... Later, Sankaran and Manchi (2008) adopted the same method to study the population of the Andaman Edible-nest Swiftlet in the caves of the North and Middle Andaman Islands. Further, as part of ongoing studies, Mane and Manchi (2017a) studied the effect of select biotic and abiotic factors on the roosting patterns of the species on the Baratang Island in the Andaman Islands. Recently, Ramji et al. (2013) used a similar method to explore the roosting behavior of the group-living White-nest Swiftlet (A. fuciphagus) in a house in Sarawak. ...
... To further the study published by Mane and Manchi (2017a) from Baratang Island, we now present spatiotemporal variations in the roosting movements of the species in relation to time, day length, and timing of sunrise and sunset at 3 different study sites. ...
... Our results regarding the effect of sunrise and day length at different sites show that the variation in some environmental factors at different locations do affect roosting movements of the species. Spatial-level studies considering several variables as Mane and Manchi (2017a) and Singh et al. (2015) may further enhance our understanding of the factors responsible for spatial variation in the roosting movement of the species. ...
We collected data from 10 caves (3 sites) in the North and Middle Andaman Islands to determine the spatiotemporal changes in the roosting pattern of the Andaman populations of Edible-nest Swiftlet Aerodramus fuciphagus inexpectatus. The echo-locating diurnal aerial forager showed temporal (hourly) variation in their round the clock entry and exit patterns. With spatiotemporal variations (site wise, cave wise, hourly, and monthly), more than 98% of birds returned daily to the roosting caves between 1700 h and 2000 h. However, their daily departure time (between 0400 h and 0700 h) did not vary spatially (site wise and cave wise). The movements of birds at the cave openings were higher during nestling period in April and May. The daily roosting period inside the caves (525.20 ± 82.98 SD min) also depicted spatiotemporal variations. The length of the day affected the movement of the birds before and after sunset and sunrise. We conclude that roosting movement of the Andaman Edible-nest Swiftlet varied spatiotemporally in the Andaman Islands. This first detailed description of such variations in the roosting movements of the species will stimulate further exploration of the various biological and environmental factors affecting movements of this cave-dwelling endemic.
... Though both the species are in the forest usually reported around the limestone caves, the Masked Palm Civet is comparatively more common (Red List of Threatened Species Duckworth 2016). In Andaman and Nicobar Islands the limestone caves were studied mostly for the Andaman Edible-nest Swiftlet ( ), Plume-toed swiftlet ( ) (Sankaran, 2001;Manchi, 2009;Mane & Manchi, 2017a;Cranbrook ., 2013;Rheindt 2017) and Bats (Chiroptera) (Aul 2014). While searching for the swiftlet nests, we encountered different fauna using such caves. ...
... km. The length between the extremities is about 355 km, while the maximum width of 60 (Kumar, 1981;Saldanha, 1989;Sankaran, 1998;Mane & Manchi, 2017a). ...
... The classif ied caves by Mane & Manchi 2017b, in f ive size classes: Very big (>40 m in length), Big (30-40 m length), Medium (20-30 m length), Small (10-20 m length) and Very small (<10 m length) were surveyed for civet presence. We used earlier classif ication of caves (Sankaran, 1998;Mane & Manchi, 2017a) cave chambers, width and length and also shapes of cave openings (Arch, Circular, Half-Circle, Oval, Rectangular, Triangular, and Irregular). We used vegetation types information around the caves (Champion & Seth, 1968) from the earlier survey (Mane & Manchi 2017b Since all the evidences encountered within the caves were indirect, we are unable to identify the species using these caves. ...
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Civets are one among the introduced mammals in Islands of Andaman and Nicobar. Masked or Himalayan Palm Civet and Large Indian Civet in the Andaman and Nicobar Islands are known to use diverse habitats. However, this is the first documentation of the civets using the limestone caves in the Andaman and Nicobar Islands. The article also tried to correlate the relationship between the physical characteristics of the caves and the presence of civet in it.
... The Edible-nest Swiftlet breeds between December and August and has a clutch size of two eggs with an incubation period of 22-25 days (Manchi 2009). Recent ecological studies (Manchi 2009;Manchi and Sankaran 2011;Mane and Manchi 2017) considered microclimate (temperature and humidity) and physical characteristics of cave surfaces as influential parameters of breeding and roosting habitat of the ENS. Further studies on ENS habitat by Manchi and Sankaran (2011) revealed the importance of nest-site characteristics, nest-site selection, and preference towards nest success. ...
