High Nothofagusflower consumption and pollen emptying in the southern South American austral parakeet ( Enicognathus ferrugineus).

We describe extraordinary aspects of the feeding ecology of the austral parakeet, Enicognathus ferrugineus – the most southerly distributed psittacid in the world – that allow this endemic species to inhabit and become a common bird in relatively species-poor temperate and subantarctic Nothofagus forests of South America. We used two sources of information to analyse temporal and spatial dietary changes of austral parakeets in subalpine forests near Lake Distric of southern Argentina: (i) relative abundance of parakeet foraging on the forest floor along an altitudinal transect from 1000 to 1420 m; and (ii) faeces analyses of seasonal collections. Austral parakeets largely relied on a protein-rich pollen-based spring – early summer diet by destructively harvesting large quantities of wind-pollinated Nothofagus pumilioflowers and efficiently emptying pollen grains – specializations previously described only in pollinating nectarivorous vertebrates. Pollen emptying rates ( c. 65%) were the highest reported for psittacids and among the highest for vertebrates in general. Parakeets made extended use of short-lived N. pumilioflowers by tracking the altitudinal shifts in flowering phenology. Additionally, parakeets complemented their diet with carbohydrates from N. pumilio insect exudates. By late summer, parakeets switched to a lipid-rich diet based on N. pumilio seeds. This resource remained available through mid-autumn because parakeets also followed in altitude the phenological delays in fruiting. In winter, parakeets fed on N. pumilio parasitic Misodendrum mistletoe buds and leaves and Cyttaria sp. parasitic canopy fungi. These results suggest that stringent food availability in these relatively high latitudes may have led to behavioural and physiological specializations of austral parakeets to obtain year-round food resources efficiently from Nothofagus trees. [ABSTRACT FROM AUTHOR]