Responses of global waterbird populations to climate change vary with latitude

Abstract

2While climate change continues to present a major threat to global biodiversity and 2 3 ecosystems, most research on climate change impacts do not have the resolution to detect 2 4 changes in species abundance and are often limited to temperate ecosystems. This limits our 2 5understanding of global responses in species abundance-a determinant of ecosystem 2 6 function and services-to climate change including in the highly-biodiverse tropics. We 2 7 address this knowledge gap by quantifying abundance responses to climate change in 2 8 waterbirds, an indicator taxon of wetland biodiversity, at 6,822 sites between -55° and 64°. 9Using 1,303,651 count records since 1990 of 390 species, we show that with temperature 3 0 increase, the abundance of species and populations decreased at lower latitudes, particularly 3 1 in the tropics, but increased at higher latitudes. These contrasting responses to temperature 3 2 increase according to latitude indicate potential global-scale poleward shifts of species 3 3 abundance under climate change, providing empirical support for predictions by earlier 3 4 studies. The negative responses to temperature increase in tropical species and populations 3 5are of conservation concern, as they are often also threatened by other anthropogenic factors. 6Our results suggest that existing biases in studies towards temperate regions could 3 7 underestimate the impact of climate change on waterbirds and other species.3 8 3 9 4 1 urgent need to understand how species respond to changing climates globally. A wide range 4 2 of species have already shown responses to climate change, such as changes in geographical 4 3 3 range 1 , phenology 2 and abundance 3 . However, the rate and direction of these responses vary 4 4 greatly among species and locations 1,2,4 . As climate-driven changes in biodiversity are 4 5 expected to affect ecosystem functioning, human well-being, and the dynamics of climate 4 6 change itself 5 , understanding how species' responses to climate change may vary globally 4 7 could provide crucial evidence for a more effective allocation of limited resources on a 4 8 priority basis for the conservation of species and ecosystems threatened the most by climate 4 9 change, and for assessing how climate-driven changes in biodiversity may affect human 5 0 societies. 5 1Existing gaps in the geographical coverage of available evidence seriously limit our 5 2 understanding of species' responses to climate change and its variations across the globe 6 . 3Earlier global reviews of species' responses to climate change have rarely incorporated 5 4 species and studies in the tropics, due to the lack of relevant information 7 . Such geographical 5 5 biases are even more prominent in studies investigating responses in species abundance 8,9 , 5 6 which is a major determinant of species extinction risk 10 , ecosystem function and services 11 . 7Research on abundance responses to climate change to date has largely been conducted in 5 8 Europe, North America and the Arctic 3,12-14 , with a rec...

Climate change exposure of waterbird species in the African-Eurasian flyways

“…In general, our models showed a strong influence of temperature and somewhat weaker effect of precipitation on species' distributions. This is consistent with the empirical results of Amano et al (2020). Surprisingly, predictors related to inundation all had relatively low importance in predicting the distribution of waterbirds in all seasons compared with the importance of temperature and precipitation.…”

“…A growing body of evidence shows that many waterbirds are already changing their distributions in response to climate change (e.g. Maclean et al 2008, Lehikoinen et al 2013, Amano et al 2020, and that their wetland habitats are also exposed to climatic changes (e.g. Winter 2000, Junk et al 2013, Mitchell 2013.…”

Nestedness theory suggests wetland fragments with large areas and macrophyte diversity benefit waterbirds

“…As a combined result of climate change and anthropogenic activities, global wetlands have been severely degraded over the past century, and their ecosystem services and functions have experienced significant degeneration (Amano et al., 2018 , 2020 ). In addition, waterbird populations that depend on wetlands for survival have markedly declined (Amano et al., 2018 ; Hu et al., 2017 ).…”