Diurnal activity budgeting
of Large Whistling Teal Dendrocygna bicolor(Vieillot, 1816) (Anseriformes: Anatidae) in Deepor Beel wetlands, Assam, India
Date of publication (online): 26 December 2011
Date of
publication (print): 26 December 2011
ISSN 0974-7907
(online) | 0974-7893 (print)
Editor: Anwaruddin
Choudhury
Manuscript details:
Ms # o2682
Received 26
January 2011
Final received
25 November 2011
Finally
accepted 22 December 2011
Citation: Das,
J., H. Deka & P.K. Saikia (2011).Diurnal activity budgeting of Large Whistling Teal Dendrocygna bicolor(Vieillot, 1816) (Anseriformes: Anatidae) in Deepor Beel wetlands, Assam, India. Journal of Threatened Taxa 3(12): 2263–2267.
Copyright: © Jyotismita Das, Hemen Deka & P.K. Saikia 2011. Creative Commons
Attribution 3.0 Unported 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: Authors acknowledge the University Grant
Commission, New Delhi for providing fund as a Research fellowship to
conduct the PhD works. The authors also acknowledge the Chief Conservator of
forest (Wildlife Division) to provide permission to conduct the work. Again, authors are grateful to Mr.
Mazedul Islam, JRF for providing necessary help regarding field
work.
Abstract: Diurnal activity budgets of the Large
Whistling Teal Dendrocygna bicolor were quantified in Deepor Beel wetlands from March 2007 to January
2008. The study revealed that the
Large Whistling Teal utilized 36.1% of time in resting, 37.1% in locomotion,
21.8% of diurnal time in feeding and 3.9% of diurnal time for preening activity. The teal spent <1% time in each, of
alert and aggressive behaviours.
Keywords: Activity, Deepor Beel wetland, Dendrocygna
bicolor, diurnal, feeding, highest, locomotion,
resting season.
For
figures, images, tables -- click here
The activity budgeting
studies quantify the time allocation of animals in behavioural activities (Rave
& Baldassarre 1989). The
activity budgeting studies of any waterfowl and other migratory birds can
provide an insight into the role of the seasonal use of habitats in relation to the
annual cycles of birds. Activity
budgets coupled with habitat analysis have been useful in formulating suitable
conservation strategies (Paulus 1984). Activity budgets reflect a combination of factors including an
individual’s physical condition, social structure and environmental conditions
(Paulus 1988). The amount of time allocated to various behaviours is therefore
critical in understanding the species’ ecological needs and the pressures
acting upon individuals.
The family Anatidae has 39
species in Assam, of which, seven species are resident and 32 are migratory in
nature (Ali & Ripley 1983). The Large Whistling Teal Dendrocygna bicolor is a Least Concern species
(BirdLife International 2009). This is a residential and local migrant duck often found in mixed
colonies with the Lesser Whistling Teal Dendrocygna javanica. In recent years, many works regarding the ecology and
behaviour of birds in Assam, such as, Barman & Talukdar (1994), Choudhury
(1993), Das & Saikia (2010), Saikia (1995), Saikia & Bhattacharjee (1996
a,b), Saikia (1998, 2000), Devi & Saikia (2010),
Saikia & Saikia (2011), Singh (1995), Singh et al. (1995), Upadhyaya &
Saikia (2009), Upadhyaya & Saikia (2010 a,b) are worth mentioning. However, no attention has been given to
studying the ecology and behaviour of the Large Whistling Teal in this region.
In Deepor Beel wetlands,
the population of the Large Whistling Teal is high (Saikia 2005) in relation to
other such wetlands of Assam. During the study period, the population
of both the Large (n=1160) and the Lesser Whistling Teals (n=8002) were found
to be highest as compared to other avian species. Both the species of teals were found to form large groups
viz., 50–500 individuals of mixed flocks. But no special attention has been made previously to study
activity budgeting of this particular species. The objective of the present study was to quantify the
activity budgets of the Large Whistling Teal in Deepor Beel wetlands, the lone Ramsar site of Assam.
Study Area
Deepor Beel is a large
natural wetland having great biological and environmental importance (Saikia
& Saikia 2010). This large
water body is home to a variety of migratory birds, amphibians, reptiles, insects,
micro and macrophytes, terrestrial weeds, lianas and arborescent taxa of
ecological and economic importance (Bera et al. 2008). The Deepor Beel Ramsar site has a
total area of 40km2 of which 4.14km2 has been declared a bird
sanctuary. At maximum flooding the
beel increases to 4m in depth and during the dry season the depth drops to
about 1–1.5 m. Deepor Beel
(26003’26”–26009’26”N and 90036’39”–90041’25”E)
is situated on the southern bank of the Brahmaputra River (Image 1).
Climate
Deepor Beel has a
meso-thermal climate, characterized by high humidity and moderate
temperature. The temperature
ranges between 10.6– 300C. Most rainfall occurs during the monsoon period (May–September). The pre-monsoon season (March–May)
has a maximum temperature of 270C and a minimum of 240C,
and relative humidity between 50.5–76.8 % (Saikia & Saikia
2010). The monsoon season (May–September)
has a maximum temperature of 320C and a minimum of 27.30C. The relative humidity is 82.5%. The retreating monsoon (September–October)
has maximum and minimum temperatures of 270C and 250C
respectively (Saikia & Saikia 2010). The relative humidity is 82%. The winter season begins in November
and continues until January. The
average field temperature during this period remains at 20±2 0C and
the relative humidity measures about 77.5%. January is the coldest month, with the average minimum
temperature at 70C, but the minimum temperature occasionally reduces
to 60C.
