DEAR JOAN: I have a question about the beautiful Steller's jays in my yard.

About three years ago, the jays built a nest under my back deck, above my cement patio. There were four babies, all of them flew, and now, I believe, they still are flying around my yard. Each spring they bring an armful a day of nest makings and put it under where their nest was.

Such a curious thing. I don't think they're dumb enough not to be able to build a nest where their old one was in the rafters. Could it be a decoy? What are they doing?

This year is particularly crazy. There's so much debris right under where their nest was. Any enlightenment would be appreciated.

A Steller’s jay holds two peanuts.
A Steller's jay holds two peanuts. (Doug Duran/Contra Costa Times)

Kim C.

Eastern Sierra

DEAR KIM: It is not a decoy nest. I could find nothing in Steller's jay studies that indicate they do this sort of thing, but if they did, they would build the fake nest far from their real nesting site, and in the trees, not on the ground.

You say the pile is under where their nest used to be, so I'm guessing there is no nest there now. The very vocal jays are exceptionally quiet when building their nests, so as not to draw attention to them, and so leaving big piles of debris beneath them would be out of character. They also want private places for their nests, and if you have tall trees around, that would be their first choice.

So if it's not nesting material, what it is? I suspect it's a food supply. The jays are known for hoarding and hiding food, burying it in the ground, beneath piles of fallen leaves or inside tree cavities. They remember all of the places where they store food, and they hide them very well, making sure everything is covered. I think all that debris is hiding a large cache of food.

The jays you are seeing now could very well be the original pair and their offspring. They are monogamous and family groups often stay together.

DEAR JOAN: I was sitting in the backyard recently and heard a commotion in one of the big fir trees. There were about six hummingbirds and the same number of small brown birds. They weren't attacking each other but flying in and around the branches chasing each other and making lots of noise. This lasted about 10 minutes and then everything became quiet.

Can you tell me what this was all about?

Polly Moniz

San Ramon

DEAR POLLY: It was about love. More specifically, about nesting and the protection of family.

I suspect that the hummers have nests in the area and they didn't appreciate interlopers in the area. Birds, like all creatures, including humans, stake out their territory and protect it.

As you can imagine, there is not a whole lot of damage small birds can inflict, so it's mostly a lot of posturing.

Scientist for a day

The UC Cooperative Extension is celebrating its 100th anniversary this year, and to celebrate they are asking folks on Thursday to become a scientist for a day, make some observations on pollinators, water use and where your food comes from, and report back to them.

To participate, go to beascientist.ucanr.edu and click on the topic you're reporting on. The site has interactive maps to record your information. You also can add photos.

Contact Joan Morris at jmorris@bayareanewsgroup.com. Read the Animal Life blog at blogs.mercurynews.com/pets.