Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 June 2024 | 16(6): 25345–25359
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8323.16.6.25345-25359
#8323 | Received 14
December 2022 | Final received 09 April 2024 | Finally accepted 07 May 2024
Nesting habits of Baya Weaver Ploceus philippinus (Linnaeus, 1766) on power and television
cables in the agricultural landscape of Kallakurichi
district, Tamil Nadu, India
M. Pandian
No. F1901, AIS Housing Complex, Natesan Nagar West, Virugambakkam,
Chennai, Tamil Nadu 600092, India.
Editor: H. Byju,
Coimbatore, Tamil Nadu, India. Date
of publication: 26 June 2024 (online & print)
Citation: Pandian,
M. (2024).
Nesting habits of Baya Weaver Ploceus
philippinus (Linnaeus, 1766) on power and
television cables in the agricultural landscape of Kallakurichi
district, Tamil Nadu, India. Journal of Threatened Taxa 16(6): 25345–25359. https://doi.org/10.11609/jott.8323.16.6.25345-25359
Copyright: © Pandian 2024. 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: None.
Competing interests: The author declares no competing interests.
Author details: M. Pandian has completed M.Sc., Ph.D., in botany and BLIS from University of Madras and Bachelor of Education (B.Ed.) from Annamalai University, Chidambaram and now serves in Tamil Nadu Police Department. His area of interest is ecology and nesting biology of birds and published a few papers on House Sparrows, Baya Weavers, Streaked Weaver and Black-breasted Weaver, Grey Francolins, Indian Flying Fox, munias and Ring-necked Parakeets.
Acknowledgements:
I thank D. Balaji (Mailam), and K. Sriram (Rettanai) for assistance in collection of data and
photography, A. Giridharan (Minnal),
T. Selvapandian (Narasingapuram),
P. Poornima, DFO (Odisha), and N. Eswari (Virudhachalam, Cuddalore
District) for data analysis/ preparation of study area map.
Abstract: The nesting habits of Baya Weaver Ploceus philippinus with nesting site (e.g., power and
television cables), source of nest materials, various developmental stages of
nests, abnormal nests, number of individuals and their association with other
bird species, and threats to their nests were studied between March and
September 2021 in the agrarian landscapes of 42 villages in Kallakurichi
District, Tamil Nadu. A total of 155 nest colonies containing 1,725 nests of
various developmental stages and 1,993 adult birds were counted on power/television
cables. The number of nests per colony found varied from one to 57. The average
number of nests per colony was eleven. Baya Weaver
had preferred power/television cables as nesting sites in the study area in
spite of availability of potential nest-supporting trees, such as Cocos
nucifera and Borassus flabellifer within 500 m radii from cables bearing
nests. Birds used fibres of sugarcane leaves (Saccharum officinarum)
for the construction of nests. Out of 778 helmet stage nests observed, 90% (n =
716) helmet stage nests had clay deposits on their inner walls and no clay
deposits were found in the remaining 10% (n = 62) helmet stage nests. Eleven
types of abnormal nests constituted 17% (n = 286) of the total nests. Sixteen
other bird species (e.g., birds of order: Passeriformes, Coraciiformes,
Piciformes, Cuculiformes
and Columbiformes) were found associated with the
individuals of Baya Weaver. These bird species
strictly shared similar roosting and foraging grounds. The avian predators such
as House Crow Corvus splendens,
Large-billed Crow Corvus macrorhynchos, Black Drongo Dicrurus macrocercus,
Rufous Treepie Dendrocitta vagabunda, Coucal Centropus senegalensis, and Shikra Accipiter badius
had damaged the nests, eggs and chicks. The study revealed that about 1.1%
nests (n = 197) were probably damaged by these avian predators. Power cables in
the study sites had provided suitable nesting sites for Baya
Weavers. The causes for utilization of power cables as nesting sites in larger
geographical areas require further studies.
Keywords: Abnormal nests, associated
birds, clay deposits, communal roosting, nest material, nest predation,
threats.
INTRODUCTION
Baya Weaver Ploceus philippinus (Linnaeus, 1766) (Aves: Passeriformes: Ploceidae) is a gregarious, social, polygamous, colonial
nester and they are commonly distributed in the Indian subcontinent (Ali et al.
