DEAR JOAN: While driving down my street today, I saw a black tree squirrel. I stopped to watch it for a few minutes. It was somewhat smaller than a red tree squirrel, and its tail was not quite as bushy.

I have never seen a black tree squirrel before, although I have lived here for 75 years. I have seen gray tree squirrels. What exactly did I see?

Mike Bernal, Morgan Hill

DEAR MIKE: You saw a black tree squirrel. They are less common than the other squirrels that scamper through the trees — and make one of my best friends hopping mad because they eat all her tomatoes — but they do exist.

The black squirrel is likely an Eastern gray squirrel with a quirk in its genetic makeup. Gray squirrels (and some Eastern fox squirrels) carry a mutant pigment gene, and if the offspring inherit one gene from mom and another from dad, the result is a black squirrel.

The black squirrels are more common on the East Coast because that’s where most of the Eastern gray squirrels live. The ones in California were imported. As the populations increase, we see more black squirrels.

Stanford and the Palo Alto area seem to have quite a few black squirrels, which has led to conspiracy theories about secret experiments and lab security breeches that unleashed a scurry of the ebony-colored squirrels on an unsuspecting populace. Just kidding. It’s just Mother Nature at work.

Mystery creature update

Earlier, I answered a letter from Art Zikorus, of San Jose, about an odd creature he caught a glimpse of in his backyard. He described the animal as dark brown with short hair and a furry, catlike tail, but with short legs and a mouselike head with small eyes. The animal also carried its tail low to the ground as it ran.

Although there is no way to know for certain, unless the creature returns and we get a good photo of it, I suggested that it might have been a young opossum or a young river otter, although neither of those animals fit the description exactly.

I’ve had a lot of readers write in with their theories, the most popular being a weasel, more specifically, a long-tailed weasel. That’s a strong contender. Although it doesn’t quite tick all the boxes, it sounds more plausible than my guesses.

Other suggestions were a ring-tailed cat, a skunk, a marten, a pack or wood rat, a nutria, an escaped pet ferret, a marmot, a mongoose, a ground squirrel, a badger and a frazzled Loch Ness monster.

Rachael Ray to the rescue

Celebrity chef Rachael Ray, who also has her own brand of pet food, Nutrish, will be partnering with San Francisco-based Muttville Senior Dog Rescue, to provide a free year of dog food for all adoptions of senior dogs by prospective owners 50 and older through February.

A private family donation is covering the adoption fees for these dogs, and new owners also will receive a year’s worth of free wellness checks for their dogs.

Find out how to adopt at https://muttville.org. Muttville caters exclusively to senior dogs in the Bay Area, with a mission to give senior dogs a second chance at life through care and by helping them secure loving homes.

Have a question for Joan?

Use this form to submit questions. Photos should be mailed separately to jmorris@bayareanewsgroup.com.