Summary The Amathole mistbelt forests in the Eastern Cape, South Africa harbour the largest remnant population of the nationally endangered endemic Cape Parrot Poicephalus robustus, a secondary-cavity nester whose persistence is limited by suitable nest sites. These are also the only forests within Cape Parrot range in which selective timber harvesting remains permitted, but the impact of harvesting on the availability of parrot nest sites has not been investigated. This study aimed to determine the degree to which current harvest selection criteria stand to impact nest site availability. Results showed that Cape Parrots have specific nest tree requirements; and that there is overlap in the species and condition of trees selected for nesting, and harvesting. The two yellowwood species found in the region, Afrocarpus falcatus and Podocarpus latifolius, represented the majority of both harvested trees (78%), and Cape Parrot nest trees (79%). Moreover, both Cape Parrot and harvest selection criteria require large (≥50 cm diameter at breast height; ≥12 m high), old, dead, dying, or crown-damaged yellowwoods, such that 32% of trees considered potential nest trees were also candidates for harvesting. Current selection criteria need to be revised to ensure that timber use is compatible with biodiversity conservation in the Amathole forests. We suggest that all harvesting of dead standing yellowwoods be discontinued; and that the harvesting of live trees with crown damage, which are frequently used by parrots for nesting, be limited by a species-specific maximum harvestable diameter.

SummaryThe provision of artificial nests can improve the conservation status of threatened bird species that are limited by nest-site availability. The shortage of natural cavity nesting sites is one factor limiting the population growth of the Southern Ground Hornbill Bucorvus leadbeateri. In an 1,800 km2 study area in north-eastern South Africa, 31 wooden nest-boxes were installed during 2002–2015. We investigated the relationships between nests, as well as environmental and social factors, with breeding. Generalised linear mixed models were fitted to the observational data and identified positive relationships between breeding attempts and each of home range size and the previous year’s rainfall; as well as positive relationships between breeding success (amongst the groups that attempt breeding) and each of earlier breeding, nest height and thickness of the nest cavity wall. The provision of nest-boxes increased the number of breeding groups and although breeding success also increased initially, it later declined as the density of breeding groups increased above 20 groups. Although nest-boxes alone did not increase overall breeding success, they are an effective conservation tool to enhance the population of Southern Ground Hornbills if spaced optimally, to enhance reproductive output in areas where suitable nest-sites are scarce or lacking.

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.

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The Cape Parrot Poicephalus robustus is endemic to South Africa where it typically occurs in high-altitude Mistbelt forests. They are listed as Vulnerable internationally with habitat loss being the primary threat to the species. They nest in natural tree hollows in large forest hardwoods which were the target of historical, exploitative harvesting, and which continue to be harvested legally but on a smaller scale. The breeding biology of the species has been described for the central population, but not yet for the southern population, in the Eastern Cape province, where the stronghold of the population resides. There, few nest sites have been located, and the study of the breeding behaviour and biology is a key knowledge gap in the species in need of conservation. This study aims to characterise natural nesting sites in the Eastern Cape, describe breeding behaviour and investigate breeding success during 2017–2021. A total of 43 nesting sites were located of which 20 were occupied. No pairs attempted breeding in 2019 and breeding success was estimated to be 58%. As found in other parts of the range, Cape Parrots in the study area nest in existing hollows predominantly in large, mature, yellowwood Afrocarpus falcatus trees. Parrots also nest in exotic species. They showed no preference for nest orientation and nested as close as 69 m away from their nearest neighbour. Most nest cavities were inaccessible by field researchers and could only be monitored from the ground, but new methods were found that facilitated the inspection of some nests that were unsafe to climb. Nest characteristics and breeding behaviour information gathered in this study provide a practical foundation for the optimisation of the design and installation of more nest boxes in future, to assist in conservation efforts of this threatened species.