Turning the tide for African grass-owls

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The African grass-owl faces an uncertain future, but ongoing conservation initiatives and education campaigns are hoping to bring positive results. For years the African grass-owl (Tyto capensis) has flown below the radar of conservationists and researchers. As a result, very little was known about the ecology of this species. However, since the inception of the (EWT) African Grass-owl Project just over 10 years ago, they have gained valuable information about this threatened ground-nesting nocturnal hunter.

Finding them is not easy as they are secretive habitat specialists, occurring only in isolated pockets
of land, with the core of their distribution falling on the Highveld region of South Africa’s Gauteng and Mpumalanga provinces. Their habitat consists of marshes and wetlands usually associated with the presence of imperata grass. These are also high-risk areas as one of the biggest threats in grasslands is fire, especially in autumn and winter when the grass is dry. Apart from fire, land use transformation and habitat loss and fragmentation associated with mining and agriculture is still the most pertinent threat to the species. All of this contributes to the loss of more than 60% of the nesting habitat on the Highveld alone.

The owls breed between December and April. Their secretive nature means they rarely leave their nesting tunnels or roosts until danger is upon them. In addition to fire posing a risk to the owls and their chicks,
it also destroys the small isolated pockets of habitat that are still intact. “Grass-owls use the same patches
of grassland to nest, but do not use the same nests and will protect their breeding territory for a number of seasons,” says Rebotile Rachuene, African Grass-owl Project field officer at the EWT’s Birds of
Prey Programme.

Many of the owls are found on private land, says Rachuene, and the EWT works closely with landowners to create awareness around the species. “Many landowners are not aware they have grass-owls on their property, or that they have the perfect habitat for them,” adds Rachuene. In many cases, mining companies also approach landowners first to purchase a property, so education is key. Other major threats are draining/degradation of wetlands, development, and invasive plants, as in the case with areas like Kyalami, Midrand in Gauteng, where there is a small population. Disturbance from livestock trampling through the grasslands also has a negative impact on the owls, which regularly abandon sites in the presence of livestock.

African grass-owls nest on the ground in grasslands

Photo: Rebotile Rachuene

As part of the project, the EWT has deployed lightweight trackers on seven owls to get a better understanding of their movement patterns. They found that these owls hold very small territories, with average home ranges of around 420ha, and depend heavily on fairly pristine habitat. The EWT also used remote nest cameras to monitor breeding and investigate predation in the species.

From this, they have learned chicks fledge when they are between seven and eight weeks old, and remain on their patches for several weeks before dispersing for good. “We don’t know anything about the dispersal patterns and survival of the chicks yet, or the age at which they start breeding. We therefore initiated the colour-ringing project for the chicks in the 2016/17 season,” explains Rachuene. The team has ringed 27 chicks, but 10 were retrieved after dying as a result of fires and predation.

“We know this will work and give us some valuable information in the long run, and have resighted three chicks so far, one of them in February,” explains Rachuene.

african grass-owl next and eggs

Photo: Rebotile Rachuene

“The future of the species is uncertain if current threats and pressures are not urgently addressed,” he adds. He hopes that education and continuous community engagement will show landowners the benefits of having wetlands and grass-owls on their properties and in this way ensure everyone works together to protect not only the owls, but other wildlife too, especially in the Highveld areas.

African grass-owl facts

  • 12: The number of owl species in South Africa.
  • 2: The number of ground-nesting owls in South Africa: the African grass-owl (Tyto capensis) and the marsh owl (Asio capensis), which often shares its habitat with the African grass-owl.
  •  4–5: The average number of eggs laid in a grass-owl clutch during peak breeding time.
  • 10: The number of vlei rats an adult grass-owl can bring to the nest in a single evening.
  • 80: The number of nests found since the initiation of the project, about 50 different territories.

Written by René de Klerk

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Main: A mature grass-owl leaves its nest. Left: Grass-owl chicks in their nest burrow. Photos:

and Rebotile Rachuene

 

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