Individual variation in food consumption and food preferences in St Lucia parrots Amazona versicolor at Jersey Wildlife Preservation Trust

Abstract

Individual food consumption and food item preference of 12 St Lucia parrots Amuionu vrrsicolor were studied at Jersey Wildlife Preservation Trust. Diet offered contained a maximum of 29 foods, mostly fruits, vegetables and pulses but also processed foods and commercial parrot pellets. Each day all birds were presented with the same selection of foods and no novel items were introduced during the study period. Birds varied in their average food intake per feeding session (mean ± SD) from 15.1 ± 5.6 g kg‐1 to 89.0 ± 138.3 g kg‐1. Diversity of food items eaten per session was determined by the Simpson's index of diversity. Food preferences were measured by Ivlev's electivity indices from the total amount of each food type consumed relative to the total amount of that food type offered during all sessions. Foods were classified as ‘disliked’ when electivity indices were negative and ‘rejected’ if not consumed at all. The order in which food types were consumed by each parrot was also analysed. Results showed that diet diversity and food intake were significantly higher for ♀♀ than ♂♂. Wild‐born parrots consumed less but ate a wider variety of foods than captive‐born ones. Significant sexual differences in overall food intake as well as in the percentage of disliked and rejected foods were found among captive‐born birds but not in wild‐born parrots. However, because all wild‐born birds in the present study were twice as old as the captive‐born ones, age of bird and origin were confounded variables. Older birds disliked less foods than younger ones but younger parrots ate more than older birds. Within paired birds, ♀♀ were more aggressive towards ♂♂ than vice versa. This may have influenced the lower feeding levels observed by subordinate ♂♂ but single ♂♂ ate even less than those kept in pairs. The results of this study suggest that it is not possible to make generalizations to satisfy optimal diet requirements of the species because of the considerable individual variation found. Quantifying intake and preference from direct observations of the birds during feeding can be a useful technique to help with the formulation of diets. Further studies are required to determine the roles of sex, age and origin on food consumption and preference. The behaviour of paired and single birds should also be assessed in order to identify suitable methods for feeding dominant and subordinate birds in an attempt to optimize nutritional intake of each individual.