[turnipsock (OP)]

When birds poo on my head, it is often white, why is that?

The food they eat is rarely white.




Nice eh? Being delivered next Tuesday.

[RD]

Guano consists of ammonia, along with uric, phosphoric, oxalic, and carbonic acids, as well as some earth salts and impurities.
Guano also has a high concentration of nitrates.

http://en.wikipedia.org/wiki/Guano


The scatalogical photographer who recorded this image must have lightning-fast reflexes...  []

 [ Invalid Attachment ]

http://en.wikipedia.org/wiki/Image:DefecatingSeagull.jpg

[JnA]

the white part is the urine, if you look closely (and who doesn't?) you'll see some darker bits of faeces.
Birds use a cloaca for all evacuations .. which adds nothing to the thread .. I just like the word cloaca.

[blakestyger]

Yes, these words are fascinating. Cloaca comes from the latin cluere, to cleanse.

[RD]

I thought cloaca was latin for sewer...

[Latin cloaca, sewer, canal.]

http://www.thefreedictionary.com/cloaca

[blakestyger]

You are right, but there are two meanings. There's the late C16 usage which is a sewer or conduit for drainage and the C19 zoological term for 'common cavity for release of digestive and urogenital products in birds, reptiles, amphibinas etc.'

The root, cluere, is the same for both.
Source: New Shorter Oxford English Dictionary, 2vols.1993