Notes
on the nesting behaviour of Yellow-footed Green Pigeon Treron phoenicoptera(Columbidae) at Jeypore Reserve Forest, Assam, India
O.S. Devi 1 & P.K.
Saikia 2
1Research Scholar, 2 Associate
Professor, Animal Ecology and Wildlife Biology Lab., Department of Zoology,
Gauhati University, Guwahati 781014, Assam, India
Email: 1 sunan_o@rediffmail.com,2 saikiapk@rediffmail.com (corresponding author)
Date of publication (online): 26 March 2012
Date of publication (print): 26
March 2012
ISSN 0974-7907 (online) |
0974-7893 (print)
Editor:Aziz Aslan
Manuscript
details:
Ms # o2715
Received 21 February 2011
Final received 04 November 2011
Finally accepted 08 February
2012
Citation: Devi,
O.S. & P.K. Saikia (2012). Notes on the nesting behaviour of Yellow footed
Green Pigeon Treronphoenicoptera at Jeypore Reserve Forest, Assam, India. Journal of Threatened Taxa 4(3): 2470Ð2475.
Copyright: © O.S.
Devi & P.K. Saikia 2012. Creative Commons Attribution 3.0Unported License.
JoTT allows unrestricted use of this article in any medium for non-profit purposes,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Acknowledgements: The authors thank the State Forest
Department, Assam for providing necessary permissions to conduct the research
work Jeypore Reserve Forest. The authors are also thank the Department of
Science and Technology for providing necessary funds to conduct the research
work under a major research project.
Abstract:We surveyed five nesting colonies of Yellow-footed Green
Pigeon at Jeypore Reserve forest to study their nesting behaviour during two
breeding seasons in 2008 and 2009. We observed the birds in five closely-watched nests and studied their
behaviour starting from pair formation till hatching of squabs. Pair formation generally starts from
the month of April followed by nest building and incubation, with ultimately,
hatching of squabs during May, which continues up to the month of June. Both sexes share the duty of nest
building and incubation. Breeding
pairs took four shifting intervals during incubation period at a time interval
of about 2Ð5 hrs in each shift. Incubation period ranges between 20Ð23 days.
Keywords:Behaviour, Columbidae, incubation, Jeypore Reserve Forest, squabs,
Yellow-footed Green Pigeon.
For figures, images, tables -- click here
The
Yellow-footed Green Pegion Treronphoenicoptera (Columbidae) has been given the status of Least
Concern (Birdlife International 2010). They belong to the important frugivorous group of tropical forests and
perform the valuable service of seed dispersal and forest regeneration (Stiles
1985; Corlett 1998; McConkey et al. 2004) and in some cases are the sole vector
for seed dispersal of certain tree species (Meehan et al. 2005). Data on their ecological and biological
aspects is deficient as very few studies have been conducted on the Columbidae
group as a whole (Wiley & Wiley 1979; Burger et al. 1989; Steadman 1997;
Bancroft et al. 2000; Strong & Johnson 2001; Walker 2007). The Yellow-footed Green Pigeon is
widely distributed throughout the Indian subcontinent and is a commonly sighted
frugivorous bird in the tropical forests of eastern Himalaya (Ali & Ripley
1987). Very few studies are
conducted on columbids in India (Ali & Ripley 1987) and some studies are
mostly based on morphological adaptations (Bhattacharya 1994). Birdlife International (2010) placed
this species under Least Concern category owing to its wide distribution and
abundance but there is little information on its eco-biological aspects. Therefore, the present study was
conducted to present preliminary data on biology of Yellow-footed Green Pigeon
with special reference to its nesting behaviour.
Study area
The Jeypore Reserve Forest
is located at Dibrugarh District of Upper Assam which falls between 27006ÕÐ
27016ÕN & 95021ÕÐ95029ÕE
(Image 1). The total area of the
reserve is 108km2. The
terrain of the reserve is slightly undulating and is continuous with the
forests of Arunachal Pradesh. Burhi-Dihing and the Dilli rivers form a part of the reserve
boundary. Many small perennial
streams and nullahs also
flow within the Forest. Swamps and
grassland patches also occur inside the forest (Kakati 2004). This forest is a part of an important
IBA - the Upper Dihing West Complex, IBA Site No. IN-AS-45 and is notified as a
reserve forest way back in 1888 (Kakati 2004). The habitat is tropical rainforest. Champion & Seth (1968) described it
as ÒAssam Valley Tropical Wet Evergreen ForestÓ (category 1B/ C1) also called
the Upper Assam Dipterocarpus-MesuaForest. The forest is
characterised by a top canopy dominated by Dipterocarpus macrocarpus reaching
heights of 50m, a middle canopy dominated by Mesua ferrea and Vatica lanceaefoliaand undergrowth consisting of woody shrubs such as Saprosma ternatum, Livistonia jenkinsianaand canes Calamuserectus etc. (Kakati 2004).
