These beautiful, deep emerald green eggs weren't laid by a dragon, but by an emu! I find people are often surprised at their size and rich color, and ask a lot of questions about them; especially how they taste and how they are incubated, so I thought I'd delve into this topic here on Patreon.
Emus are the second largest living bird (beaten only by the ostrich) and their eggs are correspondingly huge. An emu egg weighs, on average, about 1.5lbs, and has the same volume as a dozen large chicken eggs. They have more yolk to white ratio than a chicken egg, so they taste much richer. They are fantastic for baking, or for making giant, high quality omelets or fritattas, one egg being enough to feed a small family! An emu egg (in the U.S.), for eating, usually sells for about $30-40. A fertilized egg for hatching generally runs $45-60. Since emu farmers aren't too common, eggs are usually mailed (with a lot of insulation and padding). It is legal to do, and USPS postal service has long history with shipping hatching eggs and day old poultry chicks - it was actually one of their first services even when they were delivering mail via horseback!
Deviled emu eggs!
What do emu eggs taste like? Because of the extra yolk, emu eggs are more decadent and richly flavored than chicken eggs. They are rumored to be the most richly flavored egg, and in my experience this holds true. If you’ve had a duck egg, they are quite similar, but even more strongly nuanced and savory. Emu eggs have a slightly different texture than chicken eggs – their white is a bit lighter and almost more like a meringue and the yolk has a more smooth ‘putty’ consistency. The yolk holds together instead of crumbling, another quality that makes them a superb choice for baked goods. Despite the differences, on the whole most eggs taste quite similar - the diet of the bird seems to have much more of an effect on flavor than the species of bird they come from.
As an experiment one spring, with the help of a few bird-keeping friends, we hard boiled a set of eggs from a tiny canary up to a giant emu, and many in between (quail, chicken, turkey, duck, and goose). The duck and emu eggs were the richest, the canary egg was hard to get a flavor reading on since it was so tiny, but tasted a bit more like salt or fish eggs – just a little salty pop in your mouth. Interestingly enough, the ‘white’ of the canary egg cooked clear – it was white in all the other eggs.
Emu eggs range in color from a vibrant light teal to an almost-black emerald hue. Sometimes they are solid colored, more often they are flecked with darker marks. It is commonly accepted that the green color is for camouflage, as wild emus prefer to lay their eggs in grass. Since many predators hunt by scent, it has also been theorized that the dark color could just be a byproduct of strength. Based on physical structure, the darker pigments, especially those involved in the flecking (common in many birds’ eggs), create a stronger eggshell. This dark pigment strength difference is also why you commonly see black flight feathers on other otherwise pure white birds, like storks. Dark feathers are stronger, but weigh a tiny bit more. Many birds have banding of light and dark on their wing feathers, which optimizes strength vs. weight - very important when optimizing for flight.
To further complicate things, ostrich eggs, which are even thicker and stronger than emu eggs, are an ivory white. As it stands, the absolute answer to ‘why are they green?’ is unknown.
Emu eggs are very hard! They are built to withstand a 100+lb bird basically falling on them (emus aren't very graceful about sitting down, it's more of a plop), so they have a very thick shell. A dremel-type tool or hammer and chisel must be used to crack into them. The multiple layers that make up this thick shell are differently colored (dark green, turquoise, grey, and white), which lends the eggs to be fantastic subjects for intricate carving. Eggs are 'blown out' (the inner contents removed) before being used in art, so that just the shell is preserved. Here are two carved emu egg examples by artist Brian Baity.
Emus tend to form pairs during breeding season. Of our seven emus who hang out together most of the year, they split roughly into two pairs and one loose trio when time comes to lay eggs. Emus seem to have their native ‘Australia time’ baked into them no matter where in the world they are. Ours will lay eggs between December and March here in Minnesota, right in the dead of winter.
In the case of emus, females court males, and they are the ones with more flashy plumage and a booming call (a very deep noise like a bass drum, which can be heard at full volume from over a mile away). Though usually paired, multiple females sometimes court a single male and a male will occasionally allow up to three females to lay in his nest. Nests are generally a simple mound of grass or vegetation pushed together on the ground. A single female emu can lay up to 20-50 eggs in a season, though 15-25 is more the norm. That amounts to creating 25-75lbs of eggs in a season (2-3 months), for a bird who weighs about 100lbs!
