Ostrich: Journal of African Ornithology

Monitoring survival probabilities of Cape Vultures Gyps coprotheres in South Africa, using GPS tracking data

2026-04-14T08:57:43+00:00

The Cape Vulture Gyps coprotheres is a species of Old-World vulture endemic to southern Africa. Currently listed as ‘Vulnerable’ by the IUCN, they face increasing threats from anthropogenic hazards, such as collisions with man-made infrastructure and poisoning events, leading to ongoing population declines. This study aimed to investigate the survival probabilities of a sample of 20 Cape Vultures, fitted with GPS tracking devices whilst fledglings at the Skeerpoort breeding colony, in the Northwest province of South Africa. These individuals were then monitored for a period of 1 683 days, with a known fate index created to track any deaths or removal from the population, allowing for both cumulative and annual estimated survival rates to be calculated. Cumulative survival probability decreased from 0.512 at one year to 0.171 by year four, with 64% of all confirmed mortalities occurring within the first year and electrocution and collisions with power lines being the most prevalent causes (accounting for 20% and 15% of all outcomes respectively). Whilst annual survival probabilities appeared more stable, 0.512 in the first year and 0.540 in the fourth, these survival rates are markedly lower in comparison to those of other studies on Cape Vultures, as well as other vulture species and, furthermore, an extrapolated model for future survival predicted a survival probability of just 0.014 ten years after the GPS device was fitted. These findings highlight the need for targeted conservation measures, such as improved power line management and supplementary feeding stations to reduce mortality during the juvenile and subadult life stages of Cape Vultures.

Large bird collision mortality on power lines in southern Namibia

2026-04-14T09:44:30+00:00

Globally, power lines cause significant mortalities of birds through collisions and electrocutions, yet this problem has received only sporadic attention in Namibia. Vehicle-based surveys were undertaken every three months for one year to record mortalities of large birds along 349 km of transmission power lines in the Succulent and Nama Karoo biomes of southern Namibia. Four different line designs and transmission capacities were sampled: 66, 132, 220 and 400 kV. The clearing survey collected 80 carcasses; thereafter 197 bird mortalities were recorded over 12 months, of which 89% were identified to be collisions. Thirteen large bird species were recorded dying from collisions, with Ludwig’s Neotis ludwigii and Kori Bustards Ardeotis kori comprising 81% of all fatalities. There was a significant seasonal difference in collision rates, but no significant sex bias among bustard mortalities. Collision rates tended to be greater (but without statistical significance) on higher capacity lines, although the 66 kV line was the only line sampled in the Succulent Karoo, so was not directly comparable with higher capacity lines in the Nama Karoo. Collision mortalities along the four capacities of transmission lines averaged 0.5 birds·km–1·year–1, similar to rates reported in the Karoo region of South Africa. These results confirm the very serious threat of this hazard to Ludwig’s Bustard in particular. Suggestions for mitigation on new power lines are given, but the problem of thousands of kilometres of existing transmission power lines remains unresolved.

Breeding population status and nesting preferences of the White-backed Vulture Gyps africanus in western Serengeti, northern Tanzania

2026-04-14T10:01:40+00:00

The White-backed Vulture Gyps africanus is Critically Endangered because of its decline across its range in Africa, largely due to poisoning. The western corridor of the Serengeti ecosystem in northern Tanzania hosts a significant number of individuals of this species. However, there is no published information on the breeding population status and breeding success. Here, we report findings from five riparian aerial surveys conducted between 2013 and 2021 in the Ikorongo and Grumeti Game Reserves and the Ikona Wildlife Management Area, and examine changes in nest encounter rates. Nest surveys were conducted in 2021 and 2022 to examine breeding success and nesting site preferences. To better understand the potential drivers of the observed trends, we assessed changes in riparian tree cover between 2012 and 2020 using remote sensing techniques. The nest encounter rate within the survey area declined from 0.99
nests km−1 in 2013 to 0.43 nests km−1 in 2021. The breeding success was 29.4%, which was significantly lower than that reported in other sites. Tree cover declined by 28% during the study period and results suggest that habitat loss may be a contributing factor to the observed declines in the breeding population, but further investigation is needed. White-backed Vultures in the Serengeti ecosystem require continued monitoring, assessment of the drivers of tree cover decline and investigation of breeding population dynamics and the key factors influencing breeding success.

