Unlike the Red-faced Cormorant, the present species usually calls out before taking off, particularly during the breeding season.

Semisopochnoi Island also supports a significant population of Red-faced Cormorants.

The widely sympatric Red-faced Cormorant (P. urile) looks very similar.

Analysis of stomach contents suggests that the Red-faced Cormorant is mainly a bottom feeder, taking cottids especially.

Among the Compsohalieus group, the Red-faced Cormorant is the sister species of P. pelagicus.

About 1% of the global population of Red-faced Cormorants and Tufted Puffins nest on the island.

Where it nests alongside the Pelagic Cormorant, the Red-faced Cormorant generally breeds the more successfully of the two species, and it is currently increasing in numbers, at least in the easterly parts of its range.

Scientists say rats have whittled away entire bird colonies on some islands, where rats do not belong in the food chain and the birds - auklets, murres, tufted puffins, red-legged kittiwakes and red-faced cormorants - are defenseless.

The Red-faced Cormorant is closely related to the Pelagic Cormorant P. pelagicus, which has a similar range, and like the Pelagic Cormorant is placed by some authors (e.g. Johnsgaard) in a genus Leucocarbo.

In the former case, the large naked face "mask" and light bill of P. urile can be easily recognized, in the latter case its larger size (though male Pelagic Cormorants can be as large as female Red-faced Cormorants).

This is a North Pacific clade, which apart from Brandt's and the Pelagic Cormorant also includes the Red-faced Cormorant (P. urile) and probably also the extinct Spectacled Cormorant (P. perspicillatus).

Cladistic analysis suggests that it is related to other cliff-nesting species such as the Red-footed Shag, Pelagic cormorant and Red-faced Shag.