The species has often been considered a subspecies of black-necked grebe (P. nigricollis),[2] and is genetically nested within it;[3] it differed from black-necked grebe most notably in having a reddish-brown (not black) foreneck, and more orangey-toned (rather than yellow) ear tufts.

[4] The decline of the Colombian grebe is attributed to wetland drainage, siltation, pesticide pollution, disruption by reed harvesting, hunting, competition, and predation of chicks by invasive introduced rainbow trout (Oncorhynchus mykiss).

[2] The primary reason was loss of habitat: drainage of wetlands and siltation resulted in higher concentrations of pollutants, causing eutrophication across Lake Tota.

This destroyed the open, submergent pondweed (Potamogeton) vegetation and resulted in the formation of a dense monoculture of water weed (Elodea).

Intensive studies in 1981 and 1982 failed to find the species and it is now considered extinct.