The Otago Shag, also known as the Otago Pied Shag, is a large marine bird found only on the southeast coast of the South Island of New Zealand. It is part of the shag family, known for its distinctive plumage and unique behavior.
The Otago Shag has two color morphs: the pied morph, which is black and white, and the bronze morph, which is brownish-black with a green sheen. These birds are typically found in coastal waters and estuaries, with a preference for rocky cliffs and islands.
Otago Shags have a heavy build and are known for flying close to the water. Their foraging behavior involves feeding on seabed-dwelling fish and invertebrates in murky water. They are colonial nesters, breeding in large colonies on rocky cliffs and islands.
The breeding season of Otago Shags varies, but chicks are mainly fed in the afternoon and fledge at around 7-8 weeks old. The population of Otago Shags is estimated to be around 1,000 to 5,000 mature individuals.
However, these birds face threats such as set-net entanglement and disturbance at their breeding colonies. Conservation efforts are being made to protect their habitats and reduce the impact of fishing interactions.
Key Takeaways:
- The Otago Shag is a large marine bird found on the southeast coast of the South Island of New Zealand.
- It belongs to the shag family and has two color morphs: pied and bronze.
- Otago Shags prefer coastal waters, estuaries, and rocky cliffs.
- They forage in murky water, feeding on fish and invertebrates.
- Otago Shags breed in colonies on rocky cliffs and islands and have a variable breeding season.
- Conservation efforts are in place to protect the Otago Shag’s habitat and reduce fishing-related threats.
Identification and Distribution
The Otago Shag, scientifically known as Phalacrocorax varius, is a medium-sized bird with a heavy build. They measure about 60-70 cm in total length. The Otago Shag exhibits two distinct color morphs, the pied morph and the bronze morph.
The pied morph of the Otago Shag features a black head, white belly and throat, and black wings with white patches. On the other hand, the bronze morph is entirely brownish-black with a striking green sheen on the wings. Regardless of the morph, both variations have a beak in pale brown, pink, or grey, and brown iris.
During the breeding season, approximately 50% of both morphs develop small bright orange caruncles above the base of their bills. However, non-breeding birds have duller facial skin color and lack these caruncles.
The Otago Shag is endemic to the southeast coast of the South Island of New Zealand, specifically from the Catlins to the Waitaki River. These birds primarily inhabit coastal waters, harbors, and estuaries. However, in recent years, their range has been gradually expanding both northwards and southwards.
Behavior and Breeding
The Otago Shag (Phalacrocorax varius) is a fascinating seabird species known for its unique behaviors and breeding habits. Understanding the behavior and breeding patterns of these birds offers valuable insights into their ecology and overall conservation.
Foraging Behavior
One interesting behavior of Otago Shags is their group foraging strategy. These birds have adapted to murky waters, where they disturb and strike their prey instead of relying on visual tracking. This behavior allows them to efficiently locate and capture food sources, contributing to their survival and growth.
Vocalizations and Reproduction
Otago Shags are generally silent birds, but their vocalizations play a crucial role during the breeding season. Males use a unique vocalization known as a borr call to attract mates and establish territories. Additionally, during this period, chicks beg for food by emitting a distinctive squeaky ah-whee-ah call. These vocal interactions are essential for successful breeding and ensuring the survival of the species.
Growth Stages and Nesting
Otago Shags undergo specific growth stages throughout their lives. They are capable of flight and can cover significant distances, with some individuals traveling up to 10 km off the coast.
When it comes to nesting, Otago Shags are colonial nesters, with breeding colonies typically located on rocky cliffs and islands. They construct impressive pedestal nests made of seaweed, sticks, and grass cemented together with guano. The nests provide a secure and elevated platform for incubation.
Reproductive Habits
Both male and female Otago Shags participate in incubation duties, taking turns to ensure the eggs are properly cared for. The number of eggs laid varies, but it typically ranges from 1 to 3. After an incubation period of approximately 35-40 days, the chicks hatch and are mainly fed in the afternoon.
Upon reaching 7-8 weeks old, the chicks begin the fledging process and venture out of the nest. However, they remain near the colony, relying on their parents for approximately 10-11 more weeks until they become fully independent.
Conservation Status and Fun Facts
The Otago Shag is not currently considered an endangered species, although it faces several threats. Fishing interactions, particularly entanglement in set-nets, and disturbance at breeding colonies pose risks to their population. To safeguard their existence, efforts are underway to protect their nesting sites on islands and in protected areas.
Besides their conservation status, Otago Shags are intriguing from a human perspective. In the past, they were hunted by fishers who perceived them as competitors for fish. Additionally, their group foraging behavior has been exploited by humans to catch fish more effectively. Despite their name, Otago Shags are not related to ducks, but they are often compared to other shag species and can be mistaken for the smaller Foveaux Shag or the pied morph of the Stewart Island Shag.
With their distinctive appearance and fascinating behavior, Otago Shags captivate both bird enthusiasts and casual observers. These unique birds serve as a testament to the wonders of nature and the importance of conservation. As we continue to protect these extraordinary creatures, let’s also marvel at their charm and presence.