Easter eggs-stravaganza: discover these dozens of beauties, “decorated” by nature | Chicago News

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Eggs in the collection of the Field Museum. (Patty Wetli / WTTW News)

Whether simply dipped in food coloring or painstakingly hand painted with intricate designs, decorated eggs are a centuries-old tradition at Easter.

Nature has been there for eons.

A look inside the Field Museum’s egg collection, which numbers in the tens of thousands, reveals a startling range: from some the size of jellybeans to others as big as soccer balls, some are shiny, some are speckled, and some are even shaped. looks more like pears than eggs.

John Bates, curator of birds at The Field, shared a dozen of his favorites. Let’s crack.

1. Common Murre

Murre eggs.  (Patty Wetli / WTTW News)Murre eggs. (Patty Wetli / WTTW News)

Common murres are found on both the Atlantic and Pacific coasts of North America, and their eggs are notable for multiple reasons. Each female produces her own pattern, which is believed to help parents spot which ones are theirs in crowded breeding grounds. The unusual shape — heavier at the bottom and less, well, egg-like — also serves a purpose: if an egg is nudged, it tends to spin rather than roll off the cliffs where the guillemots nest.


2. Japanese bush warbler

Japanese warbler eggs.  (Patty Wetli / WTTW News)Japanese warbler eggs. (Patty Wetli / WTTW News)

These terracotta-colored eggs are particularly shiny. And no one really knows why, Bates said. “It’s a big debate,” he said. “Where does it come from and why would you want it?” Eggs have been largely overlooked in terms of scientific studies and are an untapped source of information, Bates said.


3. Cuckoo Guira

Guira cuckoo eggs.  (Patty Wetli / WTTW News)Guira cuckoo eggs. (Patty Wetli / WTTW News)

There can be up to 20 eggs in a guira cuckoo nest, not because a female is so prolific, but because they share common nests. These cracked eggs owe their appearance to a chalky white layer deposited on a blue-green base. During incubation, the powdery layer begins to fade in patches, revealing the color underneath.


4. Oystercatcher

Oystercatcher eggs.  (Patty Wetli / WTTW News)Oystercatcher eggs. (Patty Wetli / WTTW News)

Ground-nesting birds tend to lay eggs in shades of brown, Bates said. “In some cases, we know very clearly that it’s designed for camouflage,” he said. Oystercatchers live on shores and nest in beach vegetation, where these eggs blend inconspicuously.


5. Catbird

Cat eggs.  (Patty Wetli / WTTW News)Cat eggs. (Patty Wetli / WTTW News)

Blue is most associated with robin eggs, so much so that Crayola has a crayon shade named “robin egg blue.” But many other birds, including the catbird, lay eggs in shade variations.


6.Grackle

Grackle eggs.  (Patty Wetli / WTTW News)Grackle eggs. (Patty Wetli / WTTW News)

It takes about 24 hours for a bird to build a single egg, and females need to consume more calcium to produce the shell. Colors, squiggles and patterns are placed on the egg towards the very end, in a process that is not yet fully understood.


7. Cactus Wren

Cactus wren eggs.  (Patty Wetli / WTTW News)Cactus wren eggs. (Patty Wetli / WTTW News)

Where are the magenta and chartreuse eggs? Well, nature’s palette is actually quite limited, depending on the Cornell Bird Lab. Birds only use two pigments: one that produces reddish-brown colors — as seen in these pinkish cactus wren eggs — and one that produces blues and greens. All the variety on display comes from different combinations – more of one, less or none of the other – of the two.


8. Cedar waxwing

Cedar Wax Eggs.  (Patty Wetli / WTTW News)Cedar Wax Eggs. (Patty Wetli / WTTW News)

Here’s a fun fact from Cornell Lab: eggshells have pores. Depending on the species, the number can vary from hundreds to tens of thousands. Eggs will lose about 18% of their mass through these pores, mostly as water, between the time of laying and hatching.


9. Northern Jacaranda

Northern jacaranda eggs.  (Patty Wetli / WTTW News)Northern jacaranda eggs. (Patty Wetli / WTTW News)

There are a number of mysteries surrounding eggs that scientists have not yet solved. There are competing hypotheses, for example, surrounding the darker pigmented eggs, and whether it protects the embryo from harmful UV rays or heats the egg more than the lighter coloring. Another theory is that paler than normal colors could indicate a nutritional deficiency in the female.


10. Peregrine Falcon

Pergerine Falcon Eggs.  (Patty Wetli / WTTW News)Pergerine Falcon Eggs. (Patty Wetli / WTTW News)

Egg collecting was a popular pastime in the late 19th and early 20th centuries, and most of Field’s specimens date from this period. But the museum’s peregrine falcon eggs are a recent addition, as part of the Chicago Peregrine Program, supervised by Mary Hennen. Hennen collects the non-viable eggs for further study.


11. Emu

Emu eggs.  (Patty Wetli / WTTW News)Emu eggs. (Patty Wetli / WTTW News)

The emu is second only to the ostrich in terms of size, so, unsurprisingly, its eggs are huge. These shells are rock solid and can withstand a strong blow from a person’s knuckles, with a cast iron-like look and feel.


12. Elephant Bird

Elephant bird egg replica (l) and shards of a real elephant bird egg.  (Patty Wetli / WTTW News)Elephant bird egg replica (l) and shards of a real elephant bird egg. (Patty Wetli / WTTW News)

The flightless elephant bird is often described as the “largest bird that ever lived”. It took up residence in Madagascar and has been extinct for at least 800 years. The Field Museum has a replica of an elephant bird’s egg in its collection (l) – like the basketball or the softball of an emu – as well as pieces of a real eggshell. Shards are still occasionally found on beaches in Madagascar, Bates said.

Contact Patty Wetli: @pattywetli | (773) 509-5623 | [email protected]


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