Manual and semi-automatic counting
This involves printing an image of the colony, flock, or its part and
then marking off the counted birds or nests. The marked birds / nests
are grouped into tens; with larger colonies, supergroups multiplied by
10 are formed into sets of 100 nests / individuals.
Another approach is to use the object counting tool in Adobe Photoshop
(Adobe Photoshop PS 2020: Image > Analysis >
Count Tool). With this software, the clicks are counted automatically,
with the consecutive number being displayed next to the clicked object.
A third method, also using Photoshop software, is to apply a layer to
the counted object. This can be an ellipse or a rectangle with no
filling. The layer is then duplicated and moved to the next object. When
a layer is duplicated, a sequential copy number is assigned to it, so
the last layer number plus one (first layer) gives the number of
individuals in the count.