N.V. Nanda Kumar, A. Nagarjuna and D.C. Reddy

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1 World Journal of Zoology 4 (4): , 2009 ISSN IDOSI Publications, 2009 Monsoon Rainfall along South East Coast of the Bay of Bengal and Chronobiology of Pelican Migration to Nelapattu and Feeding Grounds of Bay Back Waters of Pulicat Lake N.V. Nanda Kumar, A. Nagarjuna and D.C. Reddy Department of Fishery Sciences and Aquaculture, Sri Venkateswara University, Tirupati andhra Pradesh, India Abstract: North East monsoon and cyclone storms of the Bay of Bengal along South East coast of Peninsular India bring heavy rainfall associated with major physical changes. It was presumed to act as one of external environmental stimuli for migration of Pelicans (Pelicanus philippensis) to roosting site Nelapattu and feeding grounds Pulicat Lake. Pulicat Lake is the second largest brackish water lagoon of India formed out of back waters of the Bay of Bengal. A four year study on chronobiology of Pelicans, long distant migratory birds, was carried out during the period from showed correlation to rainfall amounts. It is hypothesized and presumed from satellite pictures of cyclonic storms and wind pattern originating from Northern Peninsular India during North East monsoon, changes in temperature regime of the Bay of Bengal, is perceived as major physical change which might induce a confident Pelican s migratory instinct. Key words: Pelican migration Rainfall North east monsoon Bay of bengal Cyclone storms INTRODUCTION between October and December and Pelican numbers. It is hypothesized that monsoon wind pattern, change in Nelapattu bird sanctuary, belonging to Nellore temperature [3], rainfall in South originating from Bay of District, South coastal Andhra Pradesh, India is located Bengal and Indian Ocean due to sweeping down of winds about 30 km west of the Bay of Bengal coast line [1]. It is from Plateaus of Asia and Himalayas which brings rain one of the biggest Pelicanary and roosting site (Figure 1) and cooler weather to South East coast of [3-7] might attracting more than one thousand long distant migratory act as one of environmental stimuli. This research paper birds, Pelicans (Pelicanus philippensis) which feed on described the relationship between Pelican numbers fishes of Pulicat Lake, the second largest brackish water which feed in Pulicat Lake brackish water lagoon extended lagoon in India formed out of back waters of the Bay of in 640 sq km which are formed out of back waters of the Bengal [2]. The sanctuary was established in 1976, with Bay of Bengal and roost after feeding in Nelapattu. total area Ha. The total extent of fresh water tank is Ha having Barringtonia trees in tank bed which MATERIALS AND METHODS specially grows in freshwater stagnant water i.e., a lentic facie. The long distant migratory bird Pelicans Nelapattu bird sanctuary is located approximately (Pelicanus philippensis) visit during North East monsoon 30 km west of coast line of the Bay of Bengal in Nellore from October/November onwards, roost and breed upto District and hence the mean rainfall amount of East March/April. While literature is available on checklist of coastal line of Bay of Bengal covering Kavali, Nellore and migratory birds of Nelapattu and chronobiology, no Chennai (formerly known as Madras) was recorded. attempt had been made to establish a correlation between The coast line of the Bay of Bengal from Kavali to migration of Pelican birds arrival to Nelapattu for roosting Chennai is approximately 200 km. The rainfall amounts and for feeding to Pulicat Lake and their gradual increase were recorded from daily weather INSAT satellite imagery in population in relation to rainfall amounts and pattern. chart and data of India Meteorological Department (IMD) A four year study of was carried out to show and Meteorological Department, Chennai, India provided statistical correlation of rainfall of North-East monsoon to National News Media. The mean rainfall amounts of Corresponding Author: N.V. Nanda Kumar, Department of Fishery Sciences and Aquaculture, Sri Venkateswara University, Tirupati , Andhra Pradesh, India 256

Fig. 1 (a): Pelicans roosting at Nelapattu bird sanctuary Fig. 1 (b): Feeding at Pulicat Lake sea mouth shallow water Kavali, Nellore and Chennai were recorded.

and Chennai. years 2006-07, 2007-08, 2008-09 and 2009-10 from Pelican (Pelicanus philippensis) birds identified as September to December.

