The type of region to search for. Must be one of 'country',
'subnational1' or 'subnational2'.
parentRegionCode
The region to search within. Must be a valid
country or subnational1 code. If `regionType` is 'country' then this
parameter is ignored (since the search will automatically be world-wide).
key
eBird API key. You can obtain one from https://ebird.org/api/keygen.
We strongly recommend storing it in your .Renviron file as an
environment variable called EBIRD_KEY.