Results
Potential summering range of the East Asian
sub-population of A.
erythropus
The mean training AUC of the 100 models was 0.9510 suggested these
models are very useful (Swets 1988) for predicting the summering range
of A. erythropus . The standard deviation of AUC was very small
(0.0007) indicating the models were stable. Moreover, the mean testing
AUC was 0.9356 (SD = 0.0739), which was comparable to the training AUC,
suggesting excellent predictive power of the fitted model (Lobo et al.,
2008).
The average of summering distribution prediction of the 100 models was
presented in Figure 3. The most suitable habitats are located along the
coasts of the Laptev Sea, primarily the Lena-Delta, in the Yana-Kolyma
Lowland, and smaller lowlands of Chukotka with narrow strips extended
upstream to catchments of major rivers such as the Lena, Indigirka, and
Kolyma (Fig. 3). The binary map (Fig. 4) produced using the criteria of
minimum training presence threshold indicated that 36.44% of the study
area was suitable summering habitats.
Lowland wetlands including large deltas, estuaries, tundra, and swampy
floodplains (i.e. floodplain contains numerous ponds and shallow lakes),
which extend from the Lena Delta at the west to the Kolyma River at the
east, provide the most extensive and continuous breeding ground forA. erythropus in our study area (Figs. 3 and 4). This is
particularly the case for the very large Lena Delta
(~29,000 km2, Schneider et al .
2009), where the predicted summering habitats include tundra together
with numerous interlaced channels and lakes (Dutta et al . 2006).
Most of predicted breeding habitats are covered by a range of plant
types including grasses, sedges, herbs, as well as abundant mosses and
lichens. This tundra vegetation is also characterized by widely spaced
shrubs (e.g. Betula nana (s.l.), Dushecia fruticosa and
several species of Salix ) (Yurkovskaya 2011). Such tundra
vegetation along major rivers within the taiga biome also have potential
to be suitable habitat (Fig. 3).