Bird community composition across a land use gradient in the eastern Democratic Republic of Congo

2026-04-14T10:14:08+00:00

Cocoa agroforestry expansion is widespread in eastern Democratic Republic of Congo, posing a significant threat to the integrity of protected areas. Despite this threat, the impact of this expansion on forest bird communities remains largely unexamined. This study investigated bird community composition in the Okapi Wildlife Reserve (OWR) and surrounding agroforestry areas using a combination of mist netting and passive acoustic monitoring. Specifically, it examined species richness, diversity, evenness, feeding guild abundance and habitat-specific indicator species across 19 sites. A total of 95 bird species were documented, with acoustic monitoring accounting for 73% and mist netting 43% of the recorded species. Significant differences in species richness, diversity and evenness were observed across habitat types. While cocoa farms exhibited higher species richness than primary forest sites or annual cultures, primary forests had the highest diversity indices, followed by cocoa farms and annual cultures. Bird communities were most even in annual cultures, compared to primary forest sites and cocoa farms. Additionally, 18 bird species showed strong associations with specific habitat types based on combined data from both mist netting and acoustic methods. This study highlights the importance of protected areas such as the OWR for sustaining bird communities, as well as emphasising the potential value of structurally complex agroforestry landscapes for subsets of forest bird communities. Furthermore, it demonstrates the effectiveness of combining mist netting and acoustic monitoring methods in understanding avian community composition amid land use changes.

Updates on population status of vultures in Nazinga Game Ranch, Burkina Faso

2026-04-14T10:29:58+00:00

In the early 2000s, the ornithological community was alerted to the vulture population decline in West Africa. Since then, the situation of vultures in this area has not been updated, specifically in Burkina Faso’s protected areas. To find out more, we used transect counts to explore the current status of vultures (species diversity, abundance) to be compared with previous counts in Nazinga Game Ranch, Burkina Faso. A total of 49 individuals from three species were recorded, the White-backed Vulture Gyps africanus (59.2%), Hooded Vulture Necrosyrtes monachus (38.8%) and White-headed Vulture Trigonoceps occipitalis (2%). Two species previously recorded in small numbers were not detected: the Lappet-faced Torgos tracheliotos and the Rüppell’s Gyps rueppelli vultures. Between the 1970s and 2004, numbers of White-backed and Hooded vultures declined significantly from 19 to 4.4 and 16 to 7.7 individuals per 100 km, respectively, a decrease of 76.8% and 51.9%. Between 2004 and 2019, there was a slight increase from 4.4 to 11.9 in the number of White-backed Vultures and a relative stability in the number of Hooded Vultures. The populations of White-headed Vulture have continued to decrease from 6 to 1.9 individuals per 100 km between the 1970s and 2004 and then from 1.9 to 0.4 between 2004 and 2019. Our results reveal that Nazinga Game Ranch remains one of the bastions of resilience for vultures in Burkina Faso and offers a real opportunity for vulture conservation. The apparent growth post-2004 in the White-backed Vulture population suggests the increasing dependence of vultures on the protected area, given the increase in threats to vultures outside of protected areas. Continuing research in protected and unprotected areas is needed to update data at a national and regional scale to have a better assessment of vulture population trends. Regardless, it is imperative to urgently address the specific threats faced by each of these vulture species.

