Fig.
3.(a)The
percent
contribution
of the environment variables in current distribution of birds(b) The
comparison of percentage contribution of 5 essential variables in
different scenarios
This result indicated the 5 factors
were of great significance for the current distribution of birds. In the
future scenarios, the most important variable is
still\(t_{\min}\), of which the percent contribution is 23.89% in RCP2.6 and
31.17% in RCP8.5(Fig.3b). It can
be seen that the temperature is the main environmental factor that
affects the potential distribution area of the migratory birds. The
combined
percent
contribution of all climate variables are 53.59% in RCP2.6 and
59.13%in RCP8.5, and climate change still has a great influence on the
distribution of migratory birds in
future.
The appropriate living conditions of the migratory birds can
be
viewed through the single-factor response curves of 5 most important
environmental variables (Fig.S2). From the 5 most important variables,
we can know that birds prefer to live in the plains with a warm climate
and abundant water
resources
(Ma et al., 2019; Yong et al., 2018). Flat terrain means flying distance
to search food is shorter and consuming energy is less. The warm climate
and rich water resources mean food resources are rich for the migratory
birds (Myers et al., 2000). When the temperature changes, the suitable
area of the migratory birds shifts.
The
transferred area may overlap with the human living space, which will
cause the living space for migratory birds to be compressed(Fournier et
al., 2019).
The distribution of endangered species
The distribution of endangered
species is always used in the division of
protected areas (Lehikoinen et al.,
2019; Manish & Pandit, 2019; Runge et al., 2015; Sang et al., 2011;
Shen et al., 2015; Xu et al., 2017), which identifies areas that need
priority protection and has positive implications for planning and
constructing of protected areas. 23 species of different endangered
level on the IUCN red list were used in our model to comprehend the
current potential distribution and the future habitat. The comparison
between the current situation and future distributions of species is
showed in Fig.4.