The study was carried out in forty-seven VDCs of the adjoining districts, Rupandehi and Kapilbastu of lowland, southern Nepal. This study was focused on the distribution pattern of all heronries as well as for species, nesting trees preference relative to the overall availability on the overall landscape and nesting success of three species (LAS: Lesser Adjutant Stork Leptoptilos javanicus, AOB: Asian Openbill Anastomus oscitans and PH: Pond Heron Ardeola grayii) at heronries.
The survey was carried out from august 2014 with intensive survey of focal villages during visits of random points for nest tree preference. Bird species, tree species along with girth at breast height (GBH) and height were recorded. Altogether 75 heronries of AOB, LAS, CE: Cattle Egret Bubulcus ibis, PH, WNS: Woolly necked Stork Ciconia episcopus and RNI: Red naped Ibis Pseudibis papillosa were recorded. From Variance mean ratio (VMR), these heronries were distributed randomly. Similarly, AOB, LAS and CE were also distributed randomly as well. Heronries were distributed in all over the study area except some VDCs but they were sighted in those areas as well. AOB were distributed in six VDCs of Rupandehi while PH was distributed in two VDCs of Kapilbastu districts despite of this, their distribution pattern was random from VMR calculation. LAS and CE were distributed in both districts very well. They were also distributed randomly.
Bombax ceiba and Ficus religiosa were preferred by heronries as well as by individual species more than availability. Mangifera indica and Dalbergia sisoo were available most in the area. The preferred trees have more GBH (>200 cm) and height (>15 m) compared to random points. A single species appears to have different preferences based on the location of the study. CE preferred all range GBH trees than other bird species. The nesting success of AOB, LAS and PH were obtained to be nearly 95.12±15.8, 82.05±35.39 and 57±40.48 per heronries and the chicks fledge per nest for respective species was obtained to be 2.43±0.7, 1.51±0.69 and 1.32±1.42 respectively. There was negligible difference in numbers of chick fledged in case of AOB and LAS whereas PH has huge variation in numbers of chicks per nest.
Therefore, the landscape of lowland Nepal provides excellent condition for wide variety of large waterbirds to nest in heronries despite enormous human distribution.
Key words: Heronries, Distribution, Nest tree preference, Nesting Success.