As useful as iNaturalist can be, we need to be aware of its inherent bias, namely, the data is skewed toward easily accessible places. Today I was curious about Marajó Island – the big island at the mouth of the Amazon. Well, there is no such place in the iNat list of places, but that’s okay – I could use “explore” and zoom in on it on the map. I was disappointed to find that it was just an expanse of green, the only red squares appearing at or near its edges. Its interior is completely unexplored, at least as far as iNat is concerned.
That would explain why I have noticed, as I identify Caribbean observations, that by far the majority are either coastal (i.e. beaches) or weedy (i.e. characteristic of highly disturbed habitats). It does not necessarily mean that these islands are all dominated by degraded lands; it may just mean that the majority of observers are keeping to the accessible, civilized places. The example of Marajó Island shows this: the shores, accessible from the river, are disproportionately observed compared to the difficult-to-reach interior.
If using iNaturalist data in research, we must account for this bias, lest we overestimate the relative prevalence of heavily disturbed habitat.