Blue duck - New Zealand Bird of the Week

Hey guys, it's Henry here, and today I am back for another instalment in New Zealand Bird of the Week. Today, I will be talking about the Theo, otherwise known as the Blue Duck for most of us English speakers. Hope you enjoy! Blue Ducks are an iconic duck in the country of New Zealand, even being on our $10 banknote due to its endangered position, which is something I will get into later. This makes Blue Duck one of the country's most well-recognised bird species. Adult duck of both sexes are alike, being uniformly blue-grey in colour, with a chestnut spotting on the breast and a pale grey bill, with a conspicuously expanded black flap at its tip. This expanded black flap helps the bird in scraping its main prey of invertebrates off of rocks, whilst also protecting the bill from damage. Birds also possess unique sieve-like structures which also assist in the catching of their prey. The Maori name for the birds, Theo, is derived from a high-pitched, weaselly, disyllabic whistle which is produced by male birds. Female bird calls, on the other hand, are low-rasping growls given in response to disturbance or as a threat. Blue Ducks are monogamous, and are also fiercely territorial animals. Ducks are generally encountered year-round as territorial pairs which are dispersed serially along a river, with occasional single males attempting to reclaim space between widely separated pairs. Once a territory is established, a territory is generally held for life, with changes whether that be of male or female birds as a result of death and or displacement rarely induces a change in territory location and pattern of use. Juvenile birds first attempt to establish territories in close proximity to their natal territory, which in turn results in high levels of genetic relatedness within sections of rivers and strong genetic patterning between rivers. Due to this, finding settlements of birds beyond their natal catchment is a very rare occurrence. Theo populations are heavily reliant on high clarity and fast-flowing river systems, and are a key indicator to the health of rivers and streams. This restriction to such a specific habitat is the main reason for the Blue Duck's heavy decline in recent years. Theo were once widespread across New Zealand, but they are nowadays restricted to less modified regions of river systems like in Uruwera, East Cape and along the West Coast. This rapid reduction of habitat was of course caused by humans, with clearance of overhanging vegetation above river systems, poorer water quality and damming for hydroelectric and or irrigation schemes, and this has had a huge impact on Blue Duck populations. Not only were their habitats reduced, but the arrival of Europeans also brought upon another issue for the birds, that being ravenous predators like possums and stoats. This is highly unfortunate for the birds, as they, like many endemic New Zealand birds, have low reproductive success with their currently being a disproportionate population, with males heavily outnumbering the females. There are as of now around 640 pairs located on the North Island and just under 700 pairs on the South Island, a total population that adds up to only around 2,000 to 3,000 birds, and this population is heavily declining due to predation. Unless conservation efforts step up, the Blue Ducks have a very real chance of becoming extinct in the span of 2-3 decades if nothing is done. The most unfortunate aspect of their decline is that unlike most other endangered New Zealand birds, Blue Duck can't simply be transferred to small predator-free islands, as they rely on large areas of quality, fast-flowing riverline habitat that is otherwise completely unavailable on these predator-free habitats. In areas like Te Arawera, over 90% of Blue Duck nests failed in areas that were without predator control. With such a high threat of the birds becoming extinct in the near future, and with the lack of any backup regions, the future of this unique duck is in the balance. Thanks for watching this episode of New Zealand Bird of the Week, and I hope that you guys enjoyed it. For next week, the new bird candidate for voting is the Kaka, another one of New Zealand's marvellous endemic parent species alongside the Kea. I hope that you, the viewer, consider subscribing, and if you already are, be sure to like this video if you enjoyed it, and watch another one of my videos if you're feeling like it. Until next time, enjoy all things science. See you later!