1956), Java, Malacca, and Sumatra (Blyth 1845; Wood 1926), Nepal, China,
Indonesia, Laos, Myanmar, Singapore, Thailand, and Vietnam (BirdLife
International 2016). Several authors have studied the breeding biology (Ali
1931; Ali et al. 1956; Ambedkar 1964; Mathew 1976) and abnormal nesting behaviours of this bird in India (Ambedkar 1964; Crook
1964; Sharma 1989; Pandian & Natarajan 2018; Pandian 2021). Baya Weavers used leaf fibres of
Indian Date Palm Phoenix sylvestris and
Sugarcane Saccharum officinarum
as nest materials for construction of nests (Pandian 2021, 2023). Nests of Baya Weavers were found attached to telegraph wires running
through sugarcane fields along the Chittoor-Chandragiri routes (Kirkpatrick
1952), Kumaon Terai region,
Uttarakhand (Ambedkar 1969), Assam and Tamil Nadu (Davis 1976), and
Mysore-Bangalore-Chennai regions (Subramanya 1982). Incidents of Rufous Treepie
Dendrocitta vagabunda
damaging nests and anthropogenic factors causing damages to nests and
nest-supporting trees were recorded in Vellore and Viluppuram
districts, Tamil Nadu (Pandian 2021, 2023). The IUCN Red List of Threatened
Species has classified Baya Weaver under ‘Least
Concern’ (LC) (Birdlife International 2016) category.
In this
paper, I sought answers to questions relating to choice
of power cables for nest construction by Baya Weaver
with specific reference to Kallakurichi District,
Tamil Nadu. The following were the objectives of the study: (1) extent and
pattern of selection of cables for nesting, (2) preference of cables and
proportions of selection of potential nest-supporting trees for construction of
nests, (3) features of nest building including sources of nesting material,
stages of nest developments, plastering of clay on inner walls, and abnormal
nests with variations, (4) association with other bird species, and (5) threats
faced by the nest colonies. Detailed studies on the constructions of nests on
power cables in Tamil Nadu are still scarce. Hence the present study was
carried out to fill this gap.
MATERIALS AND METHODS
Study Area
The present
study was carried out in 42 villages in Ulundurpet
and Kallakurichi taluks, Kallakkurichi
District of northeastern Tamil Nadu. The district spreads over c. 3,530 km2,
with a human population of c. 13,40,000 (Census 2011) (Kallakurichi
2021). Agriculture is the primary occupation of the people. The major crops of
the area are paddy Oryza sativa, sugarcane, followed by Jowar Sorghum
bicolor, Pearl Millet Pennisetum glaucum, Finger Millet Eleusine
coracana, Groundnut Arachis
hypogaea, Green Gram Vigna radiata, and
Tapioca Mannihot utilisimma.
The practices of monoculture of Casuarina Casuarina
equisetifolia are very common in the district.
Flower and vegetable cultivations also occur. The maximum and minimum
temperatures in the districts are 36oC and 20oC,
respectively. The average annual rainfall is 1,060 mm (Kallakurichi
2021) (Figure 1).
Methods
With help from three field
assistants, I identified 42 villages having definite nesting habitats of Baya Weaver on overhead power transmission cables in the
cultivating lands in Kallakurichi District, Tamil
Nadu. No particular sampling method was adopted, as I followed the entire area
census covering all the arable lands in 42 villages in the district. The nests
attached to the power cables and television cables between two poles and nests
attached to service cables between electric poles and motor pump sets were
considered a single nest colony. These nesting colonies were surveyed on daily
basis covering six villages per day by each field assistant when the birds were
found active from 0600 h to 1200 h and 1500 h to 1800 h between March and
September 2021. Each nest colony was viewed daily continuously for one hour and
recorded number of nests, progress on nest constructions (nesting
developments), male birds plucking of fibres and
carrying clay, and sighting of predators in the vicinity of nest colonies. The
heights of the cables from the ground were ascertained from the data provided
on power transmission poles while heights between overhanging nests and
sugarcane crops, and the distance between the overhanging nests over the bunds
were measured using a dried bamboo stick. Then the length was converted to
standard scales of measurement. The sources of nesting materials was identified by observing the birds which plucked and
carried fibres from nearby sugarcane leaves to the
nesting sites and analysing six fallen and 15 damaged
nests. The types of cultivating crops underneath the overhanging power cables
were recorded. The locations of all the cables that bore nest colonies were
determined using GPS (Gramin Etrex
20x). The nests, their developmental stages, and deposits of clay on the inner
walls of helmet stage nests were observed by using field binoculars (Super
Zenith 20 x 50). In the completed nests, the clay deposits were studied by
dissecting the fallen nests. The nest damages by avian predators and other
factors were observed by binoculars. According to Sharma (1995), abnormal nest
is defined as abnormality in structure of nest or any part of it due to
duplication of part (s) or/and formation of additional part (s) or/and
elaboration of nests or/and abolition of normal parts. All the abnormal nests
built on power cables were photographed and classified based on the guidelines
of Sharma (1995). Type of birds associated with Baya
Weaver during perching/roosting, foraging, and nest predation by avian
predators were observed by using binoculars, without disturbing nests and their
residents. Each nest colony was observed uninterruptedly for 60 min and the
maximum number of birds observed in that colony was counted. Two types of
nest-supporting palms trees (Cocos nucifera and Borassus
flabellifer) present in the area of 500 m radii
around the cables containing nests were completely checked for the presence of
nests. Out of the total such nest-supporting trees observed, the proportion of
trees preferred by Baya Weaver for nesting and the
proportion of trees that were not preferred by the birds for nesting was also taken into account. The distance between nest colonies and
the nearest buildings/ human settlements and roads were measured using
measurement tape. No nesting activities on these trees were studied in detail
except enumerating the number of nesting and non-nesting trees. Utmost care was
taken not to disturb the nests or birds and we maintained a minimum distance of
c. 30 m during observations. Number of live nests, eggs, chicks and adult birds
were neither disturbed nor handled during the study period. Nikon P 1000
digital camera was used for photography. Collected data were tabulated, analysed using SPSS (Statistical Package for Social
Sciences) version 25.0 software and shown as graphical representation. The
relationship between proximity of roads, buildings, human settlement and
selection of cables by Baya Weavers for construction
of nests were also analysed.
