Spatial distribution of birds and terrestrial plants in Bunger Hills

Abstract

In this paper, we synthesize recorded observations of moss, lichen and bird species in Bunger Hills, East Antarctica, and assess the role of environmental controls, including sediment, salinity, moisture and geology, on species' distributions. The distribution of snow petrels (Pagodroma nivea) appears to be associated with geology; they nest by preference in crevices in bedrock outcrops around the margins of the hills or wherever jointed cliffs are found. South polar skuas (Catharacta maccormicki) are seen throughout Bunger Hills, where they nest and prey on snow petrels. Mosses and lichens were most abundant around the ice margins where fresh snow and ice meltwater are abundant. In the central area of Bunger Hills, where the highest salt concentration in sediments is found and exposure to abrasion by wind-driven mineral sand grains and ice particles is greatest, mosses and lichens are reduced in abundance and diversity. Exposure of parts of Bunger Hills from the ice sheet throughout the Last Glacial Maximum, c. 20 ka bp, means that some land and lakes could have acted as regional refugia and as a locus of recolonization of other ice-free areas.

Tafoni show postglacial and modern wind azimuths that are similar at Bunger Hills

“…At Vestfold Hills, where this phenomenon also occurs, the line delineating the salt-enriched area is known as the ‘salt line’ (Adamson & Pickard 1986, Gore et al 1996), which divides an area to the east that is rich in vegetation and with relatively unweathered bedrock from an area to the west where physical weathering of the metamorphic basement creates abundant sand and inhibits the growth of lichen and moss vegetation (Adamson & Pickard 1986). The uniform wind direction over many thousands of years has created a similar ‘salt line’ at Bunger Hills, affecting the distribution of rock weathering and the distribution and growth of salt-sensitive plants such as mosses and lichens (Gore & Leishman 2019, Leishman et al 2020). The direction of these strong winds is important for the distribution of salt spray, rock weathering and the distribution of vegetation at Bunger Hills, just as it is at Vestfold Hills (Pickard 1982, Adamson & Pickard 1986, Gore et al 1996) and Larsemann Hills (Kiernan et al 2009) to the west.…”

Salt, sediments and weathering environments in Bunger Hills

“…In these areas, rock surfaces are free from glacial polish, while tafoni, orientated wind pits and accumulations of sand testify to the breakdown of rock surfaces and sediments. These areas, particularly in the north and north-west of the hills, are biogeographically distinct as a consequence of this salinity (Leishman et al 2020), with a reduction in plant abundance and species richness in the salty areas. The naming of a ‘salt line’, similar to the salt lines at Vestfold Hills (Blandford 1975, Adamson & Pickard 1986, Gore et al 1996) and Larsemann Hills (Kiernan et al 2009), appears to be justified by the rock weathering patterns (Fig.…”

Human occupation, impacts and environmental management of Bunger Hills

“…Given that the subsurface sands have retained strata from their time of deposition thousands of years ago, it is doubtful as to whether recovery is possible, apart from by infilling of the disturbed surfaces by windblown sand over time. Fortunately, the stations and base in Bunger Hills are far from the centres of plant species richness and abundance (Leishman et al 2020), and pedestrian traffic has not yet caused much damage to mossbeds or lichens (cf. Pertierra et al 2013b).…”

“…An apparently isolated population of Weddell seals ( Leptonychotes weddellii ) occurs in the marine portion of Bunger Hills (Leishman et al 2020). Numerous species of lichens and mosses have been recorded from the area, especially along the southern ice edge alongside Apfel Glacier (Gibson 2000, Leishman et al 2020).…”

“…Vertebrate biota of Bunger Hills are limited to four bird species - Wilson's storm petrel ( Oceanites oceanicus ), snow petrel ( Pagodroma nivea ) and south polar skua ( Catharacta maccormicki ), which all breed in the area, as well as occasional visits by Adélie penguins ( Pygoscelis adeliae ). An apparently isolated population of Weddell seals ( Leptonychotes weddellii ) occurs in the marine portion of Bunger Hills (Leishman et al 2020). Numerous species of lichens and mosses have been recorded from the area, especially along the southern ice edge alongside Apfel Glacier (Gibson 2000, Leishman et al 2020).…”