Adrian Jfk Craig

Timing of moult and breeding in the Cape White-eye, Zosterops pallidus, from three different geographical regions in South Africa

Abstract Cape White-eyes are widespread in South Africa, occurring in different climatic regions. We analysed primary moult data for large samples of this species from three geographical regions. There were no apparent long-term changes in duration or timing of moult during the nine years that the Western Cape results were collected, but sites within this region had different mean starting dates for primary moult. The Eastern Cape and Free State birds began moult about a month later than those in the Western Cape. This correlated well with the earlier breeding season in the Western Cape, and there was no evidence of overlap between moult and breeding. Mean primary moult duration was not significantly different among the sites or regions, and may be a species-specific trait. There was no evidence of regular long-distance movements in this species.

Moult, breeding season, mass, wing length, and dispersal in Cape Robins (Cossypha caffra) and Olive Thrushes (Turdus olivaceus): results from mist-netting garden birds

We compared a data set from the Western Cape, South Africa (GDU, n = 170 Olive Thrushes (Turdus olivaceus), n = 475 Cape Robins (Cossypha caffra)) with our captures in the Eastern Cape, South Africa (n = 197 Olive Thrushes, n = 203 Cape Robins). In both regions Olive Thrushes began moult in December-January, while wing-moult lasted for 89 days in the Western Cape compared to 53 days in the Eastern Cape. Cape Robins began moult in early November in the Western Cape, early January in the Eastern Cape and again the duration of wing-moult was longer in the Western Cape (64 days) than in the Eastern Cape (50 days). For both species the start of moult coincided with the end of the breeding season. Cape Robins were heavier and longer-winged in the Western Cape than in the Eastern Cape. There was no significant difference in mean mass or mean wing length of the Olive Thrush between the two provinces. Both ringing and atlas data suggest that Cape Robins are relatively more common than Olive Thrushes in the Western Cape, but not in the Eastern Cape. In the Eastern Cape we observed colour-ringed robins (n = 2) and thrushes (n = 2) on their breeding territory in all months of the year, suggesting that some individuals of both species are strongly resident.

Ecology and genetics of hybrid zones in the southern African Pycnonotus bulbul species complex

Lloyd, P., Craig, A.J.F.K., Hulley, P.E., Essop, M.F., Bloomer, P. & Crowe, T.M. 1997. Ecology and genetics of hybrid zones in the southern African Pycnonotus bulbul species complex. Ostrich 68 (2–4): 90–96. The closely related Blackeyed Bulbul Pycnonotus barbatus, Cape Bulbul P. capensis and Redeyed Bulbul P. nigricans have parapatric to locally sympatric distributions within southern Africa. Extensive hybridization along narrow transition zones between each of the three species pairs is described in a region of the Eastern Cape province, South Africa. The transition zones coincide with ecotones between different vegetation types, which in turn follow escarpments or mountain ranges. The lack of population density depressions within the hybrid zones, together with the variability of the hybrids, suggests the hybrids are viable. Sharp step clines in various phenotypic characters are described across the P. barbatus/P. nigricans hybrid zone. A mtDNA analysis found evidence of possible introgression between ...

A century of Zoology and Entomology at Rhodes University, 1905 to 2005

The history of the Department of Zoology & Entomology at Rhodes University is traced from its origin with a single staff member, through the era of permanent heads of department to the present day staff. Significant achievements and developments in teaching and research are highlighted, and some anecdotal material is included.

Regional patterns in moult and sexual dimorphism of adult Southern Red Bishops Euplectes orix in southern Africa

Using the SAFRING database and the Underhill-Zucchini model of primary moult, we analysed the timing of wing moult in Southern Red Bishops Euplectes orix in relation to sex and geographical region. Birds from the winter rainfall region in the south-western sector of the Western Cape start the annual moult more than two months before any other population, but there were no significant differences in starting date within the summer rainfall region. There were striking differences in the estimates of moult duration (62–114 d), which did not follow a consistent pattern in relation to sex or geography; annual variation within a region may be an additional factor. Throughout southern Africa, both sexes showed a trend for longer-winged birds to take more time to complete their moult. We suggest that sex, geographical area and possible annual environmental variations may all influence the timing of moult in local populations. In this sexually dimorphic species, males are consistently longer-winged and heavier than females.

COMPARISONS OF THE VOCALIZATIONS AND SOCIAL BEHAVIOUR OF SOUTHERN AFRICAN PYCNONOTUS BULBULS

Summary Lloyd, P., Hulley, P.E. & Craig, A.J.F.K. 1996. Comparisons of the vocalizations and social behaviour of southern African Pycnonotus bulbuls. Ostrich 67: 118–125. Vocalizations and associated behaviour of three Pycnonotus species are described, based on field observations and tape recordings from which sonagrams were produced. These species, which are locally sym-patric and hybridize, have similar vocalizations and displays; differences are most apparent in their contact calls and songs. Quantitative analysis of the songs showed that P. barbatus and P. capensis are easily distinguished, whereas the song characteristics of P. nigricans overlap those of both the other species. Playback experiments with territorial male P. barbatus in an area of allopatry showed similar responses to songs of conspecifics and of P. nigricans, but almost no response to the song of P. capensis.