Once a female emu has laid her eggs, her work is over. Males brood and incubate the eggs, which take about two months to hatch, alone, .He will refuse to eat or even drink while incubating, and will lose a significant amount of weight while doing so. A male emu raises the chicks on his own, a strategy which allows the mother bird (who put a huge amount of physical resources into laying all those large eggs!) to go and re-build her nutrient stores for the next laying season.
Prime egg laying season ends up being in the middle of our Minnesota winter!
Because we do not pen our emus and they have a 3 acre fenced yard to roam, we tend to get eggs laid in random places during the depths of winter. This can make them hard to find and gather before they freeze (especially since they like to lay them overnight). They lay them in similar spots about half the time, but sometimes we find an egg just laying in the middle of the yard. We collect the eggs and incubate them ourselves, since especially with our winter temperatures, it would be too much on a male to allow him to do that work while it’s so cold.
Fertile eggs stored in cool temperatures can remain viable for up to two months (though hatch rates go down the longer you keep them, and drop drastically after 40 days) – so we wait until we have enough and start incubating them all at the same time. This is so they will hatch together, at the same time. A male emu does this as well, he will wait until an entire clutch is laid to start incubating them. Fertilized eggs wait in a sort of stasis until proper heat is applied, which induces growth to start. After it has started, the eggs need very steady, constant temperatures to develop properly.
My original egg incubator - the water bottles serve as a heat sink, holding heat and helping keep the temperature inside steady when I opened the door.
Emu eggs incubate at about 95-98 degrees for 51-60 days. The lower the temperature in that range, the longer the eggs take to develop, but the better the chicks tend to do overall. They need consistent, controlled temperatures and a specific humidity to thrive, which is accomplished by adding or removing water from a sponge in the incubator. They are monitored with weekly, individual weigh-ins to be sure they are losing the proper amount of weight over the incubation time (12-15 percent of their total weight when laid). Too little or too much moisture loss will kill a chick, so this must be attended to with great care. As the baby inside the egg develops, it is metabolizing and respirating through the porous eggshell, which accounts for the weight loss.
The eggs need to be turned at least 3-5 times a day, or more, for proper development. A male emu will gently turn them 10-12 times a day. At first I did this by hand, now (thanks to a very supportive patron!) I have an automatic turning incubator which does that laborious work for me on a more natural schedule. The reason for the turning is complex, but in a nutshell it allows the growing baby and yolk inside the egg to stay more centered, able to access more of the available nutrition and keeping it from getting physically 'stuck' to membranes on the side of the egg as it develops.
Because emu eggs have such a thick, dark shell, there is no way to candle them and tell if they are fertile and developing properly. (Candling is placing a bright light against the egg to see inside). If you don't have access to fancy ultrasound equipment, your first real guess is around 33 days of incubation. The eggs will then start to wiggle if you put them on a flat surface and call to them. It’s really quite magical!
About 3-4 days before their hatch date, you stop turning the eggs (the baby is well developed and needs to get into proper hatching position, which can be disturbed by movement), and move them to a brooder. In this case, it's just a special tray at the bottom of our incubator. The hatching process itself is fascinating – worthy of a whole other post sometime. I’ll give just a very truncated version here.
Emus do not have an egg tooth like many birds (the egg tooth is a sharp projection on the top of the beak that allows a bird to ‘score’ or cut a line around the inside of the egg shell, making breaking out easier. The ‘tooth’ is shed soon after hatching). A tiny baby emu has to rely on its great leg strength to kick a hole in the shell of a very strong, thick egg!
One to three days before breaking out, the eggs will start to peep. It’s a quiet noise, you often have to hold your ear up to the egg to hear it, but after awhile it can get quite loud! If you spent time talking to/calling to your eggs during the incubation process, they will recognize your voice and respond to it, just like they would to a parent emu. One year I was absentmindedly listening to Harry Potter audiobooks a ton while my batch of emu eggs were incubating in my office. When the babies hatched they responded to the audiobooks, and would peep inconsolably if I turned them off!
After a monumental effort to crack a hole in the egg’s thick shell, the baby emu often has to sleep and rest. The actual hatching process can take anywhere from a few hours to a day or two.
Eventually the emu is out, and within a day it begins taking its first wobbly steps! It is really incredible how quickly they develop from egg to functional baby emu.
An emu, just hours out of its egg.
After hatching, emus grow very rapidly! Their watermelon-like stripes help give them better camouflage. They lose the lines as they become adults.
As a bonus, here is a photographic chart from Developmental Dynamics showing this process, day by day from day 18 to hatch. You can see the super rapid changes between days 28-36, which are when the egg starts to wiggle/respond to voice cues.
