Distribution of black-necked cranes in Nyingchi City, and an evaluation
of habitat suitability
Abstract
Understanding the spatial and temporal distributions of rare species is
important for informed management. The black-necked crane Grus
nigricollis, a rare bird in China and flagship species in alpine
wetlands, is nationally protected. Using site and environmental data, we
use Maximum Entropy (MEM) and Random Forest (RFM) models to predict
suitable habitat for this bird. Environmental variables that most affect
its distribution are distance from buildings and roads, and
isothermality, with contribution rates of 15.1%, 15.05%, and 5.85%,
respectively. Using the AUC (area under curve) coefficient as an index
to evaluate model precision, the predictions of the RFM are most
consistent with the known distribution of these cranes, predicting the
highest match with known crane sites (AUC = 0.945). Suitable habitat for
this crane occurs mainly in Nyingchi city riverine wetland, where the
centre of distribution is located in a valley where the Yarlung Tsangpo
and Niyang rivers converge. A comparison between MEM and RFM outputs
reduces uncertainty in predictions of black-necked crane spatial
distribution, and filters optimal results for the distribution area.
These results enable more-informed protection of habitat for this sacred
crane.