Did it happen to you to come across a peculiar nest that shelters some blue eggs in it? We bet this chance gave you some wonders. Imagine that only in the UK, there are over five common species of birds that are laying blue eggs in their nest.

While Dunnocks, Blackbirds, Song Thrushes, or Starlings are the most common ones across the country, the world has many other birds with colorful eggs.

Although you might have viewed that bluebirds will usually lay blue eggs, you are not likely to discover these eggs so quickly. In North America, like the Mountain area, Eastern and Western sides, bluebirds lay pale blue eggs, but the occasions humans can see these nets are rare.

The cavity nesters will rarely lay their eggs outside the cavity; the only exception is when these species are desperate. There are about 4-5% of bluebirds that will lay white eggs.

However, there are hundreds of different birds capable of laying blue eggs, and people are close to them.

If you come across this nest with blue eggs, experts ask people to avoid disturbing the eggs and the nest overall. It is against the law in some countries to take eggs from a perch, even punishing this action.

Today’s little guide will tell you everything about the types of birds that lay blue eggs and their particularities. Size and markings can be a good indicator of these species, and this is why we have brought together this little guide to help you identify what types of birds have blue eggs.

Some Of The Birds That Lay Blue Eggs

Most people would probably expect only the bluebirds to lay blue eggs. However, this is partially true, as you will discover once reading the information below.

There are hundreds of bird species that have these particular and cute blue eggs, so let’s learn more together about them:

American Robin Birds

American Robin Birds
Credit: @frankconephotos
American Robin Eggs
Credit: @coffee.and.chlorophyll

The American Robin birds will usually lay their clutch between 3 and 5 light blue eggs or sky blue colored eggs. These blue eggs are between 2.8cm and 3cm in length, while their width will be around 2cm.

Blackbird Eggs

Blackbird Eggs
Credit: @swamphen_
Blackbird
Credit: @mathews.wildlife

Some of the most common blackbirds, usually the Eurasian blackbirds, will lay their blue eggs from March to July. These birds will lay somewhere between 3 and 5 eggs at a time.

The eggs have a blue-ish green shade, with specific red speckles. The average dimensions of Blackbird eggs are 22mm in width and a length of 29mm.

Song Thrush

Song Thrush
Credit: @morris_dancer73
Song Thrush Eggs
Credit: @craftymummybee

Song Thrush birds are laying a clutch of 4 or 5 glossy light-blue eggs with purple and black spots. These eggs are tiny, meaning around 21mm in width and 27mm in length.

Dunnock

Dunnock Blue Eggs
Credit: @patrickcfox
Dunnock Birds
Credit: @alan.godfrey.photos

Dunnock birds are sometimes confused with another similar species, popular as House Sparrow. Females are laying a clutch of around 4 or 5 eggs.

These blue eggs are glossy, smooth, and come with some reddish spots. The eggs are somewhere approximately 14mm and have a length of 19mm. As such, you can imagine how tiny these eggs are.

Dunnock birds are beautiful birds that don’t breed in pairs but in groups. The groups can be even up to three males and three females, but there will be only 2 of each category most of the time.

The nest is amazingly built by female skills and made of hedges and shrubs. The nest is cup-shaped and is lined with hair and moss.

Starling Blue Eggs

Starling Blue Eggs
Credit: @jennsuewild
Starling Birds
Credit: @kennethokeefe164

Starling birds are some dark species as soon as you watch them from afar; however, they come with fantastic iridescent plumage once you look at them closely. Starling birds are laying a clutch of around 2 to 9 eggs. During the first several days, the eggs turn from white to green or pale blue.

Magpies

Magpies Birds 1
Credit: @keltisk_skog
Magpies Birds 2
Credit: @nomadic_rik

Magpies are common birds across the whole UK area. The eggs of Magpies are similar to the Blackbirds’ ones. As such, they look bluish-green and have some speckles on the surface.

However, they are a bit bigger than the blackbird eggs, with a width of around 24mm and 35mm.

