Some aspects of the behavioural and feeding ecology of the rose-ringed parakeet Psittacula krameri manillensis (Scopoli) in Polonnaruwa, Sri Lanka
The aim of this study on the rose-ringed parakeet (Psittacula krameri) was designed to obtain information on:- (a) to what extent the natural food in the forest affects the feeding of the parakeets in a highly agricultural area, and (b) its behaviour and breeding in the forest, while the study in the paddy fields was designed to obtain information on:- (a) to what extent parakeets used paddy fields, and (b) to make, if possible, an assessment of the damage caused by the parakeets. The study was done at Polonnaruwa, in the North Central Province of Sri Lanka. The observation of parakeets in the forest was done by a modified version of the line transect method. Observations were made by following a predetermined path and stopping at every 100 m for 5 minutes and malting a complete survey around the point. When a parakeet was seen, its sex and the activity it was performing when first sighted were recorded. The observations were standardised, and checked for seasonal patterns by testing for significance using the analysis of variance at the 5% level. The significant behaviours and numbers of parakeets were then tested for correlations by the Spearman rank correlation coefficient at the 5% level. Paddy field studies involved (i) estimating numbers of parakeets probably feeding in the area by counting birds flying back to roost, (ii) number of parakeets visiting paddy fields during different stages, and the number of parakeets that settled to feed when the fields were protected, and (iii) the feeding rate of parakeets in the field, by counting the number of grains consumed per minute. Further to the field studies, captivity studies were done to obtain the total consumption of only paddy by parakeets. In the forest, 19 behaviours were identified, of which 11 showed significant seasonal patterns. It was possible, at least in some observations, to ascribe functional significance to the behaviours, on the basis of previous descriptions from mainly captive birds, but, on the other hand, some behaviours were completely new and functions have been suggested, e.g. debarking by females, and aggregations. On the basis of behaviours related to reproduction, bringing up nestlings, and number of newly fledged young, the breeding season, depending on which definition is considered, probably extends from August to July in its broadest sense, or from January to June in the narrowest sense. The breeding season in Sri Lanka, as in Africa and South India, appears to be influenced by the rainy season. The study showed that food in the forest played a very small role in the feeding of the parakeet, and that the feeding patterns were influenced mainly by the availability of food in the paddy fields. Paddy fields were a major source of food for the parakeets, and the use of the fields to obtain their food was clearly related to the stages of the crop. Parakeets visited fields more often during the germinating seed stage, and milky grain to harvest stage. The potential loss was probably 5--7%, while the actual loss (even under protection of the field) was only 0.03--0.04%. Finally, a literature survey showed that the distribution of parakeets (Psittacula krameri, P. eupatria, P. cyanocephala and P. calthropae) have changed over the years, most likely due to reduced forest cover and new agricultural practices.