RESULTS
A group of males with breeding
plumage started to carry fibres from sugarcane leaves
and plaited knots on power/television cables during third week of May 2021 in
the study sites. A total of 1,725 nests of various developmental stages and
1,993 adult birds were enumerated on 155 nest colonies attached to cables. The
average number of nests in each colony ranged from one to 57. In all the sites
(n = 155), the nesting cables were found overhanging sugarcane crops and no
cable bearing nests was found overhanging other crops (Table 1).
Preference of power/ television
cables for construction of nests
The study revealed that within
500 m radii from the cables bearing nest colonies, there were 2,919 potential
nest-supporting trees, such as Cocos nucifera (n = 2541) and Borassus flabellifer
(n = 378) in 42 villages. Individuals of Baya Weaver
utilized only 1.5% (n = 41) of the total trees for construction of nests. That
is, out of 2541 C. nucifera trees, the birds constructed nests on 25
trees and out of 378 B. flabellifer
trees, the birds constructed nests on 20 trees alone. Proportionately, the
birds preferred more number of B. flabellifer trees than C. nucifera
trees for construction of nests. No nests of Baya
Weavers were found on the remaining 98.5% of potential nest-supporting trees (n
= 2874) of those two palm species (Arecaceae).
Type of nesting substrata
The study revealed that overhead
power transmission aluminium cables bore 80% nests (n
= 1,375) and 80% birds. Another 11% nests (n = 217) and 12% birds (n = 238)
were reported on television cables passing over crop fields and the remaining
9% nests (n = 133) and 8% birds (n = 159) occurred on service cables connected
between electric poles and motor pump sets. The study revealed that out of
1,375 nests enumerated on overhead power transmission aluminium
cables, 17.8% nests (n = 245) were found attached to places/junctures where aluminium cables and reel insulators were connected. In one
instance, the birds plaited knots by joining aluminium
cable and the stem of a climber Cocculus carolinus (Menispermaceae) in
Emam village (11.729701oN & 79.242676oE)
(Image 1a). The stalks of all the nests (n = 217) were found attached to the
places where television cables and supporting strings/rings joined together. Similarly the stalks of all the nests (n = 133) enumerated
on pump set service wires were found attached to multiple cables or at the
junctures of cables and reel insulators (Image 1).
Preference of Baya
Weaver in building nests on cables occurring close to human dwellings
The study
also tested the relationship between proximity of roads, buildings, human
settlement and selection of cables by Baya Weavers
for construction of nests. Cables bore 62.5% nests (n = 1,078) occurred within
100 m radius from constructed structures such as cattle sheds, motor-pump
sheds, isolated human dwellings or buildings in crop fields (Figure 2). Cables
bore 61.4% nests (n = 1,059) occurred within 100 m distance from the nearest
roads. The males select apparently those cables found adjacent to roads with
busy vehicular traffic and movement of general public to build nests (Figure
3). Cables bore 32 % nests (n = 551) occurred within 200 m distance from human
settlements and the birds even built nests on power cables occurring 20 m from
human settlements (Figure 4).
Crops occurred close to nest
colonies
Even though
cables bearing nest colonies directly overhanging sugarcane crops, 63% nests (n
= 1,086) and 67% birds (n = 1,276) occurred within 200 m distance from paddy
crops. Another 37% nests (n = 639) and 33% birds (n = 640) occurred within 250
m distance from paddy and millet crops, such as pearl millet, finger millet,
sorghum, and foxtail millet. Hence, all the cables bearing nests occurred
within 250 m distance from grain and millet crops. It indicated that the Baya Weavers preferred their nesting sites close to grain
crops.
