Just spent a few days on Hokkaido. Small mammal and fox numbers are very high; hares are totally missing.
1. Sendai-Tomakomai ferry worked out great: a mixed group of Pacific white-sided and right-whale dolphins, a pod of Baird’s beaked whales, and pilot whales.
2. Rishiri-Rebun NP. Saw a distant group of killer whales from the ferry to the island and harbor porpoises on the way back. There was a least weasel at Panke Marsh picnic site (45.033367N 141.732555E). I had big hopes for the island but saw nothing worth reporting except an Ussuri whiskered myotis squeezed in a very narrow slit in a rotten snag where I forgot to get GPS coordinates.
3. Lake Oketo: what a great site! I parked at 43.613853N 143.378868 and immediately saw a Hokkaido red-backed vole across the road. Walking NW, saw 4 Siberian flying squirrels (listen for soft, short, treecreeper-like whistles). Walking SE, saw northern bats feeding around street lights; also found a Korean mouse eating ants at an anthill, but while I was watching it through my thermal imager, a boreal owl scooped it up and disappeared. Unfortunately, I was only there at night.
4. Lake Nukabira-Lake Shikaribetsu Rd. At night there was a mass flight of small geometrids (multiple spp.); the road was covered with them, and all kinds of animals were feeding on them: an Oriental scops-owl, 20+ Laxmann’s shrews (one caught by hand to confirm the ID), 5+ long-clawed shrews, 1 slender shrew, many Ikonnikov’s myotis, 30+ foxes, 1 raccoon dog, 1 sable, 3 lesser Japanese mice, and the rarest of all, 1 non-feral Norway rat. Also a few sika deer there; one was so tame that it stuck its head inside the car and licked my hand. At Horoshika-toge Pass (43.337944N, 143.161194E) there is an excellent side road, very level; it is great for birding and there are pikas at the edge of a landslide at the end of the good part of the trail. Lots of old bear tracks.
5. Akan-Matsu NP: Rd 241 just outside the park has lots of abandoned houses and I checked some for bats, but found only a few Japanese long-eared bats.
6. Ozona: the large bats flying around the village at night are particolored bats, extremely rare in Japan. They used to roost in the old gymnasium, but I found only long-eared bats there.
7. Shiretoko NP: Furepe Falls trail had lots of rather tame (but still too quick to photograph) northern and grey red-backed voles in the forested part, and fraternal myotis night-roosting in trees around the visitor center. A fin whale was visible far offshore. According to the logbook at the visitor center, a brown bear was seen daily around 8 am, but I was in the park only in the afternoon, so I had to spend a lot of time looking for bears. Eventually found one at night along Iwobetsu Rd. (44.102393N 145.053518E), but it was eating something (probably a deer fawn) in dense bushes, so I decided that taking close-up flash photos would be impolite. At Shiretoko Pass there was a surprisingly shy chipmunk. I also walked a bit along the eastern coast of the peninsula; saw fins of Dall’s porpoises far out. No salmon in rivers yet.
8. Kushiro Marsh: I followed Yann Muzika’s advice and spent a few hours at Lake Tokkobu (43.068957N 144.466051E). The area was by far the birdiest of the trip, and I found colony of myotis bats (I think Ikonnikov’s but will have to check) in a woodpecker hole in a snag on the left side of the trail soon after the end of the boardwalks. Also found a least shrew at the edge of the pond. On the main boardwalk on the W side of the marsh there was a very friendly mink. A pavilion in Murata Park (park at 43.109928, 144.489408 and walk on for a few minutes) used to have a huge roost of Asian particolored bats, but now there are only dozens of Japanese long-eared. Tsuhsui Bridge (43.108971N 144.229005E) had night-roosting Far Eastern myotis.
9. Tokachi Station of National Livestock Breeding Center has a famous old wooden building (43.064322N 143.159217E) that used to have 8 species of bats. But now only long-eared bats are left. I was really surprised to see so many of them everywhere I checked: they are supposed to be very rare, and certainly are on Honshu. Nearby, Eastern water myotis roosted under the bridge at 43.048706N 143.137257E.
Turns out the bats in woodpecker hole were Eastern water (M. petax).