Suet is a high-energy food source for wild birds, defined as the hard fat found around the kidneys and loins of beef or mutton. In bird feeding, it refers to rendered beef fat that has been purified and solidified. This fat is often mixed with ingredients such as seeds, nuts, or dried fruits to form a dense cake or plug. Offering suet supplements the diets of wild birds, especially those that forage for insects, by supplying concentrated energy when natural foraging is challenging.
The Nutritional Value of Suet for Birds
Suet, composed of nearly pure animal fat, is a dense source of calories for wild birds. This high-fat content is readily metabolized, providing a quick burst of energy to support high metabolic rates. The concentrated nature of the fat allows birds to acquire substantial energy while spending less time exposed at a feeder.
This energy reserve is advantageous during cold weather when birds must expend considerable energy to maintain body temperature. As temperatures drop, the demand for easily accessible, high-calorie food increases. Suet also substitutes for the fat and protein found in insects, which become scarce in winter. Added ingredients in commercial mixtures, like nuts and seeds, enhance the protein and mineral content, supporting overall health.
Specific Species Attracted to Suet
Suet is favored by birds with a natural clinging ability, allowing them to feed comfortably on a vertical surface like a suet cage. Woodpeckers are frequent visitors, including the Downy, Hairy, and Red-bellied Woodpeckers, which readily consume the fat. These birds use their stiff tail feathers and strong claws to brace themselves, mimicking their natural foraging posture on tree trunks.
Other acrobatic species are also drawn to suet, including nuthatches and chickadees. White-breasted and Red-breasted Nuthatches are known for their distinctive head-first descent down a tree, a behavior they use at a suet feeder. Tufted Titmice and Black-capped Chickadees are attracted to the concentrated energy, often carrying chunks away to consume elsewhere. Even insectivorous species that typically do not visit seed feeders, such as warblers, wrens, and kinglets, occasionally utilize suet as a temporary source of nutrition during migration or cold snaps.
Different Forms of Suet and Feeding Safety
Commercial suet is available in several forms. It is most commonly sold as firm, square cakes designed to fit into wire-cage feeders. Other options include plugs for log-style feeders, shredded nuggets mixed with seed, and spreadable suet butter applied directly to tree bark. These variations allow for different feeding styles and attract a wider variety of birds.
A critical safety consideration is ensuring that only rendered suet is used. Raw suet, which is unpurified animal fat, quickly becomes rancid and may harbor harmful bacteria, especially as temperatures rise. The rendering process melts and purifies the fat, increasing its stability and shelf life.
The most important safety guideline relates to temperature: standard suet should be removed when outdoor temperatures consistently exceed 70°F (about 21°C). Above this temperature, the fat can soften, risking it melting onto a bird’s feathers. Fat on feathers compromises the bird’s insulation and waterproofing, which can be detrimental to its survival. To allow year-round feeding, many commercial products are formulated as “no-melt” suets, which often substitute animal fat with vegetable shortening or blend it with dry ingredients like cornmeal to maintain a solid texture.