Ruby throated hummingbirds typically have 2 babies per brood. The female builds a tiny cup shaped nest out of plant down, spider silk, and lichens, lays 2 tiny white eggs, and incubates them for 12-14 days before they hatch. Once the chicks hatch, the female feeds them regurgitated insects and nectar numerous times per day. The chicks fledge (leave the nest) in about 3 weeks.
Nesting and Egg Laying
Ruby throated hummingbird females build nests in early spring, usually in March or April. They select a horizontal branch of a deciduous or evergreen tree, often near openings or clearings. Using spider silk and lichens as glue, the female attaches plant down and bud scales to construct a tiny 1.5 inch wide cup shaped nest. Nests are usually located 3-20 feet above ground.
About 2-3 days after completing the nest, the female lays 2 pea sized white eggs. She incubates the eggs for 12-14 days before they hatch. During incubation she sits very tightly on the nest, leaving it only briefly to drink and bathe. Incubation begins when the second egg is laid, ensuring the chicks hatch close together.
Clutch Size
The typical ruby throated hummingbird clutch size is 2 eggs. Very rarely, a female may lay 1 or 3 eggs. Larger clutches are uncommon as they are difficult for the female to incubate and raise successfully.
| Clutch Size | Frequency |
|---|---|
| 1 egg | Rare |
| 2 eggs | Typical |
| 3 eggs | Uncommon |
As shown in the table, 2 eggs is by far the most common clutch size. The female’s small body size limits her ability to effectively incubate and brood more than 2 eggs.
Raising the Chicks
Ruby throated hummingbird chicks hatch after a 12-14 day incubation period. They are born blind, naked, and helpless, weighing only 0.1 grams. Their eyes open at about 4 days old.
The female alone is responsible for caring for the chicks. She feeds them regurgitated nectar and insects numerous times per hour. As they grow, the chicks’ appetite increases and the female must visit up to 1,000 flowers per day to obtain enough nutrition for her brood.
Fledging
At 18-22 days old, the chicks are ready to leave the nest. This is called fledging. They can fly skillfully but continue to be fed by the female for another 2-4 weeks as they learn to forage on their own.
Some key facts about ruby throated hummingbird fledglings:
- Fledge at 18-22 days old
- Weigh only 2-3 grams when they fledge
- Can fly well but have poor endurance at first
- Are fed by the female for 2-4 more weeks
- Gradually become more independent and feed themselves
Fledging is a vulnerable time but the female continues caring for and feeding the chicks to help them survive. Their flying skills allow them to escape predators.
Threats and Mortality
Only about 30-50% of ruby throated hummingbird nests successfully fledge young. Some reasons for nest failures include:
- Weather – Wind, rain, and cold temperatures can kill nestlings.
- Predators – Common predators include snakes, squirrels, and blue jays.
- Parasitism – Giant cowbirds sometimes lay eggs in hummingbird nests.
- Starvation – Nestlings may starve if adequate food is not available.
Even after fledging, the young hummingbirds face hazards including predators, collisions with objects, and electric shock from perching on power lines. Only about 30-50% of fledglings survive their first year. Lifespan in the wild is typically 3-5 years.
Predation
Predators are a major cause of nest failures and mortality of young hummingbirds. Some common ruby throated hummingbird predators include:
| Predator | Method |
|---|---|
| Snakes | Climb nests and eat eggs/chicks |
| Squirrels | Knock nests from branches |
| Blue jays | Kill adults and chicks |
| Hawks | Capture flying juveniles |
Hummingbirds have evolved to reproduce quickly to offset losses from frequent predation events. Their 2 broods per year and short nesting cycle ensure maximum opportunities for success.
Conclusion
In summary, ruby throated hummingbirds typically lay 2 eggs per clutch and raise 2 chicks per brood. The female alone builds the nest, incubates the eggs, and cares for the young. Threats like predation, weather, and parasitism make raising chicks challenging, but hummingbirds have adapted reproductive strategies to persist despite losses.
Under ideal conditions, a female may fledge 4-8 chicks per year across 2-3 broods. However, on average, each female only fledges 2-3 chicks annually that survive to adulthood. This replacement rate maintains stable populations and offers ample opportunities for raising young despite the many difficulties hummingbird parents face.
