diagnostics
14-15 cm, 26 g. Sexes alike. A highly localised lark, most often located by its song given during an extended aerial display flight. Distinctive in plumage and morphology, with bulbous head, short thin tail and upright posture; hind-claw spikes straight and long (12-20 mm in length). Attractively patterned on mantle and crown, with dark feather interiors and golden-buff feather edges creating scalloped markings. Crown blackish with a pale creamy line down centre; long erectile crown feathers extend down paler nape. Face plain greyish, with pale band around eye. Breast rich buff, lightly streaked darker. Rest of underparts pale buff to whitish. Tail thin and short with white panels on outer rectrices. Flight feathers dark brown with narrow rufous outer edges, forming dull rufous patch in flight. Wing coverts, tertials and scapulars dark with buff margins. Bill horn to pink with darker patch around nostrils. Eyes grey-brown. Legs and feet flesh-pink. Birds in worn plumage are duller, greyer and less vividly marked. Juveniles are similar to adults (Peacock 2012).
trophic
Even within its restricted range, this specialised species is limited to a particular habitat, determined by a range of biotic, altitudinal, topographic and climatic variables; its distribution is therefore naturally fragmented and highly localised, both temporally and spatially (Barnes 2000). It prefers short, sour grassland on flat or gently sloping plateaus and hilltops at altitudes of 1 700-2 200 m (mostly greater than 1 800 m; Maphisa et al. 2009). It is limited to areas with high rainfall, typically greater than 600 mm per year and in Mpumalanga, 800-1 000 mm per year (Tarboton et al. 1987). Furthermore, Rudd's Lark is virtually restricted to Sandy Highveld Grassland (sensu Low and Rebelo 1996). Dominant grass species within its preferred habitat include Themeda triandra, Tristachya leucothrix, Trachypogon spicatus, Heteropogon contortus and Eragrostis curvula (Hockey et al. 1988). In optimal habitats cover of Eragrostis curvula/E. chloromelas is high relative to Themeda triandra (Hockey et al. 1988).
Rudd's Lark typically breeds in sites with moderately to heavily grazed grass with short tussocks (Hockey et al. 1988), selecting sites with shorter than average grass height early in the breeding season. The species is often most numerous in intensely grazed grasslands, usually with trampled or bare patches, which suggests that high grazing pressure does not necessarily affect the birds adversely, given that it does not lead to heavy invasion of forbs and other non-grasses (Hockey et al. 1988). However, Maphisa (2004) noted that few breeding attempts occur in heavily grazed sites, possibly due to higher predation rates. Indeed, Maphisa et al. (2009) reported that birds were absent from the most heavily grazed sites, and that an increase in the extent of bare ground, possibly due to excessive grazing, may lead to territory desertion. Conversely, territories may also be abandoned if grass becomes too tall and dense. If some open ground for terrestrial foraging remains, birds may remain in grassland up to 40 cm in height (Maphisa 2004).
An absence of forbs has been suggested as an important habitat requirement (Hockey et al. 1988), but pairs do occasionally nest in sites where forbs occur (Maphisa 2004); nevertheless, the presence of forbs (such as spinescent forb Acalypha spp.) may be a sign of deteriorating and overgrazed grasslands (Maphisa 2004). Suitable breeding habitat is maintained by annual burning and heavy winter grazing (Hockey et al. 1988); the latter was likely sustained in the pre-agricultural past by large herds of grazing ungulates, but today mostly by domesticated livestock (Maphisa et al. 2009). As nesting attempts appear to be clustered in the second half of the breeding season (with egg-laying occurring between October and April, with peaks in January to February), late burning of grasslands may shorten the breeding season, and could account for population decreases. Maphisa et al. (2009) suggested that this species does best in grassland burned before the start of the breeding season. Rudd's Larks also occur at the edges of pans and vleis (Tarboton et al. 1987), but avoid valley bottoms and lowlands, as well as dense cover, old croplands, ploughed fields, rocky areas, valley bottoms, lowlands, intensely modified grasslands, and slopes of greater than 10° (Maphisa 2004). The generation length is given as 3.8 years (BirdLife International 2014).
