ADALYA JOURNAL ISSN NO: 1301-2746

VARIATION IN PREY SUCCESS RATE OF (Anastomus oscitans) AT SEMBANARKOIL REGION, NAGAPATTINAM DISTRICT, TAMILNADU,

Thangarasu Meganathan* and Paul Jeevanandham

PG and Research Department of Zoology, T.B.M.L.College, Porayar - 609307, Tamilnadu, India.

*Corresponding author: [email protected] ABSTRACT Variation in prey success rate of Asian AnastomusoscitansatSembanarkoil region were studied at different foraging bout during the study period from 2017 to 2018. During this study period 213 in 2017 and 185 in 2018 foraging bout were observed. Conservable variation was found in prey success rate among the different season (One-Way ANOVA F=5.23 P=0.00 in 2017 and F=3.45, P=0.01 in 2018) and (F=23.24, P=0.00 in 2017 and F=10.76, P=0.00 in 2018).The mean of prey success was higher in post monsoon and compared with summer season (Student t-test= 2.23, P=0.02 in 2017 and t=3.34, P=0.01 in 2018). Agriculture habitat was higher prey success rate recorded 1.61 and 1.30 in 2017 and 2018 respectively. Lowest mean of prey success was recorded in riverine, pond habitat. Variation of the prey availability was statically significant with between the agriculture and riverine (Student t-test=2.94, P=0.00 in 2017, t=3.93, P=0.00 in 2018). Variation of the prey availability was statically significant with between post monsoon and summer season (t=3.36, p=0.001 in 2017 and t=1.89, P=0.05 in 2018). Relationship between availability of prey and prey success rate was positively correlated in both years and different habitat during study period. Present study revealed that variation of prey success rate directly associated with availability of prey. Keywords: Variation, prey success rate, season, habitat, prey availability. I. INTRODUCTION All organisms are foraging such a way so as to increase the net rate of energy intake due to ultimately maximize the reproductive success. Through this aspect several studies have been conducted for past five decades. It is widely accepted that group foraging of is increasing possibility of finding more resources. The resources are limited it can varied in relation to seasonal and spatial (Güitrón-López et al. 2018). The finding a prey in different area are more crucial in lifetime and at the same time decreased vulnerability to predator.Therefore, population size or group size at foraging site for finding a feeding habitat and gathering information on food patch at a gathering spot such as nest site selection, risk, roosting area and food resources. Rich habitats give a higher fitness (to the organism giving them), whereas poor habitat give lower fitness (Johnson 2007). How rich and poor are defined in also important for survival of offspring and adult (Meganathan and Urfi 2009). Nineteen of are found globally (Hancock et al.1993). There are nine species of stork present in India (Ali and Ripley 1994). Asian Openbill Stork Anastomus oscitans is a large wading bird among the storks belong to the family of ciconiidae. It is found mainly in the Indian subcontinent and Southeast Asia (Hancock et al.1993). It is very commonest stork in India feeding on mollusks, crabs and small fishes (Anam et al.2016). In this paper the feeding habitat selection by Asian Open bill stork is discussed. Some studies have been focused with feeding habitat selection by this species in other region. But there is no study conducted on prey success rate of the Asian Openbill Stork in Nagapattinam District, Tamilnadu, India. The main objective of this study is to understand variation in prey success rate of Asian Openbill Stork at foraging in different season, habitat and in relation to availability of prey.

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II. MATERIALS AND METHODS 1. Study Area Nagapattinam District is one among 35 Districts of Tamil Nadu, India. The District has an area of 2715.83 sq. km. It is bounded by Bay of Bengal on the east, the Palk Strait on the south, the Thiruvarur District on the west and Cuddalore District on the north. The present study was carried out in Sembanarkoil region (32sq. km) at Tharagambadi Taluk, Nagapattinam District (11º 06' N, latitude 79º 44' E longitude) in the Cauvery Delta of Tamil Nadu (Fig.1). Study was conducted more than 15 villages surrounded in Sembanarkoil. The area is dominated by wet agricultural lands with paddy (Oryza sativa) being the predominant crop cultivated. Other crops also cultivated include cotton, sugarcane, groundnut, banana, pulses and other cereals. Four seasons were distinguished at the study area based on rainfall viz., monsoon (October-December), post-monsoon (January-March), summer (April-June) and pre-monsoon (July-September). In general January is the coolest month and May is the warmest month in the study area (Meganathan and Jeevanandham 2017a). Figure-1 showing the map of India (A) followed by TamilNadu (B), Nagapattinam District (C) and Study Area (D) covered 32 sq km in Sembanarkoil region along with Cauvery and Manjalaru rivers (Sources from; Meganathan and Jeevanandham 2019a).

