Fruit-eating Jackals | Serengeti ‘Pushmi-pullyu’ | Ants Disrupting Lions | Dog Diary
Jackals pee on their favourite fruits to stop others finding them
Black-backed jackals, small fox-like carnivores that hunt small prey or scavenge on the carcasses left by larger predators like lions and leopards, will urinate on sweet, juicy melons in the Namib Desert to mask their smell and deter other jackals from pinching them.
The findings are among several made by Namibian researcher Saima Shikesho into the role that black-backed jackals play in spreading the seeds of the !nara plant, thanks to the jackals’ love for the melons.
!nara melons, which can weigh up to a kilogramme, are clad in a tough green spiny skin that doesn’t change colour, even when ripe. That makes it hard to tell ripe fruit apart from unripe fruit. Jackals, however, do it with ease.
During her experiments, Shikesho buried 55 melons, both ripe and unripe, in the sand up to 100 metres away from some of the monitored !nara plants. The jackals found every one of them.
Archaeologists believe that the !nara plant (that exclamation mark denotes one of the clicks of the local Nama language) has sustained human communities in the Namib Desert for up to 8,000 years. Until now, however, it wasn’t clear who or what was responsible for dispersing their seeds across the desert.
Shikesho studied the faeces of jackals, and found 200 seeds in just 8 of them. The seeds germinated more successfully than those extracted directly from ripe fruit. The droppings of oryx, donkeys and cattle, which also consume the fruit, contained none at all because these animals crush the seeds when they chew them.
A black-backed jackal sniffs for ripe !nara fruit | Saima Shikesho
‘Push-and-pull’ across the Serengeti
In The Story of Dr Dolittle, the pushmi-pullyu of writer Hugh Lofting’s imagination was an animal, part gazelle, part unicorn, with no tail but a sharp-horned head at each end.
In Tanzania’s Serengeti National Park, there is another kind of ‘pushmi-pullyu’: not an animal, but a phenomenon. It pushes some animals forwards on migratory routes with finite resources, while pulling others along behind.
A research team says the movement across the savanna centres around three different types of grazers: zebras, wildebeest and Thomson’s gazelles.
Using camera traps, GPS tracking collars and metabarcoding technology – that helps scientists examine animal droppings to learn what they’ve been eating – the team spent eight years studying how these three different-sized grazers moved across the Serengeti during their world-famous annual migrations.
They found that zebras – the heavyweights at around 230 kilogrammes (507 pounds) each, led the pack but were pushed forwards by wildebeest, weighing around 180 kilogrammes (396 pounds) each, following close on their heels.
The wildebeest in turn reduced grass biomass, giving rise to fresh growth that was eaten by dainty Thomson’s gazelles, at just 20 kilogrammes (44 pounds) each, who followed in their wake.
The scientists term it “grazing succession”, with the two bigger grazers competing with each other, but the wildebeest actually facilitating food growth for the gazelles.
“Our study helps to reconcile decades of conflicting results by demonstrating that competition and facilitation operate concurrently during animal migration,” the authors state.
Zebra and wildebeest in Serengeti National Park | David Dennis | Wikimedia Commons
Tiny ant invaders disrupt the hunting patterns of the king of the beasts
Invasive big-headed ants in the Kenyan savanna are wiping out native acacia ants that famously protect whistling thorn trees from elephants -- and it's having an impact on the way that lions hunt.
Whistling thorn trees provide nectar and shelter to several species of acacia ants, also known as Crematogaster ants, which attack and bite potentially-destructive browsers like elephants, giraffes and black rhinos.
A study carried out at Ol Pejeta Conservancy, in Laikipia County, showed that wherever the big-headed ants had killed off the smaller acacia ants, elephants increased their destruction of acacia trees seven-fold, stripping the savanna of cover needed by the lions to ambush zebras.
The lions responded to this alteration by switching their prey to buffaloes, the study finds. From 2003-2020, the proportion of zebra kills made by lions dropped from 67%-42%, while the proportion of buffalo kills rose from 0%-42%.
It’s believed that big-headed ants first invaded Laikipia, central Kenya, in the early 2000s, though their origins are still unknown. Some researchers have suggested they originated elsewhere in East Africa; others suggest Madagascar. The ants advance at an average rate of 50 metres (164 feet) per year.
“We show that the spread of the big-headed ant, one of the globe’s most widespread and ecologically impactful invaders, has sparked an ecological chain reaction that reduces the success by which lions can hunt their primary prey,” state the authors of the study.
Swellings on whistling thorns shelter acacia ants | Pharaoh han | Wikimedia Commons
Dog Diary: Meet Naji, intrepid explorer of Angola’s highest mountain
One of the very few downsides about going off on assignment is having to leave my family… and my dog. So, you can imagine how secretly pleased I was when the manager of the conservation team at Mount Moco, in Angola’s Huambo Province, arrived with seven-month-old Naji.
Like my dog, Naji (pronounced Nudgie) had a habit of putting her front paws up on the table to see what was available to eat, which much of the time was roasted maize cobs.
She accompanied us everywhere, and only once left our sides.
That was when she caught sight of a couple of large bulls with long sharp horns trundling down a path through the middle of Kanjonde Village that we all had to make way for by ducking into nearby maize patches.
Naji? She fled.
Here’s a picture of her guarding the entrance to the field office – a stone-walled hut with a leaky thatched roof that we had to vacate every time there was a rainstorm to take shelter in our tents.
