Thrush eggs, chicks and nests. What do thrush eggs look like? Amazing color of the eggs of these songbirds! Thrush egg color
Blackbirds are wonderful small birds belonging to the order Passeriformes, the genus Short-billed. A special feature of this bird is its musical, or rather, singing ability. The appearance of the thrush is, as a rule, not very striking. The color of the feathers can be noble brown or light olive with dark brown specks. However, there are also black birds with small bright spots on the tail.
Thrush eggs are painted by nature itself in amazing colors and shades - from blue to light green. Rarely do they have a single color. The presence or absence of specks on eggs indicates that there is a certain degree of pigmentation in the structure of the eggshell. During egg development, pigmentation is formed due to the concentration of a substance such as protoporphyrin. It is a powerful photosensitizer and contains molecules that can not only absorb light from the sun's rays, but also convert it into oxygen, light and heat, which are so necessary for the healthy development of chick embryos.
Today in Russia there are 46 species of blackbirds. Each species has its own egg color. One species of thrush can be easily distinguished from another. The differences in the shape, color and pattern of the eggs are not radical, but they still exist. The thrush eggs, photos of which are presented here, have different color shades, inclusions and sizes. Some are larger and elongated, others are round and small. Here are a few examples of egg color.
The American Swanson's blackbird has the standard color for all light blackbirds, with one difference - the top of the head, tail and tips of the wings have a reddish tint. Its eggs are blue with brown speckles. This bird builds its nest in the form of a large ball of dry grass blades. The blue color of the eggs of the American blackbird, as well as other species, has always attracted the attention of ornithologists with its brightness. The background blue color is unusual in its shades: greenish, grayish and bright turquoise. And the spots are very clear, brownish-rusty in color. They come in different sizes, from microscopic dots to spots the size of a pinhead.
Hermit thrush. This bird is very modest, loves to hide from prying eyes among the branches. Its discreet coloration is more brown, and there is a blurred spot on its chest. The eggs of the hermit thrush are monochromatic, without speckles, and have a delicate greenish-blue color. The hermit thrush builds its nests among tree branches so that the sun's rays can reach them as much as possible, feeding them with its light and warmth.
Song thrush. The size of this population is quite large. The color of the bird is dominated by faint olive and gray shades, with speckles the color of dark chocolate. The egg clutch is either small dark speckled or colored with small brown spots. The specks are often dark chocolate in color. They differ in size: they can be very small specks, or a little larger - the size of a match head.
It always looks respectable, having black plumage, a yellow beak and yellow, orange or rims around the eyes. It differs from other blackbirds in its larger size. Thrush eggs are green in color, close to dark with light brown spots. There are also eggs with a background of a grayish-green hue, with larger specks. On the wide side, each egg is completely colored with brown pigment.
Wandering Thrush's Nest (Turdus migratorius). The bird lives in the northern and central parts of North America.
Gwen's River City Images / flickr.com
The color of eggs of bird species living in cold climates is determined by thermoregulation, reports the Nature Ecology&Evolution. In cold and cloudy climates, birds lay darker eggs, and in southern latitudes, pigmentation apparently already depends on several factors - the color and brightness of eggs in inhabitants of the tropics and subtropics changes much more often.
Bird eggs come in different colors, plain or covered with spots and dots. The white color is determined by calcium carbonate, the pigment biliverdin gives them different shades of green-blue, and protoporphyrins are responsible for the brown or reddish color. But what determines the color of eggs is still not completely clear, although ornithologists have guesses on this matter. On the one hand, pigmentation may play a role in thermoregulation. Dark-colored eggs absorb more solar energy that accidentally enters the nest, and they are more likely to overheat. Therefore, it is likely that dark-colored eggs should be more common in northern latitudes, where there is less sun.
On the other hand, dark pigmentation of eggs, on the contrary, may be more common in southern latitudes, because dark eggs are less likely to attract the attention of predators. Previous studies have shown that predators are more likely to destroy nests in warm climates than in cold climates, suggesting that dark-colored eggs are more likely to be laid by tropical bird species. This hypothesis is also supported by the fact that protoporphyrins have antimicrobial properties that are activated by sunlight. The pigments that give eggs their color, especially biliverdin, are also known to protect them from harmful ultraviolet radiation. Therefore, if egg coloring has become part of adaptation to ultraviolet radiation, then green-blue eggs should be more common in southern latitudes.
To test all these hypotheses, American and Australian ornithologists, led by David Hanley from Long Island University, analyzed the color of 6.7 thousand eggs of 634 bird species, representatives of 36 of the 40 existing orders. Scientists mapped the birds' nesting range and looked at how it correlated with the color and brightness of the eggs. In addition, they paid attention to the type of nest and identified three types - open nests on the ground, nests in the shape of a bowl, and nests located in hollows or recesses. Based on nest type, the authors tracked how much sunlight reached the eggs.
