3.2 Potential spatial
distribution
The suitability prediction map representing the three individual models
and the ensemble model (Fig.5) showed that, out of the native area,
northern Australia and New Guinea were more suitable for the Asian
openbill. Some islands in the Philippines and Malaysia also had high
suitability values, but some high latitudes in the east Asia regions,
such as China, Mongolia, Japan, and the Korean Peninsula, were less
suitable.
All four maps showed that the lower latitudes were more suitable.
However, we still found some records in new distribution areas with less
suitable values, indicating that the Asian openbill can exist in
low-suitability areas. Furthermore, three individual model results
showed that there may have been more potential area in the east,
northeast, and north of China. Based on the PROC evaluation, we found
that the AUC ratio value of the RF model was significantly higher than
other models, so it was chosen for probability analysis (Fig.6).
The occurrence probabilities for the two new distribution populations,
original native populations, and random populations were extracted from
the RF model for comparison. Although values of the two new distribution
populations (China, Mean ± SD = 0.39 ± 0.07, Malay Peninsula, Mean ± SD
= 0.4 ± 0.17) were lower than for native populations (Native, Mean ± SD
= 0.49 ± 0.20), they were much higher than the expected probability
(Random, Mean ± SD = 0.09 ± 0.12)(Fig.7). Based on the above suitability
results, there is still a great potential for the stork to spread in
both directions in China and the Malay Peninsula.