Sexing Adult Pale-Winged Starlings Using Morphometric and Discriminant Function Analysis.

Accurate sexing of birds is vital for behavioral studies but can be a real problem in the field, especially for monomorphic species. Our goal here was to characterize the morphology of male and female monomorphic pale-winged starlings (Onychognathus nabouroup), a South African sturnid whose plumage is sexually monomorphic. Morphological measurements of genetically sexed animals indicated that males were statistically larger than females for five measurements: Mass, tail length, tarsus length and wing length. By using a Discriminant Function Analysis based on the measurements taken by one ringer, we were able to predict correctly the sex of 81.10% of the birds of data collected in the field and 77.9% of museum skins independently of year of capture and ringer. The model developed here should be useful for further field studies of this species.

The importance of winter-flowering Aloe ferox for specialist and generalist nectar-feeding birds

Abstract The abundance of consumers and the availability of resources are often linked, and birds are known to track food resources at a variety of spatial and temporal scales. This study describes the seasonal influx of nectar-feeding birds during flowering in a 51-ha stand of Aloe ferox in the Eastern Cape, South Africa, over 5 years (2008–09 and 2011–13). Bimonthly point counts of birds were conducted before (April—May), during (June—July) and after (August) flowering, which occurs during the austral winter. The abundance of nectar-feeding birds increased significantly during flowering each year, whereas monthly abundances of non-nectarivores were unrelated to flowering. Models fitted to bird count-data revealed a significant interaction between feeding guild (nectarivorous versus non-nectarivorous species) and the percentage of flowering A. ferox over the 5 years of the study, confirming that these guilds responded differently to flowering events. Malachite Sunbirds (Nectarina famosa), which are specialist nectarivores, responded consistently to flowering of A. ferox each year, despite the low sugar concentrations of A. ferox nectar. The arrival of nectar-feeding birds en masse during flowering, and the number of bird species (16) observed feeding on A. ferox nectar, suggest that this plant is an important source of nutrition for birds at a time when other food resources are likely to be scarce.

Nectar feeding by weavers (Ploceidae) and their role as pollinators

Reviews of nectar-feeding by birds initially focused on specialist nectarivores and ignored the role that more generalist feeders may play in plant pollination. Recent work has emphasised the range of bird species, both specialist and opportunistic, that feed on nectar. In this review, I collate published information on nectar-feeding by weavers, highlight known weaver–plant relationships, and suggest areas for future research. There are published records of nectar feeding for Plocepasser superciliosus, Amblyospiza albifrons, Anaplectes rubriceps, two Quelea spp., four Euplectes spp., all six Foudia spp., two Malimbus spp. and 22 Ploceus spp. To date, there have been no unambiguous reports of other genera feeding on nectar. The role of Ploceus species as pollinators of Strelitzia reginae, proposed by ornithologists decades ago, has recently been confirmed by botanists. Current studies of Aloe species in South Africa suggest that opportunistic avian nectarivores such as ploceids may be the chief pollinators of bird-pollinated plants in this genus, whereas specialist nectar feeders (sunbirds) may be ‘nectar robbers’ in many cases. Particularly for winter-flowering plants, weaver species are potential pollinators, but exclusion experiments are needed to establish their role, while the dietary importance of nectar, and its impact on the birds’ physiology, has not been critically studied.

Songs of two starling species: common traits versus adaptations to the social environment

We analysed, for the first time, songs of the African Red-winged Starling Onychognathus morio and compared their general characteristics with those of the European Starling Sturnus vulgaris. Both species are gregarious during the non-breeding season, but European Starlings tend to nest in colonies, form unstable pair-bonds and are occasionally polygynous, whereas Red-winged Starlings form long-term pair-bonds and occupy exclusive nesting territories. Red-winged Starlings produced the same basic song categories as European Starlings: warbles and whistles. These two categories appeared to be involved in similar social interactions in the two species. However, several aspects of song behaviour differed between the two species: Red-winged Starlings, breeding in isolated nests, preferentially used whistles for long-distance communication and showed a simpler organization of warbling song. Whistles in the Red-winged Starling were mostly shared between birds and, in contrast to the European Starling, were not indicators of individual identity. Also in contrast to the European Starling, female song in Red-winged Starlings appeared very important throughout the breeding period. Our results suggest that some song characteristics in the two species are phylogenetically conserved whereas others are affected by the distinct social systems of the two species.