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

Abstract

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 pumilio flowers 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 shortlived N. pumilio flowers 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.

Alternative silvicultural practices with variable retention improve bird conservation in managed South Patagonian forests

“…abundance and richness (Lencinas et al, 2008), while understory plants represent a secondary source (a few grass species and scarce shrub fruit availability for a few weeks during the growing season). On the other hand, Nothofagus flowers and fruits are an attractive food resource for some bird species such as Enicognathus ferrugineus reported by Díaz and Kitzberger (2006).…”

Mistletoes and epiphytic lichens contribute to litter input in Nothofagus antarctica forests

“…U. barbata is the most abundant species of lichen in Tierra del Fuego growing epiphytically on Nothofagus trees (Hawksworth and Moore, 1969). Both mistletoe and lichens are ecologically important as food, shelter and nesting materials for wildlife (Calvelo et al, 2006;Díaz and Kitzberger, 2006;Díaz and Peris, 2011). For example, the austral parakeet (Enicognathus ferrugineus) feeds heavily on buds, flowers and foliage of mistletoes during winter (Díaz and Kitzberger, 2006), and guanacos (Lama guanicoe) consume mistletoes year round, but consumption increases in winter (Soler et al, 2012) when the tree branches are more accessible due to accumulation of snow.…”

Variable retention management influences biomass ofMisodendrumandUsneainNothofagus pumiliosouthern Patagonian forests

“…In Patagonian forests, austral parakeets (Enicognathus ferrugineus) fed heavily on buds, flowers and foliage of Misondendrum sp. during the winter (Díaz & Kitzberger 2006), while a high proportion of the guanaco (Lama guanicoe) winter diet comprises this hemiparasitic plant in Tierra del Fuego (Soler Esteban et al 2011). This, along with other evidence from around the world led to the proposal that mistletoes as ecological keystones (Mathiasen et al 2008).…”

“…This lichen grows on Nothofagus trees, where Usnea barbata is the most abundant and widespread species (Hawksworth & Moore 1969). In addition to being endemic components in native temperate forests, both lichens and mistletoes are ecologically important as food, shelter and nesting material for wildlife (Calvelo et al 2006;Díaz & Kitzberger 2006;Soler Esteban et al 2011). Parasitic plants and lichens may also provide a benefit to other plant species by enhancing soil fertility and nutrient cycling through tree litter fall (Essen et al 1996, March & Watson 2007, 2010Fischer et al 2013).…”