Methods
Focal sampling method
(Baldassarre et al. 1988) was generally used to study the activity of the Large
Whistling Teal in the study area. The study was conducted from March 2008–January 2009 to analyze
the different activity patterns of the Large Whistling Teal. During the survey period the behavioural
data (activity data) were collected at least twice in a month. The total time spent in collecting the
data was 260 hours during the 10-month survey period. Diurnal observations were made using a Canon power shot 110 zoom
camera and 10×50 Zenith binoculars. To test the differences in activities in
an entire daylight period, each day was divided into different time blocks
viz., early morning (0500–0800 hr), morning (0800–1100 hr), midday
(1100–1400 hr), afternoon (1400–1600 hr) and dawn (1400–1800
hr) and activity data was collected from
these pre-divided time blocks. Large Whistling Teal
population data was monitored from a group of mixed colony of Lesser Whistling
Teal Dendrocygna javanica. During the study period a flock (n=50 to 200 individuals) was selected
randomly by pointing the binoculars towards the flock and by selecting birds
closest to eye distance. Activities of each individual bird were monitored every 15 seconds up to
10 minutes. Activities were
categorized as aggression (chasing, biting, threatening), alert (standing or
sitting with head or neck protracted), resting (sleeping & loafing),
feeding (searching & upending), preening (bathing, stretching), locomotion (flying, swimming).
Results
Resting (36.1%), locomotion
(37.1%) and feeding (21.8%) were the most remarkable activities of the Large
Whistling Teal during the study period (Table 1 & Fig. 1). Resting was found to be highest (55.7%)
in January and lowest (18.5%) in May. In winter it was seen that most of the teal engaged themselves in
resting by bending their neck in a peculiar way. However, during the day light hours some were seen to rest
in a standing position also. Sleeping was mainly observed during the early morning, mid day and late
evening hours. Locomotion was
reported to be highest (47.8%) in September and lowest in July (28.1%). Locomotion generally could be seen in
the form of flying, swimming and walking. Generally in low depth areas the teal prefers to walk, but in open water
areas it generally swims to accomplish its purpose. In the case of feeding, the teal absorbed the highest amount
of time (45.4%) in May and the lowest (0.52%) in January. The teal generally used feeding
techniques like head dipping, searching and up-ending. Up-ending is
the process where the teal first inserts one portion of the head and
subsequently the whole body. The
Large Whistling Teal spent 3.9% of diurnal time in preening (Fig. 1). Preening was reported to be highest
during October and November (6.5–6 %) and lowest (0.6%) in June. The parts of the body
which the teal generally preened were the head and the back of the
neck. The Teal spent <1% time in
each of the alert and aggression behaviours. The Time spent in aggression was the highest (0.8%) in
March. Aggression was mostly in
the form of chasing, biting and threatening. The time spent in alert was the highest (1.3%) in January
2008. The teal displays alert
postures by standing or sitting with the head and neck protracted.
Discussion
High resting in January might
reflect the tendency of the teals to rest in warmer day light hours as January
was reported to be the coldest month of the year. Tamisier (1976) had also reported that wintering
waterfowl benefit thermodynamically by feeding at night and preening, resting
and courting during the warmer day light hours. In fact, the teals were seen to rest over the large floating
leaves of Makhana Euryale ferox or other free floating and emergent vegetations. Sometimes, the teals were seen in
standing posture over the vegetation patches.
Again, July–August is
the main breeding season of of the teal, thus, after breeding, the teals have
to move different parts for feeding so, this might be the
reason of highest (47.8%) locomotion activity during September. Likewise,
high feeding in May might be due to the fact that, in monsoon season (May–September)
the beel becomes fully covered with different emergent, free floating and
submerged vegetations. So, the
Teals get sufficient feeding material to fulfill their dietary demands. Similar finding was
reported by Pyke et al. (1977) in which they mentioned that birds were
predicted to allocate the greatest time in habitats with high food abundance
and less in areas with low abundance.
High preening during
October–November might reflect the fact that individuals completing pre-
alternate moult are the first to form pairs. Rave & Baldassarre (1989) had also reported high preening in October and
November while working on activity budget of the Green-Winged Teal wintering in
the coastal wetlands of Louisiana. In waterfowl, as in many birds species, females
prefer brightly adorned males (Andersson 1994), perhaps because males with the
brightest plumages are in the best condition (Hill & Montgomerie
1994). Female ducks also prefer males
that have all of their alternative (breeding) plumage characters fully
developed (Klint 1980; Weidmann 1990; Omland 1996).
Highest aggression in March
might reflect the frequent encountering of both unpaired and paired teal. Paulas (1983) reported the same
findings in case of Gadwalls. Likewise, Rave & Baldassarre (1989) had reported the high agonistic
behaviour in March. High
aggression in March might reflect the pair formation and the establishment of
breeding territory between teals. Tomkins (1944) reported the same case while working on the Wilson’s
Plover.
The major factor affecting
the high alertness during the winter seems to be due to regular hunting of teal
when they form flocks. As winter advances the depth of water of the beel drops to 0.3–0.45
m. As the water level
decreases the bird becomes highly alert due to hunting and other life
threatening risk factors.
Conclusions
The study showed that the
Large Whistling Teal’s activity patterns varied during different months in the
Deepor Beel wetlands. The results
indicate that the whistling teal exhibits great flexibility in adjusting time
budget to maintain its daily requirements. The
study documents that the Large Whistling Teal performs different activity
patterns to utilize the valuable resources of the beel. The duck prefers mostly aquatic
vegetation as a food item. The
Beel is also the breeding ground for both the whistling teal species. But the present degradation processes
in the form of soil digging, encroachment, agricultural activities, habitat
fragmentation in the form of cutting of the beel bed, application of pesticides
brings a great danger to the proper survival of this species. Proper management of the beel habitat is quite
necessary for the proper survival of the wildlife inhabiting there.
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