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Understanding arid‐region waterbird community dynamics during lake dry‐downs

Citation

Cumming, Graeme; Henry, Dominic (2021), Understanding arid‐region waterbird community dynamics during lake dry‐downs, Dryad, Dataset, https://doi.org/10.5061/dryad.w0vt4b8rd

Abstract

These data were collected to explore changes in the bird community associated with Lake Ngami, Botswana, through successive drydown periods. Our analysis shows significant shifts, driven partially by changes in water level, in the species composition of the bird community over the period of study. The data set contains standardised half-hour point counts for the bird community of Lake Ngami, Botswana; and R code used for community-level analyses of the resulting time series. Counts were undertaken every 4 months from October 2007-July 2009.

We used the data to test three theoretical predictions: simplification of the bird community over time due to a reduction in habitat area and concurrent niche loss; large fluctuations in densities of mobile, opportunistic species; and high variance in predator and prey abundance. Despite temporal variance in species accumulation, we observed no obvious simplification of the bird community over time. There were distinct but consistent groupings of abundance and composition across transitional stages in lake water levels. The data do show some rapid shifts in functional composition, such as loss of deepwater foragers; winners and losers also occurred within foraging guilds.

Methods

We quantified changes in species diversity and the functional composition of the waterbird community over two iterations of annual drying-down and flooding. Each sampling period involved five days of standardized point counts at between 8 and 13 points. Points located at the water's edge were each visited four times, at different times of day, over each 5-day counting period. The total sample size was 228 point counts. Each count used a ten-minute habituation period followed by a half-hour counting period by stationary observers, during which all birds seen within a 150m radius in front of the observers were recorded. All counts included at least one highly skilled observer and were mostly undertaken by the same group of people. The counts contain four standardized samples for each point for 8-13 different points, and a minimum of 32 point counts (16h observation time) per sampling period.

Usage Notes

A full description of the data set is provided in the associated paper. There are no associated legal or ethical concerns. Numbers of birds vary from zero through to several thousand; particular attention should be paid to the quelea species, which occurred in exceptionally high numbers in some counting sites. Also of relevance for analysis are that (1) the number of counting sites changes over time, with some sites being lost as the lake becomes smaller; and (2) the data are zero-heavy, with many species being observed only once or only at particular times and places.

Cumming, G.S., Henry, D.A.W., Mutumi, G.L., and Ndlovu, M. (2021). Understanding arid-region waterbird community dynamics during lake dry-downs. Ecosphere 12 e03668.

These count data were collected prior to a week of bird captures and sampling. They are also associated with banding data in the SAFRING database and complementary information on avian influenza prevalence as presented in the following publications:

Cumming, G.S.., Caron, A., Abolnik, C., Cattoli, G., Bruinzeel, L.W., Burger, C.E., Cecchettin, K., Chiweshe, N., Mochotlhoane, B., Mutumi, G.L. and Ndlovu, M. (2011). The ecology of Influenza A viruses in wild birds in southern Africa. Ecohealth 8:4-13.

Gaidet, N., Caron, A., Cappelle, J., Cumming, G.S., Balança, G., Hammoumi, S., Cattoli, G., Abolnik, C., Servan de Almeida, R., Gil, P., Fereidouni, S.R., Grosbois, V., Tran, A., Mundava, J., Fofana, B., Ould Elmamy, B., Ndlovu, M., Mondain-Monval, J.Y., Triplet, P., Hagemeijer, W., Karesh, W.B., Newman, S.H. and Dodman, T. (2012). Understanding the ecological drivers of avian influenza virus infection in wildfowl: a continental scale study across Africa. Proceedings of the Royal Society B 279: 1131-1141.

Funding

Wildlife Conservation Society, Award: GAINS (Global Avian Influenza Network for Surveillance)