Naturespeak A naturalist's view of the world

April 17, 2008

Oological Manners

Filed under: Uncategorized — wykes @ 3:58 pm


I left off my discussion of the Great Blue Heron Rookery a few days ago with a promise to show you a few of their eggs.  Fortunately, or unfortunately as I will explain, I didn’t have to make the hazardous climb to obtain them. Take a glance at the above photo and you’ll see that I am holding a typical Great Blue Heron clutch. I think you’ll agree they are, just like their producers, both great and blue. 

  The birds lay up to five of these precious packages and start to incubate them sometime before the last one is laid. Both parents trade off egg sitting duty in anticipation that they’ll hatch in 25-29 days.  Incubating the clutch before it is complete results in a staggered emergence where the first chick may be several days older than the last one out. The older birdlets, because they have the biggest mouths, sometimes gain an advantage over their Johnny-come-lately siblings. As long as ample food is available, the lessers will catch up to the greaters and the whole clutch will survive – if not, the weaker ones will perish.

 You’ve probably figured out that the eggs I am holding in my hand will never hatch.  They were denied that chance over 85 years ago when they were collected, “blown,” and turned into cabinet specimens. Those perfect little holes along with the penciled numbers should have clued you in. It used to be all the rage throughout the 19th and early 20th century for folks to amass massive egg collections.  Collectors would buy or trade treasured specimens like so many rare butterflies or minerals and proudly display them in golden oak display cabinets.  These heron eggs were gathered at the tail end of the bad old days of egg collecting and are part of the trove assembled by a regional collector by the name of W.B. Purdy of Milford, Michigan.

  Mr. Purdy was a fairly small time collector but his specimens number into the thousands. You can imagine the damage done to bird populations by the activities of these amateur Oologists (the term for the study of eggs in which both o’s are pronounced). Fortunately their activity quickly went out of favor when it was outlawed. For some birds, such as the Great Auk, this moratorium came about way too late and the collectors pretty much picked them into extinction by the early 19th century. 

  Mr. P. apparently took a liking for Great Blue Heron eggs and gathered hundreds of them. Getting access to these loftily placed eggs was not an easy affair, but obviously not one that stopped climbers using rope and tackle to get access.  One colony could yield dozens of eggs in an afternoon.  If the nest was too high to reach, the collectors would resort to other tactics.  For instance there is an early 20th century record of an egg-hog chopping down a tree that held an inaccessible bald eagle nest so that the pair would re-build in a lower tree!

  The oologist methods were frighteningly efficient. Each egg was carefully prepared, recorded and labeled. A small hole saw was used to cut into the shell and a pipette was employed to draw out the yolk (they avoided “full term” eggs but would resort to mincing up the contents if it was an especially valuable species). A specific numbering system kept things, well, systematic.  Note that two of the eggs in the picture have a fraction written on them – ¼ on one and 1/5 on the other. This means that the egg is one out of four or five in the clutch.  The second number is the official A.O.U. (American Ornithological Union) number for that species. In this case 194 is the designation for Great Blue Heron.  Finally, each labeled egg has a procurement date. One was harvested on April 24, 1922 and the other on what looks like March 6, 1923.

  Based on the extremely early date, the March egg was probably gathered somewhere well south of here.  Unfortunately, most of Purdy’s records have been lost, which means much of the scientific value of his material has vanished as well.  We don’t know where these heron eggs were gathered. There are a few exceptions, such as this set of Black Tern eggs taken from the St. Clair Flats in 1926 with their label (see here).  For the most part, we are left with a mute gallery of egg art that needs to be preserved if for no other reason than they eliminate the need to collect any more of them.  Take a few minutes and take a look at a few of the specimens: Common Loon, Red-shouldered Hawk, Common Crow, Razor-billed Auk, and an unknown species dated 1874 (apparently one of the traded eggs).

  Now these specimens have no real value other than their natural history and design merits, but at one time they each had a book value. I have a 3 inch by 6 inch “Standard Catalogue of North American Birds’ Eggs” published in 1909 which contained the going price for every available bird species.  Great Blue Heron eggs were going for 40 cents a piece, Black Terns for 15 cents, and Loons were fetching $2.00 – a nice oval figure for that day.

   The most expensive egg was that of the Great Auk.  An egg from this long extinct sea bird was listed as $1.00 with an asterisk, but the accessory mark indicated that this paltry amount was for a cast only. The real ones were commanding $1,000-$1600.   Remember this is in 1909! (In case you are wondering, the 1884 Razor-billed Auk eggs that are pictured were only valued at 35 cents back then).

  Today one thing is sure; all eggs are priceless.  A Great Blue package in the nest is worth more than ten-thousand in a drawer.


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