Our Burning Planet

INFERNAL FOOTPRINT

Boomslang or bust: After the fires, Knysna battles rampant mice and lingering alien vegetation

The Knysna Lagoon as seen from Brenton-on-Sea on 29 November 2021, four years after the devastating fires. The lagoon is one of the most prominent landscape features in the greater Knysna area. (Photo: Gallo Images / ER Lombard)

More than four years later, nature is starting to return to (a new) normal. Fynbos and honey bees are flourishing; owls and some other animals are taking longer to return to their habitat.

The Knysna fires that ate their way through a chunk of the coastal Garden Route in 2017 had a devastating impact on southern Cape life, and the spheres of tourism, insurance, job creation and timber production were among those hardest hit. But, unless you live there, you probably wouldn’t have heard of the phenomenal explosion in the numbers of the extremely cute four-striped grass mouse.

“Sjoe, there were so many mice here in the summer of 2019 that many residents were catching and putting them in large bins, to be taken to the snake park,” says Brenton-on-Sea resident Hanlie van Rooyen.

A Pretoria psychologist in her previous life, Van Rooyen says there has been an explosion in the population of the rodent, officially known as the four-striped grass mouse, which occurs throughout southern Africa, ever since the devastating fires that swept through the region in 2017, when people were evacuated off the local beach.

Fires rage at Longmore Forest in Knysna on 7 June 2017. More than 10 000 people were forced to flee their homes overnight as fires fuelled by storm winds ripped through the Western Cape coastal town. (Photo: Gallo Images / Die Burger / Werner Hills)

Consequences

“I heard it’s because the snakes, their natural predators, were killed in the fire.” Not to mention mammalian predators such as caracals, and raptors driven away by the heat and violence of the inferno.

The snake numbers took a big hit, says Cobus Meiring, the Wilderness-based chairperson of the Southern Cape Landowners Initiative, a public platform for landowners and land managers with an interest in the control and eradication of invasive alien plants. “I used to get boomslang in my kitchen,” says Meiring, “but no more, not since the fires.”

A forest smoulders after wildfires ravaged Plettenberg Bay and Knysna on 8 June 2017. (Photo: Gallo Images / Die Burger / Jaco Marais)
The 2017 wildfires in Plettenberg Bay and Knysna left seven people dead and destroyed thousands of homes. (Photo by Gallo Images / Die Burger / Jaco Marais)

If we use as a “snake barometer” a Knysna-Plett Herald article dated March 2018, which noted that Knysna’s emergency services responded to a similar number of snake call-outs in Greater Knysna “between September 2017 and February 2018” to the previous year, we might think that maybe the fires didn’t have such a negative effect on the snake population.

Although it would be hard to believe anything survived, given the speed and ferocity of the inferno that melted car engines and razed homes across 16,000 devastated hectares.

Four years later, evidence of the fires that devastated Brenton remains in the stark and blackened eucalyptus (gum) trees. Gums are needed to feed bees which pollinate new crops. (Photo: Angus Begg)
Eucalyptus (gum) trees left blackened by the fires. (Photo: Angus Begg)

Snakes and drongos

Indeed, beekeeper and honey manufacturer Owen Williams, who lives at the crest of the hill between Brenton-on-Lake and Brenton-on-Sea, confirming Meiring’s observation, says he and his partner, Christa le Roux, saw “absolutely no snakes” for almost three years.

“Boomslang numbers must be down in the semi-urban context,” says Meiring, adding that wildlife numbers are affected by more than the fires. “There is food aplenty with rats and mice all over the show, surviving in the dunes.” Yet in those dunes, he says, there are no longer snakes reported, “because all the milkwood, coastal forests and dune habitat sustaining them have been removed as a result of development”.

He refers to the rapidly increasing urban development as “the concrete highway to Plett”.

Owen Williams, Christa Le Roux and Zach Appolis, the beekeeping team at Honeychild. (Photo: Angus Begg)

Relatively removed from construction of any sort, deep on the other side of the N2 from Meiring’s Wilderness home, in between the Rondevlei and Swartvlei lakes, former safari guide Tim Carr didn’t notice much change in the snake population around his home after the fires. Carr runs an eco-reserve dedicated to rewilding, a low space that was caught between the fires that raged along the coastal dunes immediately south of his tranquil home, and immediately north, along the inland mountains. “What I did note after the fires,” said the one-time Phinda game ranger while on the phone to me in Knysna, “was that about 20 fork-tailed drongos began hanging around my beehives”.