2 Fig. 1 (a): Pelicans roosting at Nelapattu bird sanctuary Fig. 1 (b): Feeding at Pulicat Lake sea mouth shallow water Kavali, Nellore and Chennai were recorded. The INSAT RESULTS AND DISCUSSION Satellite imageries were retrieved from News media weather charts provided by India Meteorological Table 1 gives weekly mean rainfall amount for the Department, Pune and Chennai. years , , and from Pelican (Pelicanus philippensis) birds identified as September to December. The mean rainfall amounts of 200 described by Salim Ali and Repley [8]. Pelican numbers km the Bay of Bengal coast line at Kavali, Nellore and were observed by direct observation and counted at Chennai was recorded. Monthly and weekly wise rainfall 6.00 to 6.30 p.m. using Binoculars [1]. The Pelican amounts and pattern are different for the years numbers were counted during bird arrival from September (Table 1 and Figure 2). The total rainfall amount and to December every year and also with technical help from Pelican numbers showed statistical correlation (Table 2). the Divisional Forest Officer, Government of Andhra In the year 2006, the total rainfall amount from September Pradesh Sullurpet, Nellore District who manage Nelapattu to December was 717 mm and Pelican (adult) numbers bird sanctuary. Photographs of Pelicans were taken before were 800. In the year 2007 the total mean rainfall was rainfall and after rainfall. The bird numbers were counted 824 mm and total Pelican (adult) numbers recorded were and the rainfall amounts were recorded from September to For the year 2008 total mean rainfall amount was December for the years from Birds arrive in 718 mm and Pelican numbers were 964 mm. For the year graded batches lasts upto December depending upon 2009 total mean rainfall was 747 mm and Pelican numbers rainfall pattern and the adult Pelican numbers remain the were The Pelican numbers not only were dependent same from December onwards and raising chicks in on total rainfall, but also show correlation to graded December/January. rainfall amounts (Table 1 and 2). However, in the 257

3 Table 1: Correlation of Pelican (Pelicanus philippensis) migration and numbers to North East monsoon and rainfall amounts Premonsoon North East monsoon season September October November December Year Rainfall (mm) Pelican Numbers Nil Nil Nil Nil Nil Nil Nil Nil Nil Nil Year 2007 September October November December Rainfall (mm) Pelican Numbers Nil Nil Nil Nil Year 2008 September October November December Rainfall (mm) Pelican Numbers Nil Nil Nil Nil Nil Nil Nil Nil Year 2009 September October November December Rainfall (mm) Pelican Numbers Nil Nil Nil Nil Nil Nil Nil Nil Rainfall: Mean rain amounts of Chennai, Nellore and Kavali covering 200 km South East coast of the Bay of Bengal Table 2: Table showing statistical correlation between Pelican numbers and rainfall Year Month r value p value Significance Sample Rainfall Vs Pelican Numbers 2006 November ns 4 Rainfall Vs Pelican Numbers 2006 December * 4 Rainfall Vs Pelican Numbers 2007 October ** 4 Rainfall Vs Pelican Numbers 2007 November ns 4 Rainfall Vs Pelican Numbers 2007 December ** 4 Rainfall Vs Pelican Numbers 2008 November ns 4 Rainfall Vs Pelican Numbers 2008 December ns 4 Rainfall Vs Pelican Numbers 2009 November * 4 Rainfall Vs Pelican Numbers 2009 December ns 4 ns = Not Significant; * = Significant at 0.05 level; ** = Significant at 0.01 level year 2008, rainfall amount in October was scanty required amount of rain along South East coast of India recording mm and Pelican numbers were nil. the Pelicans arrive at Nelapattu. Table 1 and Figure 2 (a-d) nd th Whereas, the same year in November 2 to 4 week the show mean rainfall amounts and Pelican numbers rainfall amount was 332, 372 and 690 mm. respectively and recorded weekly and monthly wise for the year the number of Pelicans were 542. Whereas in December It is a significant observation that Pelicans arrive in the rainfall amount was 719 mm correspondingly the batches in graded numbers with gradual increase in Pelican numbers were 632, 910 and 964, thus showing an numbers depending on graded increase in rainfall apparent correlation, but not statistically significant amounts [Table 1 and Figure 1 (a,b)]. A model recording correlation to rainfall. of INSAT Satellite pictures are shown for the year 2009 for the months September to December to substantiate Pelican Migration Associated with Monsoon Rains, above presumption. The INSAT picture Figure 3a showed Low Pressures, Depression and Cyclones of Bay of a clear cloud-free South East on Bay of Bengal on Bengal: The Figure 3(a-l) and Figure 4(a-f) INSAT th September The monsoon was less active Satellite imagery showing monsoon clouds, depression, recording 234, 237 and 277 mm in I, III and IV week of storms and atmospheric changes above South East Bay September 2009, respectively recording absence of of Bengal during North East monsoon. In our observation Pelicans. Whereas similar situation existed until 29 we opined that when monsoon are active and bring October recording only 1.5, 2, 2 and 45 mm rainfall. 258 th

