Browsing by Author "Barends, Jody M."

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    Sampling bias in reptile occurrence data for the Kruger National Park
    (OpenJournals Publishing AOSIS (Pty) Ltd, 2020) Barends, Jody M.; Pietersen, Darren William; Zambatis, Guinevere
    To effectively conserve and manage species, it is important to (1) understand how they are spatially distributed across the globe at both broad and fine spatial resolutions and (2) elucidate the determinants of these distributions. However, information pertaining to the distributions of many species remains poor as occurrence data are often scarce or collected with varying motivations, making the resulting patterns susceptible to sampling bias. Exacerbating an already limited quantity of occurrence data with an assortment of biases hinders their effectiveness for research, thus making it important to identify and understand the biases present within species occurrence data sets. We quantitatively assessed occurrence records of 126 reptile species occurring in the Kruger National Park (KNP), South Africa, to quantify the severity of sampling bias within this data set. We collated a data set of 7118 occurrence records from museum, literature and citizen science sources and analysed these at a biologically relevant spatial resolution of 1 km × 1 km. As a result of logistical challenges associated with sampling in KNP, approximately 92% of KNP is data deficient for reptile occurrences at the 1 km × 1 km resolution. Additionally, the spatial coverage of available occurrences varied at species and family levels, and the majority of occurrence records were strongly associated with publicly accessible human infrastructure. Furthermore, we found that sampled areas within KNP were not necessarily ecologically representative of KNP as a whole, suggesting that areas of unique environmental space remain to be sampled. Our findings highlight the need for substantially greater sampling effort for reptiles across KNP and emphasise the need to carefully consider the sampling biases within existing data should these be used for conservation management decision-making. Modelling species distributions could potentially serve as a short-term solution, but a concomitant increase in surveys across the park is needed.
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    Snake predators of bird eggs: A review and bibliography
    (Wiley, 2022) Barends, Jody M.; Maritz, Bryan
    Snakes are frequent predators of bird nests and therefore potentially have an important impact on bird population dynamics. However, while many species are known to consume nestlings and chicks, few species have been recorded consuming bird eggs. To effectively quantify the effects of bird egg predation by snakes on bird demographics, a key first step is to identify which snake species consume bird eggs. Unfortunately, detailed information on the dietary habits of most snakes is scarce and feeding records are poorly cataloged, making it difficult to ascertain which species do and do not eat bird eggs. We reviewed the literature and online community science reports to compile a global list of confirmed snake predators of bird eggs. In total, we gathered 471 feeding records of 123 snake taxa consuming the eggs of at least 210 bird species from 238 individual data sources. Geographical locations of records disproportionately represented well-sampled regions, and we infer that many snake species not included on our list also consume bird eggs.