Starlings are a type of songbird that can be found across North America, Europe, and Asia. They are medium-sized birds that grow and develop relatively quickly compared to other bird species. In this article, we will explore the different growth stages of starlings and the timeframes associated with each stage.
Egg Stage
The growth of a starling begins when the egg is laid by the mother. Starling eggs are pale blue or greenish-blue in color and oval in shape. They are approximately 27mm long by 20mm wide. The incubation period, or the time it takes for the egg to hatch, is 10-13 days.
During this egg stage, the embryo is developing inside the egg. Cell division and growth occur rapidly. Organs like the brain, heart, and eyes begin to form. By the end of the incubation period, the hatchling has grown enough to break out of the egg using its egg tooth.
Hatchling Stage
Newly hatched starlings are called hatchlings or nestlings. Hatchlings are helpless, blind, and featherless. They rely completely on their parents for food, warmth, and protection.
At hatching, starling nestlings weigh just 5-7 grams. Their eyes are closed, and they have no feathers. Within a day or two, some downy feathers start to emerge. These early feathers are gray and cream-colored. They help insulate the hatchlings.
Hatchling starlings grow incredibly fast. They can put on up to 1-2 grams per day. Here is an approximate timeline of their early development:
- Day 1-2: downy feathers emerge
- Day 3: eyes begin to open
- Day 5: eyes fully open
- Day 7: sparse juvenile plumage is visible
By two weeks of age, the hatchlings will have grown to about half of their adult weight. Their juvenile feathers will be well developed at this stage.
Fledgling Stage
Around 2-3 weeks after hatching, starling chicks will be ready to leave the nest. This is called fledging. The timing varies based on the number of siblings in the nest. Chicks from larger broods may fledge earlier to reduce competition for food.
Fledgling starlings weigh 25-30 grams. While they can hop around the nest and flap their wings, their flight skills are still poor. They will remain close to the nest and their parents during this vulnerable stage. Fledglings beg loudly for food as their parents continue caring for them.
At around 4 weeks of age, fledglings grow their first set of flight feathers. This allows them to become more independent and start flying short distances. They learn to find food on their own but still return to the nest each night.
Juvenile Stage
Between 1-2 months of age, starlings reach the juvenile stage. Juveniles are close to adult size, weighing 45-90 grams by the end of this stage. Their feathers are like the adults’ now, with black plumage spotted with light speckles.
Juvenile starlings start joining large flocks of other starlings. They become independent at finding food and roosting sites. Some juveniles may still associate with their parents until the next breeding season begins.
It takes about 6-8 weeks after hatching for starlings to reach full independence from their parents. The entire nesting cycle lasts 2-3 months on average.
Growth Rate Summary
To summarize the timeline of starling growth:
- Incubation period: 10-13 days
- Hatchling stage: 2-3 weeks
- Fledgling stage: 3-4 weeks
- Juvenile stage: 1-2 months
The hatchlings grow remarkably fast, gaining up to 30 times their hatch weight by fledging. Their rapid development equips them for independence within just 6-8 weeks in most cases.
Factors Influencing Growth Rate
Several factors can affect how quickly starling chicks grow and develop. These include:
- Brood size – Starlings from larger broods may fledge earlier to reduce competition for food in the nest.
- Hatching order – The first eggs to hatch tend to produce larger, stronger nestlings.
- Weather – Chilly temperatures can slow chick development. Sustained heat helps them grow faster.
- Food availability – Access to high-protein insects accelerates growth. Food scarcity stunts it.
- Parasites – Mites or other parasites can impede weight gain and feather development.
- Health – Illness due to viruses, bacteria, or injury may temporarily halt growth.
Starling parents do their best to provide optimal conditions for rapid chick development. However, environmental factors ultimately play a role in determining each chick’s individual growth trajectory.
Why Do Starlings Grow So Quickly?
There are a few key reasons why starling chicks are able to develop from helpless hatchlings to independent fledglings so rapidly:
- Predator avoidance – Fast growth means less time in the vulnerable nestling stage. The sooner they can fly, the better their chance of escaping predators.
- Seasonal timing – Starlings time their breeding to coincide with peak food availability. Abundant insects allow for fast chick growth.
- Small body size – Compared to larger birds, starlings don’t have as much growing to do. They reach adult size quickly.
- Both parents care for young – With two parents gathering food, starling chicks get fed frequently and grow fast.
Starling breeding ecology has evolved to enable swift nestling development. This helps maximize survival and give the juveniles time to prepare for their first migration in the fall.
Typical Adult Size and Weight
After reaching independence, juvenile starlings will continue honing their flying and foraging skills throughout the summer and fall. By the time they are a year old, most starlings achieve their full adult size.
The typical measurements of an adult starling are:
- Length: 18-23 cm
- Wingspan: 34-38 cm
- Weight: 45-90 g
Male and female starlings attain virtually identical sizes. Throughout adulthood, their weight may fluctuate by up to 25% seasonally in response to changes in food availability and breeding condition.
Unusual Rapid Growth Records
While starling nestlings typically hit growth milestones on a predictable schedule, occasionally individuals demonstrate remarkably accelerated development:
- A 3-day-old hatchling in Spain weighed 10 g and already had eyes partly open.
- Some 7-day-old chicks exceed 20 g and have well-developed wing feathers.
- There are reports of fledging as early as 13 days after hatching.
Such unusually fast growth may result from ideal environmental conditions. But it can also indicate a parasite-free, robustly-fed “superstar” nestling. These rapid growers tend to crowd out siblings and monopolize feedings.
In a Cambridge study, the heaviest nestling was found to be 3x the weight of the lightest chick in 95% of starling broods monitored. This shows how growth rates can diverge, even within the same family.
Conclusion
Starling growth and development progresses through four main stages: egg, hatchling, fledgling, and juvenile. The hatchling phase is characterized by explosive growth, with chicks gaining up to 30x their hatch weight before fledging. Starling chicks can develop from helpless newborns to independent juveniles in just 6-8 weeks thanks to abundant food resources and attentive parental care.
Their rapid growth maximizes survival by minimizing time in the nest. It also aligns with peak seasonal food availability. Adult size is reached by one year of age. While starling nestlings follow a typical growth timeline, some exceptionally robust individuals display remarkable growth rates and dramatically outcompete their siblings.
