Podilymbus podiceps is prey of:
Mustela
Chelydra serpentina
Agkistrodon piscivorus
Haliaeetus leucocephalus
Falco peregrinus
Fulica americana
Larus glaucescens
Bubo virginianus
Rattus norvegicus
Procyon lotor
Alligator mississippiensis

This list may not be complete but is based on published studies.