Often nicknamed ‘wild canaries’ for their bright color and cheerful songs, these active little birds are frequent visitors to feeders, especially during the colder months. However, if you think you know everything about their diet just from what you offer in your backyard, you might be surprised. Unlike many other songbirds that rely heavily on insects, goldfinches are remarkably specialized eaters, demonstrating a unique culinary preference that dictates their movements, breeding habits, and even their survival. The Lesser Goldfinch (Carduelis psaltria) is a small, social, seed-eating songbird.
General Dietary Preferences
The Lesser Goldfinch eats mainly seeds from the sunflower family (Asteraceae, or Compositae), although they also eat coffeeberry, elderberry, and madrone fruits, as well as buds of cottonwoods, alders, sycamores, willows, and oaks. They feed in small groups, moving through low weeds and other plants to get to the seeds, buds, flowers or fruits. Napa thistle is a primary food source. To eat seeds, the Lesser Goldfinch uses its bill to pry open the outer covering, shakes its head to loosen the husk, then swallows the seed. Like American Goldfinches, they cling to the seed heads of tall plants, bending the stem down so that it can end up hanging upside down while picking at the seeds. It will occasionally supplement its diet with insects such as plant lice.
Seeds
Goldfinches are granivorous, meaning their diet is dominated by seeds. They have a small, conical beak perfectly adapted for extracting tiny seeds from various plants. This is arguably the most vital nutrient for American Goldfinches, especially given their high metabolism and active lifestyle. Seeds, particularly oilseeds, are packed with healthy fats. Nyjer is a real favorite with very high oil content, as is black oil sunflower. All whole seeds contain fiber. Seeds provide various vitamins, though often not in as high concentrations as fresh fruits or vegetables. Vitamin B complex is prevalent and is essential for metabolic processes. It should be noted that if birds rely solely on a limited seed diet (especially in captivity), they can sometimes develop deficiencies, particularly in Vitamin A. Seeds contain various essential minerals vital for bone health, nerve function, and overall physiological processes. Calcium is important for bone strength and eggshell formation (though birds often need supplemental calcium from sources like grit). Some seeds, like Nyjer, are noted for providing a good amount of calcium.
Nyjer Seed
Nyjer seed is a tiny black seed that is absolutely central to understanding the American Goldfinch’s diet and why they are so reliably attracted to feeders offering it. Nyjer comes from an entirely different plant: Guizotia abyssinica, an annual herb commonly known as the African yellow daisy or Niger seed plant. Guizotia abyssinica is primarily cultivated in Ethiopia and India for its edible oil and seeds. The spelling “Nyjer” (with a capital N and the registered trademark symbol, Nyjer®) was actually adopted by the Wild Bird Feeding Institute (WBFI) in the late 1990s. Nyjer seeds are remarkably rich in oil, typically containing around 35-45% fat. This high-fat content makes them an incredibly calorie-dense food source, providing the abundant energy that active, high-metabolism birds like goldfinches need, especially for flight and to maintain body heat in colder weather. Beyond fats, Nyjer is also a good source of protein, usually around 18-27%. Birds simply seem to find Nyjer seeds delicious. Due to its tiny size, Nyjer seed requires specific feeders called Nyjer Socks (or Thistle Socks). These are fine mesh bags that goldfinches can cling to, pulling seeds through the mesh openings. They are a classic and highly effective way to offer Nyjer. Alternatively, there are clear tube feeders with very narrow, slit-like ports that are too small for larger birds or squirrels to access, but perfectly sized for the small beaks of finches. This high-temperature treatment prevents the seeds from germinating if they fall to the ground beneath your feeder. This is a crucial measure to prevent the introduction of non-native plant species. Nyjer seed is undoubtedly a powerhouse of nutrition that perfectly matches the specialized dietary needs and beak morphology of the American Goldfinch.