2. Methods During the study period 213 in 2017 and 185 in 2018 foraging site were recorded. Site characteristics, date, time of day type of habitat, flock size, prey availability and other relevant parameters were recorded. Habitat type was categorized into five different habitats viz., riverine, stream, pond, marshy and agriculture followed by Pramanik et al. (2016). Observation was made throughout the day in foraging site by using binocular (7X50). The flock size was identified by pointing the binoculars towards the flock and by counting the number of individuals. At each foraging ground number of preys were estimated by sampling 1m2 quadrate and each quadrate prey species including the number of mollusks, broken shell, live specimen and crab species were estimated (Meganathan and Jeevanandham 2019b). Behavioural observation was recorded using the focal sampling method (Altman, 1974). Observation was made periodically in different hours of day at foraging site using binocular, and the duration of observation was five minutes. A digital stop watch and hand tally counter were used to recorded number of prey success. Prey success was counted with

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hand tally counter for each five minutes of feeding bout. Prey success rate was estimated by number of preys caught per minute (Meganathan and Jeevanandham 2019c). 3. Data Analysis Descriptive statistics were computed for all relevant data. Spatial and seasonal variation of prey success rate and prey availability pooled data for five different habitats viz., riverine, stream, pond, marshy and agriculture, and four seasons such as pre monsoon, monsoon, post monsoon and summer were also been recorded. Prey success rate and prey availability compared with seasonal and habitat variation was studied using a One-way ANOVA test. Student t-test was used for comparing means between habitats and season. Pearson correlation was calculated for analysing the relationship between prey availability and prey success rate in during study period. III. RESULTS 1. Variation in prey success rate Considerable variation was found in prey success rate of Asian Openbill Stork among the habitat (One-way ANOVA F=23.24, P=0.00 in 2017 and F=10.76, P=0.00 in 2018) and (F=5.23 P=0.00 in 2017 and F=3.45, P=0.01in 2018) during the study period. The high mean value of prey success rate was recorded in agriculture and low mean value in pond habitat (Table-1). The mean prey success rate was significantly differed between years; Mean ± SD 0.95±0.75 (n=213) in 2017 and 0.80±0.60 (n=185) in 2018 respectively (F=4.99, P=0.02). The highest mean value of prey success rate was recorded during post monsoon and monsoon season in 2017 and 2018 (Table-2). The mean of prey success was higher in post monsoon and compared with summer season (Student t-test= 2.23, P=0.02 in 2017 and t=3.34, P=0.01 in 2018). Table-1. Prey success rate of Asian Openbill Stork at foraging site in different habitats during study period 2017-2018. Habitat type 2017 2018 Mean ± SD (N) Mean ± SD (N) Riverine 0.61±0.51 (42) 0.46±0.41(36) Stream 0.65±0.55(36) 0.68±0.52(36) Pond 0.58±0.43(42) 0.67±0.42(39) Marshy 1.14±0.71(42) 0.95±0.62(39) Agriculture 1.61±0.81(51) 1.30±0.69(35) One-way ANOVA F=23.24, P=0.00 F=10.76, P=0.00

Table-2. Prey success rate of Asian Openbill Stork at foraging site in different seasons during study period 2017-2018. Seasons 2017 2018 Mean ± SD (N) Mean ± SD (N) Post Monsoon 1.22±0.66 (63) 0.90±0.51(36) Summer 0.80±0.73(57) 0.67±0.50(36) Pre monsoon 0.75±0.86(54) 0.67±0.67(39) Monsoon 1.03±0.63(39) 1.00±0.65(39) One-way ANOVA F=5.23, P=0.002 F=3.45, P=0.018

