Last weekend Steve Linsley and I went on a 2-day, 3-night trip to the coast of N California and extreme S Oregon. The results were not what we expected.
(1) We didn’t see any interesting large mammals in a few hours of night driving in and around Hoopa Valley, but we saw record numbers of grey foxes throughout the trip.
(2) Rodent numbers seemed very low. We didn’t see a single squirrel or chipmunk (we weren’t intentionally looking for them, but normally they are everywhere), and didn’t catch or spot any voles (despite considerable effort) even in places where they were common in the past. The only rodents we caught were one very skinny dusky-footed woodrat and modest numbers of Keen’s mice (probably also one western harvest mouse, but that trap didn’t close). Interestingly, at one site there were lots of Keen’s mice in a grazed field but none in the adjacent forest. I suspect that voles have recently peaked and crashed (hence high fox numbers), and the mice are kind of filling their niche while it’s temporarily vacant.
(3) We got one shrew (Throwbridge’s) in ~20 pitfall trap-nights, which is more or less an average result. Interestingly, it was in the only trap made of coffee can (others were made of plastic water bottles). Likely a coincidence, but of a kind smart people don’t ignore 🙂 If you find me a bit agitated in the next few months, that’s because I’ll be drinking a lot of coffee.
(4) Finding good trapping sites for wetland-associated voles and moles proved surprisingly difficult. Next time I’d rather go to central Oregon coast where such habitats are abundant and soils are softer. Putting even ten pitfall traps into a mix of tree roots and pebbles was too much work.
(5) The highlight of the trip was watching a coast mole foraging on surface (in Stagecoach Hill Azalea Reserve in Humboldt Lagoons SP). I haven’t done an exhaustive literature search yet, but it looks like this behavior has never been observed in this species before, although there are records of cat kills and bones in barn owl pellets, interpreted as those of dispersing juveniles. The mole we saw (and photographed) seemed to be within adult size range, although near the lower end. I think it was the quietest mammal I’ve ever managed to find by sound.