4 (a) (b) (c) (d) Fig. 2(a-d): Graph showing North East monsoon rainfall amounts from October to December and Pelican numbers from The INSAT fig. 3b showed active monsoon along South showed active monsoon, low pressure turning into deep th East coast of the Bay of Bengal on 29 October followed depression (Figure 3k) and a cyclonic storm Figure 3(l). by high rainfall amounts within a few days i.e., in These atmospheric physical factors i.e. low pressure and November recording mean rainfall amount (200 km South depression over Bay of Bengal resulted in heavy rainfall East coast line) 374, 557, 609 and 623 mm in I, II, III and IV and the total cumulative mean rainfall (November + week, respectively. Accordingly, Pelicans arrival followed December) was 703, 716, 770 and 798 mm, respectively, and their number showed a gradual increase. The INSAT coincidentally the Pelican numbers recorded at roosting pictures fig. 3(c-h) showed monsoon activity with cloud site at Nelapattu bird sanctuary (Table 1) was 1258, 1309 formation, a visible change in atmosphere recording and 1346 in I, II and IV week of December 2009 heavy rainfall as mentioned above in The Pelican respectively. Similar trends were observed for the years numbers in Table 1 show 7, 576, 1008 and 1013 Pelican 2006, 2007 and 2008 showing graded rainfall amounts and numbers in I, II, III and IV week, respectively at roosting Pelicans numbers (Table 1) and statistical correlation site in Nelapattu bird sanctuary thus corresponding to (Table 2). It is presumed that north to South East to West rainfall amount in the year The Pelicans arrived in wind direction diagonally across India [4] and East to graded increasing number from 7 to 1013 showing a direct West wind direction over the Bay of Bengal and correlation to rainfall amount (Table 2). Interestingly Peninsular India as seen in Figure 4(a-f) delineated by st one important observation was that the 1 batch of arrows and the associated temperature, other physical seven Pelicans which visited in first week of November changes, coupled ocean-atmosphere dynamics over presumed to act as indicators or pilot Pelicans initiating a Indian oceans [3-7] might act as external environmental follow up by 576, 1008 and 1013 Pelicans in I, II, II and IV stimuli for Pelican migration to South East coast. It is week of November Further the INSAT Figure 3(i-l) hypothesized and presumed from above satellite pictures 259

5 Fig. 3(a-l): INSAT Satellite pictures showing monsoon clouds, cyclone storms/depressions in Bay of Bengal for the model year 2009 which bring rainfall to South East coast of Bay of Bengal. See North East monsoon clouds 3(b-h) and cyclonic storm and depression 3(j-l) 260

N.V. Nanda Kumar, Principal Investigator, regime of the Bay of Bengal perceived as major physical thanks University Grants

6 Fig. 4(a-f): INSAT pictures showing wind pattern during North East monsoon of cyclonic storms [Figure 3(a-l)] and wind pattern ACKNOWLEDGEMENT [Figre 4(a-f)] originating from Northern Peninsular India during North East monsoon, changes in temperature Prof. N.V. Nanda Kumar, Principal Investigator, regime of the Bay of Bengal perceived as major physical thanks University Grants Commission, New Delhi change [3-7] inducing a confident Pelican s migratory [UGC No.F /2008 (SR)] for financial instinct. assistance. 261

7 REFERENCES 5. Kothawale, DR., A.A. Munot and H.P. Borgaonkar, The temperature variability over Indian Ocean 1. Nanda Kumar, N.V., A. Nagarjuna and D.C. Reddy, and its relationship with Indian summer monsoon Vertical gradient and resource partitioning of rainfall. Theoretical and Applied Climatology, migratory birds on Barringtonia tree in Nelapattu 92(1-2): bird sanctuary. World J. Zoology, 4(3): Kripalini, R.K. and Pankaj Kumar, North 2. Nanda Kumar, N.V., A. Nagarjuna and D.C. Reddy, East monsoon variability over South Peninsular India Remote sensing and field studies on narrowing vis-à-vis the Indian Ocean dipole mode. Intn. J. of three sea mouths of Pulicat Lake Sanctuary and Climatology, 24: ecological impact. World J. Fish and Marine Sci., 7. Parthasarathy, B., A.A. Munot and D.R. Kothawale, 1(4): All India monthly and seasonal rainfall series 3. Baviskar, S.M., Weakening of lower toposhperic Theoretical and Applied Climatology, temperature gradient between Indian landmass and 49(4): neighbouring Oceans and its impact on Indian 8. Ali, Salim and S.D. Ripley, Handbook of Birds of monsoon. J. Earth. Syst. Sci., 118(4): India and Pakistan, Vol. 1, Oxford University Press. 4. Barry, R.G. and R.J. Chorley, In: Atmosphere, weather and climate. Routledge, London. 262

LONG- TERM CHANGE IN PRE- MONSOON THERMAL INDEX OVER CENTRAL INDIAN REGION AND SOUTH WEST MONSOON VARIABILITY

LONG- TERM CHANGE IN PRE- MONSOON THERMAL INDEX OVER CENTRAL INDIAN REGION AND SOUTH WEST MONSOON VARIABILITY *S.S. Dugam Indian Institute of Tropical Meteorology, Pune-411008 *Author for Correspondence