Cape GannetMorus capensis year-round presence off the southern Cape coast of South Africa

2026-04-14T10:52:37+00:00

The year-round presence and abundance of Cape Gannets Morus capensis in the greater Wilderness waters (Western Cape, South Africa) were monitored through a land-based observational study, 330 km (straight-line distance) from the nearest breeding colony, Bird Island Algoa Bay. Between 2022 and 2025, gannets were observed in 65% (n = 110) of breeding-season surveys and in 94% (n = 124) of non-breeding season surveys. The number of gannets per survey was significantly lower (U = 4373, p = < 0.001) during the breeding season compared to the non-breeding season. Per age class, the maximum number of gannets recorded in a survey was 325 adults and 74 juveniles in the breeding season, and 1 082 adults and 124 juveniles in the non-breeding season. During both seasons gannets were observed diving, resting and flying. This study supplements the (limited) available information on the distribution and abundance of the endangered Cape Gannets along the southern Cape coast, especially in the non-breeding season, necessary to aid conservation planning.

Aggressive interactions by invasive Common Mynas Acridotheres tristis with urban birds in Pretoria, South Africa

2026-04-14T11:00:56+00:00

We conducted transect surveys in urban Pretoria, South Africa, to document interspecific interactions involving the invasive Common Myna Acridotheres tristis and coexisting species. During 90 standardised transect surveys across three suburban sites from April to August 2022 (outside the main breeding season for many bird species), we recorded 36 interspecific interactions between Common Mynas and other birds. Common Mynas were observed chasing or being aggressive towards other birds such as sparrows (Passer diffusus, P. domesticus) and doves (Streptopelia capicola, Spilopelia senegalensis). Of these encounters, 26 (72%, 95% CI: 56–84%) involved aggression, with Common Mynas initiating 86% of aggressive incidents. In most aggressive incidents, the other bird fled; only larger species (Cape Starlings Lamprotornis nitens) successfully retaliated. Such aggression may facilitate the displacement of native and non-native species from feeding sites or nesting areas. These findings provide evidence for interference competition by Common Mynas in South African urban environments and highlight the need for targeted management strategies to protect native bird communities.

Reduced Blue Crane Grus paradisea breeding productivity in intensive agricultural landscapes

2026-04-14T11:55:12+00:00

We compare Blue Crane Grus paradisea breeding productivity in the Western Cape wheatlands in Overberg and Swartland (2018–2021), Karoo (2009–2011) and eastern grasslands (2009–2011 and 2013). Productivity was higher in the grasslands (0.95 fledglings/attempt, 95% CI = 0.86–1.30, n = 95) and Karoo (1, 95% CI = 0.79–1.55, n = 90), than in the Overberg (0.55, 95% CI = 0.42–0.80, n = 98) or Swartland (0.48, 95% CI = 0.34–0.75, n = 63). Swartland pairs fledged two chicks half as often as Overberg, grasslands and Karoo pairs. In 2019–2021, juveniles comprised 4.0% (range = 2.8–5.0%) of winter flocks in the Overberg, and 3.6% (3.4–4.0%) in the Swartland, which is approximately half of the estimates from the Overberg 30 years ago. Low breeding productivity and recruitment could explain the declining population in the Western Cape wheatlands and may indicate that the region has become an ecological trap for the species. Breeding productivity could be improved by reducing disturbance at nests, preventing chick drownings in water troughs and reducing fence entanglements.

Sand knobwood Zanthoxylum leprieurii as a keystone resource for birds in Nigeria: insights from observational counts and proximate analysis

2026-04-14T12:07:12+00:00

This study investigated the importance of sand knobwood Zanthoxylum leprieurii (family Rutaceae) fruits as a food source for birds in the Tree Heritage Park, Ibadan, Nigeria. We conducted focal observations over three years (2018, 2019, and 2024) during peak fruiting periods, recording bird species foraging on fruits in the canopy and on the forest floor. A total of 4 452 birds from 30 species were observed, with the Red-eyed Dove Streptopelia semitorquata being the most frequent forager (48%). Foraging activity was higher in the morning than evening. Proximate analysis revealed that sand knobwood fruits contain 8.4% moisture, 6.7% ash, 33.5% fat, 11.2% protein,
and 33.5% crude fiber, suggesting potential nutritional value for birds. These findings deepen our understanding of the intricate relationships between trees, birds, and ecosystems.