Analysis of winter survival strategies of sympatric black-necked cranes, and common cranes from the perspective of diet and gut microbiota

Abstract

Wintering migratory birds have to travel thousands of kilometers between their breeding and wintering grounds because of their distinct habits. They experience complex and changing survival pressures throughout the winter. This study is the first to investigate the overwintering strategies of sympatric foraging black-necked cranes and common cranes from the perspectives of food and gut microbiota. Non-invasive sampling technique was used to collect stool samples. Sanger sequencing was used to determine the origin of the crane species identified from the samples. The analysis of plant-based food, the gut microbiota, and their interactions in the faeces was performed using high-throughput sequencing technology. It was found that in environments with limited aquatic vegetation, both the black-necked crane and the common crane increased their consumption of potatoes, accounting for more than 50% of their diets. Black-necked cranes also competed with common cranes for food, and they quickly adapted to changes in diet by horizontally transmitting their gut microbiota. To meet body needs, the common cranes—which could not compete with the black-necked cranes—constantly searched for new food sources. They increase the metabolism of amino acids, lipids and these metabolites to adapt to the competitive pressures and dietary changes. This study advances our knowledge of how diet and gut microbiota interact in plateau wetland birds, examining the competitive tactics of interwintering black-necked and common cranes', and provides recommendations for the re-vegetation in the Caohai wetlands and artificial feeding of the two crane species.