Rico Sebastianelli can have green eggs and ham whenever he wants.
He can also do brown eggs, pink eggs, blue eggs, and, if he finds a turkey, spotted eggs.
"The green eggs are a little bit lower in cholesterol than the other eggs," says the Bon Accord-area chicken hobbyist, while the dark eggs have tougher shells than the lighter ones.
They're also perfect for Easter eggs.
"It's already partially coloured, and you just add a little more to it."
It's Easter this weekend, and that means eggs – striped, spotted and multicoloured ones, all hidden by the Easter Bunny.
But you don't have to rely on mythical oviparous lagomorphs to find non-white-coloured eggs. As Sebastianelli's chickens show, eggs come in a whole rainbow of colours.
Ornithologist Jocelyn Hudon probably has one of every shape, size, colour and pattern imaginable down at the Royal Alberta Museum. Hidden in the back in grey, locked metal closets are some 15,000 sets of wild bird eggs, with one to 13 eggshells per set.
He's got hummingbird, ostrich, flamingo, and penguin; striped, spotted, shiny and chalky. Some are milk chocolate brown or pinkish-purple. Others are nearly spherical or dead ringers for metamorphic rock. Almost all rest in individual cotton-lined boxes, each has a tiny card with details about the eggs written neatly upon them.
Hudon says wild bird egg collecting used to be a big hobby in the late 1800s. Collectors would raid nests for eggs and trade them around the world, seeking the rarest ones and driving some species to near extinction in the process.
Hudon says almost all collection and trade of wild bird eggs is banned in Alberta today, which his why many collections have ended up here at the museum.
What is an egg?
An egg is an external womb that feeds and protects an embryo, Hudon says.
Frank Robinson handles scores of eggs each year as a poultry professor at the University of Alberta's faculty of agriculture.
Whereas humans can nurture babies using a placenta, chickens lay eggs that must contain everything the chick needs to grow, Robinson says.
The egg consists of a cluster of germinating cells atop a blob of protein, vitamins and minerals called the yolk. A membrane around the yolk acts as a stomach. Ropey structures called chalazae suspend the yolk in the midst of a clear, watery fluid called the albumen, which nourishes and protects the embryo. Around all that are two membranes that act as lungs, keeping bacteria out and letting oxygen in.
Between those membranes is the shell itself. Made of calcium carbonate and protein, it starts as a bunch of crystalline columns that later collapse together to form the shell, Hudon says. The shell will have about 17,000 microscopic pores in it for gas exchange, notes San Francisco's Exploratorium.
Each egg starts as a follicle in the ovary, Robinson says. In chickens, one of those follicles (as a yolk) leaves the ovary and proceeds down the oviduct, the cells of which sequentially secrete the layers of the egg onto it.
At this point, the egg is still calcium white. Birds will have pigment-producing cells that paint colours and patterns onto the eggshell in the last part of the oviduct. While the general colour and pattern is determined by genes, the placement of the cells is unique to each bird – with turkeys, you can actually trace each egg back to its layer by its pattern, Robinson said.
The chicken is ready to lay the egg after 24 to 26 hours, Robinson says – a complex operation where it stands up, spins the egg 180 degrees and pushes it out fat-end first (presumably so it doesn't hit the ground on the pointy, breakable end). Spook the chicken, and it'll often lay an egg point-first.
This process doesn't always work right, Robinson notes. Some eggs reverse course in the oviduct, resulting in eggs within eggs.
"We had one egg out of a chicken that had 18 layers like that," he says. The hen looked like a penguin due to her bloated abdomen, and they had to kill her to get the massive egg out.
Others will lay two eggs at once, resulting in eggs with a flat, soft side where the pair squished together in the oviduct. If multiple follicles mature at once, you can get double, triple or quadruple-yolk eggs, which can produce either "one big honkin' chick" as one embryo eats the other or none at all.
"That's a real heartbreaker."
All shapes, sizes and colours
Hudon says natural egg colours come from a handful of pigments derived from haemoglobin, such as protoporphyrin (yellow, pink, red and brown) and biliverdin (blue and green).
Diet won't change the colour of an egg but will affect the yolk, say Robinson and Sebastianelli. More grass and sunshine makes for a darker yolk, for example, while flax gives you one with omega-3 fatty acids. Weeds can give yolk a foul taste, while artificial dyes can theoretically turn the yolk any colour you want.
Sebastianelli says most store-bought eggs are white since white eggs are easy to check for impurities, which is done by holding the egg in front of a light or candle to see the insides. More exotic breeds, such as the Ameraucana and Maran, produce different coloured shells (green and chocolate brown, respectively) that aren't as transparent.
Hudon says the colours and patterns on an egg both camouflage it from predators and make it easier for parents to spot intruders laid by nest parasites, such as the cowbird. Birds that nest in tree cavities often don't bother with camouflage and lay white eggs, while those with exposed nests usually go all-out with colours and patterns.
Habitat can also affect an egg's shape and texture, Hudon says.
Cormorants nest in muddy areas and have chalky shells that pick up mud to blend in. Tropical species such as the Chilean tinamou lay glossy eggs to confuse predators with reflected light.
"A bird that lives on a cliff would have an elongated egg like this," Hudon says, indicating a cone-like egg from a murre. Murres nest on bare cliffs, and this pointy shape makes their eggs more likely to roll in a circle when bumped instead of off the edge.
The size of an egg is usually proportionate to that of the bird, Hudon says. A hummingbird egg is so small that Hudon is worried he'll crush it between his fingers, for example, while an ostrich egg is about 2,000 times bigger.
But some birds lay huge eggs for their size, he notes. New Zealand's kiwis are about the size of a chicken, for example, but lay eggs that are 14 centimetres long and weigh about one-quarter their body weight.
Egg lore
Nowadays, Hudon says eggs themselves are of relatively little scientific value, although a study of old peregrine falcon eggs did help prove the influence of DDT on shell thickness.
The records associated with those eggs have proved very helpful because most collectors kept detailed notes of the time and place of where they found each one.
"We're now noticing that the timing when birds were laying eggs 100 years ago is a little bit different than now partially because of global warming," he says. Collections can also help researchers track the breeding distributions of species in the past.
The eggs are also beautiful, both in terms of their natural patterns and what collectors did to them. Egg collectors would drill neat little holes in the shells to extract the insides, and often wrote beautiful calligraphic notes on them.
"It's a lost art, really."
Sebastianelli says he personally prefers brown eggs, as that's the colour he grew up with. As for what to do with all your collected eggshells after Easter, he says he uses his to add calcium to the garden.
