Abstract
In June 2011, an unusually high mortality of the migratory Short-tailed Shearwater Puffinus tenuirostris occurred in Mutsu Bay in northernmost Honshu, Japan. One hundred and fifty six carcasses were recorded along a 1 km stretch of beach. Prior to this stranding, 40 birds had been observed floating in the nearby area of the bay. All of them were presumably juveniles that had departed from their natal places in the austral autumn in late April or early May and mistakenly entered into the semi-enclosed bay through Tsugaru Strait en route to the northern summering waters of the cooler current.