As a result of the analysis, scientists came to the conclusion that color plays the main role in thermoregulation - at least when it comes to cold climates. Darker colored eggs were found in regions with fairly cold climates and less sunlight (p< 0.0001).
Pigmentation distribution of bird eggs
P. Wisocki et al. / Nature Ecology&Evolution, 2019
At the same time, in the tropics and subtropics, color may be influenced by several factors. So, contrary to the assumption of scientists, in areas with high levels of ultraviolet radiation, birds laid light eggs, and dark green-blue eggs were found in temperate latitudes, where the level of ultraviolet radiation was lower. Humidity also affected pigmentation: in arid climates, the color of the shell was darker. Interestingly, color and brightness varied most in hot climates.
As the authors predicted, egg pigmentation also correlated with nest shape (p<0.0001). Виды, делавшие открытые гнезда на земле, откладывали более темные и коричневые яйца, чем птицы, которые устраивали гнезда в дуплах или расщелинах, и те, что вили гнезда в виде чаши. У видов, живших в более прохладном климате и делавших чашеобразные и наземные гнезда, яйца были темнее.
The authors conclude that egg color appears to play an important role in thermoregulation in cold climates. At the same time, since the color and brightness of eggs change more strongly in southern latitudes, pigmentation in warm climates may depend on several factors.
Several years ago, scientists discovered a relationship between the shape of bird eggs and the bird's ability to fly. The eggs of good flyers turned out to be asymmetrical, while those of bad flyers were round or elliptical in shape.
Ekaterina Rusakova
Every year a large colony of blackbirds settles in the forest belt. They live there white-browed thrushes (Turdus iliacus) And Field Thrushes (Turdus pilaris). In summer and autumn they will make devastating raids on the surrounding gardens, and now they are setting up nests, laying eggs and hatching chicks. These are quite noisy and scandalous birds: they try to drive away any potential enemy who enters their territory with the whole flock: loud squawking, flapping their wings, and if all these methods do not help, then targeted fire with droppings. You can often see them driving away crows in this way. Any person passing along the path also causes loud panic. But I still reasonable man, and this behavior of birds, on the contrary, unmasks their nests. It seems like I’m just walking along the trees, in one place the screams suddenly intensify, I look around - and there it is, a nest! As if I wasn’t looking for it on purpose, they slipped it in. Fieldfares have nests high, in the forks of trees, on thick branches, twisted from blades of grass and fastened on top with dirt, while white-browed nests are built low, no higher than a meter, on old stumps or half-fallen branches, or even on the ground. I pass by, one of the parents flies up from the nest, swears like a blackbird from nearby branches, and I can’t contain my curiosity, I look into the nest for a second. Here they lie, 5 neat eggs, slightly smaller in size than a quail’s. And not " blue like thrush eggs", as the song says. The color of the eggs is greenish-bluish, with grayish-brown speckles. And a week later, in these same nests, the newly hatched chicks lie, still pink, naked, with huge closed eyes. And just along their backs, like some small dinosaurs, they have a mane of white down. For now, they just sometimes change their position and yawn, but soon they will begin to actively open their beaks and squeak, demanding food from their parents.
On the picture white-browed thrush (Turdus iliacus). The smallest and one of the most common representatives of the blackbird genus on the territory of the former USSR. Length 22 cm, weight rarely exceeds 60 g. Color brownish-green (olive-brown) on the back and light with dark (olive-brown) spots below. The sides of the breast and the lower wing coverts are rusty rufous. Above the eyes is a whitish-yellow eyebrow; hence the Russian name for this bird. The female looks paler than the male.
The white-browed bird is a bird that is not afraid of the cold. This species of blackbird arrives early and leaves its nesting site late. In total, the white-browed moth stays in these places for about six months. The beginning of the arrival of birds also depends on weather conditions and can vary from one to three weeks. As a rule, mass arrivals to nesting sites begin in April and end in early May.
In city parks, the whitebrow lives more crowded, and in natural forests, where there is much more space, it is dispersed. This bird prefers small birch forests, which contain a small admixture of spruce shoots. The white brow prefers bright places where there are many bushes and ponds, and avoids dark spruce or pine forests.
The food of whitebrows consists mainly of insects, earthworms, various butterflies and caterpillars. During the period of feeding the chicks, earthworms are brought in the beaks not one at a time, but in a whole bunch, which is lowered into the nest, and then distributed among the chicks.
