[pbaumel]

Hi HN,

Liberty caps - or Psilocybe semilanceata - are a psilocybin-containing mushroom that grow naturally in many parts of the world. There is a lot of information online about where and when to look for liberty caps, but I wanted to see if data could help answer this question and boost people's chances of being in the right place at the right time.

To summarise how the map works: first, I matched the dates and coordinates of historical liberty cap growth records with data on habitat (e.g. land cover, elevation, soil acidity) and weather (e.g. temperature, rainfall). Second, I used this dataset to train a model describing the conditions in which liberty caps are more or less likely to thrive (for the statistically-inclined: kernel density estimation with model selection by maximum likelihood cross-validation). Finally, this model is used to make live predictions of the likelihood of liberty cap growth across the world on any given day.

For now, the map is limited to parts of Europe and North America (PNW + east coast of Canada) where liberty caps are known to grow.

I used the following data:

- Weather: ERA5 by ECMWF (historical) [1], GFS by NCEP (forecast) [2]

- Land cover: Corine Land Cover by Copernicus (Europe) [3], Land Cover by NALCMS (North America) [4]

- Soil acidity: SoilGrids by ISRIC [5]

- Elevation: SRTM by CGIAR [6]

- Growth records: Psilocybe Semilanceata by NBNAtlas [7]

[1] https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datas...

[2] https://www.ncdc.noaa.gov/data-access/model-data/model-datas...

[3] https://land.copernicus.eu/pan-european/corine-land-cover

[4] http://www.cec.org/north-american-environmental-atlas/land-c...

[5] https://www.isric.org/explore/soilgrids

[6] https://bigdata.cgiar.org/srtm-90m-digital-elevation-databas...

[7] https://species.nbnatlas.org/species/NBNSYS0000021551

[db39]

I found this map + twitter towards the end of last year (after the season had ended), so I'm looking forward to exploring in a few months to see how accurate it is.

I don't have much more to say - I just like niche mapping projects like this.

Congrats on launching the new features + new areas!

[pbaumel]

Thank you, and good luck out there!

[hutzlibu]

I was wondering, if there is a reason, that britain has lots of areas with high propability and the mainland has not, but then I saw that the growth records [7] indeed only cover the british islands. So I suppose the data on the map is not really accurate as of now?

Otherwise what I would have expect from such a site, would be of course also detailed informations on how the mushrooms look exactly and where to look for them specifically. (And also a warning, that if you pick the wrong ones, you die a horrible death and even if you pick the right one, but are in the wrong mentally conditions, your are into horror either)

Anyway, your project is nice and your map inspired me to have a look in my area and see, if it matches your data.

[pbaumel]

The differences in the amount of areas across countries is mainly to do with differences in the amount of suitable grassland. For instance, in countries where lots of grassland has been turned into cropland there are fewer areas. In countries where grassland is dominated by, for instance, pastures there will be more areas.

Thanks for your feedback; i've been thinking of adding a field guide on identification. Also good luck hunting!

[jamal-kumar]

I think what you're doing is cool but maybe it would be a pretty essential feature to add an overlay map of distribution of lookalike species to preserve the health, safety and wellness of the users of your website.

Pholiotina rugosa has been spotted growing amoungst liberty caps, which contains some of the same deadly toxins in amanita species, as well as maybe others out there I'm not remembering offhand which could be mistaken (It's quite cosmopolitan in distribution in the northern hemisphere).

[MattBlissett]

> [7] https://species.nbnatlas.org/species/NBNSYS0000021551

With data from GBIF you would have almost all of the British records published on the NBN Atlas (about 100 are not shared), plus 2,300 more from other sources.

→ https://www.gbif.org/species/5242507

[pbaumel]

Thank you for sharing! I'll look into this source in more detail.

[voisin]

Very cool! Is it true that they are this rare in North America? Only a small part of the Pacific Northwest and the east coast of Canada?

[pbaumel]

For liberty caps, yeah. There are some rare reports from other states in the US (mostly east coast) but I don't want to give people false hope by including those states in the map.

However, there are many other species of psilocybin-containing mushrooms in North America. You can check out the Shroomery for more info on species in your area [1]

[1] https://shroomery.org/12257/Mushroom-Locations

[Uberphallus]

Wow, it's been ages since I've seen the shroomery.org domain. What a throwback.