The Masai ostrich (Struthio camelus massaicus), also known as the East African ostrich is a red-necked subspecies variety of the common ostrich and is endemic to East Africa. It is one of the largest birds in the world, second only to its sister subspecies Struthio camelus camelus. Today it is hunted and farmed for eggs, meat, and feathers.
Taxonomy
Subspecies
The Masai ostrich is one of the three extant subspecies of ostrich currently inhabiting Africa, including the nominative ostrich (S. c. camelus) found across northern Africa and the South African ostrich (S. c. australis). It is considered one of the two red-necked forms of ostrich, along with S. c. camelus, as opposed to the two blue-necked forms (S. c. australis and S. c. molybdyphanes).
Comparative restriction-enzyme analysis of mitochondrial DNA (mtDNA) found the Masai ostrich, though genetically distinct, is most closely related to S. c. australis, despite their geographical separation, and least genetically related to S. c. molybdophanes, despite habitat overlap. Explanations for these counterintuitive findings are that while the Brachystegia or “miombo” woodlands currently serves as a zoogeographic barrier separating northern and southern ostrich populations, it is theorized that this barrier was not as dense and effective throughout evolutionary time and once allowed for brief periods of intraspecific breeding between S. c. massaicus and S. c. australis populations. Conversely, the genetic divergence observed between S. c. massaicus and S. c. molybdophanes, albeit a lack of any zoogeographic barrier, is thought to be due to the ecological differences in behavioral and reproductive cues between these populations. These differences were substantial enough to prevent intraspecific breeding throughout time. These same studies found S. c. massaicus to significantly differ genetically from S. c. camelus subspecies.
Although the now extinct subspecies S. c. syriacus was determined to also be a red-necked form of ostrich based on historical evidence, similar analysis of mtDNA found the Masai ostrich to not be as close of a relative to S. c. syriacus compared to S. c. camelus.
Description
Anatomy
Adult males are 2.1–2.7 m in height and can weigh up to 145 kg; females are typically slightly smaller in size. They have large eyes (50 mm across), long eyelashes, and exceptional vision. Their heads are relatively small compared to their body and are covered in degenerated feathers that give the upper two-thirds of their elongated neck an almost naked appearance. The skin of the neck and thighs of male Masai ostriches is bare and pink in color, which intensifies to an almost reddish hue during mating season.
Their large size prevents the capability of flight, but this is compensated by their exceptionally long and muscular legs, which allow for maximum running speeds of up to 60–70 km/h.
Plumage
The feathers of the Masai ostrich lack barbs, which gives them a soft, downy appearance. Similar to other ostrich subspecies, they possess approximately 50–60 tail feathers, 16 primaries, 4 alular, and 20–23 secondary feathers. The wing and tail feathers have evolved to serve as decorative plumes for courtship display rather than flight.
For males, the majority of the body is covered in black feathers. White feathers appear along the tips of the wings, tail, and form a small ring partway up the neck that separates the black body feathers from bare neck skin. The white tail feathers are often discolored from dirt and appear reddish-brown.
Females tend to be smaller than males and also possess bare skin on both the neck and legs, though their skin color appears more beige than pink. Adult females body feathers are a uniformly-distributed, monochromatic color scheme of brown.
Reproductive/Excretory organs
Unlike most avian species, male ostriches have a retractable penis that averages 20 cm in length and everts during defecation, urination, and copulation. The ostrich is the only bird to void urine separate from defecation due to the muscular sphincter-like folds located within the cloaca.
Environmental adaptations
Several physiological adaptations have evolved to allow the Masai ostrich to live in the extreme arid conditions of Sub-Saharan Africa. Their feathers have specialized to work as efficient insulators for proper thermoregulation during both hot and cold climates. Increased aldosterone release and use of mucous in place of water for excretion of uric acid promotes water retention in arid environments. Masai ostriches also possess salt-excreting nasal glands which allow for consumption of salt water from saline and soda lakes when necessary.