Feeding Ecology of Hummingbirds in the Highlands of the Chisos Mountains, Texas

Abstract

The feeding habits of three species of hummingbirds were examined during the summer of 1975 in the highlands of the Chisos Mountains, Big Bend National Park, Texas. The Blue-throated Hummingbird (Lampornis clemenciae), the Broad-tailed Hummingbird (Selasphorus platycercus) and the Rufous Hummingbird (S. ~-ufus) were common in the study area, the first occupying the mesic Cypress-Pine-Oak Association and the other two species inhabiting the Pinyon-Juniper-Oak Woodland. Blue-throated Hummingbirds were almost exclusively insectivorous prior to the flowering of mountain sage (Sulvia regla), after which their diet began to include its nectar. Males fed outside their territories in the morning at nectar sources in the juniper woodland. Selasphorus hummingbirds overlapped extensively in diet. S. plutycercus was common prior to the full flowering of sage, and migrating S. ru&s entered the area later, when the sage was in bloom. Males of both species typically established territories around large patches of the sage and open areas while females were relegated to smaller Sulvia stands in the woodlands. Such a pattern is appare:tly maintained by males. the aggressiveness of the dominant Recent examinations of tropical nectarivorous guilds (Feinsinger 1976, Feinsinger and Colwell 1978) have shown that such communities are organized about the distribution of nectar resources. Niche differences among tropical hummingbirds may result from aggression (Wolf 1970, Lyon 1976, Wolf et al. 1976), different foraging patterns (Linhart 1973, Feinsinger 1976), microhabitat selection (Stiles and Wolf 1970), or the exploitation of specific resources by highly specialized species (Snow and Snow 1972). Far fewer hummingbird species inhabit temperate areas than the tropics, and most species are migratory. North American hummingbirds differ from one another ecologically in the same ways as their tropical counterparts. These differences include habitat selection (Pitelka 1951, Lyon 1973, Yeaton and Laughrin 1976), spatial distribution of individuals through territoriality (Pitelka 1942, Cody 1968), and variations in foraging patterns (Feinsinger and Chaplin 1975, Yeaton and Laughrin 1976). We examined the feeding ecology of three interacting hummingbird species with emphasis on their habitat partitioning and timing. We hypothesized that these characteristics would be important to the organization of a nectarivore guild where nectar sources are uncommon. Such conditions appear to occur in the highlands of the Chisos Mountains during the summer. STUDY AREA AND METHODS Data were obtained in the Chisos Mountains (29"15' , 103018') of Big Bend National Park, Brewster Co., Texas during the summer of 1975. The study area was located in Boot Canyon (2,072 m) and centered in two highland plant associations: the Cypress-Pine-Oak Association and the Pinyon-Juniper-Oak Woodland (Wauer 1973). We also examined open areas located within Boot Canyon because they contained patches of nectar-producing flowers and were often visited by the hummingbirds. The Cypre...

Of Hummingbirds and Helicopters: Hovering Costs, Competitive Ability, and Foraging Strategies

“…By observing these and other behaviors, dominant and subordinate individuals can be identified as the chaser and the chased, respectively. Such observations have been used to study interspecific competition and community structure in many hummingbird communities (Feinsinger 1976;DesGranges 1978;Kodric-Brown and Brown 1978;Kuban and Neill 1980;Feinsinger et al 1985).…”

Flight Performance and Competitive Displacement of Hummingbirds across Elevational Gradients

“…Dominance among hummingbirds is most frequently determined from observations of chases (Feinsinger 1976;DesGranges 1978;Kodric-Brown and Brown 1978;Kuban and Neill 1980;Feinsinger et al 1985;Altshuler et al 2004b), but a potential problem with this classification technique is that success in an aerial chase does not necessarily correlate with success in competition for food or mates. Pimm et al (1985) introduced an alternative strategy for studying hummingbird competition that directly measures success at feeding territories.…”

“…Competitive interactions between these closely related species have been studied through observations of chases at the lower to midelevational ranges (2,072-2,650 m) where they co-occur, and S. rufus is most often the dominant competitor (Feinsinger and Chaplin 1975;Kodric-Brown and Brown 1978). However, even at the lower end of this elevation range (∼2,100 m), S. platycercus can be dominant or only marginally less successful than S. rufus (Dunford and Dunford 1972;Kuban and Neill 1980). The competitive interactions between the two species have not been studied at the higher elevations where they co-occur.…”

Assessment of native species and ungulate grazing in the Southwest: Terrestrial wildlife

“…Other riparian species may be characterized more by other dietary needs but have some dependence on aquatic prey during part of their life cycle. For example, the blue-throated hummingbird is better known as a flower-feeding nectivore, but during some parts of the breeding season it feeds exclusively on small insects that swarm in high abundance over creeks and streams (Kuban and Neill 1980;Wagner 1946); this may explain the importance of water sources in association with its territories. For all these species, dependence on aquatic organisms for prey will require clear, fast-flowing, and unpolluted water sources in order to maintain suitable habitat.…”