Hiroyuki Masatomi

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.

Some observations on mating behaviour of several cranes in captivity

Responding to the actions of the mate and taking somewhat fixed patterns,Grus japonensis, G. vipio, G. antigone, Anthropoides paradisea andBalearica regulorum pairs are finally led to copulation by a sequence of mating behaviours. There are slight differences in pre-copulatory behaviour patterns between the species and the females ‘wing-spreading’, being the soliciting and key posture for copulation, differs between the genera; The females wings are spread wide inGrus, fairly wide inAnthropoides, and are almost folded inBalearica. Post-copulatory behaviours, however, have definite species-specific characters. They usually consist of ‘head-down’ (bowing) or ‘warping’, ‘arching’, etc. immediately following the dismounting of the male inGrus. But a pair ofBalearica first keep their heads high, or gaze at each other for a while, and then show remarkable ‘ruffle-bowing’. These characteristic post-copulatory behaviours are obviously correlated with the threat displays, evolved under agonistic situations, typical to each species.

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.

Vertebral Formula in Red-Crowned Crane (Grus japonensis) and Hooded Crane (Grus monacha)

ABSTRACT 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.

Ecology of the Red-crowned Crane and Conservation Activities in Japan

There are several ecological differences between the migratory continental population and the nonmigratory Hokkaido population of Grus japonensis. Even though the most cranes of the latter move shortly between their breeding and wintering grounds, a few of the pairs occasionally maintain their same territories year-round. The classic nesting habitat for G. japonensis is an open wetland consisting of reed dominant vegetation. Recently, however, they have shown a tendency for nesting in the thick alder forests, accounting for over 10% of all nesting pairs in 2009. This shift in habitat selection is one of the factors supporting their recent population growth. During the coldest season, cranes concentrate at a few major artificial feeding stations and then roost in neighboring unfrozen rivers. In recent years, however, individuals feeding at minor stations are increasing because the major feeding stations and roosts are probably reaching their capacity limits. The Hokkaido population is continuously growing since the mid-twentieth century, and numbers of cranes exceeded 1500 as of January 2014. Expansion of G. japonensis distribution due to increase in population continues to progress in line with the breeding potential map of Hokkaido. Unfortunately, the population growth is challenged by issues such as (1) the lack of genetic diversity, (2) overconcentration of individuals at a few feeding stations, (3) overcrowding and exceeded carrying capacity in breeding grounds, (4) conflicts with farmers, (5) traffic accidents due to excessive habituation to people, and (6) breeding habitat degradation and disturbance of nesting activities by deer. Therefore, it is urgently necessary to consider future protection measures to maintain the population.