Sittasomus griseicapillus (Olivaceous Woodcreeper)

Vasconcelos, Marcelo Ferreira de, 2018, First avifaunal survey of a Cerrado dry forest enclave on the right bank of the São Francisco River, Minas Gerais, Brazil, with insights on geographic variation of some species, Papéis Avulsos de Zoologia 58, pp. 1-18 : 5-6

Sittasomus griseicapillus (Olivaceous Woodcreeper)

This species was frequent in the present sampling (IFL = 12.8%). In northern Minas Gerais, two subspecies of the Olivaceous Woodcreeper have been recorded: S. g. sylviellus and S. g. reiseri (Vasconcelos & D’Angelo- Neto, 2007). In this region, S. g. sylviellus is associated to semideciduous (Atlantic) forests from eastern EspinhaÇo Range, while S. g. reiseri occurs in the arboreal caatingas and deciduous forests west of this mountain range ( Vasconcelos & D’Angelo-Neto, 2007). Thus, it was unexpected that the three specimens obtained in the study area (west of the EspinhaÇo Range) exhibit the typical plumage pattern of the Atlantic S. g. sylviellus ( Fig. 5 ). Nevertheless, specimens from Curral de Pedras present underparts olive yellow (2.5Y 6/6), slightly paler than specimens of this taxon collected in moister forests eastward, which present underparts light olive brown (2.5Y 5/6). This corroborates Gloger’s ecogeographic rule, in which specimens from drier environments would exhibit lighter plumages than those from more humid regions ( Gloger, 1833). Similar results that corroborate Gloger’s ecogeographic rule were also observed in detailed studies of geographic variation of two other woodcreepers: Lepidocolaptes angustirostris (Narrow-billed Woodcreeper) (Bolívar-Leguizamón & Silveira, 2015) and Dendrocolaptes platyrostris (Planalto Woodcreeper) (Cabanne et al., 2011) .

Silva (1989) reported hybrid zones of S. g. sylviellus and S.g. reiseri in the Araguaia – São Francisco interfluve. Nevertheless, in northern Minas Gerais, we never found any signal of intergradation between both subspecies based on specimens collected over a long transect crossing the EspinhaÇo Range ( Vasconcelos & D’Angelo-Neto, 2007). A comparison between specimens of S. g. reiseri from southern Caatinga province (northern Minas Gerais) and a topotype from northern Caatinga (southern Piauí – MCNA 5386) also suggests that this taxon tends to be darker in its southernmost range. The topotype of S. g. reiseri presents breast light olive brown (2.5Y 5/4), belly yellowish brown (10YR 5/6), and head olive brown (2.5Y 4/4). Southern specimens of S. g. reiseri have breast olive brown (2.5Y 4/4), belly light olive brown (2.5Y 5/6), and head olive brown (2.5Y 4/3). Thus, further analyses and collecting of specimens in the Caatinga province are needed to test if this pattern is related to Gloger’s ecogeographic rule.

Figures

Figure 5. From left to right: specimens of Sittasomus griseicapillus sylviellus from Santa Teresa, Espírito Santo (DZUFMG 630), Mariana, Minas Gerais (MCNA 1406), Santa Bárbara, Minas Gerais (MCNA 4147), Curral de Pedras, Minas Gerais (MCNA 4970, MCNA 4981, MCNA 5052); and specimens of Sittasomus griseicapillus reiseri from Janaúba, Minas Gerais (DZUFMG 3428), and Riacho dos Machados,Minas Gerais (MCNA 2523).