Ibis (2005), 147, 225–227 © 2005 British Ornithologists’ Union Blackwell Publishing, Ltd. Reply Seeing the woodhoopoe for the trees: a response to Simmons et al. (2005) MICHAEL CUNNINGHAM 1 & MICHAEL I. CHERRY 2 * 1 Department of Genetics, University of Pretoria, Pretoria 0002, South Africa 2 Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa We conducted a preliminary mitochondrial DNA sequence study of woodhoopoes with the aim of acquiring diagnostic molecular markers to study interbreeding between two poorly differentiated forms (Cooper et al. 2001). This study revealed a surprisingly close relationship between 12 violet- mantled birds from two localities in northwestern Namibia and green-mantled birds several thousand kilometres away in South Africa and Kenya; we also found negligible differentiation between these violet-mantled birds and a single green-mantled bird from a mixed flock in Namibia. These results led us to question the phenotypic basis on which these species are recognized, which we found to be inade- quate for species diagnosis and inconsistent in application. We are not the first to do so: the Violet Woodhoopoe Phoeniculus damarensis was first described by Ogilvie-Grant (1901), but was subsequently syn- onomized with the Green Woodhoopoe P. purpureus by Peters (1945). Fry (1978) treats them as separate taxa, but Clancey (1985, p. 245) states that ‘the cur- rent policy of according the Violet Woodhoopoe specific status needs in-depth investigation’, a call reiterated by du Plessis (1997a). Observations of phenotypic variation are easily canalized by systematic interpretation; what one sees depends on what one expects to see. The central issue in Namibian woodhoopoes concerns the signi- ficance of the sole diagnostic trait – adult mantle coloration (Clancey 1985). Simmons et al. (2005) apparently believe that variation in mantle colora- tion reflects a discrete difference between independ- ently evolved species lineages, with distinct habitat preferences, distribution and behavioural ecology. They suggest that individuals with intermediate mantle coloration arise through hybridization, and that this process represents a threat to the locally endemic violet-mantled form. We propose an alternative interpretation in which the violet-mantled and inter- mediate forms result from clinal variation across an aridity gradient, with associated changes in habitat use and group size probably due to the varying avail- ability of tree holes for this communally roosting species. We contend that the ecological gradient hypothesis is more parsimonious, and more consistent with the mitochondrial DNA sequence similarity and the extensive distributional overlap between these inter- grading forms. We also contend that in the absence of a consistent phenotypic diagnosis these forms should be considered conspecific, pending further systematic research on geographical variation in green, violet and mixed groups of woodhoopoes in Namibia. Simmons et al. (2005) have criticized this work on five grounds: (1) that our sampling is flawed, (2) that our phylogenetic tree could be interpreted differently, (3) that violet and green woodhoopoes differ beha- viourally, (4) that there are biogeographical reasons suggesting that the Violet Woodhoopoe is a proper species and (5) that even near-endemic subspecies should be given special status by conservationists. Here we deal briefly with each of these points in turn. (1) Given the degree of distributional overlap, incon- sistency among authors and observers in the identifi- cation and distribution of the Namibian Violet Woodhoopoe P. d. damarensis, and the occurrence of mixed groups, there is no location that could be un- equivocally assigned to Violet Woodhoopoes. Six of our samples came from Hobatere, which is within the westernmost third of the P. d. damarensis distribu- tion (du Plessis 1997a), with most records of the species coming from further east. A comparison with the distribution map for the Green Woodhoopoe (du Plessis 1997b) shows virtually complete sympatry between these two taxa. The remaining six samples came from Omaruru, an appropriate locality as it is *Corresponding author. Email: mic@sun.ac.za