The buff-bellied hummingbird (Amazilia yucatanensis) is a small hummingbird native to the Yucatán Peninsula and adjacent regions of Mexico, Belize, Guatemala, and Honduras. Like other hummingbirds, the buff-bellied hummingbird has unique behavioral adaptations related to feeding, flight, territoriality, courtship, and nesting. Understanding the behavior of this species provides insight into its ecology and evolution. The buff-bellied hummingbird exhibits behaviors typical of hummingbirds but also has some interesting specializations related to its tropical habitat.
Feeding Behavior
The buff-bellied hummingbird feeds on nectar from flowers using its long, specialized beak and tongue. Its diet consists mainly of nectar but also includes small insects and spiders. Some key aspects of its feeding behavior include:
Nectar Feeding
– Feeds on nectar from a variety of brightly colored, mostly tubular blossoms including Heliconia, bananas, and many flowering trees and herbs.
– Favors flowers with higher sugar concentrations.
– Licks nectar with its forked tongue up to 13 times per second.
– Able to hover in place while feeding using rapid wing beats.
– Has high metabolic requirements and must feed frequently, visiting hundreds of flowers daily.
Insect Feeding
– Also feeds on small invertebrates such as insects and spiders to obtain protein.
– Uses its bill to snatch small insects out of the air or off foliage.
– More likely to eat insects during periods of nectar shortage.
– Increased insect feeding has been linked to higher reproductive success.
Energy Efficiency Adaptations
– Highly efficient at feeding with a rapid, in-and-out style that minimizes energy expenditure.
– Enter a flower, lick nectar quickly 2-5 times, then move to next flower.
– Able to stock extra nectar in its crop for energy reserves.
– Feeding efficiently allows it to survive on small amounts of nectar.
Flight Behavior
The buff-bellied hummingbird is a swift, agile flier adapted for sustained hovering and sudden movements. Key features of its flight include:
Hovering
– Can precisely hover in place by rapidly beating its wings back and forth up to 70 times per second.
– Hovering allows it to efficiently feed on nectar while remaining stationary.
– Uses unique figure-eight wing motion that generates lift on both upstroke and downstroke.
Agility
– Highly maneuverable and able to fly in all directions, even backwards.
– Makes rapid zig-zagging motions and abrupt stops while feeding.
– Able to engage in intricate courtship flights.
Speed
– Can reach top flight speeds around 30 mph.
– Typical feeding flights are slower, averaging 5-15 mph while moving between flowers.
– Fast, direct flight when travelling between foraging areas.
Other Adaptations
– Lightweight, compact body minimizes air resistance.
– Rotating shoulders allow wings to beat independently of body.
– Long wingtips provide lift needed to hover.
Territoriality
Like other hummingbird species, buff-bellied hummingbirds exhibit territorial behavior, aggressively defending feeding territories. Key aspects of their territoriality include:
Defended Feeding Sites
– Males defend individual flowering plants or clusters of flowers as feeding territories.
– Territories typically 0.5-1 acre in size with abundant nectar sources.
– Territories may be defended for hours, days, or weeks depending on quality.
Aggressive Defense
– Males defend territories through vocalizations, chasing, and physical combat.
– Dive-bombing intruders and rapid chases are common territorial displays.
– Actual physical contact is rare as most birds retreat before contact occurs.
Lek Formation
– In some habitats, males congregate into \”leks\” where they cluster their territories together.
– Leks form around prime feeding areas with abundant flowers.
– Dominant, older males occupy territories in the center. Younger males take peripheral territories.
Resource Protection
– Territoriality provides feeding rights to energy-rich nectar sources needed for survival and reproduction.
– Limits competition from other males for food sources and mates.
– Females may benefit by mating with dominant territory holders.
Courtship and Mating
The buff-bellied hummingbird has an elaborate courtship ritual used by males to attract females for mating. Their courtship behavior includes:
Aerial Displays
– Males perform aerial displays, flying in loops and dives to impress watching females.
– Complex dives consist of ascending high then diving straight down or in pendulum arcs.
– Displays highlight the male’s flight skills and aerobatic maneuverability.
Vocalizations
– Males produce buzzing and twittering sounds with their wings and tail feathers.
– These chittering vocalizations communicate aggressiveness and interest in mating.
– Females may produce soft counter-calls in response.
