The vanishing Scaly Ground-roller, a handsome version of a thrush, is seen only by the most intrepid birders in Madagascar’s “biodiversity mirage” forests.
By Rex Graham
In the most undisturbed remnants of forest habitat in northeast Madagascar, a 2008-2013 survey using motion-activated cameras determined that the ground-roller had the “lowest probability of occupancy across the landscape,” but better odds in undisturbed areas. However, it also has been seen in some secondary forest areas recovering from tree-cutting, and edges of undisturbed forest, so the glimmer of hope is slightly brighter.
The islands remaining ground-rollers are being eliminated where feral cats are found. The introduced predator also kills many other Madagascar birds, wild carnivores, tenrecs and lemurs. Feral or domestic cats are thought to have caused at least 14% of global mammal, avian and reptilian extinctions, and are primary threats to 8% of critically endangered species, according to a study in Global Change Biology.
One scientific survey at the Marojejy Strict Nature Reserve, one of Madagascar’s most important rainforest reserves, only two of the plump, long-legged birds were observed. A larger study of 2 breeding seasons at Masoala National Park, one of the world’s biodiversity hotspots, revealed 3 territorial stream-side digger of nesting burrows in undisturbed dark areas with large trees. This habitat in Madagascar is a remnant of the island’s former fauna glory.
This ground-roller may live in low-light conditions, but that hasn’t stopped it from evolving extravagant patterns and colors based on artistic combinations of melanin pigments. It has white, brown and black scaled feathers on its head and underparts, and a bronzy-green back. It’s outer tail feathers are tipped with sky-blue, a structural-feather-color feature. Both sexes look alike, including an orange-pink eye-ring and patch behind.
It is a sit-and-wait forager. Like many thrushes, it likes earthworms and centipedes. Indeed University of Oxford (U.K.) scientists reported that two Scaly Ground-rollers “stood motionless before running a few steps to catch prey by turning over leaves, rummaging in thick leaf-litter or investigating logs; one also pulled up worms from the forest floor.” The description was reported in Bird Conservation International.
Just to clarify, this ground-roller is classified on a branch of the taxonomic tree of birds that is far from the thrushes’ branch, but the Scaly Ground-roller and many thrushes are earthworm specialists of deep woods.
Last stand for Scaly Ground-roller
Andasibe-Mantadia National Park has been described as “the very best place in the world for ground-rollers,” by Birding Africa, an Africa-based birding tour company. The Scaly, Pitta-like, Rufous-headed and Short-legged Ground-rollers are seen at the park.
Masoala National Park was reported to have up to eight pairs of Scaly Ground-rollers, according to the latest online edition of Handbook of the Birds of the World. Slash-and-burn agriculture and logging hurt the species, but it may not be restricted only to primary forests.
I believe that the more that people spend watching, enjoying and photographing Scaly Ground-rollers, the better for the species, all birds, all wildlife and all humans.