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

June 1
US Announced Withdrawal from Paris Climate Agreement (2017)
June 2
Edwin Way Teale, Nature Writer, Born (1899)
June 2
Rodne Galicha, Philippine Environmentalist, Born (1979)
June 3
The World’s First Wilderness Area Established (1924)
June 4
Gaylord Nelson, Politician and Conservationist, Born (1916)
June 5
World Environment Day
June 6
Novarupta Volcano Erupted in Alaska (1912)
June 7
Thomas Malthus Published His Famous Essay (1798)
June 8
Bryce Canyon National Park Created (1923)
June 9
Coral Triangle Day
June 10
E. O. Wilson, Father of Biodiversity, Born (1929)
June 11
Jacques Cousteau, Ocean Explorer, Born (1910)
June 12
Frank Chapman, Creator of the Christmas Bird Count, Born (1864)
June 13
Ban Ki-moon, UN Secretary-General, Born (1944)
June 14
Bramble Cay Melomys Went Extinct (2016)
June 15
Global Wind Day
June 16
Gray Whale Delisted (1994)
June 17
World Day to Combat Desertification
June 18
Alexander Wetmore, Ornithologist and Smithsonian Leader, Born (1866)
June 19
Feast of the Forest, Palawan, Philippines
June 20
Great Barrier Reef Protected (1975)
June 21
World Hydrography Day
June 22
Cuyahoga River Burst into Flames (1969)
June 23
Antarctic Treaty Implemented (1961)
June 24
David McTaggart, Greenpeace Leader, Born (1932)
June 25
David Douglas, Pioneering Botanist, Born (1799)
June 26
United Nations Chartered (1945)
June 27
Tajik National Park Added to World Heritage List (2013)
June 28
Mark Shand, Asian Elephant Conservationist, Born (1951)
June 29
Mesa Verde National Park Created (1906)
June 30
U.S. Fish and Wildlife Service Created (1940)
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