Seeing a baby hummingbird is rare due to their diminutive size and the hidden nature of their nests. These tiny birds undergo a dramatic transformation, changing from a helpless, newly hatched chick to a fully feathered, flight-ready juvenile in just a few weeks. Observing the rapid changes in their physical features reveals a remarkable process of growth.
The Scale and Structure of the Nest
The journey of a baby hummingbird begins in a structure typically measuring only about 1.5 to 2 inches in diameter. This delicate, cup-shaped home is often compared to the size of a thimble or half of a walnut shell. The female constructs the nest using fine plant fibers, moss, and sometimes lichen, binding these materials together with strands of spider silk.
The spider silk provides necessary elasticity, allowing the structure to stretch outward as the two young birds grow rapidly. Inside this compact cradle, the mother lays two eggs, which are pure white and incredibly small, roughly the size of a navy bean or a pea.
Appearance of the Newborn Hatchling
The newly hatched hummingbird, known as a chick or hatchling, is an altricial bird. It enters the world completely naked, with slightly translucent, pinkish-gray skin. These hatchlings are unable to regulate their own body temperature and are entirely dependent on the warmth of their mother.
A newborn is minuscule, often measuring less than an inch long and weighing approximately 0.62 grams, lighter than a paperclip. Their eyes are sealed shut, leaving them blind for the first week of life. The hatchling’s short bill is disproportionate to the long, slender beak of its parent, resembling a small cone.
Rapid Physical Development in the Nest
The first major visual change occurs around day seven to nine when the hatchling’s eyes begin to open. Soon after, dark, spiky shafts known as pin feathers emerge across the body, making the nestling look prickly. These shafts are the sheaths of the developing feathers, rapidly filling the once-naked areas with color.
The bill begins its lengthening process during this period, preparing the bird for its specialized adult diet of nectar and insects. By the second week, the emerging feathers start to unfurl from their protective sheaths, transitioning the nestling to a fully feathered miniature bird. By the time they are ready to leave the nest, typically between 18 and 28 days old, the nestlings are visually similar to the adult female.
Distinguishing Juvenile Fledglings from Adults
Once a young hummingbird leaves the nest, it is called a fledgling, and telling it apart from an adult requires attention to subtle details. Fledglings are fully grown in body length and may weigh slightly more than adults due to fat reserves built up for their first period of independent life. The most reliable visual clues involve feather characteristics and bill length.
Juvenile males lack the full iridescent gorget of the adult male. Instead, they may show only a few scattered iridescent feathers or a streaky, dark-centered pattern on the throat. Additionally, young birds of both sexes often display pale or buffy feather edges on their crown and upperparts, creating a slightly scaly appearance that indicates youth. While their flight feathers are fully developed, the fledgling’s tail and bill are often still slightly shorter than those of a fully mature adult.