Starlings are a type of songbird found throughout much of the world. They are medium-sized birds with short tails and pointed wings. Starlings are extremely social and congregate in large flocks called murmurations. Their plumage can be quite variable, but typically adult females have brown plumage with small white speckles on their feathers.
What is the typical coloration of female starlings?
The typical plumage coloration of adult female starlings consists of brown feathers with small white speckles. The brown color can range from light brown to a darker chocolate brown. The white speckles help the birds camouflage and blend into their surroundings when in trees or on the ground. The speckles vary in size and density between individual birds.
Female fledglings and juveniles have a slightly different appearance than adult females. Juveniles have grayish-brown plumage with buff-colored streaks on their breasts. As they mature, their plumage gradually transitions to the typical adult female coloration.
Are there any variations in coloration?
While most female starlings share the typical brown and speckled plumage, there can be some subtle variations:
- The shade of brown may be lighter or darker in some individuals.
- The density of white speckling can be heavier or sparser.
- There may be a reddish-brown tinge to the tips of feathers.
- Some females may have more vivid iridescent sheens to their feathers.
These variations represent natural diversity in plumage characteristics across populations. However, the overall brown and speckled pattern remains quite consistent in adult females.
Do females ever get male-like plumage?
It is extremely rare for female starlings to develop male-like plumage coloration. Males have striking black plumage with an iridescent sheen and bright yellow beaks. Their coloration is distinctly different from females.
During the breeding season, females may develop a few black feathers on their bellies or throats as a result of hormonal changes. However, they do not undergo a full molt into male-like plumage. Cases of females with extensive male-like coloration are highly anomalous.
Why is there a difference in coloration between males and females?
The differences in plumage coloration between male and female starlings are due to a phenomenon called sexual dimorphism. Many bird species exhibit sexual dimorphism, where males and females have subtle or pronounced physical differences.
In the case of starlings, the distinct male plumage likely evolved through sexual selection. Females may have preferred mating with males that had darker black feathers and a striking appearance. Over many generations, this mating preference led to the evolution of the male’s ornamental plumage.
The more cryptic brown female plumage probably evolved as camouflage to help incubate eggs and protect nests without being noticed by predators.
Do the colors differ between juveniles and adults?
Yes, juvenile starlings have a different plumage pattern compared to adults. Here is a summary of how plumage coloration differs between age classes:
| Age | Female Plumage | Male Plumage |
|---|---|---|
| Juvenile | Grayish-brown body with buff-colored streaks on breast | Grayish-brown body with dark streaks on breast |
| 1st winter | Gray-brown mixed with adult-like brown and speckles | Black feathers start to appear among brown juvenile plumage |
| Adult | Light to dark brown with white speckles | Glossy black with bright yellow beak |
As the table shows, both male and female juveniles start with dull gray-brown plumage. Their adult colors gradually come in through partial molts over the next year or two. The full adult plumages are not attained until birds are 2-3 years old.
Do the colors fade as females age?
There are no major changes in female starling plumage coloration as they age. Females attain their mature adult plumage by their second year and can retain this coloration for many years.
However, there may be some subtle fading or dulling of colors in very old females. The browns may become lighter and less vibrant. The white speckles could potentially increase in number and size. But overall, female starlings maintain their characteristic plumage patterns throughout adulthood.
Male starlings, on the other hand, do tend to develop some pale feather edges as they age. But this effect is less pronounced in females.
Do the colors vary by geographic region?
There is some regional variation in the coloring of female starlings across their widespread geographic distribution:
- In Europe, females tend to be quite dark, with blackish-brown plumage.
- In western Asia, paler sandy brown tones are more common.
- North American birds are typically medium brown.
- Tropical Indian/Sri Lankan populations include reddish brown birds.
Researchers think these subtle differences arose from founder effects and local adaption as starlings expanded their range over thousands of years. But in all regions, the basic female color pattern of brown plumage with white speckling is present.
Do color variations have genetic causes?
The specific genes influencing starling plumage coloration are not fully understood. However, research suggests that both genes and environment play a role in determining feather colors.
One study found that captive starlings fed a carotenoid-rich diet ended up growing more colorful feathers. Carotenoids are pigments that birds ingest from their food and can deposit into growing feathers.
There also appear to be genetic differences between regional populations that influence shades of brown. For example, German starlings had darker brown tones when raised in a controlled lab environment.
So both genetic inheritance and dietary access to certain pigments likely combine to produce subtle variations in female starling coloration across their range.
Conclusion
In summary, the typical female starling has brown plumage with white speckling. This provides camouflage while nesting and breeding. Females maintain this coloration throughout adulthood, unlike males which have showier black plumage. Subtle regional variations in shade exist due to founder effects and carotenoid availability. While male starling colors are linked to sexual selection, the conserved female plumage likely evolved as an adaptation for nesting success and avoiding predation.
