You guessed right. Mr. cardinal is enjoying some safflower seeds. since we switched from a mixture of bird seeds to safflower, we have no more blackbirds calling and the squirrels shy away from them too. we do feed the squirrels though.
To get a better idea of what wild squirrels should eat on a daily basis, I googled foods for wild squirrels and came across some interesting articles and this cute picture. I took it from my computer and will post it in album two. you should see it, it's adorable.