Food provisioning is directly influenced by the availability of food resources around the nesting site and provisioning by the parents. This study was carried out to assess food provisioning in heronries with respect to i) water bird species, ii) chicks age iii) heronry size and iv) behaviour changes across the nesting season in Heronries during the 2014-15 nesting season. Study was carried out in 36 Village Development Committee (VDCs) of Rupandehi and 11 VDCs of Kapilbastu. Road routes were taken as transect for survey and covered once in 15 days during the entire nesting season (egg laying to fledging of chicks from nests; Aug 2014-Jan 2015). The food provisioning behaviour of Asian open bill (AOB) and Lesser Adjutant Stork (LAS) of varied sizes (Heronry size: no of nest in a tree) were taken for study. The food provisioning behaviour observations were carried out in the morning (6 am-12 pm) at 10-15 days interval in each heronry.
The average food provisioning time of AOB and LAS heronries was found to be 27.67±29.29 (n=341) and 38.13±49.99 (n=381) respectively. Both the species prefer short provisionig time i.e. more than 50% of provisioning time for both AOB heronries and LAS heronries was less than 20 minutes. The frequency percentage of provisioning time decreased continuously as the provisioning time increased at all stages of AOB as well as LAS heronry. Similarly, in case of heronry size for AOB heronries the average provisioning time was almost similar for all heronry size.and found to be not significantly different (χ2=0.93, P3,0.05=7.815). For LAS heronries the average provisioning time was high for heronry size 1 and size 5 and found to significantly different for heronry size (χ2=47.902, P14,0.05=12.592). Initially (first week of September) average provisioning time for AOB heronries was lowest and gradually increased till fledging of chick (late October). But in case of LAS heronries before October the average provisioning time was almost similar and increased from November to till fledging of chick (January).
Provisioning behaviour studies on waterbird species that form heronries are not available from Nepal, and are rare from South Asia. Thus outcome of this research would be step towards filling gap in ornithology and for understanding heronry ecology to help with planning, management and sustainable conservation of heronry birds in lowland of Nepal.
Keyword: Provisioning behaviour, Heronry, Nestling age, Heronry size