The Manx shearwater is a medium-sized seabird that has some truly astonishing abilities. Here are some quick answers to key questions about this incredible bird:
– Where does it live? The Manx shearwater lives on islands in the North Atlantic Ocean. Its largest breeding colonies are found on islands off the coasts of Wales, Scotland, Ireland, and New England.
– How far does it migrate? The Manx shearwater migrates over 10,000 km each year between its breeding islands and wintering areas off South America. This is one of the longest migrations of any bird species!
– How fast can it fly? Manx shearwaters can fly at speeds over 110 km/h when gliding with the wind. Their streamlined bodies and long, narrow wings make them built for speed.
– How well can it smell? Manx shearwaters have an incredibly acute sense of smell that allows them to detect prey and follow odor plumes back to their nesting burrows. Their large nasal glands give them a powerful olfactory ability.
Description
The Manx shearwater is a medium-sized seabird in the family Procellariidae. It measures around 30-38 cm in length with a wingspan of 80-95 cm and weighs between 450-650 g.
Key identification features include:
- Black cap and dark gray upperparts
- White underparts
- Long, narrow wings
- Wedge-shaped tail
- Black bill with pale yellow nasal tubes
- Pinkish legs and feet
In flight, the Manx shearwater has a graceful, effortless style. It rarely flaps its wings, exploiting updrafts to soar dynamically close to the ocean surface. On the water, it paddles across the surface while flapping its wings in pursuit of prey.
Subspecies
There are 3 recognized subspecies of Manx shearwater:
- P. p. puffinus – nominate, breeds on islands off northwest Europe
- P. p. newelli – breeds off eastern Canada and northeastern USA
- P. p. yelkouan – smaller and darker, breeds in the Mediterranean
Breeding
The breeding habits of the Manx shearwater are fascinating. Here are some highlights:
- Nests in underground burrows that can be over 3 meters long. Both parents work together excavating the burrow over many days.
- No nesting material is used. The single egg is placed directly on the bare ground in the burrow chamber.
- Egg is large and elliptical, averaging 63 x 43 mm.
- Incubation duties are shared by both parents over a period of around 54 days.
- Chick is covered in down when hatched. Parents take turns feeding the chick each night after flying enormous distances out to sea to harvest prey.
- Chick fledges at around 12 weeks old, exiting the burrow under the cover of darkness to avoid predators.
Breeding Colonies
Some of the major breeding colonies of Manx shearwaters include:
Location | Estimated Pairs |
Rum, Scotland | 7,000 |
Copeland Islands, N. Ireland | 436,000 |
Skomer, Wales | 305,000 |
Skokholm, Wales | 100,000 |
Mykines, Faroe Islands | 12,000 |
Great Island, Newfoundland | 6,000 |
Migration
The Manx shearwater undertakes an immense annual migration across the Atlantic Ocean. Some key facts about their migratory habits:
- Migrates over 10,000 km each year between breeding and wintering areas.
- Can cover over 1,000 km in a single 10-12 day foraging trip during breeding season.
- Most of the population winters off South America.
- Some birds winter off southern Africa or Australia.
- Migrates alone, not in flocks.
- Navigation likely relies on sensing geomagnetic fields, sunset/sunrise cues, and smell landscape odors.
Migration Route
Here is an overview of the annual migration cycle of the Manx shearwater:
September to April | Off the coast of South America |
April | Northward migration across Atlantic to breeding islands |
May to August | Breeding season on North Atlantic islands |
August to September | Southward migration across Atlantic to wintering areas |
Diet and Foraging
The Manx shearwater feeds on a variety of small marine prey:
- Fish (sardines, anchovies, lanternfish)
- Squid
- Crustaceans (krill, shrimp, barnacles)
- Occasionally offal and fish scraps when following fishing boats
Foraging Strategies
The Manx shearwater employs these clever tactics when foraging at sea:
- Plunge dives from flight into water to pursue prey near surface
- Pursues prey underwater propelling with wings
- Often forages cooperatively in large multi-species feeding flocks
- Uses sense of smell to locate prey patches at sea
- May snatch food scraps dropped by other seabirds
- Has special stomach oils that help digest buoyant oily prey
Population and Conservation
Here are some key facts about the population and conservation status of the Manx shearwater:
- Global population estimated at >2 million breeding pairs
- Classified as Least Concern on IUCN Red List
- Many colonies have undergone significant declines historically due to hunting, habitat loss, and predation
- Now legally protected from hunting throughout breeding range
- Main threats today include introduced predators, commercial fishing, pollution, and climate change
Population Trends
Population trends for select Manx shearwater colonies:
Location | Population Trend |
Copeland Islands | Declining around 6% per year |
Rum | Relatively stable |
Skomer | Slight decline then increasing in recent years |
Skokholm | Relatively stable |
Great Island | Declining 4.2% per year |
Conservation Efforts
Some conservation actions that support Manx shearwater populations include:
- Legal protection of breeding colonies
- Eradication of invasive predators like rats and mink from nesting islands
- Blocking burrow entrances during chick-rearing to prevent accidents
- Monitoring and regulation of commercial fisheries to reduce bycatch
- Public education campaigns to raise awareness of seabird conservation
Amazing Facts
Here are some of the most amazing and impressive facts about the incredible Manx shearwater:
- Parents incubate the egg in shifts, with one adult always present at the nest site. This continuous care can last around 115 days from egg-laying to chick fledging.
- The Manx shearwater spends over 90% of its life flying or swimming at sea, only coming to land to breed.
- To find their way back to their underground nest burrows at night, Manx shearwaters rely heavily on their phenomenal sense of smell.
- Chicks hatched on Skomer Island off Wales jump off 400 foot cliffs and fly out to sea, an incredible first flight into independence.
- Manx shearwaters living around the British Isles regularly travel over 10,000 km roundtrip to winter off South America.
- These amazing seabirds live very long lives, with lifespans often exceeding 30 years in the wild.
- By riding dynamic air currents close to the ocean surface, Manx shearwaters can achieve remarkable speeds of over 110 km/h while gliding.
- They use a technique called “dynamic soaring” to extract energy from winds deflected by waves and ridges at sea.
- Male and female Manx shearwaters form lifelong pair bonds. Partners come together each breeding season to reproduce, once the female reaches 5 years old.
- Their chicks are brooded in nest chambers up to 3 meters underground, safe from air and land predators.
Navigation Abilities
Additional evidence of the Manx shearwater’s incredible sensory capabilities:
- Likely uses both olfactory and magnetic cues to navigate during migration.
- Can orient to artificially shifted magnetic fields in experiments.
- Shown to be sensitive to infrasound below 20 Hz, possibly using it for navigation.
- Possesses extra large olfactory bulbs and nasal glands for enhanced smell while foraging.
- Able to detect incredibly dilute odor plumes and follow them to prey patches.
Conclusion
In summary, the Manx shearwater is an astonishing seabird that thrives by flying enormous distances across the ocean each year. Equipped with superior sensory capabilities, this medium-sized petrel migrates farther than any other seabird species in the North Atlantic. After traveling over 10,000 km from South America each spring, Manx shearwaters return with pinpoint precision back to their natal burrows to breed and raise the next generation. Their navigational skills, tenacity, and sheer endurance allow them to complete one of nature’s great annual odysseys. If you ever have the chance to witness Manx shearwaters effortlessly riding the winds along a cliffside, take a moment to appreciate these remarkable ocean wanderers.