Hummingbirds are widely known as high-octane energy specialists, famous for their nearly constant consumption of flower nectar or sugary water to fuel their rapid metabolism. Their legendary wingbeats demand an immense amount of quick-burning carbohydrates, which nectar readily provides. However, this sugary liquid alone is nutritionally incomplete for these tiny birds. To sustain life, develop properly, and successfully reproduce, hummingbirds must consume additional food sources that provide necessary structural components. This article will explore the often-overlooked dietary elements that provide the building blocks for these remarkable fliers.
The Critical Role of Arthropods
The most substantial component of a hummingbird’s diet, aside from nectar, is small arthropods, including insects and spiders. These tiny invertebrates are deliberately hunted to balance the carbohydrate-heavy diet. Adult hummingbirds may consume hundreds of these small creatures daily, a figure that increases dramatically during periods of high biological demand.
The diet includes a variety of soft-bodied prey such as gnats, fruit flies, aphids, small beetles, and various insect eggs and larvae. Spiders are also a favored food source, often plucked directly from their webs. Since the birds cannot dismember their food with their long, slender bills, they must target prey small enough to be swallowed whole.
Hummingbirds employ two primary methods for capturing these minuscule targets, both demanding high precision and aerial agility.
Hawking
The first method, known as “hawking,” involves catching flying insects directly in mid-air, often near swarms or bodies of water. They achieve this by flying out from a perch to snatch the prey, sometimes utilizing a slight downward flex of the lower jaw to improve capture success.
Gleaning
The second strategy, called “gleaning,” involves hovering briefly to pluck stationary insects or spiders from vegetation, bark, or spider silk. This meticulous hunting is often focused on the undersides of leaves where many small pests congregate. Arthropod consumption can be so frequent that some researchers suggest hummingbirds are better described as insectivores that also drink nectar, rather than the reverse.
Nutritional Demands Beyond Simple Sugars
Nectar is almost pure sugar and water, lacking protein, fats, and essential micronutrients. Arthropods supply the amino acids, lipids, and minerals necessary for bodily functions beyond immediate energy. This protein content is vital for continuous maintenance and repair of the powerful flight muscles, which undergo constant turnover due to their high activity level.
During the breeding season, the need for protein becomes even more pronounced, especially for females who must produce eggs. Once the chicks hatch, their development requires a diet almost entirely composed of protein. Adult females feed their nestlings a regurgitated paste of insects and spiders, which allows the young to grow rapidly and develop strong feathers and muscle mass.
The lipids and minerals found in insects, such as salts and trace elements, are indispensable for overall health and feather growth. Without a steady intake of this nutrient-dense food, hummingbirds would face serious deficiencies. The protein from arthropods ensures the long-term survival, reproduction, and structural integrity of the bird.
Opportunistic Feeding and Secondary Sources
When primary food sources are limited, hummingbirds opportunistically seek out other liquids that provide necessary sugars and nutrients.
Tree Sap
One such source is tree sap, particularly that which collects in small wells drilled by sapsuckers. The sap, rich in sucrose and amino acids, acts as a secondary carbohydrate source, especially early in the spring before many flowers bloom.
Fruit Juice and Pollen
Hummingbirds may also occasionally sample the juice from damaged or overripe fruit. Since their bills are not designed to pierce skin, they lap up the exposed fruit juices for a minor sugar boost. They also inadvertently ingest pollen while feeding on nectar, as the fine grains stick to their bills and tongues. Although pollen provides a small amount of protein, much of it passes through the digestive system undigested, making it a minor nutritional contributor.
Grit and Minerals
Finally, hummingbirds require trace amounts of grit or minerals, which they may ingest by picking up fine sand or ash. These tertiary resources help fill nutritional gaps when insects or nectar are temporarily scarce.