CLUTCH CHARACTERISTICS AND EGG DIAMETRICS OF INDIAN POND HERON (ARDEOLA GRAYII) IN JAMMU REGION (J&K)

Prof. D. N. Sahi 1 , Prof. Roopama Gandotra 2 , * PawandeepKaur 3 and Dr. Sakshi Koul 4 . 1. Professor, Department of Zoology, University of Jammu. 2. Head, Department of Zoology, University of Jammu. 3. Research Scholar, Department of Zoology, University of Jammu. 4. Research Scholar, Department of Zoology, University of Jammu. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

The present study on clutch characteristics and egg diametrics of Indian Pond Heron (Ardeola grayii) was conducted for three consecutive years i.e., 2013, 2014 and 2015 in five different stations viz., station I (Haripur), station II (Mansar), station III (Gharana), station IV (Kalyana) and station V (Gho Manhasa) during the breeding season which commenced from May up to September. The overall mean clutch size was recorded to be 3.71±1.06 varying from 1 to 5. The clutch size was found to vary among different stations viz., 3.73± 0.76 (n=41) at station I, 4.07± 0.73 (n=14) at station II, 3.68± 0.88 (n=38) at station III, 3.71± 0.85 (n= 32) at station IV and 3.64± 1.02 (n=17) at station V. The eggs were recorded to be oval with greenish blue coloration and without any markings. Overall mean values of egg dimensions were recorded to be egg length (3.90±0.16 cm), egg breadth (2.78±0.19cm), egg volume (15.57±2.41 cm 3 ), egg shape index (71.45±4.95) and egg weight (17.93±2.71gm). A statistically significant correlation was registered between egg length and egg volume (r= 0.4852) as well as between egg breadth and egg volume ( r= 0.8274).

Introduction:-
Indian Pond Heron (Ardeola grayii) commonly known as "Paddy bird" belongs to family Ardeidae of Order Pelecaniformes. It is commonly seen frequenting paddy fields, ponds, reservoirs and other natural wetlands. It usually escapes notice by its dingy coloration until it springs to life with a flash of white wings. It is found throughout much of the Indian sub-continent except parts of northwest, northeast and Himalayas upto 2150m in Nilgiris and 1500 m in Himalayas (Grimett et al. 1998). In many bird species, egg size is often considered an important index of egg quality and is correlated with the survival of their offspring (Murton et al., 1974. Clutch size is one of the fundamental elements of the reproductive strategy of a species, as it represents the number of offsprings that a pair endeavours to produce in a reproductive attempt (Anderson, 2006 475 egg and clutch characteristics are of paramount importance in determining the reproductive success of a species as the combination of egg size and clutch size determines the total energetic investment in clutch formation by a female (Flint and Sedinger, 1992). Thus, the present investigation was conducted to study clutch characteristics and egg diametrics and to analyse the correlation between various egg variables.

Materials and methods:-Study Area:-
The present study was conducted in district Jammu of J&K State. Geographically, it lies between 32º27' and 33º30' N latitude and 74º19' and 75º 20' E longitude. Altitudinally, it extends from 250 meters to 410 meters above mean sea level. During the period of present investigation, five stations were selected in the study area. 1. Station-I: Haripur: The latitude and longitude of this station are 32º36'27.56"N and 74º43'57.29" E respectively and it is located at an altitude of 271 meters from mean sea level. The station is at a distance of 31 km from Jammu city. The main water source at this station is Ranbir Canal. 2. Station-II: Mansar: This station is located at a distance of 64 km east of Jammu city. It lies between 32º41'48.36" N latitude and 75º08'44.70" E longitude at an elevation of 666m above msl. This lake harbours characteristic icthyofauna, amphibians and reptiles and has an intimate association with the wildlife and wild avifauna migratory and non-migratory of the area. 3. Station-III: Gharana, R.S. Pura: It is situated between 32º36'51.52" N latitudes and 74º38'58.15" E longitudes. It is located at an elevation of 251meters from msl. It is at a distance of 35 km from Jammu city. 4. Station-IV: Kalyana: The latitude 32º49'62.69" and longitude 74º73'66.33"are the geo-coordinates of this station. It is at a distance of 26.6 km from Jammu city. The major area of this station is under cultivation. 5. Station-V: Gho-Manhasa: This station lies between 32º43'39.59" N latitude and 74º45'41.36" E longitude at an altitude of 311 m above the mean sea level. It is at a distance of 10.9 km from the Jammu city in Marh tehsil. The Gho-Manhasa stream is the main source of water at this station. The stream itself is fed by river Chenab and it traverses through the area supporting many villages. The stream harbours thick macrophytic vegetation and provide suitable habitat for many waterbirds particularly waders.

Results and discussion:-
Breeding season of Indian Pond Heron (Ardeola grayii) commenced from May to September with June and July being the peak breeding months. A total of 142 nests were located in five study stations during March 2013 to February 2016. The nests were platform shaped generally made up of dried twigs and solid sticks but in some instances it was recorded to expend considerable effort for breaking leafy twigs and branches off the nesting tree itself. The nests were located near streams, marshes as well as agricultural fields.

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Clutch characteristics:-During the present study period, clutch size was recorded to vary from 1 to 5 with a mean clutch size of 3.71±1.06. Among 142 nests studied, clutch size of 4 eggs per nest was reported to be the most common (n=70) with a percent share of 49.29% followed by clutch size of 3 (n=33) contributing 23.23%. Moreover, there were 26 nests with clutch size of 5 (18.30%); 9 nests with clutch size of 2 (6.33%) and 4 nests with clutch size of 1 (2.81%). Thus, it is evident from table-1 that nests with clutch size of 4 were significantly more common. The clutch size of herons may differ between years (Custer et al., 1983) or it may remain constant (Tremblay and Ellison, 1980). Earlier workers Whistler (1949) and Ali and Ripley (1969) (Table-2).

Correlation between various egg variables studied:-
A statistically significant and strong positive correlation was recorded between egg length and egg volume (r= 0.4852) as well as between egg breadth and egg volume (r= 0.8274). The egg weight also had a positive correlation with egg length (r= 0.125) while a negative insignificant correlation with egg shape index (r= -0.070). Besides, a strong negative correlation was reported between egg length and egg shape index (r= -0.339). Panda (1996) stated that egg length and egg shape index have negative relationship because egg length is the denominating factor in estimating shape index. However, a strong positive correlation was registered between egg breadth and egg shape index (r= 0.788) and plausible reason for this might be the fact that shape index is directly proportional to egg breadth. The correlations between egg length and egg breadth (r= 0.301) were also statistically significant (Table-4).

Conclusion:-
From the present study it can be inferred that the optimum clutch size of Indian Pond Heron (Ardeola grayii) was recorded to be 4 and showed significant positive correlation between egg length and egg volume.