The Swallow-tailed Gull is one of the most interesting seabirds on the planet. This species, native to South America, is the only gull that lives a fully nocturnal life. Swallow-tailed Gulls are the only gulls to hunt at night. They have adapted perfectly to their oceanic habitat. These seabirds, with their unique physical features, fascinating behaviours, and strong connection to the Galapagos Islands, are marvels of evolution.
The Nocturnal Seabird: A Seabird With a Difference
The Swallow-tailed Guillemot is the only gull that feeds exclusively during the night. The nocturnal nature of their behaviour allows them to access prey that rises closer to the surface of the ocean after sunset. These gulls have evolved to see at night with dark-adapted, large eyes. They are unique in the bird world because they can fly, hunt and navigate in complete darkness. This allows them to take advantage of food sources that other birds cannot.
Habitat and distribution: Masters of the Pacific Ocean
The pelagic bird spends the majority of its life soaring over the waters of the eastern Pacific Ocean. Swallow-tailed Gulls can be seen most often near the Galapagos Islands. This is their primary breeding ground. The islands are located approximately 1,000 km off Ecuador’s coast and provide nesting areas with their rugged coastal cliffs.
During breeding season, large colonies gather on islands such as Hood (Espanola), Tower (Genovesa), and Wolf Island. These islands provide nesting sites and easy access to warm waters rich in food. Outside of the breeding season, Swallow-tailed Gulls migrate widely, usually along the coasts of Colombia and Peru. They can also be found as far south as Central Chile. The birds may nest in smaller groups on Malpelo Island, off the coast of Colombia.
A Striking Seabird
The plumage of the Swallowtailed Gull differs noticeably during the breeding season and the non-breeding season. Adults display a strikingly black head that is contrasted with a brightly red eye-ring during the breeding season. This is their most distinguishing feature. The body plumage of the eagle is predominantly gray, white and black with dark black wingtips. This gives them a graceful appearance when they fly.
During the non-breeding seasons, the black heads molt to reveal a a white head with a dark eye ring. This gives them a subdued appearance. The males and the females have similar plumage, making it difficult to tell them apart visually. The species’s forked, deeply forked tails are most noticeable when in flight, and contribute to its graceful, aerodynamic shape.
Adaptations to Night Hunting
The Swallow-tailed Gull’s ability to adapt to living in total darkness is one of its most impressive characteristics. They have large, oversized eyes that help them catch more light at night. Their eyes are up to 30% bigger than those of other gulls. The retinas of these birds are filled with rods that are optimised for low light conditions. They can detect the movement of prey in the water, even when there is no light.
In addition, the unique structure of their facial features (including the red eye ring) may be a factor in the communication between birds at night. Their behaviour and anatomy demonstrate the power of evolution.
Food and Feeding Behaviour
The food of the Swallowtailed Gull reflects their nocturnal habits. These seabirds feed mainly on squid as well as small fish like clupeid species that rise to the surface of the ocean at night to feed on plankton. They can catch prey that is moving quickly below the surface with their nimble flight patterns and precise vision.
Swallow-tailed Guillemots, unlike many gulls, are skilled hunters. They use sharp reflexes, expert coordination, and a keen eye to catch live, moving prey. They are an important predator because of their active foraging.
Reproductive Cycle and Nesting Habits
The Swallow-tailed Gull reaches sexual maturation at about five years old. After that, they typically form monogamous lifelong pairs. During breeding season, they form loose colonies with nests far apart. This nesting pattern helps reduce conflict and predation between neighbouring birds.
Nests are made from stones, coral or other materials. They’re often constructed on cliffs, ledges, or rocks near the sea. Some individuals nest on isolated cliffs to protect themselves from predators.
The Egg Laying and Chick Raising
In general, each breeding pair lays one speckled egg per clutch. The egg incubation process and the chick raising process are both joint efforts. Both the male and the female stay at the nest during the day. They alternately brood the egg. The non-breeding parent will feed at night.
