Hummingbirds

♂ Broad-tailed Hummingbird, Selasphorus platycercus

Hummingbirds are known for their coloration which has earned them the nickname of flying jewels. Birds with colors such as red or yellow are due to pigmentation within the feathers. Those of blue are a result of selective scattering of light due to particles dispersed in the material of the feathers. Green coloration comes from a combination of pigmentation and light scattering, but iridescence, as seen in hummingbirds, comes from interference. As observed by Newton, thin film on the feathers of birds cause an interaction of light waves. This is why some species, such as the Broad-tailed Hummingbird, often look to have a black chin rather than the characteristic red expected depending on the viewing angle.

♀ Broad-tailed Hummingbird, Selasphorus platycercus

Hummingbirds are often associated with red flowers, but the associate of the two is not exclusive. The assumption that these birds prefer red has always been prevalent, but it does not hold up to experimentation. While a reasoning for a higher prevalence of red floral colors in hummingbird flora is seen, the reason has not been found. What has been discovered is hummingbirds visiting a vast variety of colored flowers, not just red flowers; however, there is a clear link between flower shape and hummingbirds. As expected with long bills, tubular flowers are properly associated with hummingbird. There has even been evidence of a link between sexual dimorphism in some hummingbird species and the flowers they visit. The bill differences in particular of male and female Purple-throated Carib Hummingbird of the Caribbean is a reversal of floral dimorphism of Heliconia plants, of which these birds are the sole pollinators. One species, Heliconia caribaea, is associated with the short, straight bills of males, while the species, Heliconia bihai, relates to the long, curved bills of females.

Hummingbird with a bird band on its leg.

The flying and hovering abilities of hummingbirds are well-known and studied. Although there are musculoskeletal differences between species within the family Trochilidae, the aerodynamic mechanisms hummingbirds employ are somewhat similar to those used by insects. As with other birds, the downstroke contributes the most to weight support, but upstroke plays an important role for hummingbirds in particular. The added creation of tip vortices from the wingbeats also helps to support the body weight of hummingbirds. While hovering is essential for hummingbirds, it proves an interesting issue with banding. Unlike most birds, if a hummingbird spots a mist net, it can stop midair before collision. A pull-string trap is often used to capture and band hummingbirds instead of mist nets. As expect, the bands themselves are incredibly small, varying in diameter to 0.3 mm up to 35 mm.