Assessing the extent to which temporal changes in waterbird community composition are driven by either local, regional or global factors

Abstract

1. Lough Neagh and Lough Beg Special Protection Area (SPA, hereafter Lough Neagh) is an important non-estuarine site in Britain and Ireland for overwintering wildfowl. Multivariate analysis of the winter counts showed a state-shift in the waterbird community following winter 2000/2001, mostly due to rapid declines in abundance (46-57% declines in the mean mid-winter January counts between 1993-2000 and 2002-2009) of members of the diving duck guild (pochard Aythya ferina, tufted duck Aythya fuligula and goldeneye Bucephala clangula) and coot (Fulica atra), a submerged macrophyte feeder.2. Only pochard showed correlations between declines at Lough Neagh and those of overall species flyway population indices to suggest that global changes could contribute to declines at the site. However, indices from the Republic of Ireland showed no overall decline in the rest of Ireland. Tufted duck indices at the site were inversely related to indices in Great Britain. Lough Neagh goldeneye indices were positively correlated with indices in the Republic of Ireland and Great Britain, suggesting that short-stopping could contribute to declines at the site. Coot declines at Lough Neagh did not correlate with trends elsewhere, suggesting local factors involved in the decline.3. These analyses indicate that although there are potentially different explanations for the dramatic declines in these four waterbird species at this site, the simultaneous nature of the declines across two feeding guilds strongly suggest that local factors (such as loss of submerged macrophytes and benthic invertebrates) were involved. An assessment of the food supply, local disturbance and other factors at Lough Neagh is required to find an explanation for the observed adverse trends in wintering numbers of the affected species.4. This study highlights the potential of waterbird community structure to reflect the status of aquatic systems, but confirms the need to establish site-specific factors responsible for the observed changes in abundance of key waterbird species at a site.

Trade-Offs Between Biodiversity Conservation and Nutrients Removal in Wetlands of Arid Intensive Agricultural Basins

“…Recent studies have tried to discriminate which factors, operating at different geographical scales-from the site where the waterbirds are counted to the whole biogeographical population range-explain the change in waterbird numbers recorded by IWC and other monitoring schemes (Tománková et al, 2013). Nor do the increase in bird abundances necessarily relate to local environmental factors.…”

Spatiotemporal Assessment of Littoral Waterbirds for Establishing Ecological Indicators of Mediterranean Coastal Lagoons

“…YEAR expressed temporal changes in waterbird populations reflected in local surveys, but partly due to processes operating at larger scales (e.g., reproductive success, migration patterns, survival; [63]), and partly due to local interannual changes [64,65]. Since BAND was a measure of the distance to attractive or deterrent shoreline features, the decrease of H and R from B1 to B2-B4 suggested that winter community structure was affected by them, as well as by depth (inversely related with BAND), which determines the distribution of bird morphological types, feeding styles and foraging strategies [66,67].…”

Chlorophyll‐a concentrations and macroinvertebrate declines coincide with the collapse of overwintering diving duck populations in a large eutrophic lake

“…Any change in the macroinvertebrate community due to changes in water quality is likely to have an impact on consumers higher in the food chain, most notably waterbirds. Indeed, long‐term monitoring of waterbirds at Lough Neagh has shown a marked decline in overwintering diving ducks, particularly pochard ( Aythya ferina ), tufted duck ( Aythya fuligula ) and goldeneye ( Bucephala clangula ), since the winter of 2000/2001 (Tománková et al ., ). Between the winters of 2000/2001 and 2008/2009, the overall population of diving ducks on Lough Neagh declined by 63% (Tománková et al ., ).…”

“…Indeed, long‐term monitoring of waterbirds at Lough Neagh has shown a marked decline in overwintering diving ducks, particularly pochard ( Aythya ferina ), tufted duck ( Aythya fuligula ) and goldeneye ( Bucephala clangula ), since the winter of 2000/2001 (Tománková et al ., ). Between the winters of 2000/2001 and 2008/2009, the overall population of diving ducks on Lough Neagh declined by 63% (Tománková et al ., ). Different possible explanations for this decline have included site‐related factors (Maclean, Burton & Austin, ) and migratory short‐stopping, that is, as new (and previously unsuitable, for example, due to ice cover) habitats become available to migratory birds, they are able to reduce the distance between breeding and wintering grounds (Allen & Mellon, ; Lehikoinen et al ., ).…”

“…Since the relevant statutory agencies are responsible for maintaining the lake and its waterbirds in ‘favourable conservation status’, it is essential to determine whether factors at Lough Neagh are responsible for changes in diving duck abundance and, if so, whether management actions can be implemented to restore their abundance. Recent research suggests that local factors are likely to be at least partially responsible, with reduction in local food supply at the Lough being one possible hypothesis (Tománková et al ., ).…”