Hummingbirds have an extremely high mortality rate, especially in the early stages of life. As with any animal species, baby hummingbirds are the most vulnerable and face many threats to their survival. Understanding the challenges they face and their chances of making it to adulthood can give us insight into the lives of these fascinating creatures.
Egg and Hatchling Mortality
The journey begins even before a hummingbird chick hatches. Female hummingbirds lay between 1-3 tiny eggs, each about the size of a jellybean. The mothers incubate the eggs for 2-3 weeks before they hatch. Even in the egg stage, mortality can be high due to predators, storms, insufficient food for the mother, or infertile eggs.
Once hummingbirds hatch, the chicks are completely helpless. They have no feathers, their eyes are closed, and they are entirely dependent on their mothers for warmth, protection, and food. The first 2 weeks are the most precarious. If anything happens to the mother during this period, the hatchlings will not survive. They may starve, get eaten by predators, or succumb to exposure.
Studies estimate that between 10-70% of hummingbird eggs fail to hatch. Of those that do hatch, anywhere from 10-50% die within the first 2 weeks. So even before leaving the nest, the mortality rate for baby hummingbirds is extremely high.
Nestling Stage
If a hatchling survives the first 2 weeks, they enter the nestling phase. At this stage, the chicks develop pin feathers and their eyes begin to open. They still cannot regulate their own body temperature and rely completely on their mothers for food and protection.
The nestling stage lasts 2-5 weeks, depending on the species. This continues to be a high mortality period for several reasons:
- Nest predation – Snakes, lizards, squirrels, and birds of prey will raid hummingbird nests and eat the chicks.
- Starvation – The mother may not be able to find enough food to feed all her chicks.
- Exposure – If the mother dies or inadequate nest provides little protection, the chicks may die from hypothermia.
- Competition – Older, stronger siblings may monopolize food and lead to weaker chicks dying.
- Falling – Some young hummingbirds fall or are knocked out of the nest before they can fly.
Studies have found that in any given brood or clutch, it is common for at least 1-2 chicks to die during the nesting period. Overall mortality rates during this stage range from 20-50%.
Fledgling Stage
The next phase in a hummingbird’s early development is the fledgling stage. This is when the chick leaves the nest and attempts flight for the first time. Most fledglings are 25-30 days old. Their flight feathers are not fully developed, so they cannot travel far or sustain long flights.
During this transitional time, the juveniles are testing their wings and learning to hunt for nectar on their own while still relying on their mothers for some feedings. Fledglings face hazards such as:
- Starvation – Learning to feed on flowers takes time and trial and error.
- Predators – Their weak flight makes them vulnerable.
- Collisions – They may fly into windows, cars, fences, or objects.
- Injury – Attempting to fly too early leads to falls and harm.
In the first days and weeks after fledging, juvenile hummingbirds have a high mortality rate. Up to 50% may die as they learn to survive on their own.
Factors Affecting Mortality Rates
Studies of hummingbird mortality have found that survival rates can vary significantly based on certain factors:
Factor | Impact on Mortality Rate |
---|---|
Clutch Size | Chicks from smaller clutches (1-2 eggs) have higher survival than larger clutches (3 or more eggs). More competition in large broods leads to higher mortality. |
Hatching Order | The first chicks to hatch tend to be larger and stronger. Later hatchlings are smaller and have higher mortality rates. |
Predators | Areas with more predators and nest raiders see higher baby hummingbird mortality. |
Weather | Cold temperatures, storms, and flooding can decrease survival, especially for younger hummingbirds. |
Food Availability | Access to nectar-rich flowers improves the chances of fledglings learning to feed. |
In ideal conditions with plentiful food, mild weather, low predators, and smaller clutch sizes, mortality rates may fall at the lower ends of reported ranges. But in harsher conditions, mortality can be near total loss of a brood.
Mortality After Fledging
The mortality rate remains high for juvenile hummingbirds even after fledging. In the first year, studies show up to 70% mortality. By the end of their first year, only 1-4 individuals may survive out of an original clutch of 3-4 chicks.
However, for those that make it to adulthood, lifespan improves dramatically. Adult hummingbirds may live 3-12 years, with an average of 3-5 years. With each passing year, they become more efficient at feeding, flying, reproducing, avoiding predators, and migrating.
So while very few hummingbirds survive to leave the nest, those that do continue face high mortality risks as juveniles. But the birds that make it to adulthood have much better chances of living multiple years.
Key Takeaways on Hummingbird Mortality
Here are some key points on the high mortality rates for baby hummingbirds:
- Between 10-70% of eggs fail to hatch.
- For hatchlings, 10-50% die in first 2 weeks.
- In the nest, mortality ranges from 20-50%.
- Up to 50% may die after fledging.
- By end of first year, only 1-4 birds may survive per clutch.
- Survivors that reach adulthood live an average of 3-5 years.
- Mortality is affected by predators, weather, food availability and other factors.
Why Is Mortality So High?
Hummingbirds have an extremely high reproductive output because very few individuals actually survive. They lay multiple clutches per season to essentially “hedge their bets” against the low odds.
There are several reasons mortality is so high in baby hummingbirds:
- Small size – Their tiny size makes them vulnerable to predators with almost no means of defense.
- High metabolism – They need huge amounts of energy and nearly starve if food is inadequate.
- Challenging development – Weak or underdeveloped chicks often die in the nest.
- Dangers of flight – Learning to fly to survive is an imperfect process.
- Lack of parental care – On their own after a few weeks, many starve or succumb to elements.
While the odds are stacked against them, hummingbirds are resilient. These evolutionary adaptations allow some individuals to overcome the challenges and thrive into adulthood. Their tenacity ensures the continuation of the species despite daunting mortality rates.
Conclusion
Baby hummingbirds face a range of threats from the moment they hatch until adulthood. Studies have shown mortality rates in the nest may range from 10-70%, while additional losses after fledging can reach 50% or higher in the first year. However, hummingbirds have evolved reproductive strategies to compensate for their vulnerability.
While the mortality rate is tragically high, especially in the first weeks and months, those that do survive can live several years as they develop efficient feeding and flying skills along with instincts for predator avoidance. Understanding the challenges hummingbirds overcome illuminates how they continue to thrive despite the odds.