Six Geese A-Laying

December 30 is the sixth day of Christmas.  In the song, “The Twelve Days of Christmas,” the sixth day is reserved for bird reproduction—six geese a-laying.  So, let’s talk today about the extremes that birds go to when they are a-laying.

Six gees a-lalying, maybe…( photo by Graham Horn)

            Let’s start with the Bee Hummingbird of Cuba.  This is the world’s smallest bird, about two and one-half inches long, half the size of the common Ruby-throated Hummingbird.  It looks more like a real bee than a bird, flitting around from flower to flower, hence the name.  So, it isn’t surprising that the Bee Hummingbird also holds the record for the world’s smallest egg,  It measures about one-third of an inch in diameter and weighs about .02 grams (right, basically nothing). 

Bee Hummingbird (photo by Charles J. Sharp)

            At the other end of the spectrum is the Ostrich, native to Africa (and earlier to Asia).  The Ostrich is the world’s largest bird, standing up to 9 feet tall and weighing up to 250 pounds.  So, it isn’t surprising that it also lays the world’s largest egg.  Ostrich eggs are 6 inches long and weigh about 3 pounds.  The shells are so strong that an adult human can stand on the eggs without damaging them—a good trait since their incubating parents weigh in at about the size of a football linebacker.  Historically, however, the Ostrich comes in second to the fossil Elephant Birds, a group of species that lived in Madagascar as recently as 3,000 years ago.  With eggs twice the size of Ostrich eggs, the Elephant Bird produced the biggest eggs ever known.

Kiwi (photo by Glen Fergus)

            Another way to look at size, however, is relative.  When egg size is expressed in terms of a bird’s overall size, the accomplishment of the Ostrich or Elephant Bird isn’t so impressive.  Ostrich eggs are about 2% of the weight on an adult, hardly worth an honorable mention  The champion is New Zealand’s national symbol–the Kiwi.  The Kiwi is a small (about 1.5 feet tall and weighing 2.5 pounds); it doesn’t fly and its feathers look more like hair, prompting some to call it an “honorary mammal.” But it is all bird when it comes to its egg.  The Kiwi lays a gigantic egg for its size, up to 25% of its body weight.  Imagine this in human terms—a 120-pound woman would be giving birth to a 30-pound baby!

Megapodes (photo by Jason Thompson)

            Well, maybe we need to look at the egg championship from even one more perspective.  The Kiwi lays a big egg, but it produces only one at a time.  So, perhaps we should think about egg-laying records in terms of the total amount of egg-stuff produced.  Which bird lays the most eggs?  That award goes to a series of Australian species (comprising the family Megapodes) collectively known as “mound builders.”  These ground-nesting birds excavate shallow depressions which they fill with decaying vegetation and cover with sand.  The decomposition produces heat that incubates the eggs, so the adults don’t have to mind the nest.  They don’t take care of the chick either.  I guess the mound builders figure they do enough by making the nest and filling it with eggs.  Lots of eggs.  World-record numbers of eggs.  One female can lay up to 35 eggs in a single brood.  When this mass of eggs is considered together, the Megapodes surpass all other bird groups in the relative amount of material—eggs and their contents—devoted to reproduction. 

            From big to small, few to many, egg-laying is one big job for our feathered friends.  Next time you make an omelet, pause to recognize the miracle you are about to crack into the frying pan!

References:

Bradford, Alina.  2014.  Ostrich Facts:  The World’s Largest Bird.  LiveScience, September 17, 2014.  Available at:  https://www.livescience.com/27433-ostriches.html. Accessed January 19, 2020.

Bryce, Emma.  2015.  The Champion Egg-Layers of the Bird World.  Audubon, February 6, 2015.  Available at:  https://www.audubon.org/news/the-champion-egg-layers-bird-world. Accessed January 19, 2020.

Dean, Sam.  2015.  Why Is the Kiwi’s Egg So Big?  Audubon Science, February 25, 2015.  Available at:  https://www.audubon.org/news/why-kiwis-egg-so-big. Accessed January 19, 2020.

Encyclopedia Britannica.  Elephant bird.  Available at:  https://www.britannica.com/animal/elephant-bird.  Accessed January 19, 2020.

Encyclopedia Britannica.  Megapode.  Available at:  https://www.britannica.com/animal/megapode. Accessed January 19, 2020.

McCann, Mary.  2018.  Get to Know the Bee Hummingbird, the World’s Smallest Bird.  BirdNote, September 17, 2018.  Available at:  https://www.audubon.org/news/get-know-bee-hummingbird-worlds-smallest-bird.  Accessed January 19, 2020.

Science Epic.  2015.  Which Bird Lays the Smallest Egg?  May 25, 2015.  Available at:  http://www.sciencepic.com/which-bird-lays-the-smallest-egg/. Accessed January 19, 2020.

This Month in Conservation

October 1
Yosemite National Park Created (1890)
October 2
San Diego Zoo Founded (1916)
October 3
James Herriot, English Veterinarian, Born (1916)
October 4
Feast Day of St. Francis of Assisi, Patron Saint of Ecology
October 5
Catherine Cooper Hopley, British Herpetologist, Born (1817)
October 6
Mad Hatter’s Day
October 7
Henry A. Wallace, Secretary of Agriculture, Born (1888)
October 8
World Octopus Day
October 9
Vajont Dam Disaster (1963)
October 10
Dnieper Dam Began Operation (1932)
October 11
Big Cypress and Big Thicket National Preserves Created (1974)
October 12
William Laurance, Tropical Conservationist, Born (1957)
October 13
International Day for Disaster Risk Reduction
October 14
Timpanogos Cave National Monument Created (1922)
October 15
Isabella Bird, Pioneering Eco-traveler, Born (1831)
October 16
World Food Day
October 17
Oliver Rackham born (1939)
October 18
Clean Water Act established (1972)
October 19
Research Vessel Albatross Launched (1882)
October 20
OPEC Oil Embargo (1973)
October 21
“Ding” Darling born (1876)
October 22
Wombat Day
October 23
Cumberland Island National Seashore established (1972)
October 24
Antoni von Leeuwenhoek born (1632)
October 25
Secretary of the Interior Convicted in Teapot Dome Scandal (1929)
October 26
Erie Canal Opens (1825)
October 27
Golden Gate and Gateway National Recreation Areas Created (1972)
October 28
Henry Mosby, Wild Turkey Biologist, Born (1913)
October 28
First Ticker-tape Parade Held (1886)
October 29
Stanley Park, Vancouver, Dedicated (1889)
October 30
UNESCO Designates 9 Natural World Heritage Sites (1981)
October 31
Lincoln Highway Dedicated (1913)
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