Do hummingbirds sit on their eggs to hatch them?

Quick Answer

No, hummingbirds do not sit on their eggs to incubate them. Instead, female hummingbirds build cup-shaped nests out of plant materials and spider silk, lay two tiny white eggs, and rely on their body heat while feeding to keep the eggs warm enough to develop and hatch. The eggs hatch in about 2-3 weeks without the mother ever sitting on the nest.

Do Hummingbirds Sit on Their Eggs?

Hummingbirds have very unique nesting and incubation behaviors compared to most other birds. Here are some key facts about how hummingbird eggs are incubated and hatch:

• Female hummingbirds build nests out of plant down, moss, lichen, and spider silk. The nests are only about 2 inches wide and half an inch deep – just big enough to hold two pea-sized eggs.
• The female lays two white eggs, only about half the size of a jellybean. She does not start sitting on the eggs right away.
• The female only sits on the eggs briefly during the day to rotate them. She does not have a brood patch and lacks the ability to transfer sustained body heat.
• Instead, the female hummingbird relies on the ambient temperature and her brief visits to keep the eggs at the proper incubation temperature.
• She continues to feed regularly throughout the incubation period, gaining enough calories to sustain herself and keep the eggs developing.
• The eggs hatch in about 2-3 weeks without being continuously sat upon or brooded by the mother.

So in summary, no – hummingbirds do not sit for long periods on their eggs like most other birds. The eggs successfully develop and hatch with the female just briefly rotating and checking on them periodically while she continues to feed.

Why Don’t Hummingbirds Sit on Their Eggs?

There are a few key reasons why hummingbirds have evolved this unique incubation strategy of not sitting on their eggs:

• Small body size – Hummingbirds are the smallest birds, and do not have enough body mass to effectively incubate eggs. Their high metabolisms also generate little excess body heat.
• Lack of brood patches – Most birds develop bare brood patches to directly transfer body heat. Hummingbirds do not develop these featherless areas and would lose too much heat.
• High energy needs – Hummingbirds have very high metabolisms and need to feed frequently. Sitting on the nest would risk starvation.
• Nest predation – Continuously sitting on the nest would make it more vulnerable to predators. Brief visits help avoid detection.

So the hummingbird’s tiny size, energy needs, and risk of nest predation have driven the evolution of this unique incubation strategy of not sitting on the eggs for extended periods. The embryo development is able to sustain itself from the female’s brief periodic visits.

How Do Hummingbird Eggs Get Enough Heat to Hatch?

Even though hummingbird mothers do not sit on the eggs, the eggs still get enough heat to successfully develop and hatch after 2-3 weeks. Here are the key factors that allow hummingbird eggs to get the proper incubation without being brooded:

• The female’s body heat during brief daily visits helps regulate the temperature.
• Insulative properties of the nest materials help retain ambient heat.
• The tropical/subtropical climates hummingbirds live in provide warm ambient temperatures.
• The female feeds regularly, fueling her high metabolism which generates body heat.
• The embryo’s metabolism also generates some heat as it develops.

Researchers have found hummingbird eggs left unattended for periods of up to 45 minutes were able to maintain temperatures high enough to sustain development. The combination of these factors allows the eggs to stay at the ideal 99-100°F temperature needed for healthy growth.

Hummingbird Incubation Period and Hatching

Here are some key facts about the hummingbird incubation and hatching process:

• Incubation period lasts 14-23 days, depending on climate and species.
• The female may lay each egg up to 2 days apart, so they hatch asynchronously.
• The mother does not help the chicks hatch; they use an egg tooth to break the shell.
• Chicks hatch at only 2 grams – smaller than a penny!
• Chicks are born naked, blind, and completely dependent on the mother.
• The female feeds the chicks with regurgitated nectar and insects.
• Chicks fledge and leave the nest at 3 weeks old.

So in just about a month after laying her tiny eggs, the hummingbird chick goes from egg to fledgling without ever being incubated by the mother sitting on the nest! The rapid development allows hummingbirds to take advantage of seasonal food sources.

Unique Adaptations for Hummingbird Reproduction

Hummingbirds have many unique reproductive adaptations that allow them to breed and raise chicks despite being the smallest birds:

These adaptations allow hummingbirds to breed and raise young successfully, despite the energetic challenges posed by their tiny size. Not sitting on the eggs is just one of the many unique strategies hummingbirds use to reproduce.

Conclusion

In summary, hummingbirds have evolved a specialized form of incubation where the female does not sit for extended periods on her two tiny eggs. Brief daily visits provide just enough heat from the mother’s body to keep the eggs developing. Reliance on ambient warmth and the female’s high metabolism provides the rest of the needed temperature. After 2-3 weeks, the eggs hatch without ever being brooded. This allows the female to continue feeding and avoid predation. Not sitting on the eggs is just one of many amazing adaptations that allow hummingbirds to successfully breed and raise chicks despite being the smallest bird species.