Tubenoses are a group of seabirds characterized by having external tubular nostrils on their upper bills. The tube-like nostrils help give these birds an excellent sense of smell, which aids them in locating food across vast expanses of open ocean. Some of the most well-known tubenoses include albatrosses, petrels, shearwaters, and storm petrels. In this article, we will explore what defines a tubenose, how their unique nostrils help them survive in marine environments, and provide an overview of some of the major tubenose species.
What are Tubenoses?
Tubenoses, also known as tubinares, are a group of seabirds united by their distinctive tubular nostrils on their upper mandible. Their nostrils take the form of tubes sitting on top of their bills rather than the oval or slit-like nostrils found in other birds. The tube arrangement helps funnel air into the olfactory chamber during flight.
This specialized nostril structure allows tubenoses to have an exceptional sense of smell, which they rely on to locate patchy food resources across vast stretches of ocean. By picking up scents trailing downwind from potential prey, tubenoses can pinpoint the location of distant food sources such as schools of fish or whale carcasses. Their sense of smell is considered to be one of the keenest in the animal kingdom.
In addition to their unique nostrils, tubenoses share some other anatomical traits:
– Webbed feet for surface swimming
– Salt glands to excrete excess salt from the marine food sources
– Oily feathers that repel water
– Long, narrow wings ideal for gliding over ocean waters for hours or days
There are four living families of tubenose birds:
– Albatrosses – The largest tubenoses, with the largest wingspans of any living bird. Known for their soaring flight.
– Petrels and shearwaters – Medium-sized tubenoses, adapted for diving to catch prey underwater.
– Storm petrels – Smallest tubenoses, largely limited to pattering on the water surface.
– Diving petrels – Smallest of all tubenoses, champion divers capable of diving to 30 m depths.
How Do the Nostrils Help Tubenoses Survive at Sea?
The tubular nostrils of these seabirds confer several key survival advantages:
Enhanced sense of smell
As mentioned, the tube shape helps direct scents into the nasal chamber while in flight. Tubenoses have a large olfactory bulb in their forebrain to process all of the incoming odors. They can detect scents from miles away, allowing them to find food and navigate accurately across huge stretches of featureless ocean.
One-way air flow
The tube nostrils allow air to flow in just one direction, which maintains their ability to smell even during rapid flight. With oval nostrils, air would tend to flow straight through instead of circulating within the olfactory chamber.
Prevents water entry
The narrow tube openings prevent seawater from entering the nasal passage during take-offs, landings, and dives for food. Oval nostrils would be more vulnerable to taking on water.
Reduces drag
The small, streamlined nostrils minimize drag forces during flight, allowing tubenoses to fly efficiently for very long distances.
Major Tubenose Species
There are around 125 living species of tubenoses worldwide. Some of the major groups include:
Albatrosses
– Wandering albatross – Has the largest wingspan of any living bird (3.5 m). Known for circumnavigating the southern oceans.
– Black-footed albatross – Most common albatross off the western coasts of North America.
– Laysan albatross – Named for Laysan Island, part of the Hawaiian island chain where it nests.
Petrels
– Northern fulmar – Abundant petrel of the northern Atlantic and Pacific oceans.
– Southern giant petrel – Scavenger species found off Antarctica. One of the largest petrel species.
– Bermuda petrel – Thought extinct for 300 years until rediscovered in 1951. Still critically endangered.
Shearwaters
– Manx shearwater – Most abundant tubenose in the North Atlantic, nesting on islands off the UK.
– Great shearwater – Makes one of the longest migration journeys of any bird, from Tierra del Fuego to North Atlantic waters.
– Flesh-footed shearwater – Common off the coasts of Australia and New Zealand. Gets name from its pinkish legs.
Storm Petrels
– Wilson’s storm petrel – The most widespread storm petrel, found across all southern ocean basins.
– Fork-tailed storm petrel – Distinctively forked tail and swift, erratic flight make this species easily identifiable.
– Leach’s storm petrel – Nest on isolated islands off the Northeastern coast of North America. Give off a strong, musty odor.
Diving Petrels
– Common diving petrel – Found off southern Australia and New Zealand. Dives to about 10 m depth.
– Peruvian diving petrel – Endemic to Peru and northern Chile. Was thought extinct until rediscovered in the 1990s.
Unique Adaptations for Life at Sea
In addition to their hallmark tubular nostrils, tubenoses possess other anatomical and physiological adaptations that aid their marine lifestyle:
– Salt glands – Allow them to excrete excess salt acquired from their food and from drinking seawater. Located above the eyes to remove salt before it reaches body.
– Waterproofing – Their feathers are oiled for water repellency. Some species also have more down feathers and fluffier plumage to retain body heat.
– Webbed feet – Provide propulsion and steering while swimming on the surface. Species like diving petrels also use their feet for diving and pursuing prey underwater.
– Keen vision – Many have large, sharp eyes that aid in spotting prey patches and other birds across vast distances at sea.
– Hooked bills – Well-adapted for grabbing slippery fish and squid. Some have saw-toothed edges for gripping large prey.
– Wing-propelled diving – Larger species like petrels and shearwaters use their wings to “fly” underwater. Smaller storm petrels flutter their wings or paddle with their feet.
Reproduction and Lifespan
One of the defining features of tubenoses is their long reproductive cycles and lifespans relative to other birds of similar size.
– Delayed maturity – Tubenoses typically don’t begin breeding until 5-15 years old. Allows time to learn complex migratory routes.
– Small clutch size – Usually lay just 1 egg per season. Some larger species like albatross only nest every 2 years.
– Slow chick development – Chicks are dependent on parents for 4-10 months, the longest developmental period of any birds.
– Long lifespan – Many species live upwards of 50 years. The oldest known wild bird was a 67-year-old albatross.
– High mate and site fidelity – Tubenoses show lifelong loyalty to their mate and nesting site. Critical when breeding habitats are limited.
These reproductive traits limit their capacity to recover from population declines. Many tubenoses are threatened by pollution, overfishing, invasive predators, and habitat destruction. Protecting their breeding colonies is crucial.
Famous Tubenoses in Culture
Tubenoses have made their mark on human culture in various ways:
– Ancient mariners viewed albatross as the souls of dead sailors. Killing one was thought to bring bad luck.
– The Rime of the Ancient Mariner poem by Samuel Taylor Coleridge popularized the superstition of albatrosses as an omen of doom.
– Petrels and shearwaters were given names linked to the supernatural – “devil birds”, “ghost birds” – for their eerie nighttime habits and cries.
– Puffins are a beloved cultural icon of the North Atlantic despite not technically being tubenoses (their nostrils are oval-shaped).
– The albatross “Wisdom” attracted media attention for raising over 30 chicks during her 60+ years and surviving the 2011 tsunami in Japan.
– The story of a Laysan albatross named Wisdom inspired the Pixar animated short “Piper”.
– Bio-logging tags attached to tubenoses have provided insights into their incredible migrations covering 100,000+ km per year.
Conclusion
In summary, tubenoses are an ecologically important group of seabirds defined by their unique tubular nostrils that confer an exceptional sense of smell. This key adaptation allows them to forage widely across expansive oceans and underpins their success as some of the most efficient traveling birds on the planet. However, many tubenose populations currently face serious threats from human activity. Protecting their breeding colonies and marine habitats will be crucial for ensuring the survival of these iconic ocean wanderers into the future.
