While out on a wildlife nature walk have you ever stumbled across an egg shell?
Every Easter the supermarket shelves are stocked with rows of eggs of all shapes, sizes and colours with attractive packaging. Outside of the supermarket there is a more subtle display of eggs being stocked in nests hidden from view or so well camouflaged they go unnoticed.
The shape, size and colour of eggs relate to the species of bird and its nesting characteristics. As a general guide:
- Blue or greenish eggs are usually from birds who build their nests in trees or shrubs.
- White or pale blue eggs are more likely the eggs of hole nesting birds.
- Brown or speckled eggs are produced by birds who lay their eggs in the open and on the ground.
But why do birds produce eggs with different patterns and colours? Ground nesting species such as the Oystercatcher rely on the camouflage provided by the specked pattern and pale colouration to protect the egg from predators. A study by Glasgow University found that quails seemed to learn their egg patterns and match their nesting location to give the best possible camouflage. This may be one reason why first nest attempts aren’t always successful, as the birds have not seen their eggs before and are not able to choose the best place to lay them.
The white or pale blue eggs allow hole nesting species such as the Puffin to find their eggs in the darkness and avoid breaking them.
Many common bird species like the Dunnock, Blackbird and Song Thrush lay blue or blue-green eggs which can be vibrant in colour. They don’t offer camouflage and as these birds nest above ground, they can easily see their eggs in daylight. The blue colouration has been found to help the egg absorb the right amount of light to warm it but not allow the egg to get too hot. An article in Science Daily showed that brighter blue Robin eggs seemed to indicate a healthier female bird and encourage the male to take more interest in helping to raise the young.
The Easter eggs at the supermarket don’t have these amazing adaptations but you can get novelty, personalised and luxury eggs.
Here are some top tips from the Wooldands Tust that will help you identify some of the more common shells you’re likely to find on a wildlife nature tour. Click here.
Why not have an Easter wildlife nature hunt with our Ranger in Glenesk. Jackie will be out and about in the Cairngorms on Sunday and Monday. For more information click here.