Decision rules allow individuals of a species to decide whether or not to return to the same site in the following year or season, based on their immediate breeding success. We checked the decision rule phenomenon and simultaneously tested the prior-experience hypothesis for the cave-dwelling Edible-nest Swiftlet (Aerodramus fuciphagus inexpectatus; ENS) in the Baratang Cave Complex, Andaman and Nicobar Islands, India. We used the capture-mark-recapture method to understand the decision rule in ENS. Assuming that breeding success affects the decision, we monitored 234 individuals for two consecutive breeding seasons (2017 and 2018). We also documented habitat variables (cave morphometry and microclimate) to understand the correlates of breeding success. We captured 88% (207 birds) of adult birds from the study caves in 2017 and recaptured 66% (137 birds) of adults from the same caves in 2018, which confirmed fidelity towards the cave by the species. There was no significant correlation between the rates of breeding success in 2017 and 2018. Multiple regression models revealed an insignificant relationship between cave structure and breeding success of the species. Additionally, microclimate variables (temperature and humidity) did not influence the breeding success of the birds. Our results indicate that ENS individuals seem to chose decision rule by rejecting the prior-experience hypothesis. The existing conservation strategies associated with enhancing the ENS population in the Andaman and Nicobar Islands can benefit from our findings. We further recommend long-term studies and population monitoring to understand the breeding cave fidelity in ENS.
... The cave complex between Wraffter's Creek and Naya Dera on Baratang Island is spread across 0.77 km 2 (Mane & Manchi, 2017; and has more than 175 limestone caves (Sankaran, 2001;Manchi & Sankaran, 2014;Bandopadhyay & Carter, 2017), mostly inaccessible to people. We surveyed seven accessible caves to study the population and distribution of cave crickets. ...
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Cave-dwelling organisms share different ecological and evolutionary relationships with caves. Based on these interactions, they are categorized as troglobites, troglophiles, and trogloxenes. In India, caves are meagerly explored, and thus cave study is in its infancy in India. Through the present study, we attempted to understand and model the distribution of crickets (Family Phalangopsidae), a critical group of insects-being the primary consumers in the cave ecosystems. We sampled seven caves using belt transects (N = 184; total area covered = 1294.9 m 2) with 1 m width. During the survey, we encountered 818 individual crickets (116.85 ± 47.16 SD per cave). Of these, 87.7% encounters were on walls, 7.09% were on the ceiling, and 5.13% were on the cave floor. We used the Single-species Multi-season occupancy model to calculate the overall, zone-wise, and cave-specific occupancy. Cricket occupancy in Baratang caves is seasonal and highly zonal, with detectability ≤1. The cave with less distinct zones has more consistent occupancies and zero chances of extinction and colonization. Hence, these caves serve as suitable habitat for the source population. A negative correlation of cave morphometric features (cave volume, wall surface area, and floor surface area), and density of crickets (p < 0.05), might need further validation. The study shows the need for detailed studies regarding cricket taxonomy and ecology towards establishing the conservation importance of the species and their habitat in the islands. cave fauna, cave zones, occupancy, subterranean ecosystem, species distribution
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Edible-nest swiftlets have many health benefits. The availability of edible-nest swiftlets from caves is decreasing, while the demand for edible-nest swiftlets is getting higher. Swiftlet farming is carried out to meet this demand. The location of swiftlet farming should be close to the feeding sources. Swiftlet is flying insectivorous animals. A financial feasibility assessment is carried out to determine the feasibility of the business. This study aims to determine the composition of land cover, determine the insect order of feed sources, and analyze the production and financial feasibility of swiftlet farming. The study was carried out from June to December 2019. The composition of land cover was determined using the supervised classification method, the order of insects was known using the insect determination key, while production and financial feasibility were analyzed using the Net B/C, NPV, IRR, and PP methods. The observed location and swiftlet farming were determined purposefully. The results of this study show that the land cover was dominated by shrubs (56.58%) and secondary forest (27.3%); both types of land cover are suitable for swiftlet farming locations. The dominant insects found in shrubs and wetland shrubs are Diptera (78.25%), in rice fields are Diptera (86.7%) and in oil palm plantations are Diptera (29.4%) and Hymenoptera (27.78%). Edible-nest swiftlets harvest begins in the third year, with a production period of between 17-34 years. From the financial feasibility, it can be concluded that swiftlet farming is feasible.
Full-text available
When they have the opportunity, swiftlets nest in totally dark parts of caves. This prevents most predation on eggs, young and incubating adults. However, a few predators are able to either reach the nests or prey on birds flying to and from nests. In response, swiftlets have developed anti-predatory behaviour. To reduce predation, adult birds enter and exit caves in groups, increase flight speed at the entrance (where most predators attack), and feed their young less frequently than comparable species that do not nest in caves. Where there have not been predators consistently at entrances the birds do not form groups but fly singly and slowly. In most colonies a few birds use alternative entrances. Predation at the nest is reduced by adults clumping their nests on high, smooth, overhanging rock surfaces. When such safe surfaces are not available or predators are able to climb the walls, swiftlets respond by spacing nests widely, reducing the chance that a predator will find them.