Methods
We studied the Yellow-footed
Green Pigeon at Jeypore Reserve Forest between January 2008 and December 2009
for two years and made observations on its nesting behaviour. Visits were made on the five nesting
colonies encountered during the breeding seasons starting from early April to
late July each year.
Pigeon activities were
observed using binoculars (8x40 and 7x35). Telephoto lenses (135Ð500 mm) on
35mm still cameras were used to record behavioural activities. Digital camcorders were also used to
film the behavioural activities which were later analyzed. Behavioural
sequences were timed with a wristwatch. Observations at five closely watched
nests were made from an elevated platform about 5Ð10 m from the
nests. At the nests, at least two
hours each was spent recording pigeon activities at morning
(0600Ð0800 hr), noon (1100Ð1300 hr) and evening (1600Ð1800
hr) but these timings changed according to weather conditions. Bad weather hampers bird activities as
observed personally in case of the pigeons.
All nests located were
assigned numbers and were plotted on maps of the study area. In general, activity at the closely
watched individual nests was checked every two days throughout the breeding
period starting from nest building to hatching of squabs.
Results
Pair formation: Pair
formation usually started in the month of April at Jeypore Reserve Forest in
2008 and 2009. At this time, birds
were seen flying together, feeding together, roosting and preening together in
pairs on feeding trees (Image 2a).
It was observed that formation
of pairs usually began when the male pigeon starts calling from a perch
simultaneously performing a ÒtailÐwaggingÕ dance display. Whenever a pigeon landed near its
territory, the resident male flew to the newly arrived pigeon and started
displaying with the dance and Òwooh-woo-whoo-wooÓ whistle. If the arriving pigeon was a female
then she stayed near the displaying male in a submissive posture. Chasing of females by displaying males
was frequently observed until the arriving female gave in and joined the male
in the dance. During the first days of
pair formation, the pairs allo-preened, fed and rested together in suitable
tree branches.
Courtship and Copulation: Courtship
display among the Yellow-footed Green Pigeon was usually started by the male
calling from a prominent perch. Whenever a female arrived at the perch, the male started to
perform the display by turning 1800 on the perch, then he expanded
his throat subsequently bowing deeply and making the Ôwooh-wooÕ sound. Afterwards he spread his tail and
turned another 1800 and repeated the display. Initially, the female remained still
watching the male perform but later on she joined the male and eventually moved
close to the male in a submissive posture. After about five seconds, the male stepped onto the femaleÕs
back and twisted his tail under the femaleÕs tail to make cloacal contact. During the act, the male gave a quick
wing flutter and then stepped off the femaleÕs back. The copulation lasted for about three seconds and the pair
stayed on the branch for about 10Ð15 minutes before they set off to the
nearby fruiting trees. Courtship
and copulation were mostly seen during early morning 0600Ð0800 hr and
evening 1600Ð1800 hr respectively during our study period.
Nest building: Building of
nests by the Yellow-footed Green Pigeon was watched closely at five nests for
more than 50 hours. It was
observed that both the sexes share the duty of nest building, although the male
did majority of the work ranging from gathering of nest materials to delivering
while the female sat on the nest mending it (Image 2b). Most of the nest building activity
occured between 0700Ð0930 hr and 1500Ð1800 hr. Nest materials such as twigs were
collected from dried branches of trees about 20Ð40 m from the nest sites. The twig gathering areas were defended
against intruding pigeons. The
male pigeon broke suitable twigs from the branches and carried towards the nest
and the waiting female gently arranged it into the nest structure securely.
Apart from these, the frequency
of nest building by the parents was maximum during the early stage of nest
building activities but it gradually declined during later stages. The frequency of nest building trips
was maximum during the 2nd and 3rd day which gradually
decreased in the following days (Table 1).
Exchange of incubation duty: Both male
and female pigeons shared the duty of incubation (Image 2c). They were seen exchanging incubation
duty about four times a day at an average interval of 2Ð4 hours depending
upon the weather condition and food availability.
