Wintering status of Raven in Eastern Hokkaido.

Tamada Katsumi

doi:10.3838/jjo.57.11

The Raven Corvus corax was well-known as a rare winter visitor to Hokkaido, but recently observations have increased. To clarify the current wintering status of the Raven, records were collected from field studies and from the literature. Ninety-four observations were made in the Kushiro district, and 124 records from eastern Hokkaido were collected from the literature. Ravens are winter visitors that inhabit inland areas, and 89% of the records were in forested habitats. Changes in the distribution of the species in eastern Hokkaido were examined based on these 218 records. From 1969 to 1978, Ravens were found in just three coastal municipalities. From 1991 to 1997 Ravens were found in nine municipalities and from 1998 to 2005 they were found in 16 municipalities. In these two later periods, Ravens were found in both coastal and inland areas of eastern Hokkaido. In eastern Hokkaido, hunting of Sika Deer Cervus nippon has increased since the 1990s and some reports have shown that Ravens forage at deer carcasses. The increase in the number of deer shot, and hence the amount of carrion available, and the expansion of the Raven's range have coincided, suggesting a causal relationship between the two.

Wintering status of Raven in Eastern Hokkaido.

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