Crop bunds
The study on the relationship
between the distance of nest colonies (n = 155) with bunds in the crop fields
were as follows: two nest colonies were found directly overhanging bunds; 21
colonies were found 1–2 m away from the bunds; 68 colonies at 3–4 m distance;
43 colonies at 5–6 m; 21 colonies at >6 m. The study revealed that only 1.3%
nest colonies (n = 2) were found directly overhanging crop bunds and the
remaining 98.7% nest colonies (n = 153) were found away from bunds and
overhanging sugarcane crops.
Source of fibres
Study on the source of nest
materials revealed that male Baya Weaver used leaves
of Sugarcane Saccharum officinarum
as nesting materials.
Stages of nest constructions
A total of 1,725 nests observed
at the end of the breeding period (2nd week of November 2021) that
included: wad stage nests–3.5% (n = 61), Ring stage–2.8% (n = 48), helmet stage
nests–55.5% (n = 958), egg-chamber closed stage nests–7.2% (n = 125), complete
nests–14.3% (n = 247), and abnormal nests–16.6% (n = 286). An average of 11
nests per colony was found in the study area (Figure 5).
Nest colonies
The number of nests in each nest
colony varied: 63.8% of nest colonies (n = 99) bore nests ranged between 1–10.
These include 13 nest colonies contained solitary nests, whereas 17.5% of nest
colonies (n = 21) bore 11–20 nests, 10.3% nest colonies (n = 16) bore 21–30
nests, 5.2% (n = 8) colonies bore 31–40 nests. The remaining 3.2% nest colonies
(n = 5) contained 41–57 nests. The average number of nests per colony was 11.
The heights between the overhanging nest colonies and the tip of sugarcane
crops were found varied 1–2.5 m. However, nests of 27 colonies were found
directly touching the sugarcane crops.
Abnormal nests
Abnormal nests constituted 17% (n
= 286) of the total nests (n = 1,725) with 11 types of variations: 55% (n =
156) abnormal nests belonged to 1+1/2 storeyed type,
followed by 16% (n = 46) mixed abnormal types, 8% (n = 23) 1+1 storeyed type, 7% (n = 21) chain storeyed
type, 5% (n = 14) ½+½ storeyed, 5% (n = 14) fused
nests, and 2% (n = 6) multi-stalked type. The remaining four nests (2%)
constituted: two nests were bell-jar shaped and one was meshed type and another
nest contained three openings.
Deposition of clay in the nests
The study on 778 helmet stage
nests using binoculars revealed that clay deposits were found in 90% (n = 716)
nests and no such clay deposit was observed in the remaining 10% helmet stage
nests (n = 62). Exceptionally the birds plastered the entire outer walls of 42
completed nests with wet clay. The examination of six fallen nests of such
category reveals that spaces between interwoven fibres
were completely filled with clay and the nests resembled unfired wet clay pots
(Image 3).
Associated birds
The study revealed that 16 other
bird species were found associated with Baya Weaver
during perching/roosting on power cables, sugarcane crops, Prosopis juliflora trees and while foraging on grain/millet
crops. Of them only three other bird species have shared common foraging
grounds. No antagonistic behaviours were observed
between them over sharing of common perching/roosting and foraging sites. All
the bird species had followed mixed communal roosting behaviours.
Apart from that four pairs of Indian Silverbill Euodice malabarica
had occupied complete nests (n = 4) of Baya Weaver,
but it was not possible to ascertain whether they occupied the abandoned nests
or usurped the nests of the latter (Table 2; Image 4).
Nest predation
Six avian predators were observed
in the proximity of nesting colonies. Incidents of nest predation by Rufous
Treepie Dendrocitta vagabunda
(24) and Coucal Centropus
senegalensis (12) were recorded. A total of 197 nests (egg-chamber closed
stage 55; complete nests 82; and abnormal nests 60) were observed in a damaged
condition by having circular holes near egg-chambers or torn the nests (Table
3; Image 5). The study revealed that out of 1,725 nests recorded, about 1.1%
nests (n = 197) were probably damaged by the avian predators.
Nest damages by fire
In one of the nesting sites in Poraiyur village (11.69460N—79.14720E),
an incident of c.300 sq.km area of sugarcane crop below the power cables
bearing nests were gutted to fire probably due to scratching of moit nests after rainfall. In that fire accident, all the
nests overhanging the sugarcane crop were burnt. It was not possible to ascertain the number of
nests gutted to fire. The accidental fire occurred probably due to electrical
short circuits.
