Vertebral formula in red-crowned crane (Grus japonensis) and hooded crane (Grus monacha).

Red-crowned cranes (Grus japonensis) are distributed separately in the east Eurasian Continent (continental population) and in Hokkaido, Japan (island population). The island population is sedentary in eastern Hokkaido and has increased from a very small number of cranes to over 1,300, thus giving rise to the problem of poor genetic diversity. While, Hooded cranes (Grus monacha), which migrate from the east Eurasian Continent and winter mainly in Izumi, Kagoshima Prefecture, Japan, are about eight-time larger than the island population of Red-crowned cranes. We collected whole bodies of these two species, found dead or moribund in eastern Hokkaido and in Izumi, and observed skeletons with focus on vertebral formula. Numbers of cervical vertebrae (Cs), thoracic vertebrae (Ts), vertebrae composing the synsacrum (Sa) and free coccygeal vertebrae (free Cos) in 22 Red-crowned cranes were 17 or 18, 9-11, 13 or 14 and 7 or 8, respectively. Total number of vertebrae was 47, 48 or 49, and the vertebral formula was divided into three types including 9 sub-types. Numbers of Cs, Ts, vertebrae composing the Sa and free Cos in 25 Hooded cranes were 17 or 18, 9 or 10, 12-14 and 6-8, respectively. Total number of vertebrae was 46, 47, 48 or 49, and the vertebral formula was divided into four types including 14 sub-types. Our findings clearly showed various numerical vertebral patterns in both crane species; however, these variations in the vertebral formula may be unrelated to the genetic diversity.

Origin of three Red-crowned Cranes Grus japonensis found in northeast Honshu and west Hokkaido, Japan, from 2008 to 2012.

The Red-crowned Crane Grus japonensis is an endangered species that has two separate breeding populations, one in the Amur River basin and the other in north and east Hokkaido, Japan. So far, only two (Gj1 and Gj2) and seven (Gj3-Gj9) haplotypes in D-loop of mtDNA were identified in Japan and in the continent, respectively. We obtained feathers from three cranes found in northeast Honshu. The crane in Akita in 2008, which also arrived at west Hokkaido, had a novel haplotype (Gj10). Another crane in Akita in 2009 showed a heteroplasmy (Gj7 and a novel type, Gj12). The third crane in Miyagi in 2010 also showed another type, Gj11. These results suggest that three Red-crowned Cranes appeared in Honshu and west Hokkaido were from the continent.

Physical body parameters of red-crowned cranes Grus japonensis by sex and life stage in eastern Hokkaido, Japan.

Red-crowned (or Japanese) cranes Grus japonensis are native to eastern Hokkaido, Japan--the island population, and mainland Asia--the continental population that migrates from breeding grounds along the Amur River Basin to winter in east China and the Korean Peninsula. The island population was reduced to about 50-60 birds in early part of the 20th century. Since 1950s, the population has increased to more than 1,300 as a consequence of human-provided food in winter, resulted in change of their habitats and food resource. From the carcasses of 284 wild cranes from the island population, collected in Hokkaido since 1976 until 2010, we measured six physical parameters (body weight and lengths of body, wing, tarsus, tail and exposed culmen) and divided into groups by sex and three developmental stages (juvenile, yearling and adult). All parameters of males were larger than those of females at the same stage. Total body length of females tends to grow up earlier than males, in contrast to body weight. Obvious time trends were not observed in these all parameters during 34 years for these six categories measured, except total length of male juveniles, which showed a significant increasing trend. These results provide the first extensive data on body size and mass in the wild red-crowned cranes.

Large-scale survey of mitochondrial D-loop of the red-crowned crane Grus japonensis in Hokkaido, Japan by convenient genotyping method.

The Red-crowned Crane, Grus japonensis, is an endangered species of crane that has two separate breeding populations, one in the Amur River basin (continental population) and the other in eastern or northern Hokkaido, Japan (island population). So far, only two haplotypes (Gj1 and Gj2) have been identified in the mitochondrial D-loop in island population, whereas seven haplotypes have been found in continental population (Gj3-Gj9). We developed a rapid and inexpensive method of extensive genotyping of D-loop haplotypes in Red-crowned Cranes, based on amplification refractory mutation system (ARMS) PCR assay. Two hundred and three cranes in eastern Hokkaido were studied with this method and supplemental DNA sequencing. Only two haplotypes, Gj1 and Gj2, were confirmed in eastern Hokkaido with Gj2 as a major haplotype. Additionally, only Gj2 was identified in twelve feathers from both sexes found in northern Hokkaido. These results suggest scarce genetic diversity in island population of Red-crowned Cranes in Hokkaido, Japan.

Changes of mercury contamination in red-crowned cranes, Grus japonensis, in East Hokkaido, Japan.

Red-crowned cranes (Grus japonensis) are native to eastern Hokkaido (island population), in contrast to the mainland, which migrates between the Amur River basin and eastern China-Korea peninsula. During the 1990s we found that Red-crowned cranes in Hokkaido were highly contaminated with mercury: however, the source was unknown. We investigated the time trend of mercury contamination in Red-crowned cranes. Total mercury levels in the livers and kidneys from cranes dead in the 2000s were lower than those dead in the 1990s. Feather is a major pathway of mercury excretion for many bird species and is used as an indicator of blood mercury level during feather growth. As internal organs from the specimens collected before 1988 were not available, we analyzed the flight feather shavings from stuffed Red-crowned cranes dead in 1959-1987 and found that the mercury level of feathers from cranes dead in the 1960s and 1970s was not more than those from the cranes dead in the 2000s. These results suggest that mercury contamination in Red-crowned cranes in Hokkaido decreased temporally during the 1990s-2000s. This indicates the possible occurrence of some mercury pollution in Red-crowned cranes' habitat in this region in the 1990s or before.

Heavy metal contamination status of Japanese cranes (Grus japonensis) in east Hokkaido, Japan--extensive mercury pollution.

Japanese cranes (Grus japonensis) of eastern Hokkaido, Japan, and migrants between the Amur River basin and the eastern China-Korea Peninsula, live around fresh and brackish wetlands. Only a few thousand cranes are confirmed to exist in the world, so they are under threat of extinction. To understand the adverse effects of metal accumulation, we measured concentrations of three heavy metals in the liver, kidney, and muscle of 93 Japanese cranes from Hokkaido. The cranes were classified into six categories according to their sex and three life stages. Cadmium and mercury (Hg: total mercury) showed age-dependent but not sex-dependent accumulation in the liver and kidney. Twenty cranes showed 30 microg/g or higher levels of Hg in dry tissue and five adult cranes had more than 100 microg/g in their livers or kidneys. Cadmium concentrations were generally lower in all samples. Two adult cranes showed extremely high lead levels of more than 30 microg/g in their livers, suggesting lead poisoning. These results have highlighted the widespread and high levels of Hg pollution in Japanese cranes in Hokkaido, Japan.