It made perfect sense. I had been observing drongos from my Knysna holiday balcony every morning and evening darting from their perches on tree branches and performing their acrobatic manoeuvres in pursuit of insects. For four months after the fires, there were no insects in Knysna, so the drongos appear to have adapted, with some finding Carr’s beehives a source of food.

Carr, who also freelances as a birding guide, is well known to Williams, who has some hives in the coastal fynbos, a falcon’s swoop to the dunes in the south. But Williams’s close focus is on his bees (he says 600 hives were burnt in the fires) and his immediate natural environment.  

The green is back, four years after the 2017 Knysna fires that forced the elderly to be evacuated from the beaches below. (Photo: Angus Begg)
Boomslang numbers are said to be down after the 2017 fires, and there has been an explosion in mice. (Photo: William Warby/Flickr)
Owen Williams has seen only one puff adder since 2017. (Photo: Bernard Dupont/Flickr)

Return of fynbos and mammals  

“Only later in 2018 did we see any mammal life in Brenton-on-Sea – a very friendly genet. The collective community opinions were that all mammal and reptile life had been eradicated.”

Then, in the summer of 2019, he says, they noticed a sudden boom in striped field mice, with a concurrent “beautiful increase” in birds of prey, rattling off a list including forest buzzards – “even here in the coastal fynbos” – jackal buzzards, steppe buzzards and black-winged kites. Williams says, with a note of amazement reserved for an epic sunrise or sunset, that in June that year, when returning home at about 7pm, Le Roux saw a female caracal and two kittens in their driveway. Beyond his bees, this Simon’s Town-born beekeeper is passionate about all parts of the environment, working to make a sustainable, healthy whole.

A fork-tailed drongo. (Photo: Supplied)

“The fynbos began to flourish, along with the honeybees and endemic pollinators.” Apparently they noticed a big increase in bushpig and bushbuck prints on the nature trail on their property. He says the snakes were still on his mind.

“Things continued to improve in nature, and from June 2020 we made an arrangement with the snake-removal guys of the Knysna Fire Brigade that any endemic snakes they removed from either Brenton-on-Sea or Brenton-on-Lake would be brought here. We then take the snakes and let them loose in the fynbos below the house.” Nevertheless, in this summer of 2021/22 Williams says they have only just seen their “very first free-roaming puffie [puff adder] since 2017”.

A four-striped grass mouse. (Photo: Derek Keats)

Mouse explosions and poison

He and Le Roux refer to the mouse explosions (there were a few) of 2019/20 as “next level”, describing mice “climbing up walls, everywhere… we moved the fridge and washing machine away from the walls so that the dogs could get them.”

“People were making homemade, humane mouse traps with buckets and plankies [sandwiches] smeared with peanut butter”, says Van Rooyen. “At least there are fewer mice now.” But she says Knysna and apparently the “entire Garden Route” is still infested with rats, providing what she terms “the pest-control poison monsters” with a field day.

“They claim their poisons are eco-friendly… but eish, my @#$&, seeing the poisoned mice and rats taking so loooong to die was ghastly.” And that, of course, would have decimated the owl and raptor population, because mice and rats form a substantial part of their diet.

“We always used to have owls, but no more. During the height of the mouse epidemic we had so many buzzards over Brenton, but they left too,” says Van Rooyen. She sends me a video she took of a heron standing by the roadside, convulsing, in clear distress, after eating what she and Williams presume was a poisoned mouse or rat.

“Ja”, says beekeeper Williams, “maybe the birds ate mice killed by rat poison put out by residents.” Le Roux says the absence of nesting sites for the raptors is likely to be the reason for the decline in their numbers.

