Red-winged blackbirds are a common sight across much of North America. The males are unmistakable with their jet black bodies and bright red shoulder patches bordered in yellow called epaulets. Females are brown-streaked black overall. These birds build nests low in vegetation near water and lay pale blue or greenish eggs marked with brown or black scribbles.
What color are red-winged blackbird eggs?
Red-winged blackbird eggs are a pale blue or greenish color with darker brown or black markings. The background color can range from a very light blue-green to a deeper greenish-blue. The markings often form scrawls, scribbles, and spots clustered more heavily around the larger end of the egg.
The colors help camouflage the eggs when the female is off the nest. By blending in with the surroundings, the eggs are less likely to get noticed by predators. The pale base color matches dried grasses and reeds. The darker markings break up the egg’s outline so it doesn’t stand out as a perfect oval shape.
What do the markings look like?
The darker brown or blackish markings on red-winged blackbird eggs vary quite a bit from egg to egg. They often look scrawled on in abstract patterns made up of wiggly lines, scattered dots, and splotches of color.
Some common marking styles include:
- Scribbles – loose wavy or zig-zag lines twisted randomly across the egg’s surface.
- Spots – specks and blotches of dark color clustered more at the large end.
- Splotches – larger blotchy patches creating uneven coloring over parts of the egg.
- Splashes – looks almost like droplets of dark color were flicked onto the egg randomly.
In general, the darker pigment tends to be concentrated more heavily at the large end of the egg where the wider part of the egg offers more surface area. The distribution and color intensity of the markings are unique to each egg. So every clutch will show a range of patterns and styles of scribbles and spots.
What shapes and sizes are the eggs?
A red-winged blackbird egg is shaped like a typical bird’s egg – symmetrically oval with one end larger than the other. The larger end of the egg contains the air cell and is where the chick’s head will be positioned to start pecking a hole in the shell when it’s ready to hatch.
Eggs of most blackbird species are quite pointy at the small end and rounded at the larger end. Red-winged blackbird eggs tend to be a bit more elongated than other blackbirds’ but still follow that basic shape.
The eggs measure about 27 mm long by 18 mm wide on average. But each egg in a clutch may vary slightly in size from the others. The female produces eggs that are roughly 10% of her own body weight.
Size comparisons
To picture the size, red-winged blackbird eggs are:
- About the size of a grape
- 1 inch long
- Larger than a hummingbird egg
- Smaller than a chicken egg
What does a full clutch look like?
A complete clutch of red-winged blackbird eggs can range from 2-5 eggs. The average is usually 3-4 eggs per clutch. The female builds a sturdy basket-like nest and lines it with softer material to cushion the eggs.
When complete, the clutch has a neat, organized look with eggs carefully spaced in the nest. Since each egg differs in exact size, shape, and markings, the overall effect is mismatched but aligned in the nest.
The blue-green eggs are well-camouflaged in the brown woven grass nest. But on closer inspection, each oval has a unique pattern of scribbles and spots in dark ink-like color.
Similar eggs
Some birds lay eggs that look similar to a red-winged blackbird’s including:
- Yellow-headed blackbird
- Brewer’s blackbird
- Common grackle
- Brown-headed cowbird – lays eggs in other birds’ nests
But the red-winged blackbird’s brown shoulder patches help distinguish them from look-alikes. No other blackbird in North America sports such bold red and yellow epaulets.
How many broods per year?
Red-winged blackbirds produce 1-3 broods per breeding season. Each brood may have up to 5 eggs. So a single female could potentially lay 15 or more eggs each year.
They often raise 2-3 successful broods each season. After eggs hatch and nestlings fledge from the first brood, the female starts again and builds another nest. She then lays and incubates another clutch.
Nesting begins fairly early, with first broods underway by late March or April across most of the range. Multiple broods continue through summer, wrapping up by August at the latest across Canada.
Further south, they may nest a bit earlier and extend the season slightly longer. In warmer southern states, red-wings may start siting on eggs by early March and continue into September.
What is the incubation period?
Once a full clutch of eggs is laid, incubation begins. Red-winged blackbirds have an incubation period of 11-14 days.
Only the female incubates the eggs. She sits on the nest almost continuously once incubation starts. She leaves the nest for short periods of time to quickly forage and then returns to her duty.
The male guards the nest area and brings food to the female while she incubates. But he does not sit on the nest himself.
Both parents feed the hatchlings once they emerge. The nestlings fledge 10-14 days after hatching if all goes well. So from egg-laying to fledged young is about a month.
How many eggs survive to hatch?
Not all eggs in a clutch will survive to hatch. Some may be infertile or fail to develop. Predators and weather events also take a toll.
On average, 1-3 eggs from a typical red-winged blackbird clutch will hatch successfully. From those, usually 1-2 young will fledge from each brood. Overall nest success is estimated around 26% for red-winged blackbirds.
Eggs and young in ground nests or lower vegetation are most vulnerable to predators. Nests built over water offer more protection since they are harder to access.
Conclusion
The pale blue-green eggs with dark scribbles that are characteristic of red-winged blackbirds do an excellent job blending into wetland vegetation. While variable in exact color and patterning, they share the same oval shape and speckled appearance that helps camouflage developing embryos.
Females incubate up to 5 of these eggs for about two weeks before hatchlings emerge. The nestlings are fed by both parents and leave the nest after another couple weeks. With up to 3 broods per season, red-winged blackbirds are prolific producers of the cryptically-marked eggs that give rise to the next generation of these familiar wetland birds.
