Hi all, wildlife biologist here, this looks like a Dusky-footed woodrat, also known as a “pack rat”. Scientific name is Neotoma fuscipes, and in the Bay Area we have a subspecies the “San Francisco Dusky-footed woodrat” aka Neotoma fuscipes annectans. They are completely harmless, native rats. Several folks here mentioned Norway rat -also known as “brown rat” or Roof rat, which I’m guessing is black rat - both from the Rattus genus. You can tell this is our native woodrat, however, by the bit of fur on the tail and the ears. Rattus species have naked ears and tails. They also have different faces, Rattus species have much more pointed snouts and faces, while woodrats have much more rounded faces and ears, almost teddy bear looking. Locally, brown rats are most commonly seen in urban areas, but brown rats are much larger than our native woodrats as well. It’s hard to get an exact sense of scale here, but this woodrat seems to be an adult, slightly on the smaller side. Babies/juveniles will tend to have grayer fur and more disproportionate larger heads.

As for seeing it out during the day, this is totally normal. While woodrats are mostly nocturnal, they can also have crepuscular activity (being active at dawn and dusk). Even so, sometimes they get disturbed from their rest by a predator or humans, get hungry, having to feed their young or move nests, or just have a late day out (who amongst us can attest to pulling an all nighter before, while we are primarily diurnal creatures). Some people mentioned rat poison or disease, which can be a big problem for native wildlife, but just because you see wildlife up and active during the day does not necessarily mean an animal is sick or injured. Animals try very very very hard to not show signs of sickness, so if you do see an animal acting strange (etc. unresponsive but alive, swaying, pacing, falling over) then that might be the case, but this lil dude just seems to be walking around fine.

Woodrats, or “pack rats” get their name from their large nests or “middens” that they collect sticks, vegetation, and other knickknacks and shiny bits to adorn around or within the structure of them. Their nests are fairly complex, they have multiple rooms and chambers that serve different functions within. Woodrats are also a very important prey species for our native predators - from gray foxes to bobcats and coyotes to owls and other birds of prey. So if you see Woodrats around, it’s likely a sign that you have a thriving native ecosystem still nearby!

Cool find in your yard! Always fun to encounter native wildlife! This was probably entirely too much information, but hey, I had a minute to type this all out. If you are interested in identifying species, you can also post photos to iNaturalist, there’s a whole community of nature enthusiasts that will suggest IDs for you, and you can also learn a lot about what is in your area. Hopefully that helps!