DOI: 10.5061/dryad.w0vt4b8rd
title: Understanding arid‐region waterbird community dynamics during lake dry‐downs

description: 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.
description: 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.
description: 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. <em>Proceedings of the Royal Society B</em> 279:
 1131-1141.