Understanding interspecific and intraspecific aggression is important for wildlife management and sustainability of populations. The objective of this study was to evaluate whether there is a difference in number of occurrences of interspecific aggression between American coots (Fulica americana) and mallard ducks (Anas platyrhynchos) and intraspecific aggression among American coots in the Ballona wetland habitat of Southern California. Trends in literature describe coots as highly aggressive toward other coots year-round and toward other bird species during the breeding season. Because we conducted observations outside the breeding season, we hypothesized that more instances of intraspecific aggression would be observed. We found a significant difference between the number of occurrences of interspecific and intraspecific aggression based on four behaviors specific for American coots: charging, paired display, splattering, and churning. There were more instances of intraspecific aggressive encounters than interspecific aggressive encounters, which indicate the interacting species at Ballona are not competing for resources and their respective niches may not overlap.