DISCUSSION
Preference of cables for
construction of nests
In the study areas, Baya Weavers had commonly built their nests on power
cables. Baya Weavers constructing nests on telegraph
and electric wires are common in India (Bhargava 2017), between Chitttoor and Chandragiri regions (Kirkpatrick 1952), Kumaon Terai region of
Uttarakhand (Ambedkar 1969), Tamil Nadu and Assam (Davis 1976) and between
Bangalore (Bengaluru) and Madras (Chennai) regions (Subramanya 1982). However in the present study, all the nesting colonies (n =
155) were found attached to cables overhanging sugarcane crops corroborate the
findings of Ambedkar (1969), Kirkpatrick (1952), Davis (1976), and Subramanya
(1982). However, no nest colonies were found overhanging paddy crops in the
study areas.
Birds have been found to have
made nests at odd places like electric transmission cables when other suitable
nesting sites were scarce (Toland 1990; Chace & Walsh 2006). However, in
the present study area, it was found that in spite of availability of sufficient
number of potential nest-supporting palm trees (2,874) in a
500-m radii, Baya Weaver chose cables,
indicating that in this instance, it is not the absence of traditional nesting
sites that was reason to choose the cables as found by Toland (1990) and Chace
& Walsh (2006).
Preference of Baya
Weaver in building nests on cables occurring close to human dwellings
Baya Weavers built nests close to human settlement and
foraging sites and also trying to coexist with humans (Ulman 2020). The study
on the relationship between proximity of roads, buildings, and human settlement
and selection of nesting sites, i.e., power/television cables revealed that the
birds preferred to build nests on cables occurred close to areas, such as human
dwellings, buildings like cattle shed and motor-pump sets, and roads as stated
by Ulman (2020). The birds might have selected agricultural landscape due to
the availability of nesting sites like power cables and palm trees and also the
availability of grain crops close to nesting sites as Baya
Weaver are granivorous.
Crop bunds
The preference of nesting sites
on cables away from crop bunds indicate that the birds might have preferred
power cables away from bunds/pathways probably to keep a distance/height from
the reach of humans, and terrestrial predatory animals.
Source of fibres
Baya Weavers were found to have used fibres from palm fronds and grass leaves to construct nests
in Sri Lanka (Wood 1926), coarse grass, paddy, and Phoenix spp.,
in Kolaba District, Maharashtra (Ali 1931), and
paddy, sugarcane, maize, guinea grass and palm fronds in Assam (Ulman 2020),
whereas in this study, the birds used fibres from
leaves of sugarcane alone. Since all the nests were found on cables overhanging
sugarcane crops, the birds had preferred fibres of
sugarcane leaves due to proximity of sugarcane crops than other palm trees.
Nest colonies
Baya Weaver is a colonial bird and
hence lives in large colonies (Ulman 2020). Sharma (1989) had observed that
each nest colony had consisted of 1–250 nests in Rajasthan, 5–24 nests in South
Goa (Borkar & Komarpant
2003), 20–30 nests in Assam (Ulman 2020), and 1–61 nests in Vellore District,
Tamil Nadu (Pandian 2021). In the present study, the number of nests per colony
was found ranging from one to 57 nests.
Nesting substrata
Out of a total of 1,725 nests,
933 nests were found attached to more than one cable or attached at the joints
of cables and reel insulators. But in the remaining 792 nests, the knot of one
nest was found attached to the knot of adjacent nest and in this manner the
knots of all nests were connected adjacently on the cable and formed a mesh
like structure. Probably due to the slippery nature of aluminium
power cables and smooth surface of service/television cables, the birds might
have plaited knots using multiple cables or at the junctures of cables and
insulators. Hence, it revealed that the birds required coarse surface or
sufficient grip on the cables for plaiting initial knots.
Abnormal nests
The behaviour
of construction of abnormal nests also occurs in some other species of the
family Ploceidae, such as Black-breasted
Weaver Ploceus benghalensis,
Spectacled Weaver Ploceus ocularis, African Black-headed Weaver Ploceus cucullatus,
Streaked Weaver Ploceus manyar,
and Sakalava Weaver Ploceus
sakalava (Delacour 1947; Collias
& Collias 1962; Maclean 1985; Mishra 2004). In
India, the abnormal nests of Baya Weaver was studied by several authors like Ali et al. (1956),
Ambedkar (1958), Sharma (1985, 1988, 1995), and Pandian (2018). The present
observations of 11 types of abnormal nests in the study area corroborate the
findings of the authors cited above.
