Specimen Showcase | Egg Guardian

Who are these new bird species visiting Hong Kong during the dry season?🦅 These species are migrating species establishing themselves here for a few months, escaping the cold temperatures in the northern regions where they spend the rest of the year.

As Hong Kong is located on the East Asian – Australasian Flyway, the warmer climate offered in the region attracts these species where they could still find food and some good rest after a trip of several thousands of kilometres. 𝘛𝘶𝘳𝘥𝘶𝘴 𝘩𝘰𝘳𝘵𝘶𝘭𝘰𝘳𝘶𝘮 (Sclater, 1863) or grey-backed thrush is one of the common winter visitors, they stay in Hong Kong during winter and move back to Northern when the spring comes. They are small birds, around 20 cm in size, with a large area of grey feathers at the back which is the reason that they are called grey-backed thrush. They mainly feed on small insects and some fruits that they find by scratching through the leaf litter on the ground. If you visit the woodland in winter🌳, you may observe them searching for food on the grass.

Their reproduction, however, does not occur in Hong Kong but in northern China, North Korea and Russia, where they will lay 3 to 5 eggs🥚 each year, with a relatively short incubation period of 12 to 15 days. In nature, some birds lay their eggs in the nest of other birds in order to let other birds rear their young. This is known as brood parasitism and some of the Cuckoos species represent the most famous example. This strategy, however, does not work in grey-backed thrush, as these birds have turned into experts against parasitism. 🤓They can recognize their egg and reject the foreign eggs. Once they recognize there are foreign eggs, they will kick out the foreign egg from the nest and prevent parasitism. However, their skills have some limitations; and while grey-backed thrush can identify eggs coming from other species, they fail in detecting those laid by other sneaky grey-backed thrush. As the result, they sometimes end up raising the youngs from other thrush parents as well!😢

Text: Zoey Chung

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