I created new observation field to further describe the nature of organisms occurring at built environment in particular observation. It currently accepts following values:

• deterioration (when structure has broken to allow eg. animal in or plant growing)
• spontaneous (unintended feature of built structure, eg. cavity in the wall for animal to enter)
• planned (bird nest box, ground left undermanaged on purpose... )
• natural (as close as it gets: organisms at trees planted/grown long ago, organisms at near natural and undermanaged areas?? close to spontaneous or planned)
• failed (trapped or injured because of element of built environment)
• multiple (eg. planned element used by unintended organism, unintended elements left still for organisms to use after renovation...? )
• unknown (eg. intentions for features of old building are unknown vs. spontaneous/planned)

I may still change the classfication and words used - suggestions are welcome.

You can add the field by typing "rewilding" (without quotes) at observation fields section of your observation page. I could consider iNaturalist asking to add it when observation is added to "Built Environment" project, but that may cause further complications and occasionally cause some observation not added to project, and it's possibly not needed for all observations.

Further details of the "Rewilding" field and observation examples: https://www.inaturalist.org/observation_fields/17884

Btw, there's also already existing "Built Environment type" observation field but still unsure how useful it is: https://www.inaturalist.org/observation_fields/15145

Project has recently gathered many new members, adding plenty of observations well representing varied nature enhabiting and interacting human modified environment. Thanks all!