Guano

Blue-footed Boobies, Sula nebouxii                                        photo by A. Sternick

 

August must be a slow month for birding since my mind has turned to the fascinating topic of bird excretions.  It may also be because of the daily reminder found on my dock.  Early in the season the dock was guano-free, perhaps due to the policing of the nearby nesting Osprey which mobbed any intruding gull.  But now the Laughing, Ring-billed, and Herring Gulls are back big time and the Osprey all seem to have given up the dock patrol, perhaps preoccupied with planning their upcoming long migration to the south.

Royal, Least, and Forster’s Terns, as well as an occasional Double-crested Cormorant are now all contributing to the mess.  The rotating gull sweep and wind socks help some, but I sense the Laughing Gulls are defecating on my poor plastic owl with vocal hilarity.

Laughing Gull, Larus atricilla

Seriously, guano is much more interesting than you’d think.  It represents millions of years of evolutionary success and has even caused wars among us enterprising and competitive humans.

Caspian Tern, Sterna caspia

All animals require dietary protein (composed of nitrogen-containing amino acids) for maintenance of body structure and function.  The metabolic breakdown products of proteins are a toxic nitrogenous waste that must not be allowed to accumulate.

Double-crested Cormorant, Phalacrocorax auritus (the first step in guano creation)

In humans and other mammals these wastes are excreted in the urine as urea, dissolved in large amounts of flushing water.  First dinosaurs, and later birds, have evolved kidneys that have the ability to concentrate these wastes as uric acid, requiring only 1/20th the amount of water needed by us humans.  It’s these uric acid crystals that give guano its distinct white color that daily spots my dock.

Masked Booby, Sula dactylatra                           photo by A. Sternick

When various berries are ripe the spots are a slightly more pleasing pink, red, or blue, reflecting the diets of my avian friends.  If you examine the guano closely you’ll see small piles of tiny bone and shell fragments, the remains of fish and blue crabs finely chopped in the bird’s gizzard.  If so inclined I could monitor the contents of the birds’ excretions and publish a significant research paper.  I’m not so inclined.

Herring gulls, Larus argentatus

The word “guano” is derived from “huanu”, coined by the indigenous Quechuan people of the Andes and South American highlands to describe bird dung.  For at least 1500 years these people recognized the fertilizing power of guano, later shown to be due to its high concentrations of nitrogen, phosphates, and potassium.  Alexander von Humboldt introduced guano to Europeans in 1802, forever changing their desire for this valuable fertilizer.  It allowed much more intensive farming with significantly higher yields per acre.

While some Americans headed west to stake their gold-mining claims in California, others headed south to the guano islands to make their fortune.  The U.S. Guano Island Act of 1856 gave exclusive rights of guano deposits to citizens staking their claims on any unclaimed island.  Some of these small islands in the Caribbean and off the west coast of South America had guano deposits 50 meters deep.  100,000 indentured servants from China came to the New World in the 19th century, specifically to become guano harvesters.  The “guano rush” was on.  Conservation laws were enacted to protect the valuable islands and the guano-producing birds.

Double-crested Cormorants, Phalacrocorax auritus

The “best” guano is found along the dry western coast of South America.  The control of this guano paid a key role in the Chincha Island War of 1864-6, fought by Spain against an alliance of Chile and Peru.  Peru and Chile later fought each other in 1879 for this same guano.  Some people speculate that it may have been guano from Mexico, infested with the Phytophthora infestans mold, that cause the severe potato blight and famine in Ireland in the mid 19th century.

Pelagic Cormorants, Phalacrocorax pelagicus

Things began to quiet down in 1909 when the process of industrial nitrogen fixation became the primary way to produce ammonia-based fertilizers.  To this day, however, guano is still used as an effective natural fertilizer, and is especially cherished by organic farmers and consumers.

Northern gannet, Morus bassanus

Knowledge begets toleration.  Tomorrow as I hose off the dock I’ll not be mumbling about all the b.s., but rather pondering the structures of urea and uric acid and the eons that evolved the differing kidneys that excrete them.  And how enterprising man found a use for the foul of the fowl, and even fought wars over the control of it.  I’ll also consider planning a trip to South America and the islands, and maybe even see a Guanay Cormorant, Peruvian Pelican, or a Peruvian Booby, the most prolific guano producers of all.

9 thoughts on “Guano

  1. Really enjoyable piece!

    I live in the midwest near a small lake. As with you, the gulls – all ring-billed gulls in our case – don’t appear on the fishing pier until mid-July, when they appear to take up residence and leave copious deposits. Same with the great blue heron. I wonder if it is because they are breeding elsewhere and show up only after their chicks have become independent?

    Anyway, love your blog, thanks for taking the time to write it.

    Liked by 1 person

    1. That’s very interesting and you may be right. Each spring and early summer I get a false sense of security that the gulls and terns are finally going to leave me alone–but then August hits and its business as usual. It’s funny that some neighbors less than a mile up the river never have this problem. Someone recently suggested I lay out some fake plastic snakes. I may give it a try. Thanks for commenting.

      Like

      1. Hmm, a dock strewn with fake plastic snakes (in addition to a fake plastic owl) does have a certain appeal. How about a fake plastic skua? Joking aside, I do kind of envy you your terns though. Lovely birds.

        Liked by 1 person

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