Clay deposits
The habits of smudging of clay in
the nests are common in three species of Asian weavers (P. philippinus, P. manyar,
and P. benghalensis) and not found in
African weaver (Crook 1963; Davis 1973). Plastering of inner walls of nest with
wet clay is done when the nest construction reaches the helmet stage prior to
pairing with females (Dewar 1909; Ali 1931; Ambedkar 1969; Borkar
& Komarpant 2003). Hence, the present
observations of clay deposits on the inner walls of helmet stage nests
corroborate the findings of above authors.
Davis (1973) had recorded that
18.33% nests did not show presence of mud blobs on the inner walls of nests in
South Goa. In the present study also 10% helmet stage nests did not show traces
of clay and hence it matches with the observations of Davis (1973). As a
peculiar feature, plastering of clay on the entire nest walls (n=42) were
observed. Probably the birds might have plastered the entire nest walls with
wet clay to reinforce the nest walls to protect the nests from avian predators.
In this aspect, further detailed study is required.
Associated birds
The mixed communal roosting
consisting of different species serves as centre for
the instant exchange of information regarding the location of food sources and
receives warning about the approach of any predators (Zahavi
1971; Gadgil 1972; Ward & Zahavi
1973; Gadgil & Ali 1975). In the present study
also Baya Weaver was found associated with 16 other
bird species and shares common roosting and foraging sites among them without
any competitions and hence, it matches with the observations of Zahavi (1971); Gadgil (1972);
Ward & Zahavi (1973); and Gadgil
& Ali (1975)
Nest predation
Nest predation by House Crow,
Large-billed Crow, and Rufous Treepie were reported by Ali et al. (1956) and
Pandian (2021). In the present study also incidents of
House Crow and Large-Billed Crow damaging nests of Baya
Weaver were observed. Nest predations by piercing circular hole near
egg-chamber by Rufous Treepie and Coucal were
recorded. Instances of nest damages by Black Drongo
were observed but no predation of eggs/chicks was noticed. It clearly indicates
that these predators might have damaged the nests (n = 197) probably to predate
eggs/chicks. Apart from nest predation, nests damage by electrical short
circuit was also reported in one village. The impact of nest predation by avian
predators and nest damages by short circuit on the breeding of Baya Weaver on larger geographical areas need further
studies.
CONCLUSION
This is a first systematic study
on the preference of Baya Weaver towards overhead
power transmission cables, service cables connected between electricity poles
and motor pump sheds, and television cables as nesting sites, stages of nests,
abnormal nests, associated birds, and threats to the nests in the agrarian
landscape of the study area. The survey revealed that Baya
Weavers preferred and built nests on power cables/television cables and avoided
readily available potential nest-supporting trees, such as B. flabellifer and C. nucifera for
nesting in the study areas. The Baya Weavers had used
only leaf fibres of sugarcane for building nests.
They preferred power cables hanging over sugarcane crops as nesting sites and
shared common roosting sites and foraging grounds with other associated birds.
Increasing urbanization by conversion of cultivated lands into residential
areas, industrialization, widening of roads along with indiscriminate felling
of these principal nest-supporting trees that are vital for Baya
Weaver will pose a threat to the populations of this bird in the landscape.
Considerable damages to nests occurred due to avian predators. The practices of
monoculture of Casuarina, sugarcane, vegetables, and flower crops by
abandoning the traditional cultivation of cereals and millets crops in the
study sites may cause shortage of food grains to adult birds. Though this bird
falls in the least concern status of IUCN, it is better to start protecting the
populations of this species and their habitats. Local communities, particularly
land holders, agricultural workers, and school students should be sensitized to
understand the need to preserve the nesting habitats of this species.
Table 1. Details of villages, GPS coordinates, nest colonies, number of
nests of Baya Weaver, developmental stages of nests,
and number of birds in the study area (as on 2nd week of September
2021).