Field Thrush (Turdus pilaris) is also a common species of thrush. Body length - 22–27 cm. The back plumage is dark brown, the belly and underwings are white, the wings and tail are blackish-brown. The chest and sides are buffy with dark streaks. A restless and very active bird, constantly emitting characteristic sounds chuck... chuck... chuck, in an alarming state a deafening chatter of ra-ra-ra begins
The fieldfare differs from other thrushes primarily in its way of life. Although some pairs nest in isolation, most of them gather in medium-sized colonies of 30-40 pairs. They love to settle in parklands and copses, along the edges of forests, closer to wet meadows. Fieldfare is not found in dense forests. Fieldfare feeds on both animal and plant foods. In winter, flocks of field berries flock to feast on ripe mountain ash and other berries (for example, sea buckthorn).
Fieldfare nests in colonies (up to 30 pairs). The nests are strong and deep bowls, which are located either high or low, sometimes completely open, sometimes camouflaged. Some colonies are completely destroyed by crows, jays and magpies. Blackbirds defend themselves by throwing themselves at their enemies with downward stones and dousing them with droppings. Bombs made from droppings are a dangerous weapon, as they can contaminate and gum up the feathers of enemies so much that they cannot fly. People will expect the same “shelling” if they come to the colony.
The nest of this species of birds is built by the female. The male’s task is to accompany and protect the nesting site and his mate. If possible, the female collects materials for construction nearby. The nest is cup-shaped, quite massive, lined with soft grass on the inside.
White-browed birds begin building nests at the end of April; about a week after the start of construction, the first egg is laid. If a bird settles in a ready-made nest, then egg laying accelerates. When choosing a nest or building it, the bird becomes very careful; it does everything to make the nest invisible. It is common for white-browed birds to place their nest close to the ground. If only there is reliable camouflage and support, birds are happy to nest there. They love the bases of various trees, or use small, half-rotten stumps.
It is extremely rare to see a white-browed nest located on a hill, in hollow trees, or on fences and fences. But, if white-browed birds have a choice - to make a nesting site on a hill, or simply on the ground overgrown with grass, then the second option for these birds will be preferable. The only exception is parks that are frequently visited by people. In this case, white-browed birds make nests in trees, out of the reach of park visitors.
The shape of the nest in white-browed birds may vary depending on the nesting site. If the base is strong, then the nest will be more massive and larger. And if the nest is built on thin branches of a bush, then it will be light and elegant. You can see a chaotically made nest if it is located on the ground, and a primitive nest in the form of a hole located in the depths of a rotten stump.
There are from 4 to 7 eggs in a clutch. The eggs are greenish in color with brown spots. Incubation begins after the last egg is laid and lasts 12 days. During the summer, masonry occurs twice.
Let's look at the color of thrush eggs, are they really blue, and why did nature choose such an impractical and rather noticeable color for them? In the color catalog there is a completely official name “robin egg blue” for the color with the code #00CCCC, it’s like this:
I found an interesting article on the Popular Mechanics website: Why do blackbirds have blue eggs?
It would seem that the bright color of eggs that attracts predators is a dubious evolutionary advantage; chicks that hatch from speckled or plain-colored eggs that mimic their environment are much more likely to survive.
However, the colorful, fashionable eggs of some songbirds, including the thrush, are an undeniable fact that scientists have long been trying to explain. Obviously, the blue color of the eggs must be an advantage that outweighs the increased risk of the clutch being discovered by a snake, marten or hedgehog. The most common theory among ornithologists today is that the blue pigment in the shell serves as protection from the sun for blackbirds.
Some songbirds lay eggs of different colors and shades - from white to bright azure. This is what made it possible to determine exactly how the shells of eggs of the same species, but of different colors, conduct sunlight. It turned out that the blue pigment reflects ultraviolet radiation, which is harmful to DNA; however, at the same time, the blue shell absorbs that part of the infrared rays that heat the contents of the egg, accelerating embryonic development, which leads to a number of other problems.
The conclusion is this: the blue coloring of nest eggs is the result of a delicate balance between the desire to protect themselves from UV rays and not to overheat the egg; This strategy only works in certain climates, and even then not in every case - which is why some birds lay eggs of different colors.
In the same nests as in the previous photos, after some time the chicks hatched: pink, wrinkled, with a sloppy tuft of fluff on the head and along the spine. These are microscopic pterodactyls.
They are very small, with huge black eyes that have not yet opened, relative to the size of their heads.
They will not be in the nest for long: the chicks will quickly grow up, jump out of the nest, and will already be hiding in the grass, where their parents will bring them food.
After the chicks leave the nest, and this happens 10-12 days after birth, they live right on the ground. Even without being able to fly, they are very mobile and move quite long distances from their homes. However, they do not lose each other, since they constantly hear the voice of other chicks, and parents direct the actions of their children, showing where to move.
As soon as the chick masters the ability to fly, its mobility increases even more, but they take off only if they are in danger.
And a short video with white-browed thrush chicks in a nest where there are still a few unhatched eggs:
