White Shark Tale | Brand New Ecoregion | ‘Junk Food Fodies’ | Hiking and Hill-babblers
South Africa’s White Shark Population is ‘Contracting From the Edges’
A group of scientists has challenged the findings of a study last year that suggested the great white shark population in South African waters was stable, and had migrated east in response to predation by orcas in their traditional strongholds.
The scientists led by Enrico Gennari, director of Oceans Research, state that the decline in white shark sightings in their key habitats of False Bay and Gansbaai, in the Western Cape, began in 2011 and 2012 respectively – before the orca duo known to researchers as Port and Starboard were recorded making their first white shark kills in 2017.
If white sharks had moved east en masse, more of them would have been caught in bather protection nets in South Africa’s Kwa-Zulu Natal Province, which is the sharks’ easternmost range, Gennari and his colleagues argue. Instead, shark-net captures there have been going down since 2015.
That, and the decline in white shark sightings in the west "might be more consistent with the hypothesis of a population decline contracting from the edges of its distribution,” they warn.
The team behind last year’s study has not responded publicly to this critique of their work. It’s likely they’ll stand by their findings.
At least one of the shark-hunting orcas is now able to kill white sharks without the need for a hunting partner or pack, according to a recent study, meaning more pressure could be facing South Africa’s white sharks.
The last population estimate 20 years ago put white shark numbers in South African waters at fewer than 2,000 individuals. An up-to-date survey, encompassing the entire coast is needed, experts say.
A great white shark breaches the surface of False Bay | @chrisfallowsphotography
New ‘Ecoregion’ Defines Boundaries of Biological Treasure Trove
A group of scientists has documented dozens of unique species of plants and animals in what they say is a threatened ecological region, or ecoregion, in southern Malawi and northern Mozambique.
The team has named this ecoregion the South East Africa Montane Archipelago. It is distinguished by isolated granite mountains known as inselbergs, whose high-altitude forests and grasslands have been separated from each other for millennia.
But those habitats are now threatened by deforestation and frequent fires, risking the extinction of species before they’re even described by biologists. Already, this ecoregion is known to harbour 217 species found nowhere else on earth. They include 127 plant species, and 90 species of amphibians, reptiles, birds, mammals, butterflies, and freshwater crabs.
Since the researchers began surveying the region in 2004, the area has lost around 18% of its primary forest cover. Some sites have lost nearly half their forests.
The research team believes that the recognition of this treasure trove of biodiversity as a distinct ecoregion will promote coordinated conservation efforts.
“Through looking at the geology and the climate we’re able to draw a boundary around these 30 mountains and what that does is it provides an entity for management prescriptions; it is an entity that now exists through which you can then apply for funding for conservation,” Julian Bayliss, lead author of a new study describing the ecoregion, told me.
The Worldwide Fund for Nature currently recognizes 867 Terrestrial Ecoregions of the World.
Mount Namuli, one of the 30 mountains within the newly-defined ecoregion | Julian Bayliss
Endangered Mauritian Songbirds Face Junk Food Threat
The Mauritius fody is a small yellow weaver bird that came close to extinction in the 1990s due to habitat loss and introduced rats and crab-eating monkeys, or macaques, that ate their eggs and chicks.
Although still endangered, the birds have been brought back from the brink of extinction, and their population has stabilized at around 220 individuals, according to BirdLife International. It’s thanks in large part to the work of conservationists from the Mauritian Wildlife Foundation (MWF).
One of the MWF’s strategies was to hand-rear fody chicks and release them on Isle aux Aigrettes, a tiny island lying a few hundred meters off the south-eastern coast of Mauritius that is predator-free. Now, however, the birds are facing a new threat: junk food.
The birds have recognized that when tourist boats arrive at the island, visitors will bring food with them and toss scraps for the photogenic fodies to feed on.
Both the male fodies, which have bright red heads and chests, and the females have been observed abandoning their nests and their chicks to go in search of a junk food fix, according to the MWF.
The birds typically eat fruit and insects and getting the wrong food “could cause health conditions, and even deaths of these birds or disturbance to breeding behaviour,” the MWF says in its newsletter.
MWF staff have asked boat skippers who visit Ile aux Aigrettes to tell their passengers not to feed the fodies.
A Mauritius fody on Ile aux Aigrettes | Charles J. Sharp | Wikimedia Commons
Nature Notes: A Detour to Remember (on a recent trip to Angola)
Descending from the summit of Mount Moco onto a grassy plateau, we notice a forest patch we hadn’t seen on the way up.
We take a closer look, despite the 40-minute delay this will inevitably cause us, and the approaching thunderstorm that will soon drench us.
Sunbirds flicker between protea shrubs and tree branches. We spot an Angola slaty-flycatcher skulking in the shadows. The large, moss-coloured trunks begin to sway and creak.
A torrent of sweet notes announces the arrival of an African hill-babbler. It perches in low tangled branches at the forest edge. My scientist companion, crouching in the grass, gets some good photos.
The hill-babbler is a dainty bird, with a grey head and breast and chestnut wings. It’s a type of warbler, from the same family as the common whitethroat.
Its patchy distribution is that of the evergreen mountain forests it lives in, from Ethiopia to Malawi and across southern DRC to ones just like this, on the slopes of Angola’s highest mountain.
