Haiku are a Japanese form of poetry. If you learned about them in school you may have learned that they are 17 syllables long (three lines in a 5-7-5 syllable pattern) and not much else. In fact, there is much more to haiku than that. The syllable count isn't even necessarily a strict feature, given that Japanese syllables are very different than English syllables. Most writers of literary haiku in English these days accept haiku of seventeen or fewer syllables which may be spread over two or three lines (there is even such a thing as a one line haiku).
The relevance of haiku to 30 Days Wild is that this is a poetic form that is meant to be a direct observation of nature, recorded directly as soon as possible after the event. The best haiku is not edited or polished but exists as a record of a moment in time. Haiku writers aim for the 'a-ha!' moment, but it is worth commenting that one person's 'a-ha!' may well be someone else's 'so what!'.
You can read more about haiku by following the links below:
NaHaiWriMo (National Haiku writing month, which is fittingly held every February)
Aha poetry (which includes links to several excellent essays about haiku and related poetic forms)
So, looking out of my window on this rainy day in Edinburgh, here is a haiku, written from the moment:
overcast skies -
in the garden