The spatuletail hummingbird, also known as the marvelous spatuletail, is a species of hummingbird found in Peru. The male and female spatuletail hummingbirds display striking physical differences. The most noticeable difference is in the tail feathers. Male spatuletail hummingbirds have extraordinarily long, forked tail feathers that can measure up to 30 centimeters, while the female’s tail is much shorter and more fan-shaped.
In addition to the tail feathers, male and female spatuletail hummingbirds differ in size, coloration, courtship displays, and behavior. Understanding the differences between the sexes provides insight into the unique adaptations and breeding strategies of this endangered hummingbird species.
Physical Differences
The most obvious physical difference between male and female spatuletail hummingbirds is in the tail feathers. The male has just two tail feathers that can grow up to 30 cm long and end in violet-blue spatule-shaped discs (Alvira and Lebbin 2020). This is the longest tail feather relative to body size of any bird species. The female’s tail feathers are much shorter, measuring only around 5 cm long, and fan out in a rounded shape rather than long spats (Schulenberg et al. 2010).
In addition to the specialized tail feathers, male and female spatuletails differ significantly in overall size and mass. Male spatuletails have an average body length of 10-12 cm and mass of 4-5 grams. Females are smaller, with an average body length of 9-10 cm and mass of 3-4 grams (Alvira and Lebbin 2020). The difference in size likely allows the smaller female greater maneuverability and energy efficiency while foraging, while the larger male is able to display greater fat reserves for energy-intensive courtship displays.
Coloration is another distinguishing feature between the sexes. The male has an iridescent emerald green forehead, violet-blue cheeks, and a brilliant velvety black body. The female has gray-green upperparts, a buffy underside with green streaks along the throat, and white tips on the tail feathers (Schulenberg et al. 2010). The more colorful and eye-catching plumage of the male plays an important role in courtship displays to attract potential mates.
Tail Feathers
– Males have two extremely long, spatula-shaped tail feathers up to 30 cm long
– Females have short, fan-shaped tail feathers around 5 cm long
Size and Mass
– Males average 10-12 cm in body length and 4-5 grams in mass
– Females average 9-10 cm in body length and 3-4 grams in mass
Coloration
– Males have iridescent green forehead, violet-blue cheeks, and velvety black body
– Females have gray-green upperparts, buffy underside with green streaks, white-tipped tail
Behavioral Differences
In addition to physical differences, male and female spatuletail hummingbirds exhibit distinct behaviors, especially relating to courtship. The elaborate courtship ritual of the male plays a critical role in mating.
Males are highly territorial and perform dramatic aerial displays to attract females and ward off rival males from their lekking grounds. These displays involve flying in loops and wide circles up to 100 meters in the air while making a loud buzzing noise with their tail feathers (Schuchmann 1999). The displays showcase the male’s iridescent plumage and advertise his energetic health to potential mates.
Females assess potential mates based on the quality of these energetic courtship flights. They do not participate directly in the competitive displays. Once a female chooses a male, she will signal receptivity by hovering in front of the displaying male. This initiates mating which takes place on a perch in the lekking territory (Schulenberg et al. 2010).
While males focus on courtship displays, females take sole responsibility for building the nest, incubating eggs, and raising young. The nest is a small cup made of plant fibers and spider webs attached to a vertical stalk or cliff face. The female lays just two tiny white eggs and will incubate them for about 15-19 days. After hatching, the chicks remain in the nest where the female provides all parental care for another 20-28 days until fledging (Alvira and Lebbin 2020).
Male Courtship Displays
– Performed to attract mates and defend lekking territory
– Involves flying in loops and circles up to 100 m high while buzzing tail feathers
– Showcases coloration and advertises health to potential mates
Female Nesting Behavior
– Females build nest, incubate eggs, and raise young alone
– Nest is small cup of fibers and webs attached to stalk or cliff
– Female incubates 2 eggs for 15-19 days, cares for chicks another 20-28 days
Causes of Differences
The pronounced physical and behavioral differences between male and female spatuletail hummingbirds can be attributed primarily to the forces of sexual selection.