|
|
Name of the village |
GPS coordinates |
Total no of nest
colonies |
Total no. of nests |
Developmental stages of nests |
Total no. of birds |
|||||
|
Wad stage |
Ring stage |
Helmet stage |
Egg-chamber closed
stage |
Complete nests |
Abnormal nests |
||||||
|
1 |
A. Mazhavarayanur |
11.641323oN–79.207476oE |
1 |
1 |
0 |
1 |
0 |
0 |
0 |
0 |
1 |
|
2 |
Alangiri |
11.720209oN–79.143198oE |
1 |
23 |
0 |
0 |
12 |
0 |
3 |
8 |
26 |
|
3 |
Anganur |
11.742198oN–79.218901oE |
3 |
46 |
2 |
2 |
26 |
7 |
4 |
5 |
55 |
|
4 |
Chithalur |
11.675684oN–79.077867oE |
1 |
24 |
0 |
1 |
12 |
0 |
10 |
1 |
30 |
|
5 |
Elavanasoorkottai |
11.717443oN–79.174617oE |
8 |
133 |
1 |
7 |
57 |
24 |
23 |
21 |
130 |
|
6 |
Eraiyur |
11.775540oN–79.194864oE |
1 |
6 |
0 |
0 |
6 |
0 |
0 |
0 |
6 |
|
7 |
Gudiyanallur |
11.675005oN–79.115207oE |
3 |
13 |
0 |
0 |
11 |
2 |
0 |
0 |
68 |
|
8 |
K.Kunjaram |
11.763302oN–79.176961oE |
4 |
108 |
12 |
0 |
53 |
9 |
16 |
18 |
101 |
|
9 |
Keezha palayam |
11.702912oN–79.193709oE |
2 |
53 |
0 |
0 |
28 |
3 |
16 |
6 |
64 |
|
10 |
Kurur |
11.714977oN–79.035672oE |
2 |
8 |
0 |
0 |
7 |
0 |
0 |
1 |
15 |
|
11 |
Madur |
11.734778oN–79.015647oE |
2 |
53 |
2 |
7 |
28 |
0 |
5 |
11 |
70 |
|
12 |
Mavidandhal |
11.622296oN–79.219110oE |
1 |
11 |
0 |
0 |
10 |
1 |
0 |
0 |
12 |
|
13 |
Moolasamudhiram |
11.703817oN–79.266068oE |
3 |
15 |
0 |
1 |
10 |
3 |
0 |
1 |
18 |
|
14 |
Mugamathiyarpettai |
11.613614oN–79.126747oE |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
|
15 |
Nathakali |
11.720346oN–79.242060oE |
1 |
2 |
0 |
0 |
2 |
0 |
0 |
0 |
4 |
|
16 |
Niraimathi |
11.727576oN–79.015314oE |
2 |
24 |
1 |
4 |
9 |
0 |
0 |
10 |
22 |
|
17 |
P. Konalavadi |
11.720749oN–79.266429oE |
2 |
9 |
0 |
0 |
5 |
2 |
0 |
2 |
10 |
|
18 |
P. Malaiyanoor |
11.689187oN–79.215930oE |
1 |
23 |
0 |
1 |
19 |
0 |
0 |
3 |
38 |
|
19 |
Periyamambattu |
11.730288oN–79.107724oE |
3 |
26 |
0 |
1 |
19 |
4 |
2 |
0 |
30 |
|
20 |
Pinnalavadi |
11.746075oN–79.140752oE |
1 |
20 |
2 |
3 |
8 |
0 |
4 |
3 |
31 |
|
21 |
Poraiyur |
11.694635oN–79.147242oE |
10 |
149 |
1 |
0 |
79 |
7 |
22 |
40 |
153 |
|
22 |
Prithivimangalam |
11.736117oN–79.062063oE |
2 |
22 |
2 |
1 |
10 |
5 |
2 |
2 |
30 |
|
23 |
Pudhukeni |
11.656788oN–79.178831oE |
2 |
9 |
0 |
0 |
9 |
0 |
0 |
0 |
18 |
|
24 |
Pudu Uchimedu |
11.627965oN–79.109939oE |
2 |
45 |
0 |
0 |
8 |
6 |
24 |
7 |
63 |
|
25 |
Ravuthanayankuppam |
11.684929oN–79.267855oE |
3 |
13 |
0 |
0 |
8 |
2 |
2 |
1 |
17 |
|
26 |
Rottumangalam |
11.71844oN–79.153619oE |
1 |
8 |
0 |
0 |
4 |
2 |
0 |
2 |
6 |
|
27 |
Saalapakkam |
11.723739oN–79.156647oE |
4 |
19 |
2 |
1 |
15 |
0 |
0 |
1 |
18 |
|
28 |
Seevamangalam |
11.660459oN–79.170434oE |
3 |
86 |
0 |
1 |
65 |
3 |
7 |
10 |
23 |
|
29 |
Sembatta malayanoor |
11.757158oN–79.218858oE |
7 |
78 |
8 |
2 |
41 |
8 |
8 |
11 |
90 |
|
30 |
Sembimadevi |
11.719075oN–79.160805oE |
5 |
43 |
3 |
0 |
29 |
0 |
5 |
6 |
60 |
|
31 |
Sirunagalur |
11.679898oN–79.157217oE |
4 |
19 |
0 |
1 |
18 |
0 |
0 |
0 |
19 |
|
32 |
Sirupakkam |
11.712586oN–79.225664oE |
1 |
30 |
6 |
1 |
14 |
0 |
2 |
