The mountain bluebird is a small thrush found in open country across much of western North America. They are migratory birds, breeding at high altitudes in the mountains and wintering in the deserts and grasslands further south. Mountain bluebirds build nests in tree cavities or nest boxes and lay eggs in the spring. But how long does it actually take for mountain bluebird eggs to hatch? Let’s take a closer look at the incubation period for this beautiful blue bird.
How Many Eggs Do Mountain Bluebirds Lay?
Mountain bluebirds typically lay a clutch of 4-8 eggs. The female incubates the eggs alone while the male brings food to her. She will lay one egg per day until the clutch is complete. The eggs are small, smooth, and pale blue in color. They measure about 22 mm x 17 mm on average.
Incubation Period
Once the final egg has been laid, the incubation period begins. The female mountain bluebird will sit tight on the nest, keeping the eggs warm with her body heat. Incubation lasts for about 14 days before the eggs begin to hatch.
The exact incubation period can vary slightly based on environmental factors. In colder temperatures, incubation may take a day or two longer. In warmer weather, the eggs could hatch a bit sooner after 13 days of sitting. But 14 days is the average and expected incubation period for mountain bluebird eggs.
Hatching of the Eggs
The eggs will not all hatch at exactly the same time even though they were laid over a period of several days. The first egg laid is usually the first to hatch after about 14 days of incubation. The others pip out of their shells over the next day or two in the order they were originally laid.
When the chicks start to hatch, they will use their egg tooth to break open a hole in the egg shell. It takes many hours of pecking and pushing before they finally emerge. The tiny hatchlings are naked, blind, and helpless at first.
Caring for Hatchlings
The mother mountain bluebird will stay on the nest after the eggs hatch, brooding her altricial chicks. She provides warmth and protection as the newborns are very vulnerable. The chicks hatch with their eyes closed and very little downy feather coverage on their bodies.
The father mountain bluebird works hard to find enough insects to feed the growing chicks. For the first week after hatching, the chicks eat insects brought by both parents. As they get bigger, the chicks’ appetites grow rapidly too. The parents may feed the nest up to 100 times per day!
Fledging from the Nest
The mountain bluebird chicks develop quickly under the attentive care of their parents. They open their eyes at around 5 days old. Their juvenile feathers start growing in after a week. At 15-21 days old, the young birds are ready to take their first flight from the nest. This is called fledging.
The whole cycle from egg laying to fledging takes just over a month. Thanks to the parents devotion and the chicks rapid development, the mountain bluebird hatchlings transform from helpless newborns to flying fledglings in a matter of weeks.
Conclusion
In summary, mountain bluebirds lay clutches of 4-8 pale blue eggs. The female incubates the eggs for about 14 days before they hatch. The hatchlings are altricial, hatching naked, blind, and helpless. But they mature rapidly under their parents care. Approximately three weeks after hatching, the juvenile birds fledge the nest and make their first flight. The incubation and nestling period lasts just over a month in total. Understanding the mountain bluebird’s breeding timeline helps appreciate the incredible growth these tiny songbirds undergo in their first few weeks of life.
Detailed Timeline of Mountain Bluebird Breeding and Chick Development
Breeding Stage | Timeline |
---|---|
Egg laying | 4-8 eggs laid over 4-7 days |
Incubation | Female incubates eggs for 14 days |
Hatching | Chicks pip shells and hatch over 1-2 days |
Care of hatchlings | Parents brood and feed chicks for first 7 days |
Feather growth | Juvenile plumage starts growing in at 7 days |
Eyes open | Chicks open eyes at 5 days old |
Fledging | Chicks leave nest at 15-21 days |
This table summarizes the timeline of key milestones in the mountain bluebird breeding and chick rearing process from egg laying to fledging. The total nesting period lasts about one month.
Egg Laying
The mountain bluebird breeding season begins when the female starts laying eggs. This occurs in the spring, with mountain bluebirds at higher elevations breeding later into the summer.
The female constructs a nest in a cavity or nest box and lays one pale blue egg per day. She lays between 4-8 eggs to complete her clutch. The eggs are small, smooth, and oval shaped. They measure about 22 mm long by 17 mm wide.
Mountain bluebird eggs are pale blue with no markings. Some people say they resemble robin’s eggs in color. The female sits on the nest each evening after laying her daily egg. But full incubation doesn’t start until the clutch is complete.
How Many Days Between Eggs?
Mountain bluebird eggs are laid approximately one per day. However, they may occasionally skip a day between eggs. The full clutch of 4-8 eggs takes 4-7 days to complete. Then the female begins incubating when the last egg is laid.
Incubation
Once the final egg is laid, the female mountain bluebird stays on the nest constantly to incubate them. She uses her body heat to keep the eggs at the proper temperature for embryo development.
The average incubation period for mountain bluebirds is 14 days. It may be slightly shorter in hot weather or a bit longer if temperatures are cold. But 14 days from the last egg laid is typical.
The female leaves the nest periodically for short breaks to eat and drink. The male mountain bluebird helps feed her so she doesn’t have to leave the eggs alone for long. She diligently incubates until the hatchlings start to pip from their shells.
Incubation Temperature
Mountain bluebird eggs must be kept at about 99-102°F throughout incubation. The female’s brood patches transfer her warmth to the developing embryos. If the eggs get too cold, the chicks won’t develop properly. Overheating is also detrimental.
The natural insulation of the nest and the female’s diligent incubating behavior maintains the optimal temperature for 14 days until hatching.