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The taxonomy of South-East Asian swiftlets (Apodidae, Collocaliini) has proved challenging because of their limited variation in size and plumage colouration. Of particular interest are 'white-nest' swiftlets, whose nests, built almost entirely of hardened secretions from paired sublingual salivary glands, are valued in the edible birds'-nest trade. The natural breeding sites of white-nest swiftlets are caves or grottoes but, for over a century, there has been a progressive increase in numbers occupying man-made structures. Through most of South-East Asia there is now a developed industry, utilising sophisticated practices to attract and retain white-nest swiftlets in purpose-made buildings, known as 'house-farms'-a novel form of domestication. A review of the systematics of wild populations based on museum skins collectedin late nineteenth and early twentieth centuries, before the expansion of house-farms, concludes that there are two largely allopatric species of white-nest swiftlet in Malaysia, identified as Grey-rumped Swiftlet Aerodramus inexpectatus, with subspecies A. i. germani and A. i. perplexus, and Thunberg's or Brown-rumped Swiftlet Aerodramus fuciphagus, with subspecies A. f. fuciphagus and A. f. vestitus. During 2003 to 2010, house-farm swiftlets in southern Thailand, east and west coasts of Peninsular Malaysia, Sarawak, Java and southern East Kalimantan, Indonesia, were photographed to show variability in plumage of the rump. House-farm birds of Sarawak resembled neither of the wild species occurring naturally in the state. Tissue samples from embryos in eggs were collected for genetic studies from house-farms in Medan, Sumatra, west and east coasts of Peninsular Malaysia, and Sibu, Sarawak. Results of phylogenetic analyses, AMOVA and pairwise FST comparison based on the partial cytochrome-b sequence are presented. Of the 11 haplotypes identified, two are restricted to a wild population of Brown-rumped Swiftlets A. f. vestitus of Middle Baram, Sarawak, thereby shown to be genetically distinct from house-farm birds. One haplotype is common among all house-farm birds, two are unique to Medan, three and one to Kuantan and Endau-Rompin, respectively. The birds from Sarawak share haplotypes with all other house-farm populations in Peninsular Malaysia and Medan, Sumatra. The evidence for two clades within house-farm samples indicates that Peninsular Malaysian birds combine genetic components from north (A. inexpectatus germani) and south (A. f. fuciphagus). Sarawak house-farm birds are similar to east coast Peninsular Malaysian populations in plumage characters and genes, and apparently arrived by spontaneous immigration from Peninsular Malaysia. If hybrids have arisen among Malaysian house-farm white-nest swiftlets, they are excluded from regulation by the International Code of Zoological Nomenclature.
During his period of interest in swifts, David Lack drew attention to the importance of nesting behaviour and nest type as guides to the systematics of the Apodidae (Lack, 1956). This approach has been particularly fruitful among the Indo-Pacific assemblage known colloquially as ‘swiftlets’, recognised as a tribe Collocaliini by Brooke (1970) and as a subfamily Collocaliinae by Condon (1975). Among these swifts, in several instances, the type of nest built has proved to be critical in specific determination. Another characteristic exhibited only by the living bird that has claimed attention is the capacity of some (but not all) swiftlets to orientate in darkness by echolocation. Because the component frequencies of the click-like orientation sound fall largely within the range audible to man, it is detectable without instruments in field conditions. As a consequence, the distribution of this capacity among the swiftlets is now reasonably well known. Together with those included in this chapter, sound spectrograms have been published of the orientation clicks of six taxa, representing four species. Tests of the ability to detect and avoid obstacles in darkness have been made on three of these taxa. Data are thus available for evaluating the importance of echolocation in the ecology of these birds, and for considering its significance as a taxonomic character.
Echolocation detection of 3.2 mm obstacles was significantly less than of 6.3 mm and 10 mm obstacles.
In Vietnam this species breeds in island caves from the provinces of Quang Binh to Ha Tien. Over 90% of the population nests in C Vietnam. The study was carried out in caves of Con Dao, Khanh Hoa, Binh Dinh, and Da Nang. Throughout the breeding season data was collected monthly. The swiftlet builds its nest in the dry season and breeds during the first rainy season, when insects are in abundance. The breeding season ends before the second, stormy rainy season. This is clearly an adaptation to meteorological conditions. Generally birds moult after their breeding season (June-December), to avoid energy competition between the two processes. -S.R.Harris
We determined meal size frequency and timing of chick feeding by Cory's Shearwaters at a colony in the Azores by weighing chicks every 4 h. Chicks were fed mainly on fish, but occasionally on cephalopods. Meal sizes delivered to the chicks averaged 60 g (S.D. = 32.2 g). Overnight positive mass increments ranged up to 180 g. Inter-feed mass loss due to respiration and excretion was positively correlated with the chicks' initial masses. The minimum amount of food required by the chicks to maintain constant mass (44.2 g day-1) was well surpassed by actual meal sizes received. The mean growth rate of the chicks (24.8 g day-1) also suggest the presence of a plentiful and nutritious food supply available to the colony. Most feeds were between 2000 h and 0400 h (GMT). The timing of adult returns was, however, dependent on ambient light conditions. Birds fed their chicks less on moonlit nights and tended to return to nests later. This response to variations in nocturnal illumination is in remarkable contrast to the diurnal return of birds of the same species at Selvagem Grande, 1400 km distant. The effects of ambient light on food provisioning behavior may be related to nocturnal food availability rather than predator avoidance by adult birds. Comparisons are made with chick-feeding patterns of other pelagic Procellariiformes.