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2. Prey Availability The mean prey availability values between year was not significant (5.93±3.67, n=213) in 2017 and (5.81±3.48, n=185) in 2018 respectively (One-way ANOVA F=0.06, P=0.79). Variation of mean prey availability was found to be significantly different among the habitat (Table-3). The high mean value of prey availability was recorded in agriculture and marshy habitat. Variation of the mean prey availability was statically significant with between the habitat’s agriculture and riverine, (Student t-test=2.94, P=0.00 in 2017, t=3.93, P=0.00 in 2018). The high mean value of prey availability was recorded during post monsoon and monsoon season (Table-4). Variation of the mean prey availability was statically significant with between post monsoon and summer season (t=3.36, p=0.001 in 2017 and t=1.89, P=0.05 in 2018). The relationship between the availability of prey and prey success rate was positively correlated (Pearson correlation in 2017 and 2018 (Fig-2). Figure -2. Showing the relationship between prey success rate and prey availability in different habitat during study period 2017-2018.

Riverine-2017 Stream - 2017

y = 0.1369x y = 0.1268x

2 R² = 0.8806 2.5 R² = 0.826 1.5 2 1.5 1 1 0.5

0.5 Prey success Preysuccess rate/m Prey success Preysuccess rate/m 0 0 0 5 10 15 0 5 10 15 Prey availability (m²) Prey availability (m²) Pond -2017 y = 0.1242x y = 0.1722x

Marshy-2017 1.5 R² = 0.9319 R² = 0.8004 3 2.5 1 2 1.5 0.5 1

0.5 Prey success Preysuccess rate/m

0 Preysuccess rate/m 0 0 5 10 15 0 5 10 15 Prey availability (m²) Prey availability (m²) y = 0.2243x Agriculture-2017 Riverine -2018 y = 0.1135x R² = 0.91 4 2 R² = 0.4324 3 1.5 1 2

1 0.5

Prey success Preysuccess rate/m 0 0 Prey success Preysuccess rate/m 0 5 10 15 0 5 10 15 Prey availability (m²) Prey availability (m²)

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Pond - 2018 Stream - 2018 y = 0.1206x

y = 0.1253x + 0.0246

R² = 0.748 2.5 2 R² = 0.6292 2 1.5

1.5

1 1

0.5 0.5 Prey success Preysuccess rate/m 0 Preysuccess rate/m 0 0 5 10 15 0 5 10 15 Prey availability (m²) Prey availability (m²)

Agriculture -2018 Marshy -2018 y = 0.1422x y = 0.1702x R² = 0.609 R² = 0.7027 3 2.5 2.5 2

2 1.5

1.5 1 1

0.5 0.5 Preysuccess rate/m Preysuccess rate/m 0 0 0 5 10 15 0 5 10 15 Prey availability (m²) Prey availability (m²)

Table-3. Prey availability of Asian Openbill Stork at foraging site in different habitats during study period 2017-2018. Habitat type 2017 2018 Mean ± SD (N) Mean ± SD (N) Riverine 4.78±3.11 (42) 4.22±2.20(36) Stream 5.58±3.24 (36) 5.97±3.25(36) Pond 5.00±2.65 (42) 5.20±2.68(39) Marshy 6.57±4.11 (42) 6.43±4.21(39) Agriculture 6.94±3.95 (51) 7.25±4.01(35) One-way ANOVA F=3.35, P=0.01 F=4.29, P=0.00

Table -4. Prey availability of Asian Openbill Stork at foraging site in different season during study period 2017-2018.

