The breeding ecology of the Agulhas Long-billed Lark: an endemic bird dependent on the remnant Renosterveld of the Western Cape Province, South Africa

Abstract

The Agulhas Long-billed Lark Certhilauda brevirostris is restricted to the Agulhas Plain, South Africa, a region extensively transformed for crop production and sheep grazing. We present data on nest and egg characteristics, clutch and brood size, parental care and breeding success previously undescribed for this species. During field surveys in 2020 and 2021, 29 nests were located. Of these, 16 were monitored by camera traps. Laying started in late winter (July) and continued until early summer (late November). Most nests (66%) were in Renosterveld, a unique vegetation component of the Fynbos Biome, with the remainder in human-modified landscapes. Female larks were responsible for nest construction and incubation. Both sexes provisioned nestlings, with provisioning rate related to nestling age and time of day but not brood size. Breeding success was low, with only 14% of nests fledging any young. Only one repeat nesting attempt following a predation event was observed, but the attempt was abandoned. Nest predation was the main cause of nest failure, with eight species of nest predators identified. An apparent preference for nesting in Renosterveld highlights the need for protection of this endangered habitat type. As a ground-nesting species in an agriculturally transformed landscape, this lark faces numerous threats associated with habitat loss, altered predation pressure, exposure to pesticides and disturbance at nest sites.