Fearless drongos | Hyraxes need help | Rare lizard rediscovered | ‘Birds on the moon’
You can't fool a fork-tailed drongo (not if you're a cuckoo)
A new study shows that while cuckoos are really good at disguising themselves as hawks to spook their hosts and grab space in their nests, they've met their match in southern Africa's fearless fork-tailed drongos who refuse -- sometimes violently -- to be taken in.
3D-printed models of African cuckoos (whose barred breast feathers and yellow eyes make them hawk lookalikes) and little sparrowhawks, were presented at dozens of cup-shaped drongo nests in northern Zambia.
A control model of a harmless dove was also presented. The response was always the same, the drongos attacked both hawk and cuckoo models, in one instance decapitating the hawk model.
Aggression levels decreased later in the nesting cycle, when parasitism by cuckoos was no longer a threat, suggesting the drongos were treating the hawks as cuckoos, and not cuckoos as hawks.
Despite the threat of injury faced by the cuckoos when they lay their single eggs in a drongo nest, the benefits are enormous.
Nestling survival among drongos was far greater than co-occurring species such as dark-capped bulbuls and black-crowned tchagra-shrikes, the study found.
The two latter species (which aren't parasitized by African cuckoos) were tested for their response to the presence of the sparrowhawk models. They showed none of the aggressive instincts of the drongos, proving the cuckoos' choose of host right. Drongos make formidable adversaries, but excellent foster parents.
Deforestation in Kenya causes tree hyraxes to go terrestrial
A relic population of eastern tree hyraxes – a species distantly related to elephants, sea cows and elephant shrews – has been discovered living in limestone caves on the coast of Kenya.
It’s believed the small, stout, furry mammals, which are classified as “near-threatened with extinction”, have resorted to the caves in response to the clearance of coastal forests.
The caves, which are populated by bats, are considered sacred to the local Giriama community. Their surrounding trees, therefore, have been left mostly intact.
But one of the three sites surveyed by a group of researchers is earmarked to become a limestone quarry. The team believes that if it goes ahead, the quarry will extirpate the tree hyrax population there.
Tree hyraxes are non-migratory: they are incapable of migrating to other forest patches if they are more than 1.5 kilometers (less than a mile) away, hence the need to safeguard the current sites.
The research team has called for a reassessment of the species by the International Union for Conservation of Nature, not only to update its geographical extent of occurrence, but also to assess the threats it is facing in these areas.
“Effective conservation of the tree hyrax requires the protection of all remaining fragments of natural forest in the region,” the authors note.
“Mining at these sites should be prevented.”
An eastern tree hyrax pictured in Mbole, Tanzania | Valentin Moser | Wikimedia
Rare lizard rediscovered in South Africa is likely to be listed as threatened
A rare lizard – the orange sandveld lizard – has been rediscovered in South Africa’s Western Cape Province for the first time in a decade.
Conservation group, the Endangered Wildlife Trust, made the discovery during a survey in the Lambert’s Bay area in December.
Lambert’s Bay is a farming district, and prospecting rights have recently been granted for mining too. So, gathering data on the lizard is seen as imperative.
Currently the lizard is classified by the International Union for Conservation of Nature (IUCN) as “data deficient”.
If a species is data deficient, it doesn’t trigger red flags when Environmental Impact Assessments are done for developments in its habitat. An IUCN listing would help with its conservation.
The orange sandveld lizard is one of 10 South African reptile species currently deemed data deficient. “This exclusion leaves these species vulnerable to extinction before we can understand their ecology, habitat requirements, population dynamics, and threats,” the EWT said.
Given its scarcity and the transformations happening in the only area where it is found, the lizard is likely to be uplisted to one of the threatened categories on the Red List kept by the IUCN: Critically Endangered, Endangered, Vulnerable, or Near Threatened.
Nature Notes: Butterflies and ‘moon birds’
The two butterflies pictured below look so different they were once thought to be separate species. In fact, they’re the same species -- the gaudy commodore.
The one on the left is the “wet season form”. I saw one dancing around a wooded rocky hillock near the Ewanrigg Botanical Garden, north of Harare. It landed near me and sat with its wings obligingly open on the woodland floor.
The photo on the right is the “dry season form”. I saw it one winter’s morning in Mutare, in Zimbabwe’s Eastern Highlands.
These stark differences are what lepidopterists refer to as “seasonal dimorphism”.
I posted about this on Facebook a while ago, and one of my friends had this to say:
“Somewhat relatedly, I listened to a fascinating podcast about animal migration. One of the old theories was that the birds transformed from one type (seen in winter) to another (seen in summer). Which is sort of what your butterflies are doing, so not such a crazy notion after all. Two other theories -- that the birds turned into fish and hibernated in the water, or that they wintered on the moon. Sadly, both of these turned out not to be the case, but they are rather lovely thoughts.”
The gaudy commodore, in its two seasonal forms, Zimbabwe | Ryan Truscott