Sexual dimorphism in bill morphology and body size may have similar ramifications as these attributes in the Purple-throated Carib (E. jugularis), which is associated with a reversal in oral dimorphism of its Heliconia food plants. Temeles and Kress (2003) and Temeles et al. (2005, 2006) summarize these relationships at length. Briefly, each sex in that species prefers and feeds most efficiently from the Heliconia species that most matches its bill (Temeles and Kress 2003). The energetic rewards of the flower morphs correspond to the body sizes of the male and female hummingbirds. The males are bigger and so H. caribaea offers slightly more nectar and has more bracts than H. bihai (Altshuler and Clark 2003). Birds at both shared and solitary patches preferred multiflowered to single-flowered inflorescences, but the magnitude of this preference depended on food availability and competition. During low flower availability periods females visited multiflowered inflorescences more often than single-flowered inflorescences only when nectar availability was enhanced; similarly, females at shared patches exhibited preferences for multiflowered inflorescences only after experimental increases in nectar availability. Asymmetry in the benefit received between males and females from foraging at three Heliconia morphs may reinforce resource partitioning between them, in addition to differences in size and fighting abilities (Temeles et al. 2005, 2006). Similar patterns may exist in the much less thoroughly studied Green-throated Carib.
Little information is available for this species. Wolf (1975) reports that females at least occasionally hold flower-centered territories in the nonbreeding season. However, the congener has received a fair amount of attention. Temeles et al. (2006) examined the effects of nectar availability and competition on foraging preferences and revisit intervals of traplining female Purple-throated Caribs (E. jugularis) to Heliconia patches shared by two individuals or visited solely by one individual. Birds at both shared and solitary patches preferred multiflowered to single-flowered inflorescences, but the magnitude of this preference depended on food availability and competition. During a year of low flower availability, females visited multiflowered inflorescences more frequently than single-flowered inflorescences only when nectar availability was experimentally enhanced; similarly, females at shared patches exhibited a significant preference for multiflowered inflorescences only after experimental increases in nectar availability.
Not known, but presumably similar to the other Eulampis, presumably breeding from March-July. Breeding may depend on the timing of rain (Raffaele et al. 1998). Males probably occupy feeding territories year-round, whereas females exhibit such behavior only during the non-breeding period. Displays may be similar to Purple-throated Carib (E. jugularis), including "arc-display" with wings stretched from the body and pendulum flights (Schuchmann 1999). Presumably also exhibits ventral mounting for sperm transfer in mating, possibly because of a pronounced reduction of the feet as is the case in the other Eulampis.
Social and interspecific behavior
May occur as pairs, but usually only singles in isolation (Farnsworth personal observations, Raffaele et al. 1998, Schuchmann 1999). Heliconia patches may support several individuals at once, as is the case with Purple-throated Carib (Eulampis jugularis; Temeles and Clark 2003, Temeles et al. 2005, 2006). This species is dominant over the substantially smaller Antillean Crested Hummingbird, which it may aggresively chase from flowers (Lack 1973, Wolf 1975). Apparenly, the two Eulampis are specialized sufficiently to coexist with minimal competition for resources, indlucing flowers and arthopods (Askins et al. 1987). Green-throated Carib feeds side-by-side with Bananaquit (Askins et al. 1987) without agreesive interaction.