After the incubation period of 31-34 days is over, the chick hatches and starts its rapid growth. The young Swallow-tailed Guillemots stay in the nest between 60 and 70 days. During this time, they are regurgitated by both parents. The juvenile is still dependent on its parents even after it has fledged.
Social Behaviour and Parental Cooperation
Swallow-tailed Gulls are known for their strong parental cooperation. This cooperative parenting strategy ensures not only the survival of chicks, but also the energy requirements of nighttime foraging. Both males and females share the same responsibilities, which is a good example of a balanced parenting model. According to RSPB, this species is well documented.
The bird’s small clutch is a major factor in its success. The survival of the species is dependent on the chicks’ success, as there is only 1 egg per breeding cycle. This is especially true for remote islands, where the environment can be harsh. According to BirdLife International, this species is well documented.
Unique Vocalisations & Communication
The Swallow-tailed Gull’s unique vocal behaviour is one of its most striking features. Swallow-tailed Gulls make sounds that are less harsh and more complex, as opposed to the raucous cries produced by many gulls. Their most common alarm call has been described as a “rattle-and-whistle”, consisting of gurgling screams accompanied by rhythmic head movements.
These birds also make a series of rapid contact calls,” Kweek, Kweek, “, to communicate with their mates or chicks. These calls are closer to those of Black-legged Kittiwakes or Sabine’s Gulls than any other traditional gulls. This highlights their unique position within the gull family.
Conservation Status: Stable, but Vulnerable
The IUCN Red List currently lists the Swallowtailed Gull as Least Concern due to its stable population. As a species that breeds only on a small number of distant islands, it is vulnerable to a variety of threats. Climate Change can disrupt the oceanic food chain, and Invasive species may compete for food or raid nests.
The Galapagos Islands conservation efforts have played an important role in maintaining the breeding environment of these birds. The Swallow-tailed Gull’s long-term survival depends on the protection of marine ecosystems and the continued surveillance of seabird populations.
The Role of Ecological Importance
Swallow-tailed Gulls are important to the marine ecosystem. They help maintain species balance in the upper layers by feeding on small fish and squid. They also provide valuable information about the state of the marine food chain by predating on these creatures.
Seabirds’ nocturnal behaviours contribute to the diversity in predation patterns found in marine environments. This shows the wide range of ecological niches they can occupy.
Galapagos Jewels: A Rare Gem
Swallow-tailed Gulls are a wonder for birdwatchers, nature lovers, and conservationists. The Swallow-tailed Gull is one of the world’s most unusual seabirds. Its nocturnal behaviour, striking features and fascinating life story make it unique. It is a rare opportunity to see them in their natural habitat, especially along the Galapagos Islands’ cliffs.
The presence of these species in these remote regions serves to remind us of the delicate equilibrium of island ecosystems and the importance of continuing conservation efforts for these rare species.
Alternate (Global) Names
Chinese: ??? … Czech: Racek galapážský … Danish: Svalehalemåge … Dutch: Zwaluwstaartmeeuw … Estonian: öökajakas … Finnish: Yölokki … French: Goéland / Mouette à queue fourchue … German: Gabelschwanzmöwe … Italian: Gabbiano coda di rondine, Gabbiano codadirondine … Japanese: akamekamome … Norwegian: Svalestjertmåke … Polish: mewa widlosterna … Russian: ????????????? ????? … Slovak: ?ajka lastovi?kovitá … Spanish: Gaviota de las Galapagos, Gaviota Rabihorcada, Gaviota Tijereta … Swedish: Svalstjärtad mås
Final Thoughts – Celebrating Nature’s Night Navigator
The Swallow-tailed Gull is a great example of evolutionary adaptation and behavioural innovation. This bird’s unique features, from its highly specialised eyes to its nesting strategy and musical call, continue to fascinate researchers and bird enthusiasts alike. Swallow-tailed Gulls, as guardians of night skies over the Pacific Ocean and powerful symbols of nature’s creativity, are an important part of Earth’s biodiversity.
Swallow-tailed Gulls are nocturnal creatures that can be seen by birders and nature lovers alike.
Where the moon guides the hunters and the waves whisper secrets to those who are listening.
