Determining the trophic linkage of the red-crowned crane Grus japonensis in Zhalong wetland in northeastern China

The trophic relations of the red-crowned crane in Zhalong wetland, northeastern China may significantly be altered due to the rapid decrease in accessible food resources. To confirm this hypothesis, we determined the trophic status of this vulnerable species by using stable isotope (carbon (delta C-13) and nitrogen (delta N-15) methods. The delta C-13 and 15 Nsignatures in the red-crowned crane species were in the range of -17.8% to -18.5% and 6.9% to 8.1%, respectively. The majority of the ecosystem of Zhalong wetland has an average food-chain length of 3.9, and the trophic level of the examined species, i.e., red-crowned crane, was approximately 3.1. The trophic relations of red-crowned cranes have changed over the period of 2004 to 2014, as the biological species in the bottom trophic level significantly exhausted in the past years. The conflict of food demand by red-crowned cranes versus the livelihood demand of local wetland residents should be resolved to ensure sustainability of food supply sustainable for rare and extinguishable species.