A characteristic of the Pomarine is white shafts in at least four primaries while Long-tailed Jaegers show only two. Parasitics, however can show three or more. The NatGeo book also says that the tips of the Pomarine's primaries are dark while the Parasitic's tips are "fringed with pale"; these are definitely dark and not fringed. Note that the rump is still partially barred