Seasons 2017 2018 Mean ± SD (N) Mean ± SD (N) Post Monsoon 7.14±3.00 (63) 6.70±3.18(48) Summer 5.21±3.26 (57) 5.61±3.22(49) Pre monsoon 4.33±3.52 (54) 4.16±3.30(49) Monsoon 6.69±3.96 (39) 7.02±3.64(39) One-way ANOVA F=8.09, P=0.00 F=6.96, P=0.00

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IV. DISCUSSION Birds are deciding where to forage in relation to various factors including biotic and abiotic factors while this may differ depending on the individual fitness. Many large wading birds suddenly depend on the external environmental factor like rainfall. This variation was found in large wading birds in relation to water level of foraging sites (Gimenes and Anjos 2011). Ali and Ripley (1987) and Urfi (1998) also suggest that monsoon pattern linkage with availability of prey in storks. Evaluating foraging habitat selection, and foraging success of wading birds in a system which is controlled by prey availability (Hollander et al.2013) and it is a powerful tool in understanding how seasonal changes as India. Storks mainly prefer foraging habitat depending on the water depth. Water depth is playing a vital role for the prey success of Black-necked Stork asiaticus in Dudwa National Park, UttarPradesh (Maheswaran and Rahmani 2002). Water depth was negatively correlated with prey success rate of Asian Openbill Stork (r=-0.14 in 2017 and r=-0.204 in 2018) and availability of prey (r=-0.18 in 2017 and r=-0.31 in 2018). As the water depth increased the success rate decreased due the reason that visual foraging of Asian Openbill stork and lesser depth was preferred for capturing prey in this region (Meganathan and Jeevanandham 2019d).

The success rate varies in relation to different habitat. In the agriculture habitat success rate was higher, compared when with the other habitats, while availability of prey also higher. This variation is directly associated with availability of prey and rich prey availability present in agriculture habitat. Majority of feeding habitat preference by Asian Open bill Stork in agriculture habitat was reported by Meganathan and Jeevanandham (2019a). Lantz et el. (2011) stated that effect of Emergent vegetation on the foraging success and habitat selection of wading birds in the Everglades. Many studies have been reported that natural habitat is lost due to increasing urbanization and preferred large wading birds shifting over to agriculture habitat. So, further study is needed for this aspect. Although the availability of prey species occurred higher at agriculture and marshy habitat, particularly in pre-monsoon period was recorded by Meganathan and Jeevanadham (2017a). The study suggested that influence by amount of rainfall is major factor for availability of Species and variation of success rate in relation to habitat because of abundance of prey. Therefore, during the pre-monsoon season increasing the prey availability and prey success rate also maximized. Agriculture land used by the bio-fertilizer will enriched the density of prey for bird species particularly the large wading bird like herons, egrets, storks, ibises etc, (Meganathan and Jeevanadham 2017b). It certainly leads to the rich avian diversity in agro- ecosystem since the avian species also help the pest control in agriculture field (Regmi 2003).This information may be further useful for conservation, as the study animal is categorized as the Least Concern (Birdlife International 2001). V. CONCLUSIONS The present study revealed that variation of prey success rate of Asian Openbill Stork in relation to different season and habitat. The higher prey success rate was recorded in pre monsoon and monsoon season. In the agriculture and marshy habitat prey success rate and prey availability was higher in compared with riverine and pond habitat. The prey success and availability of prey are directly associated with the habitat.

