Analysis of Crop Consumption Using Scatological Samples from the Red-Crowned Crane Grus japonensis in Eastern Hokkaido, Japan

Total DNA extracts from the intestinal contents of 60 flying red-crowned cranes (juveniles, subadults and adults) found dead in 2006-2021, and the feces of 25 chicks collected in June and July of 2016-2018, were used for PCR reactions with primers specific for 16 crops, followed by high-throughput sequencing. The most predominant crop detected was corn in adult and subadult cranes (61.7%). Other grains (barley, wheat, soybean) (5.0-8.3%) and vegetables (tomatoes, Chinese cabbage, etc.) (1.7-6.7%) were also detected in flying cranes. Surprisingly, some of the detected crops were not grown in the Kushiro and Nemuro regions. There was no significant difference in crop intake status in winter and that in other seasons for most of the crops. Corn (28.0%), soybeans (8.0%), wheat and beet (4.0%) were detected in crane chicks in summer, though the detection rates were generally lower than those in flying cranes. Alfalfa, which is not grown in eastern Hokkaido but is used in some cattle feed, was detected in some cranes. Rice, buckwheat, adzuki beans, common beans, potatoes and carrots were not detected at any life stage, indicating the preferences of red-crowned cranes. The results suggest that red-crowned cranes in Hokkaido are dependent on dairy farmers for their feed supply.

Automated summary

The study analyzed the intestinal contents of red-crowned cranes in Hokkaido, Japan to determine their dietary preferences. The results showed that corn was the most consumed crop by adult and subadult cranes, followed by barley, wheat, soybean, and vegetables. Some of the detected crops were not locally grown, indicating the reliance of red-crowned cranes on dairy farmers for their feed supply. The study provides valuable insights into the feeding habits and dependencies of red-crowned cranes in Hokkaido.