DEAR JOAN: We have three bird feeders, three bird baths, and bird and bee friendly plants, including two large bottlebrush shrubs that the birds hang out in.

Some days we have a great number of birds at the feeders and baths. It was always entertaining. About a week ago, they left. There are hardly any sparrows, finches or other songbirds.

What happened? I did not think these type of birds migrated. To our knowledge, nothing has changed in our yard.

Charlene Cella, Benicia

DEAR CHARLENE: Something did change in your yard. The birds, mostly, left. Don’t take it personally, however. It likely wasn’t because of something you did, but something Mother Nature did.

According to the Cornell Lab of Ornithology, birds often abruptly desert feeders and backyards when nature has supplied an abundance of food for them. Nothing against your blend of seeds and water features, but it’s hard to compete with the natural stuff.

The birds are most likely feasting in open spaces where plant and insect life is thriving. No banquet lasts forever, however, and if you keep your bird restaurant open during the slowdown, they’ll be back.

In the meantime, take an inventory of your plants and then talk with an expert at your favorite nursery about what plants you could add or replace that would be the most appealing to those fickle birds.

DEAR JOAN: I have a small deck that is about 2½ stories above the ground. I put some paper bags out there so the sun could kill any virus and a day later, when I collected the bags, there were two tiny frogs under them.

I live on a canyon near a lake and there are lots of frogs there. But how did these make it to my deck and why? This has happened before.

Mary Louise Morrison, Mountain View

DEAR MARY LOUISE: I can’t say for certain what attracted the frogs to your deck — I’m going to assume it’s a stunning architectural achievement — but most likely they thought there was a good chance some tasty insects were up there.

As for how they got there, I’m going to assume, again, that the tiny frogs are of the tree frog variety, quite adapt at climbing most natural and manufactured surfaces, although regular frogs and toads have climbing capabilities.

DEAR JOAN: Why are a flock of geese dipping their heads in the middle of the lake in Aquatic Park in Berkeley? Is there some kind of food below the surface or are they just washing their heads?

Pete Najarian, Berkeley

DEAR PETE: It sort of depends on the type of geese we’re talking about, but most geese, including Canada geese, eat aquatic plants, so they do a lot of head-dipping when on the water.

Dipping their heads also is part of the mating ritual for many geese species, a move that signals to potential mates that they are in the mood.

Geese spend about half of their time each day foraging on land and in the water. They also swallow silt and gravel from the pond’s bottom to help them with digestion. Their diet changes a bit in the fall and winter, when they eat more carbs to bulk up for the cold nights and, for those that do migrate, long flights.

And yes, they use the water to wash their faces and flush out their beaks and nostrils.