Hummingbirds are known for their iridescent plumage and rapid metabolism. These tiny birds must consume nectar and insects almost constantly to sustain the speed of their wings. Their reproductive cycle, including their nests and eggs, is seldom seen by the average person. The process of creating and raising their young begins with the egg.
The Distinctive Appearance of Hummingbird Eggs
The eggs of the hummingbird are typically a plain, dull white or creamy white color, which contrasts with the spotted or tinted eggs laid by many other bird species. This simple coloration is consistent across most of the hundreds of hummingbird species found throughout the Americas. Unlike eggs with elaborate patterns, the smooth, ovoid shell of the hummingbird egg is largely unadorned. The lack of dark pigmentation may serve a function by helping the eggs reflect sunlight and avoid overheating during incubation, especially in exposed nests.
The female hummingbird will almost always lay a clutch of two eggs, which is considered the optimal number for her to successfully raise alone. This small quantity is a significant reproductive investment considering the female must undertake all the feeding and care without the male’s assistance. Laying only two eggs maximizes her chances of providing enough protein-rich insects for her fast-growing offspring. The shells possess a smooth texture and are usually matte rather than glossy.
The Miniature Scale of Hummingbird Eggs
Hummingbird eggs are the smallest bird eggs in the world. The eggs of the Ruby-throated Hummingbird, for example, measure only about half an inch in length. A hummingbird egg is often described as being roughly the size of a small jelly bean, a coffee bean, or a green pea.
The smallest of all, the egg of the Bee Hummingbird, is barely larger than a tic tac. These tiny eggs weigh less than half a gram, with a Ruby-throated egg weighing approximately 0.62 grams. Despite their minuscule size, a single egg can represent up to 17% of the mother’s body weight, demonstrating the physical demands of reproduction for these small fliers.
Where Hummingbirds Construct Their Nests
The female hummingbird builds the nest entirely on her own, a process that can take up to a week. The resulting structure is a tiny, cup-shaped nest, often no wider than a golf ball. Nests are typically situated on small, downward-sloping branches in trees or shrubs, often at a height of 10 to 40 feet above the ground.
The outside of the nest is meticulously covered with bits of lichen and moss, secured with spider silk to create camouflage. This exterior gives the nest the appearance of a natural knot or bump on a branch, making it difficult for predators to spot. The spider silk’s elastic properties allow the nest to stretch outward as the nestlings grow.
The Incubation and Hatching Timeline
Once the nest is complete, the female will lay her two eggs, usually spaced one or two days apart. Only the female performs the duty of incubation, a period that typically lasts between 12 and 18 days. She will not begin constant, full incubation until both eggs are laid, which ensures that the nestlings hatch at roughly the same time.
During this time, the mother must leave the nest periodically to feed, but she keeps the eggs warm, maintaining a temperature near 96 degrees Fahrenheit. After hatching, the young are born blind and mostly naked, entirely dependent on the female for warmth and sustenance. The mother feeds them a slurry of regurgitated nectar and tiny insects, concentrating on protein-rich insects for rapid growth. The nestlings remain for an additional 18 to 28 days until they are ready to fledge, a rapid developmental timeline essential for survival.