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VI. ACKNOWLEDGEMENT We thanks to the Principal, HOD Department of Zoology, T.B.M.L. College, Porayar for providing necessary facilities during the study period. VII. REFERENCES 1. Ali, S., Ripley, S.D. 1987: Handbook of the Birds of India and Pakistan; Oxford University Press, Delhi; 737pp. 2. Anam, J., Ahmed, M., Saikia , M. K., Saikia, P.K. 2016. Food and feeding behavior of Openbill Stork Anastomus oscitans in Assam, India . Journal of Global Biosciences.5(6), 4188-4196. 3. BirdLife International.2001. Threatened birds of Asia: theBirdLife International Red Data Book. Cambridge. U.K.: BirdLife International. 4. Güitrón–López, M. M., Huerta–Martínez, F. M., Báez–Montes, O., Estrada–Sillas, Y. F.and Cha-pa–Vargas, L., 2018. Temporal and spatial variation of waterbirds at Sayula Lagoon, Jalisco, Mexico: a five year winter season study. Arxius de Miscellània Zoològica, 16: 135–150. 5. Gimenes, M.R., Anjos. L.do.2011. Quantitative Analysis of Foraging Habitat Use by Ciconiiformes in the Upper Paraná River Floodplain, Brazil. Brazilian Archives of Biology and Technology54(2): 415-427. 6. Hancock, J.A., Kushlan, J.A., Kahl, M.P. 1993: Storks, ibises and Spoonbills of the World. Academic Press. London. 7. Hollander, F.A., Titeux, N., Dyck, H, V. 2013. Habitat-dependent prey availability and offspring provisioning explain an ecological trap in a migratory bird. Functional Ecology 27: 702–709. 8. Johnson, M. D. 2007. Measuring habitat quality: a review. The Condor 109: 489– 504. 9. Kalam, A., Urfi, A.J. 2008. Foraging behaviour and prey size of the ( leucocephala).Journal of Zoology 274: 198–204. 10. Lantz, S.M., Gawlik, D. E., Cook, M. I. 2011. The Effects of Water Depth and Emergent Vegetation on Foraging Success and Habitat Selection of Wading Birds in the Everglades. Waterbirds. 34 (4): 439- 447. 11. Maheswaran, G., Rahmani, A.R. 2002. Foraging behaviour and feeding success of the black-necked stork Ephippiorhynchus asiaticus in Dudwa National Park, Uttar Pradesh, India. Journal of Zoology 258: 189-195. 12. Meganathan, T., A.J.Urfi .2009. Inter-Colony Variations in Nesting Ecology of Painted Stork (Mycteria leucocephala) in the Delhi Zoo (North India). Waterbirds.32(2): 352-356. 13. Meganathan, T., P. Jeevanandham, 2017a. “Seasonal and Spatial Variation of Flock Size of Asian Openbill Stork Anastomus oscitans at Foraging Site in Nagapattinam District, Tamilnadu, India”. International Journal of Advanced Scientific Research & Development (IJASRD), 04: 56– 62. 14. Meganathan, T., P. Jeevanadham, 2017b. “Morphometric Variations on Apple Snail Pila globosa (Swainson, 1822) at Foraging Selected Site of Asian Openbill Stork Anastomus oscitans in Sembanarkoil Region, Nagapattinam District, Tamilnadu, India”, International Journal of Scientific Research and Modern Education. 2(2) 86-94. 15. Meganathan, T., P. Jeevanandham, 2019a. Population size and feeding habitat preference of Asian Openbill Stork Anastomus oscitans in relation to availability of prey at Sembanarkoil region, Nagapattinam District,

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Tamilnadu, India. Journal of Emerging Technologies and Innovative Research (JETIR). 6 (4):257-263. 16. Meganathan, T., P. Jeevanandham, 2019b. Prey and Prey size-selection of Asian Openbill Stork Anastomus oscitans inSembanarkoil region at Nagapattinam District, Tamilnadu, India. International Journal of basic and applied research. 9 (9):132-140. 17. Meganathan, T., P. Jeevanandham, 2019c.Foraging behaviour of Asian open bill Stork Anastomus oscitans in Different Habitat at Sembanarkoil Region, Nagapattinam District, Tamil Nadu, India. A Journal of Composition Theory. 12 (8): 46-51. 18. Meganathan, T., P. Jeevanandham, 2019d. Water quality parameters in foraging site of Asian open bill Stork Anastomus oscitans at Sembanarkoil region, Nagapattinam District, TamilNadu, India. The International journal of analytical and experimental modal analysis. 11 (7): 1071-1077. 19. Pramanik, A.K., Santra, K.B., Manna, C.K. 2016. Some Observations on Breeding Behaviour of the Asian Open-Billed Stork (Anastomus oscitans) in the Raiganj Wildlife Sanctuary, West Bengal, India. International Research Journal of Environment Sciences. 5(9), 10-21. 20. Raynor, E. J., Beyer, H.L., Briggs, J. M., Joern, A. 2017. Complex variation in habitat selection strategies among individuals driven by extrinsic factors. Ecology and Evolution.7:1802–1822. 21. Regmi,N. 2003. Role of birds in Agricultural Pest Control. Our Nature 1: 68-70. 22. Urfi, A.J. 1998. A monsoon delivers storks. Natural History.107: 32–39.

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