i do all the time. i use shortning or lard or ground suet or beef tallow or bacon grease. The only concern i have heard is some people say that the bacon grease has salt from the curing bacon. but most say by the time you add all the other ingredients it is not enough to matter. we don't cook bacon much anymoe but i save the grease and freeze it till i want to use it. And lots of the time i will use up the bacon grease along with suet or lard to make a bigger batch which also dilutes down what salt might be in the bacon grease

How much salt is in bacon grease?? What is a good "recipe" for bird suet? And how much salt is good or bad for wild birds?

i have googled use of bacon grease and also bing search and asked about it with a bunch of different audubon societys in different states. the majority of them recomend useing bacon grease as long as the birds have sufficient water supplys. I have used bacon grease for many years and have lots of birds but i do keep fresh water or heated water trays in winter. I usually mix equal parts of suet or lard or bacon grease or tallow or shortning with peanut butter and add some chopped nuts and then thicken it with cornmeal and rolled oats or grits or flour to make a paste. we don't eat a lot of bacon or fatty meats anymore but do save the fats and freeze them. and mix whatever i have on hand into the mix and the bacon grease is usually pretty well diluted down.
Most say it attracts the woodpeckers and chickadees and nuthatches but i get almost every kind of bird i get eating mine. including the jays and juncos and finches ect.

I have used raw suet, rendered suet, and Snow cap lard in my mixture for the birds, with only minor adjustments. The birds have loved it all.

My son has been eating pork bacon lately, and I've been saving the fat in paper cups and put it in the freezer. I will add it to the suet or lard next time making the bird mixture. Because it will be mixed with other fat, peanut butter, corn meal, flour, nuts, etc. I think the salt content would be significantly diluted from pure bacon fat. I'm not sure how much salt is too much though.

Here is an an interesting web page to read if you want to know more about using fats in home-made mixtures for the birds:

"The Great Crisco Debate" - The Suet vs. Lard vs. Shortening question

Bacon grease is a soft spreadable fat. Not good at all, if they get it on their feathers they will starve to death trying to clean it off of themselves.