A clarion call to protect the last refuge of the Endangered Black Harrier

Words by Rona van de Merwe.

A black harrier looking for a tasty morsel below. Image by Megan Murgatroyd.

One of the most prominent and iconic species to call the West Coast home is the graceful Black Harrier, Circus Maurus. Scientifically named after its circling flight patterns, you may notice how the male twirls and spins during a spectacular display of sky-dancing. This undulating repertoire attracts females at the onset of the breeding season. On the West Coast, there is a reason to keep your eyes on the waves, but don’t forget to look towards the sky.

But perhaps we should look further. The black harrier faces probable extinction in as little as 75 years if you take current mortality rates into account. Add multiple mining operations in one of its last remaining breeding strongholds, and the future of this special raptor looks catastrophic. How did we manage to send South Africa’s most iconic coastal raptor on this trajectory?

Harriers are a specialist species. They are ground nesting raptors adapted to open natural scrub-, grass- and wetlands (some of the most threatened ecosystems in the world). Sixteen harrier species are found on earth, and only four of them adorn African skies: the black harrier (endemic to southern Africa); the African marsh harrier (sub-Sahara); and the Reunion and Madagascar harriers (on those islands).

Specialist species evolve and adapt in environments where they rely on specific ecological processes. They are often classified as the ‘losers’ when it comes to survival in a rapidly changing, man-altered landscape. Generalist species can adapt and exploit a range of conditions, basically mimicking the human species. As a result, in the long run, it is the survival of the fittest few that can thrive in a changing world.

An unprecedented number of species have been lost in the Anthropocene (our current geological age). Ironically, this biodiversity loss will ultimately threaten the ability for humans to exist. Worldwide, more than one in eight species of birds are threatened with extinction – classified as Vulnerable, Endangered or Critically Endangered. Recently classified as Endangered by the IUCN red list of threatened species, black harriers are part of this statistic. Only about 1,300 mature breeding individuals survive, and the population continues to decline.

A black harrier perched upon a dead tree. Image by Megan Murgatroyd.

They are considered rare not just because of their small population, but also due to their limited geographical range. The black harrier has the most restricted distribution of all continental harriers, with an even smaller breeding area that is restricted to southwestern South Africa along the coast between the Western Cape Renosterveld and Fynbos biome to the Northern Cape Succulent Karoo biome.

Over the last two decades, there has been a huge leap in our understanding of black harrier biology and ecology. A number of research projects led by world-renowned harrier specialist, Dr Rob Simmons, and the Fitzpatrick Institute of African Ornithology at UCT, have shed light and helped us to determine what impacts threaten their survival. Long term data from many citizen scientists have provided evidence of landscape requirements, dietary preferences, breeding behaviour, population genetics, health status and movement patterns, all of which were mere speculation previously. Research continues, and more is needed to better understand the anthropogenic threats that impact black harrier survival, and to enable policy and decision makers to conserve the species.

Research shows that as a specialist species, black harriers depend on large areas of natural vegetation to breed and hunt. Unfortunately, little remains intact. The Overberg renosterveld has been largely cultivated. Many coastal areas have been fragmented by development and infrastructure. Black harriers are sensitive to the size of an unspoiled area. Larger natural spaces support larger densities of breeding pairs. They provide greater access to prey resources that mainly consist of small rodents. The wonderful West Coast still supports areas like this, with protected land favouring greater numbers of breeding pairs.

A black harrier swooping low to get a better look. Image by Jacque Smit.

Apart from breeding along the coast, black harriers also, at much lower densities, make use of inland mountainous areas where more natural vegetation survives. Satellite and GPS-tracking data has confirmed that black harriers are nomadic and migrate towards greener natural pastures in Lesotho, KwaZulu-Natal and the Eastern Cape, during the summer months or between breeding seasons. The protection of nomadic species is tricky because it requires cross-country or interprovincial efforts from authorities and conservation entities. However, the protection of breeding sites is the most critical element to an endangered species’ survival.

Black harriers breed along the coast from mid-May to mid-December. The better the coastal environment conditions, the greater the breeding success within a population. Rainfall, plant growth, and seed availability all impact on prey availability, and in turn, the ability of adults to provide for their chicks. Unlike inland areas faced with sharp fluctuations in temperatures and shorter growth seasons, the more temperate coastal climate brings more abundance of prey for a longer period of time.

Research highlights how important the coastal Fynbos biome is to population stability and sustainability.

As black harrier ecologist Sophia García-Heras concludes in her PhD thesis: “This (coastal) region and the Fynbos habitat seems to provide better conditions for successful breeding in terms of food availability and weather conditions, but the habitat is also most limited in space. Overall the scarcity of black harriers may thus be related to a lack of optimal, i.e. unurbanised, unpolluted, unfragmented and food-rich, areas for breeding. The preservation and protection of the Fynbos should therefore be prioritized to insure optimal and sustainable conservation of black harriers in the long term, but also for the conservation of many other terrestrial species that face similar threats.”

Habitat loss is the main driver for plummeting black harrier numbers. GPS tracking data on the West Coast reveals further threats, such as birds dying when they hit electricity power lines or wind turbines. Birdlife South Africa has developed guidelines for wind energy developers to mitigate impacts on black harriers, especially where they are known to breed. Other developers, including mining companies, must be made to follow such guidelines – to avoid destroying large areas of natural vegetation where black harriers hunt and breed.

A continuous drought on the West Coast also negatively impacts black harrier reproduction. Research shows that breeding success is linked to rainfall and negatively related to temperature. Genetic research reveals a tiny genetic pool, with little variation. Alarming data shows that West Coast black harriers have compromised immune systems due to DDT and PCB poisoning from agricultural and electrical infrastructure.

Watercolour painting by Rona van de Merwe.

This exacerbates the impact of climate change – models predict drier and hotter weather trends – on an already fragile species. It is of critical importance that we protect as much natural vegetation that remains to ensure their survival and recovery.

Changes in raptor occurrences are crucial indicators of the ecological health of an ecosystem. As apex predators, raptors are badly hit by a loss of species abundance at lower trophic levels. Sensitive to habitat change, the disappearance of black harriers gives us an idea of the state of the natural habitat and its level of degradation. The protection of black harriers and the habitat on which it so desperately depends leads to the protection of many other species. Call it a trophic cascade, or domino effect.

A great part of the West Coast of South Africa remains rich in unspoilt natural coastal environments that should not be given up to mindless, ruthless and short-sighted mining activities. The current state of the black harrier is an urgent cause for concern and reason for alarm. Every single adult lost has a detrimental impact on the total population size. PTWC aims to protect this iconic and special species and ensure its future survival through the protection of its vital habitat and core breeding area within the last remaining natural areas along the West Coast of South Africa.

To help us protect these magnificent creatures’ habitats from mining destruction, please donate to our cause HERE.

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