Guano

The word "guano" means "the droppings of sea birds", in the language of the Inca, who collected guano from the seabird colonies off the coast of Peru for use as a soil enricher. Guano was so valuable to the Incas that they restricted access to it and anyone disturbing the birds was punished with death!

Guano consists of nitrates, ammonia, along with uric, phosphoric, oxalic, and carbonic acids, and some salts and impurities. This makes it a very effective and sought-after organic fertilizer that increases crop production and improves the quality of food and fodder – it was (and is) so valuable that it has been dubbed “white gold”.

There’s an island (Ichaboe) that lies on West Africa’s shore,

Where penguins have lived since the flood or before,

And raised up a hill there, a mile high or more.

This hill is all guano, and lately ’tis shown,

That finer potatoes and turnips are grown

By means of this compost, than ever were known;

And the peach and the nectarine, the apple, the pear,

Attain such a size, that the gardeners stare,

And cry, “Well, I never saw fruit like that ’ere!”

One cabbage thus reared, as a paper maintains,

Weighed twenty-one stone, thirteen pounds and six grains,

So no wonder Guano celebrity gains.                                 

Ex-member of the Committee (1845)

In his memoirs published in 1832, an American sealing captain, Captain Benjamin Morrel Jr, noted that 6.5ha Ichaboe Island (Namibia) was covered in the manure of birds (guano) to a depth of 25 feet.  The response to this by an astute businessman from Liverpool, Andrew Livingston, resulted in the “guano rush” between 1843 and 1845, when no less than 450 boats lay off this small island and an estimated 6 000 men scraped guano, with over 300 000 tons of this valuable nitrogenous fertilizer shipped to Britain. Other seabird islands off the coasts of Namibia and South Africa were also scraped down to bedrock, with some 1.8 million tons removed between 1841 and 1983. Guano is no longer collected at South African islands but guano harvesting continues in Namibia, where in 2010 it was collected at Ichaboe and Mercury islands.

Injudicious harvesting of guano resulted in severe habitat degradation and disturbance to breeding seabirds; this exacerbates the decline in their populations. African penguins historically nested in burrows excavated from accumulated guano deposits; after the removal of the guano, the birds have been forced to nest on the surface, where they are susceptible to overheating, flooding of nests, disturbance and predation by marauding kelp gulls.