Ornamentation
– Males have bright, iridescent throat feathers used as visual displays.
– The feathers are erected and shimmer in light during courtship flights.
– Females lack ornamental feathers and are a duller green color.
Mating
– If displays are successful, the female allows the male to mate with her.
– Mating is very brief, lasting only a few seconds.
– Females then build a nest and raise young alone without male assistance.
Nesting and Parenting
Female buff-bellied hummingbirds undertake all nest construction and parenting duties. Their nesting behavior consists of:
Nest Construction
– Females build a small cup-shaped nest out of plant down, spider webs, and lichens.
– Nests are typically placed on low, horizontal branches 5-20 feet above ground.
– Nest building takes 6-12 days and nests are about 2 inches wide.
Egg Laying and Incubation
– The female lays 2 tiny white eggs over 2 days.
– She incubates the eggs for 15-19 days until they hatch.
– Incubation is nearly continuous with short breaks for feeding.
Nestling Care
– Nestlings are altricial, blind, and mostly featherless at hatching.
– The female feeds the chicks regurgitated nectar and insects.
– Nestlings fledge about 20-26 days after hatching.
Brood Rearing and Defense
– Females may raise up to 3-4 broods per year, especially in seasonal tropical habitats.
– Aggressively defends the nest from predators and other hummingbirds.
– Nest failure is common from predation, weather, and infection.
Migration
The buff-bellied hummingbird exhibits some seasonal movements in response to food availability but overall is considered a resident species:
Seasonal Migrant
– Makes seasonal migrations within its breeding range to track flower/nectar abundance.
– More common in coastal regions in winter; moves inland to breed in spring/summer.
– Short-distance elevational migrations up and down mountains.
Year-Round Resident
– Most individuals remain within their home range year-round.
– Does not make long-distance migrations between distinct wintering and breeding grounds.
– Some individuals may wander outside normal range in winter.
Irruptions
– Rarely exhibits sporadic irruptions outside core range, especially in Texas.
– These temporary movements are likely tied to variable food supplies.
– Does not persist long-term outside normal resident range.
Interactions with Other Species
The buff-bellied hummingbird interacts in various ways with other organisms within its tropical ecosystem, including:
Plants
– Important pollinator for many tropical flowering plants, including ornamental and wild species.
– Dependent on nectar plants for food, with preferences for red tubular flowers.
– Also disperses seeds through regurgitation while feeding and elimination of waste.
Insects
– Preys on small insects like gnats, aphids, and spiders to obtain protein.
– Traplining behavior allows specialization on certain productive trees or shrubs.
Other Birds
– Competes with other hummingbird species for food within its range, leading to exclusion and niche differences.
– Chases away other hummingbirds from its territory and nectar sources.
Predators
– Predators include birds of prey like falcons, hawks, roadrunners, and orioles. Snakes, lizards, and cats also sometimes prey on hummingbirds.
– Vigilant behavior and swift evasive flight help avoid predation. Camouflaged female plumage provides additional protection while nesting.
Behavioral Adaptations
Key behavioral adaptations of the buff-bellied hummingbird include:
Hovering Flight and Nectar Feeding
– Allows specialization on dispersed, ephemeral nectar sources from a variety of flowers.
Energy Efficiency
– Rapid feeding strategy and ability to store extra energy as fat help meet high metabolic requirements.
Agility and Maneuverability
– Enhances feeding, territorial defense, predator evasion, and courtship abilities.
Colorful Ornaments
– Male’s colorful gorget and courtship displays attract mates and intimidate rivals.
Female Parental Care
– Nest building and brood rearing by female allows males to devote energy to defending territories and attracting additional mates.
Conclusion
In summary, the buff-bellied hummingbird exhibits a suite of behavioral specializations related to its nectarivorous diet and tropical ecosystem. Key behaviors include energetic feeding and foraging strategies, aerial agility and speed, elaborate courtship displays by males, year-round territoriality, and sole parental care by females. These behaviors allow buff-bellied hummingbirds to thrive across a range of tropical habitats and ecological conditions throughout Mexico, Central America, and the Caribbean. Understanding the behavioral ecology of hummingbirds like the buff-bellied provides insight into their evolution as specialized nectar feeders and how they coexist with other tropical species. Additional study of buff-bellied hummingbirds and comparisons with related species will continue to reveal new complexities of their behavior and adaptations over time.
