An internal function to include spillover observations to the gridcells. This function moves spillover observations to the gridcells were the focal visit has the most observations (or at random if ties)
includeUniqueSpillover(birdData, grid, visitCol)
An OrganizedBirds object, which is the input to the overlayBirds
-function.
A sf or SpatialPolygonsDataFrame object of the grid over the study area
A character string for specifying the columns that identify a visit.
A ObservationsInGrid list