Hummingbirds are among the smallest birds on the planet, with some species weighing less than a penny. This necessitates a remarkably high metabolism to sustain their rapid wing beats and hovering flight. This unique biology dictates many aspects of their life cycle, including their reproductive strategy. The female undertakes the entire process of reproduction alone, from building the nest to raising the young, which represents a significant energy investment, balancing the mother’s capacity with the demanding needs of her offspring.
Standard Clutch Size
Hummingbirds almost universally lay two eggs per clutch. This number balances the energy demands on the solitary mother against the goal of successful reproduction. While laying a single egg would not maximize the female’s reproductive potential, three eggs would likely exceed her ability to feed the rapidly growing chicks. The standard of two is a highly successful evolutionary strategy across many species.
The eggs themselves are minuscule, often compared to the size of a small jelly bean, typically measuring less than half an inch long. These tiny, fragile eggs are usually pure white in color. This color may be an adaptation to help keep them cooler by reflecting light, as lighter colors are less susceptible to heat in the open nests. The female typically lays the two eggs one to two days apart, and incubation often does not start until the second egg is laid, ensuring both hatch at roughly the same time.
Nesting and Incubation Period
The female constructs the nest, a process that can take about a week to complete. She weaves a deep, cup-shaped structure using fine plant fibers and downy materials for insulation and cushioning. The nest is anchored and secured to the branch using stretchy spider silk, which allows the structure to expand as the nestlings grow.
For camouflage, the exterior is often decorated with fragments of lichen or moss, making it nearly indistinguishable from a knot on a tree branch. Once the eggs are laid, the mother begins the incubation period, which typically lasts between 14 and 22 days, depending on the species and ambient temperature. The female spends a significant amount of time on the nest, sometimes up to 75% of the daylight hours, to keep the eggs warm.
Raising the Young and Fledging
When the young hatch, they are altricial, meaning they are naked, blind, and completely helpless, requiring constant care. The mother must brood them to provide warmth, as they cannot regulate their own body temperature for the first few days. Their diet is a mixture of regurgitated nectar, providing necessary carbohydrates for energy, and small insects or spiders, supplying the protein crucial for rapid growth.
The mother feeds her nestlings frequently, often multiple times per hour, a demanding schedule driven by the chicks’ fast growth rate. The young develop rapidly; their eyes open around nine to ten days after hatching, and feathers emerge shortly after. The period from hatching until the young leave the nest, known as fledging, typically takes between 18 and 30 days. The mother may continue to feed the fledglings for about another week while they hone their foraging and flight skills before becoming fully independent.