Suet is technically defined as the hard fat around the kidneys and loins in beef and mutton, but in common usage, most kinds of beef fat are also called suet and can safely be fed to birds. Suet is particularly attractive to woodpeckers, nuthatches, chickadees, jays, and starlings. Wrens, creepers, kinglets, and even cardinals and some warblers occasionally visit suet feeders. Animal fat is easily digested and metabolized by many birds; it's a high-energy food, especially valuable in cold weather.
Red-headed Woodpecker. Mike Smith © Cornell Lab of Ornithology
Raw suet grows rancid quickly when temperatures are above freezing; don’t offer that except in winter. When suet is melted and the impurities removed (“rendering”), it keeps much better, but can still get soft during warm weather. When suet gets soft, it can coat belly feathers, a dangerous situation especially in spring and summer when birds are incubating—tiny pores on the birds’ eggs may get clogged, preventing the developing embryo from getting enough oxygen.
Suet cakes are blocks made from suet or a thick substitute mixed with other ingredients, such as corn meal, peanuts, fruits, or even dried insects. Because corn and peanuts can provide a growth medium for dangerous bacteria, it’s important for you to make your own suet cakes or to buy them from reputable dealers. It may be prudent to keep suet cakes made with corn, cornmeal, or peanuts refrigerated until using.
Starlings are very fond of suet. To dissuade them, offer suet in a feeder that requires birds to feed hanging upside down. Woodpeckers, chickadees, and nuthatches will access it easily, but starlings cannot.
Bacon drippings are also animal fat, and many birds love the taste. But bacon virtually always has detectable amounts of nitrosamines, carcinogenic compounds formed from some of the preservatives used in bacon. In particular, the very high cooking temperatures used to fry bacon are conducive to nitrosamine formation. So despite the fact that birds love it, bacon and bacon fat pose too much of a risk to the long-term health of birds to warrant using it.
In winter, especially in cold climates, peanut butter is a nutritious food to offer birds. Peanut butter sold in grocery stores is certified safe for human consumption, and is safe to offer birds when cold or cool temperatures keep it fairly hard. In warmer weather it must not be kept outside long enough to become rancid or soft.
There is some concern that soft peanut butter can stick to birds’ mouths. To make it grittier, cornmeal can be added, but because both corn and peanuts provide excellent media for bacterial and fungal growth, make sure peanut butter feeders are cleaned out frequently. Peanut oils can separate in both pure peanut butter and in mixtures. If these oils adhere to a nesting bird’s feathers, they can be transferred to eggs, plugging the pores, so never provide peanut butter mixtures that become soft or oily.
Mealworms are larvae of a flightless insect called the darkling beetle. They’re a serious pest in granaries, but are safe and easy to maintain in our houses, confined in buckets or plastic bins.
Mealworms. © Peter Halasz
Mealworms can be an excellent source of protein, calcium, and vitamins for a great many birds, including some that normally don’t visit feeders, but mealworms are only as healthful as the diet they are fed. If you order them in bulk, they usually come packaged in wads of newspaper, and will eat the paper, ink and all. So make sure to remove them from the paper as quickly as possible when they arrive. It can be tricky to remove them from their packaging—it’s easiest to avoid setting them free in your house if you transfer them from the packaging to your buckets outdoors, or over a very large piece of white paper so you can spot any runaway mealworms before they get far. They don’t live long away from an easy supply of food, but few people relish the thought of them, dead or alive, in crevices in their homes.
To maintain a large number of mealworms, fill the bottom of an ice cream bucket, dishpan, or similar bin with an inch or two of dry oatmeal or wheat bran. Add chunks of raw potato or apple for moisture, and then put the mealworms in. To improve the levels of many nutrients, especially during the nesting season, you can add powdered hand-feeding bird food (the kind marketed as a complete diet for hand-reared baby parrots).
Mealworms can’t escape a plastic enclosure such as a bucket as long as there are at least two or three inches of vertical wall between the surface of the medium and the lip. Keep them in the coolest place in your house—usually a basement is a great choice—on a surface where the bucket won’t easily get knocked over.
