Like all Plasmodium species P. polare has both vertebrate and insect hosts.

The vertebrate hosts for this parasite are birds.

[1] It is relatively small and produces on the average nine merozoites per infection.

Hosts of this species include the bald eagle (Haliaeetus leucocephalus),[2] the barn swallow (Hirundo rustica), yellow wagtails (Motacilla flava)[3] and American cliff swallows (Petrochelidon pyrrhonota).

"Observations on the Sporogony of Plasmodium-circumflexum Kikith and Plasmodium-polare Manwell in New-Brunswick".