A bushbuck named ‘Freddie ‘ by Owen Williams and Christa le Roux, on account of his regular visits. Le Roux says he was one of the first returning mammals after the fires. (Photo: Christa le Roux)

Scenarios

So the scenarios put forward for the boom in the number of striped mice are limited: a snake population – the rodents’ chief predators – devastated by the 2017 fires and only slowly recovering; poison put out for the mice consumed by (and thus killing) raptors; and an absence of nests for the raptors, in trees licked by the flames. But that was then.

When I bumped into a few striped mice on the lookout deck above Storms River two weeks earlier, watching children interact with them to their parents’ delight, I had no idea of the ruckus they were causing up and down the Garden Route.

Slowly, says Williams, who has a nature trail through the fynbos on their property, the snakes have started returning. “About three weeks ago we saw the first juvenile [puff adder] since the fires on our property,” he says. “The other morning, at about 5am, we saw a giant eagle owl sitting on the swing I built for Christa and my daughter – the first owl in a very long time.” DM168

Sidebar: Knysna’s Featherbed Nature Reserve: an exercise in restoring biodiversity

The fires that swept through the Garden Route and raged for about 10 days from 7 June 2017 destroyed almost 20,000 hectares of the region and, at Featherbed, reduced most of the vegetation to ashes, with 95% of it burnt.

Aerial photos of the reserve taken in the days after the smoke cleared reveal a largely charred landscape with only a few small portions of indigenous forest left standing.

This was no surprise, says Knysna horticulturist and author Martin Hatchuel, since multispecies, evergreen, indigenous forests are always the most fire-resistant habitats in the regions where they occur.

New shoots

Despite nearly everything being razed, the reserve started to notice that new seedlings began sprouting within weeks of the inferno.

“They looked magnificent.” Hatchuel says the bad news, however, was that in large areas of the reserve, the greatest number of seedlings that were germinating were those of the rooikrans or red-eye wattle (Acacia cyclops), which is an invasive alien that is a particular threat to the fynbos of the Western Cape.

Although the fires had killed almost all of the old rooikrans, “they also burnt the fynbos that had survived the onslaught of the invasive aliens”.

This veteran Knysna resident and “hort” – the nickname horticulturalists give to themselves – says because the good rains after the fires encouraged rapid germination of the rooikrans, as well as other exotic species, he set about the rehabilitation of the reserve with a team of 14 workers.

Acacia cyclops, commonly known as coastal wattle, rooikrans or rooikrans acacia, is a coastal shrub or small tree in the family Fabaceae. Native to Australia, it is distributed along the west coast of Western Australia as far north as Jurien Bay, and along the south coast into South Australia. (Photo: Wikimedia Commons)

In hindsight, they had realised that “six months after the burn was in fact just the right time for the team to begin its work – because by now [mid-summer] the seedlings had reached a workable size, and they were thus both easy to identify, even from a distance, and easy to grip and remove”. They covered every inch of the steeply sloped reserve that they could get to, working in blocks of 900m2, using a tool Hatchuel says was invented in South Africa for the purpose: the Tree Popper.

During the process, Hatchuel says he marked out a square-metre test plot, and personally pulled out and counted every one of the seedlings he found there – there were 217. “Two hundred and seventeen seedlings times 900m2 equals 195,300 future rooikrans trees.”

Fourteen people pulled 195,300 invasive rooikrans seedlings out of one, steeply sloping, 900m2 block of land in less than a single morning. That’s the labour-intensive task of restoring biodiversity after a fire. DM168

This story first appeared in our weekly Daily Maverick 168 newspaper which is available for R25 at Pick n Pay, Exclusive Books and airport bookstores. For your nearest stockist, please click here.

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  • Great article. None of those so called eco-friendly rat poisons are really eco friendly. The answer is to put up several owl roost poles of 3 m high with a simple T-piece top latte. Also one must NOT let rats and mice get to any food, particularly chicken feed. You will get owls using the perches in the evening. An owl will catch many mice or rats in an evening. Our farm was partly burnt in the 2017 fires. We had an invasion of rats afterwards. The owl perches made a huge difference. At night we often hear the owls calling to each other.

  • In the Eastford area the snakes have made a great recovery. Some very large boomslang seen and caught by snake catchers and night adders aplenty. Mouse numbers much lower this year.

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