Two nests were closely
watched during 2008 and 2009 at Jeypore Reserve Forest to determine the time
interval between each shift and it was found that the average time interval
between each shift in Nest 1 which was on a Bombax
ceiba tree was approximately 3, 4 and 2 hours respectively between 1stÐ
2nd, 2ndÐ3rd and 3rdÐ4thshifts. Similarly, the average
time interval at the Nest 2 which was on a Michellia
champaca tree was found to be 4, 2 and 3 hours respectively between 1stÐ2nd,
2ndÐ3rd and 3rdÐ4thshifts (Fig. 1).
It was also observed that
shifting incubation duty was delayed and took longer time when the food source
is far from the nesting tree and it took place regularly when plenty of food
was available near the nest.
Clutch size: The clutch size of
Yellow-footed Green Pigeon, ranged from 1Ð2 in all the live nests located
during 2008 and 2009. Eggs are
spotless white, typical Columbidae, about 5cm long and weigh about
9.5Ð14.3 g.
Nest exchange behaviour: During
shifting of incubation, the breeding pair showed some peculiar behaviour while
exchanging their duty (Image 2d). The incoming bird stayed on the perch for about 30Ð40 minutes,
preening and resting before going to the nest. Sometimes the bird also whistled in a typical Ôwhoo- woo-
whoo-wooÕ sound by frequently moving its tail. After this, the other bird sitting on the nest earlier,
responsed to the advertisement call of the incoming bird by moving its tail rhythmically. Both the pair moved their tail for
about two minutes before the incoming bird slowly walked inside the nest and
checked the eggs. The resident
bird then flew away to the nearby fruiting tree.
Nesting season and days of incubation: During the study period of two years, the nesting season started during the month of
April and ended by June.
During the breeding season
of 2008, seven live nests were discovered near Tipam Mandir and were watched
closely for nesting behaviour and incubation period. The average incubation period of five nests was 23 days
while two nests were destroyed by storm on the eleventh and fifteenth days of
incubation (Fig. 2). One squab
each hatched on all the five successful nests. In 2009, pair formation and nest building was observed from
the first week of May. A total of
twelve live nests were closely watched for nesting behaviour and incubation
periods. The average incubation
periods of seven nests was 21 days and one squab each were hatched in six nests
while one nest hatch had two squabs (Fig. 2). The remaining five nests were abandoned or destroyed before
hatching due to heavy storm and thus were not successful.
Post-hatching behaviour: It was
observed that nest attentiveness declined after hatching of the young one. The nest with newly hatched young
squabs were left a unattended for few hours after the fourth day of hatching
and was largely unattended after the tenth day of hatching. After the tenth day
the parents come to the nest only to feed the young and left soon after
feeding. Sometimes they stayed on
the nearby perch to protect the young from predators as in one case the parents
were seen chasing away a crow which circled the nest.
Discussions
The Jeypore Reserve Forest
is one among the few remaining tropical forest patches of eastern Assam
which is unique for its varied avian fauna (Saikia & Devi 2011). The present study was one of the
few attempts to gather valuable data regarding the birdÕs nesting behaviour and
breeding biology.
From the study it was
revealed that the breeding season of Yellow-footed Green Pigeon starts from
April and lasts till June at the study area. The season may start even earlier in other areas, but no birds
were observed to breed during March here. Pair formation and nest building starts by early April and they make
open nests of mostly twigs in tall trees near the forest edges and human
habitation areas. It is
interesting to note that during the two breeding seasons, not a single nesting
colony of Yellow-footed Green Pigeons were encountered inside the closed
forest. Both sexes were seen
sharing nest building and duty of incubation. As per the observations, only one or two squabs are hatched
as the clutch sizes were normally one or two eggs per pair and that the days of
incubation range between 20Ð24 days. Parental care and nest attentiveness declines after 10 days
post hatching of squabs and parent were seen chasing away predators such as
crows, hawks etc. during the first few days after hatching.
It may be mentioned that
the present population status of Treronphoenicoptera in the wild is unknown but evidences suggest
that the species might be facing serious threat from habitat loss and hunting
(Walker 2007). Long-term
population monitoring and ecological studies are required immediately.
Conservation programs must also focus on these least studied important
frugivores which are abundantly available now-a-days but might become rare and
threatened in the near future if left unchecked.
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