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Species in the spotlight – Black Harrier

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Words by Tanya Heald

Black Harrier – Circus maurus

The black harrier is a raptor species that’s being threatened by habitat destruction, alien vegetation and man. It’s believed that there are only about 1000 to 1500 adult individuals left in the world, and the largest breeding population is in South Africa’s West Coast National Park, thanks to the coastal vegetation preferred by the black harrier, and the high number of rodents, small birds, amphibians and reptiles that make up the bulk of its diet.

The male’s distinctive tail pattern, with white and black stripes across the width of the tail and its white underside primary and secondary feathers, makes it easy to identify in flight. The females have a duller coloration of brown tones and are less distinctive. They have yellow legs, cere and eyes, with feathers down to their ‘knees’, and are medium-sized, averaging 50 cm. Their various calls have been documented, but the most common experienced by humans is that of alarm, signified by a ‘chak-chak-chak’.

Breeding usually takes place from around 
June to November, and nests are built on the ground in colonies of about five or six breeding pairs, 50 to 100 metres apart. On average, there are three eggs per nest, and the incubation period is roughly 34 days. Both males and females tend to the young, which are fully fledged within six weeks. Their range covers most of South Africa and extends as far as the northern reaches of Namibia. However, even though they have a large range, they are classified as vulnerable, with small populations dotted throughout their range. This is due to the introduction of alien vegetation such as the rooikraans. The population around Stanford, for example, had disappeared by the end of the 1950s, after the introduction of this plant species to the area in the 1930s . This is primarily because the birds do not breed in vegetation more than a metre high, preferring to breed on the ground. Interestingly, once the rooikrans had been removed to make way for a poultry farm, the black harriers returned.

The progress of man is the main cause of the species’ decline. The eradication of precious fynbos and renosterveld for agricultural purposes is one of the biggest culprits. Unseasonal veld fires eliminate all vegetation, rendering the breeding grounds unsuitable for lengthy periods. This demonstrates the need to conserve these habitats, which can only be done by controlling the amount of development taking place in these fragile environments. • Tanya Heald is CEO of HOW Wildlife Rescue.

 

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