The short-term response of coastal thicket bird communities to fire in the southeastern Cape, South Africa

Fire ecological research within the Cape Floristic Region is largely restricted to fynbos vegetation and, amongst fauna, birds. Nothing is known about post-fire responses of birds in subtropical thicket, which burns on much longer cycles than fynbos. Extensive fires in subtropical thicket along the southeastern Cape coast (in the Knysna area during June 2017) presented the opportunity to assess the response of these birds to fire. We predicted that (1) fire reduces bird species diversity, richness and abundance in thicket during the first two years post-fire; and (2) fire changes feeding guild composition and results in the loss of frugivorous birds. Bird surveys (point counts) were undertaken between 12- and 21-months post-fire in burnt (n =7) and unburnt (n = 7) thicket sites to determine bird community structure and abundance. A total of 66 bird species and 2404 individuals were recorded of which 52 species and 1176 individuals were recorded in burnt thicket and 60 species and 1228 individuals in unburnt thicket. Ten species occurred only in burnt thicket and 13 species only in unburnt thicket. There was a 21% loss of bird species (mainly forest birds) after fire. The Sorenson similarity coefficient was 60% for bird species composition between burnt and unburnt thicket. The most common feeding guilds in terms of richness and abundance in both burnt and unburnt thicket were insectivores and generalists. Frugivores were most abundant in unburnt thicket, whereas granivores were most abundant in burnt thicket. Changes in thicket bird community composition following the fire were minor and are likely to be short-lived as thicket shrubs re-sprout vigorously after fire resulting in rapid recovery of vegetation and thus bird habitat structure.