Waterbirds: Birds of a feather flock together

iii Large concentrations of animals have long invoked a sense of wonder among humans. Waterbird aggregations are perhaps some of the best examples of this, where human interest in seeing these spectacular flocks has contributed significantly to ecotourism (Green and Elmberg 2014). In addition, public interest in waterbirds has led to a greater consciousness of conservation issues in general and promoted the protection of waterbird populations and their habitats (Ramsar Convention Secretariat 2013; Green and Elmberg 2014). In this special issue of Ostrich, ‘Waterbirds – Birds of the African aquatic environments’, we showcase the remarkable research that is being undertaken on African waterbirds and highlight our continued need to understand the unique avifauna of these aquatic environments. The articles in this special issue are grouped largely into those focused on waterbirds of inland aquatic environments (de Souza et al. 2019; Gula et al. 2019; D’Urban Jackson et al. 2019; Lee et al. 2019; Neb et al. 2019) and those focused on waterbirds in coastal and marine environments (Brown et al. 2019; Dyer et al. 2019; Sherley et al. 2019; Tree et al. 2019; Vanstreels et al. 2019). Among the studies concentrating on inland waterbirds is one of the first attempts to quantify the long-suspected hybridisation between invasive Mallard Duck Anas platyrhynchos and native Yellow-billed Duck A. undulata in South Africa (de Souza et al. 2019). De Souza et al. (2019) used mitochondrial DNA to show that there is little evidence of hybridisation between these two duck species. The authors suggest that quick and decisive management action eradicating the Mallard Duck in South Africa should go a long way in helping preserve the genetic diversity of our native duck species. Lee et al. (2019) is a further example investigating emerging threats to inland waterbirds, this time in the form of contaminated water from hydraulic fracturing for shale gas extraction. Based on an extensive trait analysis, Lee et al. (2019) estimated that between 60 and 141 Karoo bird species could be exposed to this contaminated water, stressing the urgent need to consider mitigation measures for this developing threat. Empirical data for conservation assessments are desperately lacking and can be incredibly difficult to acquire for wide-ranging species like waterbirds. However, Gula et al. (2019) illustrate just how valuable citizen-science platforms can be in this regard. Gula et al. (2019) developed an updated distribution map for the Saddle-billed Stork Ephippiorhynchus senegalensis using citizen-science data and clearly reaffirm that protected areas across Africa are critical for the protection of the species. Brown et al. (2019) also harnessed the power of citizen-science data, but this time to corroborate a rare conservation success story. The team shows increases in the reporting rate and distribution of the African Black Oystercatcher Haematopus moquini between the two periods of the Southern African Bird Atlas Projects, thereby supporting the down-listing of the species on the IUCN Red List of Threatened Species. Seabirds are remarkable in the fidelity that they show to their breeding colonies, thus facilitating long-term data collection by biologists. Several contributions to this special issue make use of long-term datasets to explore relevant spatial and temporal trends in seabird diet, population status and movement ecology (Dyer et al. 2019; Sherley et al. 2019; Tree et al. 2019). For example, Sherley et al. (2019) show a 44% decline in the Cape Gannet Morus capensis population since the 1960s. Using a state-of-the-art modelling technique, they were able to determine that lower recruitment into the current population was accounting for steeper population declines seen in recent generations. Although appearing to be a message of doom-and-gloom, it is these kinds of analyses that provide key insights into important bottlenecks for waterbird populations and thus allow for targeted conservation approaches to be implemented. Sadly, while editing this special issue I could not help but reflect on the uncertain future faced by many waterbird species in Africa. Most of the submissions either featured a threatened waterbird species or highlighted key threats to waterbirds and their habitats. Thus, despite waterbirds having major cultural, economic and ecological value (Green and Elmberg 2014), these extraordinary birds and their once magnificent congregations remain at risk from anthropogenic pressures. However, what does give one a glimmer of hope is that timely and thoughtful interventions can have profound outcomes for our waterbird species, as illustrated by the success story of the African Black Oystercatcher. This special issue provides a rich and varied assortment of research providing fundamental data for addressing such issues in the conservation of African waterbirds.