Something is eating your leaves. I have grown sunflowers and have never once seen chickadee interest in anything but the mature flower head.

I googled 'birds eating sunflower leaves' and found lots of discussions. Apparently the leaves are nutritious during breeding season. There were lots of suggestions like mesh covering the plant, but I liked 'plant more sunflowers' the best. I love my sunflowers and will be distressed if my birds start picking up this bad habit.

Not even sure if it'll work but steep dried hot peppers in water. Maybe add a little soap to help adhesion and spray it on the leaves. Neem oil might also work, just don't use it when flowering. Sparkle tape tied around the plant might scare them away.

Hence the common advice to add hot pepper to your bird feeders to discourage the squirrels.

There are some videos out there of squirrels sampling "hot" bird seed. They really don't like it at all.

It really looks like insect damage. Could the birds be after the bugs? If it is birds I guess you can try the usual anti bird garden tricks - netting, shiny things that move in the breeze, etc.

Thanks, Kali.

cute too! decorated sunflower plants

I need to make one for my strawberries.

….that are on the leaves. Cut the old beaten up leaves off the plant, keep the plant watered,
and spray the new leaves with a deer or rabbit repellent or a very very dilute insecticide…. The plant
will push new leaves. If you watch the plant closely you’ll more than likely to see some kind of
caterpillar or worm on it. The damage from what I can tell is cosmetic. Spraying the plant with
H2O might knock some of the critters off of it.