‘Sky Island’ Snails | Dung-Dining Tortoises | Malagasy Trees | Ode to Lucky-Beans
‘Sky Island’ Snail Survey
A survey of nearly 14,000 snails in northern Kenya has revealed at least 75 species, including six carnivorous “hunting snails” that are new to science, living in the region’s “sky islands”.
Many of these snails are found nowhere else on earth, and some are unique to each of four “sky islands” — forest-capped mountains created by ancient geological activity that pushed them high above the surrounding plains.
But the authors behind the study in the African Journal of Ecology also reveal the extent of forest losses on these mountain “oases” that could threaten the molluscs that live there.
The moist cool air captured at the summits of the sky islands sustain forests, including juniper trees and yellowwoods. These create the perfect habitat for the snails that would stand no chance of surviving in the hot, dry semi-desert below.
Out of the four sky islands surveyed only Mount Marsabit — an extinct volcano — is formally protected and has 87% of its original forests intact.
Mount Kulal — another extinct volcano and a UNESCO biosphere reserve located east of Lake Turkana — has lost 95% of its original forests. In an indication of how rich in snail life it is, the fraction of forest that does survive sustains nearly the same percentage of endemic snails as Mount Kenya, around 300 kilometres (186 miles) to the south.
The other two sky islands — Mount Nyiro and the Ndoto mountains — retain just 17 and 11% of their original forest cover, the authors of the study say.
"It is not known whether these changes [in forest cover] have led to any mollusc extinctions in the region,” they state, “but they are certain to have reduced the area of habitat for forest [-dwelling groups of snails]."
The high number of unique species found on each of the mountains, “adds to the forests' conservation value,” they add.
Mount Marsabit, northern Kenya | Filiberto Strazzari | Flickr
Tortoises in the Kalahari Eat Hyena Dung to Strengthen Their Shells
Kalahari desert soils are known to be very poor in nutrients, and so are its grasses. This leaves vegetarians like tortoises in a quandary.
Where do they get minerals like calcium and phosphorus to grow and strengthen their shells?
Thankfully, help is at hand, courtesy of the region’s hyenas, who conveniently deposit their dung in communal latrines or middens that leopard tortoises were documented eating from. And, because hyenas are bone crunchers, their dung is full of bone fragments that tortoises have the time and patience to pick out.
These are the findings of a group of researchers at Tswalu Kalahari Reserve, a private wildlife reserve located in the far north of South Africa where the Kalahari desert extends into the country from neighbouring Botswana.
The team set up camera traps at a number of middens to detect leopard tortoises coming to dine on dung deposited by both brown and spotted hyenas.
They captured eight videos of one or more tortoises visiting the latrines, and made direct observations of tortoises eating hyena dung on another four occasions. The team acknowledges that tortoises likely visited the latrines a lot more – but didn’t always trigger the camera traps because they move so slowly.
Tswalu is a managed reserve, and throughout the year artificial blocks of minerals are put out for wild animals to lick to supplement their diet with key nutrients.
These licks were also frequently visited by the tortoises, sometimes five at a time, though the visits were fraught with risk because of the other animals congregating there.
One of the camera trap videos captured the moment a tortoise was nearly trampled beneath the hooves of a giraffe.
A leopard tortoise | Charles J. Sharp | Wikimedia Commons
Ten New Tree Species Identified in Madagascar — Some Face Extinction
Researchers have described ten new species of Turraea trees and shrubs from parts of Madagascar threatened by fires, shifting agriculture and sapphire mining.
Out of the 10 new Turraea species, two are listed as critically-endangered; three as endangered and three as vulnerable to extinction. One of the critically-endangered species is T. bardotiae, more of a shrub than a tree, that grows in cracks in limestone in the Ankarana massif, northern Madagascar.
Despite its protected status, the massif has been heavily mined for sapphires and is subject to wildfires, the researchers state in the journal, Adansonia.
Another critically-endangered species is T. sambavensis — a small tree that produces sweetly-scented, sulphur-yellow flowers and grows in coastal forests in the north-west of Madagascar. It was known from just two unprotected areas, which are now threatened by logging, firewood collection and palm oil plantations.
The samples used to describe this tree as a new species were actually collected in 1966.
The trees haven’t been observed since and, the authors say, could now be extinct.
“Several of these new species have a very restricted range as is often the case in Madagascar explaining their threatened status,” one of the researchers told me.
“For several of those new species, forests where they are restricted are under lots of pressure or already gone.”
There are 68 species of Turraea found in both continental Africa and Madagascar, and their pretty flowers aren't their only attributes.
Some of the African species are known to be rich in curative compounds known as limonoids, and a 2015 study found extracts from two species were effective against malaria parasites and some cancer cells.
Ankarana Reserve, northern Madagascar | Lemurbaby | Wikimedia Commons
Nature Notes: Ode to the Lucky-Bean
At this time of the year in Zimbabwe, the lucky-bean trees are full of flowers. They form splashes of scarlet against the golden brown winter landscape.
Their colour is accentuated by the trees’ dark bark and branches stripped bare of leaves.
In Harare’s Haka Park, where I took the picture below, the flowers also provide welcome seasonal nourishment to the resident giraffes.
I asked a botanist friend if there was an established relationship between giraffes and lucky-bean trees, like there is between giraffes and their most important food source – Acacia trees. The botanist thought not. Giraffes didn’t occur historically in this part of Zimbabwe, she pointed out, so their feeding on the flowers of the lucky-beans is likely only due to the absence of their normal “high-quality” Acacia food.
The flowers aren’t the only standout feature of the lucky-bean tree. There are its knobbly pods containing their distinctive red and black seeds — the eponymous “lucky-beans” that children invariably find so fascinating.
These seeds are actually reported to contain a highly toxic chemical which, if injected into the bloodstream, would be lethal. Botanists assure us, though, that the seeds aren’t harmful if handled or accidentally ingested whole.
Maybe that’s why they’re called lucky-beans.