House Finch Eggs

House Finch Eggs
Credit: @willowworker

House Finch birds are laying eggs that have a bluish-green color, with some specklings. Sometimes, the birds will use nest boxes and lay up to 4 and 5 eggs.

The ideal period of laying eggs is between late March to late July. It only depends on the location. The dimensions of these eggs are between 1.6 to 2,1cm and have a width between 1.3 to 1.5 cm.

Now that we have described the most common birds with blue eggs, let’s mention other species with similar characteristics:

  • Gray Catbird
  • Red-Winged, Tricolored, or Rusty Blackbirds
  • Blue Mockingbird
  • Blue-footed Booby
  • Gray Catbirds
  • American, Tamaulipas, or Hawaiian Crow
  • Blue Jays
  • Common Myna
  • Cassin’s Finch, Oriental Greenfinch, House Finch
  • Snowy Egret
  • Clay-Colored, White-throated, Wood Thrush, Dusky
  • Little Blue Heron, Great Blue Heron
  • Dunnock
  • Starlings
  • Snowy egrets
  • Eastern, Western, and Mountain Bluebirds
  • Eurasian Jackdaw, Mountain Bluebirds

Main Reasons Why Birds Lay Blue Eggs

The bird’s anatomy is impressive. The female birds have two ink cartridges placed in their reproductive system: Protoporphyrin and Biliverdin. The birds possess these two molecules, but it does not mean that all of them are using them.

However, the ones who are using this molecule are producing amazing colored eggshells. What makes the eggs blue is what we scientists call Biliverdin, a molecule that has a green pigment in eggshells. So, the higher is the concentration of Biliverdin, and the bluer is the egg.

On the other hand, Protoporphyrin is that pigment that will make the eggs brown or red or create visible patches and speckles all over the eggshells. These types of inks will be added to the new shell right during the very last few hours of production.

What is even more interesting is that the color of the eggs, whether blue or other pale shades, will change all through the primary cycles of birds. This process happens as long as the winged animals are laying their multiple eggs at a time.

While it seems like the eggs are running out of the pigment at the first glimpse, what happens is what scientists call “the mother running out of nutrients and calcium.

Considering that 10% of the calcium that stays in eggshells comes from the female birds, the little mother will need to take some extra nutrients while she is laying her eggs.

If she cannot procure the nutrients she needs, then the eggs will vary in color. So now that we have explained the reason why eggshells turn blue, let’s understand better why this shade is necessary:

Camouflage

As you might already know, lots of animals from the wild kingdom are colored so they can blend with the environment they live in. This way, they can escape from predators.

This way, fragile eggs will be safe from possible enemies. Considering many hungry predators cannot wait to eat some fresh snack, camouflage is mandatory.

Unfortunately, that camouflage is not that successful when it comes to blue eggs, as the shells are not necessarily blending away into the nesting material.

The facade applies to the more pale eggs. However, mother birds will add a layer of protection and put the nest material over the eggs to keep their blue eggs safe.

Temperature control

This might seem odd to you, right? Well, trust us, it will make a lot of sense. Eggs are truly delicate, so they need protection from coldness. The radiation of the sun will quickly warm up the fragile eggs. So the darker the egg, the better will be the blue eggs protected against UV radiation.

The only downside here is that eggshells might heat up and cause an unhatched chick. So once the egg shade is lighter, overheating is probably less likely.

Because of the powerful connection between UV radiation and eggshells, birds will need to do everything possible to balance the eggshells and the surroundings.

How To Notice Blue Eggs In Nests

Sometimes, bird lovers and nature enthusiasts will get way too excited when they see a nest with blue eggs inside. But experts will recommend the exact opposite. If you notice this kind of nest, you should stay away from it.

Try only observing the mothers from far away and their partners. Only do not disturb the eggs and keep the distance.

Last Thoughts

Blue eggs are pretty peculiar and unique to see. If you are lucky enough to notice some blue eggshells, make sure you won’t disturb the winged animals but only admire the richness of Mother Nature.

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