Many a child at Easter has been puzzled by the mechanics of a rabbit laying eggs. While it's hard to logically dissect the origins of the Easter Bunny, other symbols of the holiday have some scientific significance.

A Spectrum of Eggs

Whether you're dyeing your eggs with the synthetic colors found in store-bought kits or going with a more au natural method, such as boiling them with onion skins, cranberry juice, or chili powder, nature is already way ahead of you.

While white and brown chicken eggs are the most common sights at the grocery store, birds in the wild produce eggs in a much more varied spectrum, usually to camouflage predators.

Blue and green shades -- seen in the eggs of the robin and the South American tinamou, respectively, primarily come from the pigment biliverdin. Female birds are thought to make this pigment in a portion of their oviduct that secretes the eggshell. Humans also make biliverdin in the liver - it's what gives bruises a greenish color as they heal.

Eggs also come in brown and reddish varieties, which get their tints from a class of chemicals called protoporphyrins, which also help strengthen the eggshell.

Colored Chicks Ruffle Feathers

Some Easter enthusiasts don't stop at coloring eggs, and are making baby chickens in all the colors of the rainbow.

Pete Theer, a retired Texas poultry rancher, provides instructions for one method of making Technicolor chicks on his website: take an egg that's incubated for about 16 or 17 days, drill a small hole in the eggshell, inject dye and seal the hole with paraffin.

The color is just on their fluff and only lasts a few weeks until their feathers grow in, Theer says on his website.

Some animal rights groups think the practice of dyeing chicks is traumatic and cruel, and about half of US states have laws against the practice. Florida's legislature recently passed a bill to overturn its ban, provoking an outcry.

Humane societies are overflowing with these animals after Easter every year, Don Anthony of the Animal Rights Foundation of Florida told the New York Times. This law has protected thousands of animals from neglect and abuse.

Easter lilies - the beautiful (cat) killer?

Lilium longiflorum, the Easter lily, is a native of Japan and Taiwan first sold in the US in the 1880s, after it was cultivated in Bermuda.

The lily, like its cousin the tulip, can reproduce without casting seeds in an asexual reproductive process also known as vegetative propagation.

Pet owners should take care before planting a lily bulb in their garden or bringing a bouquet of these blooms home, though. Much of the lily family is extremely poisonous to cats, which become ill within a few hours of eating a bit of the plant.

Scientists are puzzled by the feline specificity of the Easter lily's poison. Attempts to replicate lily poisoning in dogs, rabbits and rats have thus far been unsuccessful, Michigan State University scientists wrote in a 2004 study in the Journal of Veterinary Diagnostic Investigation.

Rabbits Unwelcome Down Under, Even at Easter

The hyper-fertility of the rabbit is a common joke in cartoons, but it does have a grain of truth to it.

Rabbits are prolific breeders; they can start breeding at 3 to 4 months and can produce five or more litters a year with up to 5 young per litter... even during drought times they can still produce 2 litters per year, says David Eldridge, an ecologist at the University of New South Wales in Australia.

Bunnies are breeding especially well in Australia, where they were first introduced to the country when English settlers arrived in the late 18th century. They're now the number one vertebrate pest, causing damage to the bark of trees and soil erosion and competing with native animals for habitat and food.

Plus, about 20 rabbits eat as much as a sheep, so farmers hate them, Eldridge says.

The Foundation for Rabbit-Free Australia is actually trying to promote the bilby, or rabbit-eared bandicoot, as an alternative symbol for Easter. Rabbits displaced the once-common bilby and bettong, also known as a rat kangaroo, from their underground warrens, according to Eldridge.

Very young children are indoctrinated with the concept that bunnies are nice soft fluffy creatures whereas in reality they are Australia's greatest environmental feral pest, the foundation says on their website.

To dethrone the invasive and destructive Easter Bunny, Australian confectioner Haigh's Chocolates and other candymakers have been promoting chocolate bilbies as the new, more environmentally-conscious treat of choice down under.

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