Johann Hendrik van Niekerk

The crested francolin complex comprises geographically variable populations assigned to three African species, Ortygornis grantii, O. rovuma and O. sephaena. We examined phenotypic differentiation across Africa using 272 photographic records, museum specimens and mitochondrial data. Seven plumage characters were scored, with repeatability assessed by blind intra-observer rescoring of 61 stratified records. Breast markings, gorget-line position, abdominal feather structure and abdominal colour were retained for formal statistical inference. Gower ordination showed geographic structuring among eight historical forms, and PERMANOVA confirmed this pattern (R² = 0.717), although morphospace overlap persisted. Northeastern/eastern populations were predominantly high-gorget, whereas southern populations were mainly low-gorget, with intermediate combinations in eastern contact areas. Ugandan ochrogaster were high-gorget with a predominantly weak or fine abdominal vermiculation, differing strongly from neighbouring grantii. The form spilogaster showed weaker centroid separation from grantii than from rovuma, although mean Gower dissimilarities were similar. Mitochondrial divergence was lower between spilogaster and grantii (1.4%) than between spilogaster and rovuma (3.8%), supporting qualified placement with O. grantii. Southern O. sephaena forms also showed phenotypic structure despite shallow mitochondrial divergence. Overall, the results support geographically structured phenotypes and selected subspecific units within the established three-species framework. Several transitions remained clinal or overlapping rather than sharply bounded.

Little is known about landbird group dynamics in response to predation. Here, we describe the interactions between the Helmeted Guineafowl (Numida meleagris) and its predators regarding the survival advantages grouping behaviour may provide. Livestream webcam observations were conducted in Madikwe Game Reserve (South Africa) from August 2020 to August 2021. Emphasis was placed on predator–prey interaction and its effect on group size and structure in a spatial framework. We hypothesise that while grouping is crucial for a number of daily activities in this highly social species, it might turn into a higher predatory pressure. We found, indeed, that the probability of attacks by black-backed jackals (Lupulella mesomelas) significantly increased with guineafowl group size, unlike what happened with raptors. Moreover, when attacked by jackals, the birds responded by standing close to each other. These results suggest, in line with the proposed hypothesis, that a trade-off occurs between the defensive function of grouping in this galliform and the probability of jackal attack that increases as a function of prey group size. Nevertheless, we argue that Helmeted Guineafowl cooperative social groups also play a role as a defensive strategy against predators, with the many-eyes and dilution effects likely compensating for the higher predatory pressure.

Little is known about landbird group dynamics in response to predation. Here, we describe the interactions between the Helmeted Guineafowl (Numida meleagris) and its predators regarding the survival advantages grouping behaviour may provide. Livestream webcam observations were conducted in Madikwe Game Reserve (South Africa) from August 2020 to December 2021. Emphasis was placed on predator–prey interaction and its effect on group size and structure in a spatial framework. Although Black-Backed Jackals (Lupulella mesomelas) are not adept at hunting birds, they might negatively impact guineafowl by curtailing their feeding time during winter with constant harassment. We found that these canids often approach larger and denser groups in the morning and late evenings. Surprisingly, guineafowl most often responded by standing nearby. On the contrary, a higher predator-induced response was associated with the presence of predatory birds, arguably as part of an evolutionary stable prey-predator system. This line of thought is also supported by the lack of a precise defensive mechanism elicited by jackal attacks, unlike those of aerial predators. Nevertheless, we contend that grouping in Helmeted Guineafowl is a defensive strategy to respond to predator attacks while individuals engage in daily activities.

The study of diel and seasonal variation in vocal interactions of Crested Francolin Ortygornis sephaena territorial males helps clarify its purpose, thus delivering insights into the behavioural ecology of this species. The goals of the present paper are to describe the vocal footprint of neighbouring Crested Francolin territorial males and understand the purpose of collective calls. We logged remotely into a HD webcam with microphone located in Tembe Elephant National Park (KwaZulu-Natal, South Africa) to listen to male vocal exchanges from August 2018 to November 2019. Territorial call exchanges among three neighbouring males at dusk took place at the onset of, but not during, the breeding season and then again during the non-breeding season. In the latter case vocalisations were emitted even beyond dusk time. Call duration and intensity (calls per minute) did not increase at the onset of the breeding season. Males exchanged calls in a leader-follower manner seemingly unrelated to female attraction and guarding. On the contrary, this cordial collective calling is likely a form of cooperation to detect vocal responses by interlopers.

Conserved remnants of indigenous vegetation patches and corridors are regarded as important components of the built environment for the survival of birds. Field research was conducted at Boknes and... Les vestiges conservés de parcelles de végétation indigènes et de couloirs sont considérés comme des éléments importants de l’environnement bâti pour la survie des oiseaux. Des recherches sur le te...

This paper describes the plumage and morphology development of 11 age classes of Red-necked Spurfowl Pternistis afer to assist with field observations. Sixteen spurfowl were marked with coloured leg rings in the Cannon Rocks Holiday Resort, Eastern Cape, South Africa during March 2006 and observed daily until June 2008 to describe plumage and non-plumage morphological changes. The age classes include natal chicks, six discernible juvenile phases, post-juvenile phase, near-adult phase, non-territorial and territorial males. Red-necked Spurfowl only attain the adult plumage phase at about 240 d. However, if the development of the bare red throat and spurs are excluded, this near-adult plumage stage is attained at about 180 d. Territorial male Red-necked Spurfowl have long spurs similar to other Pternistis spp. The cryptic downy pattern of chicks assist the birds to blend in with their habitat. However, the plumage of juveniles is simply a transitional phase between the cryptic plumage of downy chicks and th... Classes d’âge de développement du Francolin à gorge rouge Pternistis afer en fonction du plumage, de la morphologie et du comportementCet article décrit le développement du plumage et de la morphologie de 11 classes d’âge du Francolin à gorge rouge Pternistis afer afin de faciliter les observations sur le terrain. Seize Francolins ont été marqués avec des anneaux de jambe colorés au centre de vacances Cannon Rocks, dans la partie Est du Cap, en Afrique du Sud, en mars 2006, et ont été observés quotidiennement jusqu’en juin 2008 pour décrire les changements morphologiques liès au plumage mais aussi à d’autres caractères. Les classes d’âge comprennent les poussins à la naissance, six phases juvéniles discernables, la phase post-juvénile, la phase presque adulte, les mâles non territoriaux et territoriaux. Le Francolin à gorge rouge n’atteint la phase du plumage adulte que vers 240 jours. Toutefois, si le développement de la gorge et des éperons nus et rouges est exclu, ce stade du plumage presque adulte se ...