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

SIMPLE SUMMARY: The red-crowned crane (Grus japonensis), which is an endangered and highly protected bird species, is distributed in two populations: a mainland population in far eastern Eurasia and an island population in Hokkaido, Japan. Red-crowned cranes in Japan are resident birds mainly in the eastern part of Hokkaido. As omnivores, they feed on plants, grains, insects, and fish. Most cranes spend the winter around feeding stations in southeastern Hokkaido, where people provide corn. Since most of the cranes in Hokkaido now live near areas inhabited by humans, cases of crop damage caused by cranes have recently been reported. This study showed that the cranes feed on various crops of human origin, mostly outside farmlands. ABSTRACT: 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.