Sunflower Seeds
Sunflower seeds are a universal favorite. They come from the common sunflower plant (Helianthus annuus) and are highly prized in bird feeding for their high nutritional content and versatility. The black oil sunflower seed is smaller, with a thinner shell and a higher oil content than striped sunflower seeds. The shell is uniformly black. It contains a high percentage of fat (around 35-40%), which is crucial for a bird’s metabolism, warmth, and overall energy needs. Birds love it because the thinner shell is easier for a wide variety of birds to crack open, from large cardinals and grosbeaks to smaller chickadees and finches. The high oil content makes it incredibly palatable and provides vital calories. Striped sunflower seeds are larger than the black oil variety with a thicker, harder shell and distinct black and white stripes. They typically have a lower oil content, making them still nutritious, but generally offer less fat and similar protein compared to the black oil seeds. The thicker shell also makes them harder to open. Shelled sunflower seeds are simply the de-hulled kernels of either black oil or striped sunflower seeds. They come as whole hearts or smaller chips. They have all the good stuff (fat, protein, carbohydrates, vitamins, minerals) without the indigestible shell. This makes them incredibly efficient for birds to consume, as they don’t have to spend energy cracking the shell. While more expensive per pound, you’re paying for pure nutrition, and there’s no waste. Black oil and striped sunflower seeds are best offered in tube feeders, hopper feeders, or platform feeders. Shelled seeds, chips and hearts can all be offered in virtually any feeder type - tube, hopper, platform, or even mesh feeders.
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Asteraceae Family
The Asteraceae family, also known as the daisy family or composite family, is one of the largest and most diverse plant families globally. Its characteristic feature is the composite flower head, which looks like a single flower but is actually made up of many tiny individual flowers (florets) tightly packed together. For American Goldfinches, this family is a goldmine because these plants are prolific seed producers. Many produce small, lightweight seeds that are perfectly sized for a goldfinch’s slender, conical beak. While ‘Nyjer’ isn’t true thistle, the goldfinch’s common association with thistle stems from its strong preference for the seeds of native thistle species. Goldfinches are uniquely adapted to extract these seeds. They can cling directly to the thorny flower heads, often hanging upside-down, meticulously pulling out the parachute-like seeds. Beyond food, the downy pappus (the fluffy parachute attached to thistle seeds) is also a crucial nesting material for goldfinches, used to line their nests, providing insulation and softness for their young. Various native Cirsium species (e.g., Tall Thistle, Field Thistle) provide this resource. Often considered a garden weed, the common dandelion is a surprisingly important early-to-mid summer food source for goldfinches. Their large, easily accessible seed heads provide a readily available meal. Goldfinches will perch on the stem and pluck out the wind-dispersed seeds. These plants produce tall stalks with numerous seed pods. Goldfinches are adept at prying open the dry seed capsules to extract the small, dark seeds. Popular in perennial gardens, coneflowers are a magnet for goldfinches once their petals fade and the central cone dries and produces seeds. Goldfinches will perch directly on the rigid central cone, sometimes upside down, picking out the seeds. These popular annual flowers, when allowed to go to seed, become irresistible to goldfinches. While notorious for causing allergies, ragweed is a significant natural food source for many seed-eating birds, including goldfinches. The abundance and reliable maturation of seeds from the Asteraceae family (and others) in late summer is a key reason why American Goldfinches delay their nesting until June, July, or even August. They ensure a steady supply of their preferred food for their growing young, who, unlike most birds, are fed almost exclusively a seed diet. For bird watchers, observing goldfinches on wild seed heads offers a glimpse into their most natural foraging behavior, showcasing their agility and specialized beaks. You can also attract them to your garden by allowing some native plants like coneflowers or evening primrose to go to seed, or tolerating weeds like dandelions and ragweed in less manicured areas.
Protein
Proteins are essential for growth, tissue repair, feather development, and enzyme production. While goldfinches aren’t eating insects like most birds, they still get sufficient protein from seeds. Nyjer has surprisingly high protein for a seed, around 19−24%. Sunflower seeds come next with around 15−18%.
Foraging Behavior
The Lesser Goldfinch is an active and acrobatic forager in trees, shrubs, and weeds. They forage actively and acrobatically in trees, shrubs, and weeds. Except when nesting, usually forages in flocks. The Lesser Goldfinch is a quick little bird, constantly hovering about and jerking its tail while feeding. On the wing, it has the same dipping, bouncy flight of the American Goldfinch. And like other goldfinches, the Lesser is gregarious, forming large flocks at feeding sites and watering holes. They feed in small groups, moving through low weeds and other plants to get to the seeds, buds, flowers or fruits. Like American Goldfinches, they cling to the seed heads of tall plants, bending the stem down so that it can end up hanging upside down while picking at the seeds.
Seasonal Shifts in Diet
While summer is prime time for American Goldfinches due to the abundance of ripening wild seeds, their dietary behavior shifts subtly with the seasons. In late summer and early fall, goldfinches intensify foraging as natural seed sources peak, aligning with their delayed breeding cycle. By winter, however, many wild seeds are depleted, and backyard feeders become critical. During this time, their reliance on calorie-dense oilseeds like Nyjer and shelled sunflower chips grows dramatically. This seasonal dependence on supplemental feeding explains why goldfinch numbers at feeders often spike in colder months, even as their core diet remains consistent.