Hatching
Mountain bluebird chicks start hatching after approximately 14 days of incubation. The eggs do not all hatch on the same day despite being laid over a span of several days. This is because incubation doesn’t start until the last egg is laid.
The first egg to be laid is usually the first to hatch. The hatchlings then pip out of their shells in the order the eggs were laid, over a period of 1-2 days.
To hatch, the baby birds use their egg tooth to break open a hole in the egg shell. It takes many hours to fully emerge from the cracked shell. The female continues brooding during the hatching process.
Newly Hatched Chicks
When mountain bluebird chicks first hatch, they are naked, blind, and completely dependent on their parents care. Their eyes are fused shut and they have very little downy feather coverage on their pink skin. Their egg tooth, located on the tip of their beak, falls off within a week or two after hatching.
The hatchlings huddle under their mother in the nest cup for warmth and protection. They are very vulnerable at this stage and cannot regulate their own body temperature. The female mountain bluebird is essential for brooding the chicks and shielding them from predators.
Caring for Hatchlings
For the first week after hatching, mountain bluebird chicks are fed insects by both parents. The male and female take turns gathering food and bringing it back to the nest. The chicks’ appetites are small at first but quickly grow.
The parents may feed the nest up to 100 times per day as the chicks get older and bigger! They consume a diet of grasshoppers, beetles, caterpillars, ants, and other small invertebrates. Proper nutrition helps the chicks develop feathers and get ready to fledge.
In addition to feeding, the female mountain bluebird continues to brood the hatchlings for 7-10 days after hatching. Her body heat keeps the chicks warm until their juvenile plumage starts growing in. She also protects the helpless chicks from weather, predators, and other threats in the environment.
Division of Parental Care
Parent mountain bluebirds divide some duties when caring for newly hatched chicks:
- Female: Brooding, feeding chicks (more frequently at first)
- Male: Defending territory, bringing food to female and chicks
But both parents participate heavily in gathering the enormous quantity of insects required to feed a growing brood. They work together to raise their altricial hatchlings.
Feather Growth
At around 7 days old, mountain bluebird chicks start growing their juvenile plumage. Feather quills begin emerging from the skin follicles. Over the next two weeks, sleek feathers develop to cover the hatchlings’ naked bodies.
The chick’s downy neonatal down is very sparse at hatching. So juvenal feathers are essential for regulating body heat once the female stops brooding full time. Full feather growth takes about 2 weeks.
Juvenile mountain bluebirds lack the bright blue coloring of adults. Their feathers are drab brown and grey with some pale spotting. This plumage helps camouflage the fledglings after they leave the nest. Adult blue feathers don’t emerge until the first molt later in summer.
Changing Appearance
Here are the notable appearance changes as a mountain bluebird chick matures:
- Hatchling: Naked body, sparse white down
- 1 week: Quills of juvenile feathers emerge
- 2 weeks: Full covering of brown/grey feathers
- 3 weeks: Resembles mature juvenile plumage
Rapid feather growth transforms them from naked and helpless into fledgling mountain bluebirds ready for their first flight.
Eyes Open
Mountain bluebird hatchlings pip from the egg with their eyes fused completely shut. Vision is not critical in the first days while the female broods them in the dark nest. But their eyes soon open as they grow.
At around 5 days old, mountain bluebird chicks open their eyes for the first time. Clear vision enhances their ability to interact with parents, compete with siblings for food, and prepare for fledging.
Once their eyes open and feathers start to emerge, the nestlings become increasingly alert and active. Good eyesight coordinates with physical maturation. Fledging and flying require keen vision to navigate obstacles and predators.
Improving Vision
Here are key milestones in the visual development of mountain bluebird chicks:
- Hatching: Eyes sealed shut
- 5 days: Eyes open, some vision
- 2 weeks: Clear, coordinated sight
Like all altricial songbirds, mountain bluebirds hatch blind and gain vision with age. Good eyesight is imperative for surviving outside the nest.
Fledging
The culmination of mountain bluebird chick development is fledging. This is when the juvenile birds take their first flight from the nest at 15-21 days old. Fledging requires strength, feathers, coordination, and keen sight.
Parents encourage fledging by reducing feedings. This motivates the chicks to try flying to find food. The male mountain bluebird may lead the fledglings out one by one, coaxing them to fly short distances.
Fledglings cannot fly perfectly at first. They may spend several days flying from branch to branch, returning to the nest each night. But soon their flight skills improve and they leave the nest for good.
The parents continue bringing food and watching over the fledged juveniles for several weeks. But fledging completes the crucial nesting phase. The chicks are now independent juvenile mountain bluebirds.
Signs of Fledging
Here are signs mountain bluebird chicks are getting ready to fledge:
- Flapping wings in nest
- Perching on nest edge
- Hopping and flying short distances
- Leaving nest 15-21 days after hatching
Fledging mountain bluebirds marks a major milestone. The juveniles must now use their flying skills to forage and evade danger while completing their development into adulthood.
Conclusion
Mountain bluebird breeding starts when the female lays eggs and concludes when the hatched chicks fledge the nest. This entire process takes just over one month.
Key phases include:
- 4-8 eggs laid over 4-7 days
- Incubation for 14 days
- Hatching over 1-2 days
- Feather growth and eyes opening
- Fledging at 15-21 days old
Understanding this timeline provides insight into the rapid yet complex development of altricial songbirds like mountain bluebirds. From helpless hatchling to fledged juvenile ready to fly, they undergo an incredible transformation in a few short weeks, thanks to dedicated parental care.