Great slaty woodpeckers are mostly seen in groups consisting of 3 to 6 individuals, which consist of a breeding pair and their young from prior years. Groups often forage on shared feeding sites in the form of nests of social insects such as
ants,
termites, wood-boring
beetles and
stingless bees. Ants seem to be generally favored in the diet, though larvae of other species may be eaten quite regularly as well. Occasionally, small
fruit may supplement the diet. Females spend more time searching for feeding sources and males, which have slightly larger bills, spend more time opening the sources. Preferred feeding sources are mostly found in large branches or trunks of large, living trees. The groups will travel considerable distance to access these trees and, as such, the home ranges of the species are quite large. Occasionally, though, they will feed at lower levels in trees and even amongst saplings. Usually, feeding groups of these woodpeckers do not linger in any given area for long. Sometimes this species associates with slightly smaller
white-bellied woodpeckers and considerably smaller
greater flamebacks, with the foraging methods of the very different woodpeckers minimizing competition between the species. Perhaps more considerable competition for food sources generally comes in the form of
hornbills and arboreal (or tree-dwelling) mammals. The great slaty woodpecker usually works a tree upwards and, though capable of swifter movements, has been described while foraging as if moving in "slow motion". It forages by gleaning, probing, pecking, prising off bark and hammering with powerful and loud blows to excavate the wood. Gleaning is the most important foraging method for the species, with the long neck and bill allowing it to reach out over a considerable distance into the cracks and crevices of trees. This species often flies high over the trees for long distances between successful foraging patches. In flight, its feather rustle noisily. The great slaty woodpecker usually engages in less dipping than other woodpeckers and flies in a mixed flying style described as quite
crow-like. Like all woodpeckers, breeding pairs roost in separate tree holes but regularly vocalized to stay in contact. The pair bond appears to be lifelong. These woodpeckers engage in displays, largely for territorial purposes. Displays include head-swinging, where the appears to lag behind the body in swinging movements, whinnying calls and widen their wings and tail considerably. Few nests of the species have been described in detail, but at least occasionally nests are raised cooperatively by groups. Known nests, at anywhere from in height in the trees, were located in very large trees. When excavating the nest hole, both parents participate but reportedly the male does the majority of the work. The nest hole entrance will be around across, but much wider inside the tree. The pair will only use a nest from a prior year if competition is too overbearing for a newly constructed hole. The nesting season, in
Malaysia at least, appears to be from March to August. The clutch reportedly consists of two to four eggs, which are incubated by both parents. Both parents also feed and generally brood the young. The young great slaty woodpeckers probably stay with their parents until the next breeding season. ==Status==