Feeding the Young
For most songbirds, the rule is simple: insects for nestlings! The vast majority of species switch from a primarily seed or fruit diet as adults to an insect-heavy diet when feeding their young. This is because insects (caterpillars, spiders, aphids, etc.) are packed with protein, fat, and crucial moisture, all vital for the rapid growth and development of altricial (helpless at hatching) chicks. Goldfinch parents feed their nestlings and recently fledged young a diet that consists almost entirely of regurgitated seeds. They consume seeds themselves, partially digest and moisten them in their crop (a pouch in the esophagus), and then bring this seed paste back to the nest to feed their chicks. The seeds primarily used for this purpose are the same highly nutritious, oil-rich ones they consume as adults: Nyjer and thistle seeds are paramount, followed by dandelion and other small, oil-rich wild seeds. This unique dietary requirement is the direct reason why American Goldfinches are among the latest nesting birds in North America, typically not beginning nesting until late June, July, or even August. They wait for the natural ripening and dispersal of thistle seeds, milkweed seeds, and other composite seeds. By nesting later, they ensure that this vital food source is abundant and readily available when their demanding chicks hatch. This seed-exclusive diet is why American Goldfinch nests are often considered a death trap for Brown-headed Cowbird chicks. Cowbirds are brood parasites that lay their eggs in other birds’ nests. However, cowbird chicks are genetically programmed for an insect-heavy diet.
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Supplemental Foods
Goldfinches have been observed nipping at the nascent buds of trees like elms, birches, and alders. They might also peck at the tender inner bark of young twigs. They are particularly attracted to the catkins of birches and alders, which are rich in pollen and tiny developing seeds. This behavior is most common in early spring, particularly after a long winter when stored wild seeds may be depleted and new seed crops (like thistles) haven’t yet matured. Buds and bark offer some limited carbohydrates, fiber, and trace minerals. While not as energy-dense as seeds, they provide sustenance when other options are scarce, helping to bridge the gap between winter and the burgeoning spring/summer bounty. Maple sap is primarily composed of sugars (carbohydrates) dissolved in water. It provides a quick burst of energy and hydration. This is a very specific behavior observed primarily in early spring when maple trees begin to produce sap. Goldfinches typically don’t drill for sap themselves like woodpeckers do. Instead, they will visit the sapsucker wells - small, orderly rows of holes drilled by sapsuckers - to drink the flowing sap. Eating these is occasionally observed throughout the growing season, but not a significant part of their diet. Goldfinches might peck at very young, tender shoots or fresh green leaves of various herbaceous plants. It’s crucial to always remember that these minor components are truly supplemental and opportunistic. They represent less than 5% (and often far less) of the goldfinch’s total caloric intake throughout the year. The vast majority of their nutritional needs, including those for growth and reproduction, are met by the fats, proteins, and carbohydrates derived from a specialized diet of oil-rich seeds.
Attracting Goldfinches
Knowing that goldfinches are almost exclusively seed-eaters, and particularly fond of tiny, oil-rich seeds, allows birdwatchers to offer the exact foods that will reliably attract them. The number one draw, of course, is Nyjer seed. Understanding its unique properties (high fat, thin shell, tiny size) means you’ll invest in the right seed and the specialized feeders (thistle socks or tube feeders with tiny slits) required to offer it effectively. You won’t waste money on seeds they won’t eat. Their pickiness means knowing the importance of fresh, dry seed. If Nyjer gets wet and clumps, or if any seed goes stale, goldfinches will likely abandon the feeder, leading to frustration for the birder. Their diet directly explains their fascinating breeding schedule. Birdwatchers who know that goldfinches rely on mature thistle and other composite seeds for their young won’t be confused by their unusually late nesting period (often starting in July-August). Their ability to cling upside down or sideways on slender plant stems (like thistle, coneflowers, or zinnias) is a direct adaptation to accessing their preferred seeds. Their diet also influences their social structure. Outside of breeding season, goldfinches often form large, nomadic flocks that move together in search of abundant seed sources. Knowing their reliance on wild seeds, particularly from the Asteraceae family, empowers birdwatchers to design their landscapes to attract and support goldfinches naturally. Cultivating native plants like coneflowers (Echinacea), various native thistles (Cirsium species - ensure they are native and not invasive in your region!), zinnias, cosmos, asters, and evening primrose ensures a sustainable, natural food source.
Providing Water
Lesser Goldfinches need a reliable source of water. They drink frequently, probably owing to their seed diet.
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