Changes in vegetation structure and species composition affect habitat use and behavior in most bird species by altering the distribution and abundance of their resources. We explore how the mating and foraging behavior of Cassin's Kingbirds (Tyrannus vociferans) varies by habitat type within a 2,450 ha urban park in Mexico City. The study site includes primarily water bodies, riparian vegetation, willow and Montezuma cypress stands, maize fields, and grasslands. We recorded kingbird behavior twice a week along 21 transects throughout 2012 and 2015. Courtship and reproductive behaviors were displayed in autumn (Sep) and early winter (Dec). Intraspecific agonistic behaviors were associated with courtship and mating events, particularly in 2015. Cassin's Kingbird generally favored open vegetation. The main foraging strategy in open habitats was flycatching but foliage gleaning became frequent when mistletoe plants produced fruits in infested willow stands. The use of mistletoe fruits, presumably a secondary diet item, coincided with the breeding season. In addition to these observations, our study is the first report of Cassin's Kingbird winter mating at low latitudes.