7 |
48 |
|
33 |
Siruvathur |
11.678482oN–79.204069oE |
4 |
20 |
0 |
0 |
17 |
0 |
0 |
3 |
20 |
|
34 |
Thakka |
11.704111oN–79.267421oE |
1 |
4 |
0 |
0 |
3 |
1 |
0 |
0 |
4 |
|
35 |
Thenerikuppam |
11.145194oN–79.138345oE |
9 |
65 |
4 |
3 |
38 |
0 |
9 |
11 |
64 |
|
36 |
Thimmalai |
11.730138oN–79.123026oE |
16 |
216 |
6 |
4 |
110 |
8 |
50 |
38 |
262 |
|
37 |
Tiruppeyar |
11.648811oN–79.200328oE |
2 |
4 |
0 |
0 |
4 |
0 |
0 |
0 |
5 |
|
38 |
Vadakurumboor |
11.774587oN–79.213622oE |
2 |
10 |
0 |
0 |
7 |
2 |
0 |
1 |
11 |
|
39 |
Vazhavandankuppam |
11.724222oN–79.124699oE |
8 |
69 |
0 |
1 |
46 |
8 |
4 |
10 |
94 |
|
40 |
Vellaiyur |
11.722458oN–79.241880oE |
22 |
198 |
6 |
1 |
99 |
18 |
29 |
45 |
237 |
|
41 |
Vengaivaadi |
11.679030oN–79.095074oE |
1 |
7 |
2 |
4 |
1 |
0 |
0 |
0 |
7 |
|
42 |
Emam |
11.736110oN–79.243968oE |
3 |
12 |
1 |
0 |
10 |
0 |
0 |
1 |
12 |
|
Total |
155 |
1725 |
61 |
48 |
958 |
125 |
247 |
286 |
1993 |
||
Table 2.
Details of other bird species found associated with Baya
Weaver during perching/roosting and foraging in the study area.
|
|
Name/common name of
the bird |
Binomial |
Total no. roosting
with Baya Weaver |
Total no. of
foraging with Baya Weaver |
|
1 |
Common Myna |
Acridotheres tristis (Linnaeus, 1766) |
35 |
0 |
|
2 |
Common Babbler |
Argya caudata (Dumont, 1823) |
26 |
02 |
|
3 |
Indian Silverbill |
Euodice malabarica (Linnaeus,1758) |
70 |
07 |
|
4 |
White-rumped Munia |
Lonchura striata (Linnaeus, 1766) |
63 |
13 |
|
5 |
Re-vented Bulbul |
Pycnonotus cafer (Linnaeus, 1766) |
11 |
0 |
|
6 |
Red-whiskered
Bulbul |
Pycnonotus jacosus (Linnaeus,1758) |
08 |
0 |
|
7 |
Coppersmith Barbet |
Psilopogon haemacephalus (Statius Muller, 1776) |
13 |
0 |
|
8 |
Pied Bush Chat |
Saxicola caprata (Linnaeus, 1766) |
23 |
0 |
|
9 |
Grey-breasted Prinia |
Prinia hodgsonii (Blyth, 1844) |
42 |
0 |
|
10 |
Long-tailed Shrike |
Lanius schach (Linnaeus, 1758) |
06 |
0 |
|
11 |
Pied Cuckoo |
Clamator jacobinus (Boddaert,1783) |
17 |
0 |
|
12 |
Asian Green
Bee-eater |
Merops orientalis (Latham, 1801) |
85 |
0 |
|
13 |
Spotted Dove |
Spilopelia chinensis (Scopoli, 1768) |
06 |
0 |
|
14 |
Black Drongo |
Dicrurus macrocercus (Vieillot, 1817) |
127 |
0 |
|
15 |
Common Kingfisher |
Alcedo atthis (Linnaeus, 1758) |
42 |
0 |
|
16 |
Indian Roller |
Coracias benghalensis (Linnaeus,1758) |
35 |
0 |
|
Total |
609 |
22 |
||
Table 3.
Details of sightings of avian predators and their impact on the nesting colony
in the study area.
|
|
Name of the
predator |
Binomial |
No. of sightings
noted |
Damages caused to
nests |
|
1 |
House Crow |
Corvus splendens (Vieillot, 1817) |
12 |
2 |
|
2 |
Large-billed Crow |
Corvus macrorhynchos (Wagler,
1827) |
8 |
1 |
|
3 |
Coucal |
Centropus senegalensis (Linnaeus, 1766) |
15 |
12 |
|
4 |
Black Drongo |
Dicrurus macrocercus (Vieillot, 1817) |
127 |
4 |
|
5 |
Shikra |
Accipiter badius (Gmelin, 1788) |
5 |
2 |
|
6 |
Rufous Treepie |
Dendrocitta vagabunda (Latham, 1790) |
34 |
26 |
|
|
Total |
|
201 |
47 |
For
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