The elaborate courtship displays and bright coloration of males evolve through mate choice. Females preferentially select males with the longest, most symmetric tail feathers and most vigorous flight displays, leading to strong sexual selection on these traits (Schuchmann 1999). The short female tail is likely an adaptation to improve agility and efficiency during foraging.
The differences in size and mass between the sexes reflect the different reproductive pressures faced. Males have higher energy and nutritional needs to support energetically expensive courtship and competition. Smaller female size improves foraging efficiency to meet the demands of nesting and raising young (Temeles et al. 2009).
Division of parental duties also shapes behavior. Female-only care likely allows males to devote more time and energy solely to courtship activities rather than offspring provisioning. This separation of reproductive roles is common in species where males face intense competition for mates (Kodric-Brown and Brown 1978).
Sexual Selection
– Male traits evolve through female mate choice for long, symmetric tail and vigorous displays
– Short female tail improves agility and foraging efficiency
Differing Reproductive Pressures
– Larger male size supports energy needs of courtship
– Smaller female size enhances foraging for nesting/raising young
Division of Parental Duties
– Allows males to focus on courtship while females provide sole parental care
Survival Impact
The differences between male and female spatuletail hummingbirds have important impacts on survival that relate to their contrasting reproductive strategies.
Male survival is intricately tied to success in courtship. Males with the longest, most symmetrical tail feathers have higher mating success (Schuchmann 1999). Long tails likely also support more vigorous flying displays advertising the male’s fitness. However, the lengthy tail feathers come at a cost of reduced agility that likely makes males more vulnerable to predators (Clark 2009).
In contrast, female survival revolves around nesting success and raising offspring. The short female tail provides greater agility and efficiency during foraging to provision young (Temeles et al. 2009). Duller female plumage provides camouflage that aids in nest concealment and protection. However, the high energy demands of sole parental care take a toll that leads to high female mortality after the nesting period (Robinson et al. 1996).
Overall, the flashy traits and displays that give males a mating edge come with survival costs, while female adaptations aid parental duties despite mortality risks. This reflects the different selection pressures driving male and female traits.
Male Survival
– Long tails aid courtship success but reduce agility and increase predation risk
Female Survival
– Short tails and camouflage aid provisioning young but high maternal care increases mortality
Conservation Concerns
Due to threats from habitat loss and collection for the illegal pet trade, the spatuletail hummingbird is listed as endangered by the IUCN Red List. Ongoing conservation efforts will need to take into account the males’ specific needs for suitable lekking grounds and the females’ requirements for nesting sites and foraging areas.
One conservation priority is preserving intact forest areas that males use as lekking arenas for their courtship displays (Schulenberg et al. 2010). These open areas with scattered shrubs and perches are critical courtship habitat.
Another priority is conserving patches of forest with suitable nesting sites along cliff faces and riverbanks for females. Providing connectivity between nesting areas and flower-rich feeding grounds will support females in brooding and provisioning young (BirdLife International 2016).
By protecting critical breeding habitats for both males and females, conservationists can help safeguard courtship, mating, and successful reproduction in this unique hummingbird species. Ongoing monitoring of population trends will be needed to evaluate conservation efficacy. Preserving the marvellous spatuletail’s specialized adaptations and breeding behaviors is crucial for its long-term survival.
Priorities for Males
– Protect intact forests used as lekking arenas for courtship
Priorities for Females
– Conserve nesting sites along cliffs and riverbanks
– Provide connectivity to feeding grounds for provisioning young
Conclusion
Male and female spatuletail hummingbirds exhibit striking differences in tail structure, size, coloration, courtship behavior, parental duties, and survival pressures. While males have flashy, elongated tails and vibrant coloration for attracting mates, females have shorter tails and camouflaged plumage that aid in nesting and provisioning young. Ongoing conservation efforts for this endangered species must protect key habitats needed for successful courtship and breeding. Understanding the evolutionary forces that drive differences between the sexes provides critical insights into the biology and conservation needs of these intriguing hummingbirds. Their unique adaptations showcase the power of sexual selection and highlight the importance of habitat protection for vulnerable species.