There’s a lot of excellent information about mealworms on the North American Bluebird Society website and about how to raise them on the Sialis website.
So very many birds will voraciously gobble up mealworms at feeders that offering them is only affordable if you set out a few at a time, at feeders inaccessible to birds you don’t want to subsidize. Small acrylic window feeders work well; if yours has drainage holes, make sure to plug them because mealworms can squeeze through surprisingly tiny spaces. Special bluebird feeders that exclude most other birds are available commercially, or plans are available here.
Fruits and fruit seeds
A Northern Cardinal and a Pyrrhuloxia are attracted to an apple. ©
In the tropics, many people set out fruit for birds, attracting a large number of tanagers and other species that people in North America seldom consider “feeder birds.” But even in the north, robins, thrushes, waxwings, bluebirds, mockingbirds, catbirds, and tanagers can sometimes be attracted to feeders providing fruit. Because few people in the United States or Canada offer fruit at feeders, few individuals of these species have experience eating at feeders, so it can be tricky to entice them to get close enough to figure out the concept. Fresh berries; chunks of fresh apples, melons, or grapes; or frozen berries, are excellent choices. Raisins or currants that have been softened by soaking in water may also be good. Orange halves are particularly attractive to orioles during spring migration, especially to orioles.
Providing fruits can cause some serious problems. It spoils quickly, so feeders must be emptied and cleaned very frequently. Offering fruit in a plastic cereal bowl makes this an easier task. Unfortunately, in summer, fruit attracts ants and wasps; fortunately, there’s no compelling reason to feed fruit in summer and fall when so much fresh fruit is available naturally.
Pumpkin seeds and other squash or melon seeds can be extremely attractive for birds. Bake them or spread them out to dry completely, and then run them through a food processor to chop them up, which will make them easier for smaller birds to eat.
Orioles, catbirds, and sometimes Cape May Warblers can be enticed to visit feeders offering jelly. Make sure to only offer very small quantities at once, because jelly gets extremely sticky; small birds can become mired in it. Also, jelly has much higher sugar concentrations than any natural food. It’s probably not unhealthful for adult birds to supplement their diets during severe food shortages associated with unseasonable cold spells in spring, or in small quantities during the rest of the year. Sometimes adult orioles and other birds visit jelly for a quick snack while searching out insect food for their young in summer; this won’t hurt them, but bring in the jelly if adults are bringing their young to it more than once a day. Growing fledglings need proteins far more than carbohydrates, and jelly is probably a very unhealthy meal for them.
Some birds eat bread and other leftovers. Moldy or spoiled food may harm birds, and table scraps are far less likely to provide nourishment for native songbirds than for invasive starlings, pigeons, and House Sparrows, along with rats, mice, and raccoons.
Grit and Minerals
Seed-eating birds need to eat grit to help them digest their food. They lack teeth, and grit grinds the seeds they eat in the gizzard, a highly muscular stomach chamber, while the grit itself is slowly ground down and dissolved, the minerals entering the bloodstream. Tiny stones or sand can be excellent sources of grit. Broken oyster shells and “cuttlefish bones” not only aid in digestion; they also provide calcium, which is especially critical to birds during the breeding season. You can purchase grit at most feed and pet stores.
Eggshells are an excellent source of grit and calcium, but chicken eggs may harbor the salmonella bacteria. Shells from hard-boiled eggs were sterilized in the cooking process, but if you provide eggshells that weren’t cooked, bake them for 20 minutes at 250 degrees Fahrenheit, let them cool, and then crush them into pieces smaller than a dime. Offer eggshells on the ground, in a dish, or on a low platform feeder, separate from your seed feeders.
To learn more about birds and calcium, read the following Birdscope articles:
Birds and Calcium, by Tracey L. Kast, Paul E. Allen, and Andre A. Dhondt (1998). Results of the Lab's Birds and Calcium Project show that calcium use varies among species.
Feeding Calcium to Birds, by Andre A. Dhondt (1999). The Lab's Birds and Calcium Project determines we should offer calcium on the ground and on platform feeders.