The fruit of the Sambucus plant, commonly known as elderberries, represents a significant food source in many avian environments. Birds consume these dark, fleshy fruits, making them one of the most sought-after late-season berries in the landscape. These small, nutrient-rich drupes attract a wide spectrum of avian life, signaling a seasonal feast that coincides with crucial periods of migration and preparation for colder months.
The Birds That Seek Them Out
A diverse assembly of North American bird species actively seeks out and consumes elderberries, particularly when they ripen in late summer and early fall. Among the most frequent visitors are the Cedar Waxwings, known for their nomadic, fruit-focused flocks that can quickly strip a bush clean. American Robins are also enthusiastic consumers, as are several members of the thrush family, including the Wood Thrush and Gray-cheeked Thrush, who gorge on the fruit to build up fat reserves.
The list of avian consumers extends to species like the Northern Mockingbird, Eastern Bluebirds, and various grosbeaks and tanagers, such as the Rose-breasted Grosbeak and Scarlet Tanager. These birds often consume the entire berry, pulp and seed alike, which contributes to the plant’s reproductive success. Studies show that during the peak ripening period, the diet of certain species, like the Rose-breasted Grosbeak, can consist of fruit, including elderberries, for as much as 95% of their intake.
This mass consumption is tied to the seasonality of the fruit, as the late-maturing berries appear when other food sources may be dwindling. The birds are storing energy for migration or to sustain themselves through winter. The high concentration of berries allows a large number of birds to feed efficiently.
Elderberries’ Safety Profile for Birds
The concern surrounding elderberry consumption stems from the presence of cyanogenic glycosides, which are naturally occurring defense compounds within the Sambucus plant. These glycosides, such as sambunigrin, are concentrated mainly in the plant’s leaves, stems, roots, and the unripe fruit, as well as being present in the seeds. When these compounds are broken down by enzymes, they can release toxic hydrogen cyanide, which is why raw, unprepared elderberries are not recommended for human consumption.
Birds, however, are largely unaffected by these trace toxins in the ripe fruit, due to their digestive physiology and foraging behavior. The ripe elderberry pulp contains only negligible amounts of the cyanogenic compounds, as the toxins are primarily sequestered within the seed coat. When birds eat the berries, they typically swallow the small seeds whole without chewing them, preventing the release of toxic compounds.
Furthermore, the avian digestive system operates with an exceptionally rapid gut transit time, meaning the seeds pass through the bird quickly. This rapid passage minimizes the duration the seeds spend in the digestive tract, preventing the chemical reaction necessary for the enzymatic hydrolysis of the glycosides to release hydrogen cyanide. This physiological adaptation allows birds to safely acquire the energy from the fruit pulp while serving as an effective means of seed dispersal.
The Role of Elderberries in Avian Ecology
Elderberries provide a distinct nutritional benefit, particularly as a source of energy for birds preparing for lengthy migratory flights. The fruit is rich in sugars and carbohydrates, which are essential for building up the fat reserves necessary to power long-distance journeys. Beyond simple calories, elderberries are packed with beneficial compounds like phenolic acids and flavonols, which function as potent antioxidants.
These antioxidants help birds manage the oxidative stress that results from the physically demanding processes of migration and rapid weight gain. The deep, dark color of the berries is a sign of high anthocyanin content, a type of flavonoid that provides the fruit’s pigment and offers health benefits. This late-season surge of nutrient-dense fruit is perfectly timed to meet the heightened energy and physical demands of avian life cycles.
The relationship between the bird and the plant is a classic example of mutualism, known ecologically as ornithochory, or bird dispersal of seeds. The elderberry produces an attractive, fleshy fruit, which serves as a reward to the bird. In return for the meal, the bird carries the indigestible seeds away from the parent plant, depositing them in a new location via its droppings.
This dispersal mechanism is fundamental to the elderberry’s survival and colonization of new habitats. For homeowners and gardeners, planting native varieties, such as the American Elderberry (Sambucus canadensis) or Blue Elderberry (Sambucus cerulea), is an effective way to support local ecosystems. These native shrubs reliably attract a high volume of avian life and provide necessary food, cover, and nesting sites.