I'm interested in estimating how much time do birds (independent of their taxonomic group) spend in contact with soil, particularly on heathland ecosystems. I would use this information as a proxy to assess whether birds would be more or less likely to pick up (either accidental or active -phoresy-) non-parasitic soil arthropods in comparison to other groups (e.g. rodents, herpetofauna, etc.). This approach is at an exploratory stage, so depending on how detailed is this information -if available-, I will decide if it makes sense to use it or not.