Evaluating compositional changes in the avian communities of eastern North America using temperature and precipitation indices

Abstract

Aim: Species distributions are altered by climate change, resulting in changes in community composition. How communities are changing with climate is important for understanding the dynamics of changing diversity patterns. In this study, we employ two community weighted means (CWMs) of temperature (CTI) and precipitation (CPI) to evaluate patterns in climate-driven community changes.Location: Eastern North America between −100° and −60° longitude and 25°-50°N latitude. Taxon: North American birdsMethods: We used North American Breeding Bird Survey (BBS) data from 1990 to 2018 to test the spatiotemporal trends of these indices at a sub-continental (across all BBS routes) and at a regional scale (sub-continental scale partitioned by 5° latitude bands). We employ a jackknife analysis to highlight individual species contributions to CTI and CPI trends and further identify group characteristics of species based on relative abundance trends and range expansion and contraction trends.Results: Across all BBS routes, temperature marginally increased and precipitation significantly increased. At the sub-continental scale, we found no correlation between CTI and temperature, but a positive correlation between CPI and precipitation. CTI and CPI both increased, driven by increased abundances of "warm" and "wet" dwelling species expanding in range. Regional scale CTI and CPI patterns deviated from sub-continental patterns. CTI was driven by "warm" dwelling species increasing in abundance and expanding in range, whereas decreases in "dry" dwelling species contracting in range drove CPI trends at the highest latitudes. Main conclusions:The concurrent use of CTI and CPI highlights that community dynamics are more complicated than using temperature metrics alone. Employing more than one community index demonstrates how simultaneous increases in two separate evaluative indices can have disproportionate effects on the number of species that contribute to a trend and highlight disparate mechanisms that contribute to these underlying differences.

Climate‐related range shifts in Arctic‐breeding shorebirds

“…While species distributions are much more complex than simple climate relationships, this index has been a useful approach for describing how population trends and demography of bird populations are responding to climate change (Gaüzère et al, 2020 ; Godet et al, 2011 ; Princé & Zuckerberg, 2015 ). The collective contributions of individual species responses can give an indication of how the ecological community is responding to change (Curley et al, 2022 ; Gaüzère et al, 2019 ). Species with low STI consistently show more negative population trends in response to high temperatures (Pearce‐Higgins et al, 2015 ).…”

Temperature niche composition change inside and outside protected areas under climate warming

“…A similar spillover effect is driving generalist species from managed to natural areas (Frost et al., 2015; Häkkilä et al., 2017). Consistent with the spillover effect, earlier studies show that the CTI change in eastern North America is driven by warm‐dwelling species (Curley et al., 2022) and that the colonizations of warm‐dwelling species drive the increase in the number of bird species overwintering in urban areas in North America (Princé & Zuckerberg, 2015). In parallel, cold‐dwelling species are declining in northern European breeding bird communities (Tayleur et al., 2016).…”

“…The CTI combines species abundances and traits and may thus be driven not only by climatic forces, but also by other drivers of population change, such as land‐use change (Clavero et al., 2011). However, several studies have documented increases in CTI (Curley et al., 2022; Lehikoinen et al., 2021) and mismatches in the rates of change of CTI and temperature change (Bertrand et al., 2011; Santangeli & Lehikoinen, 2017). Nevertheless, it is often unclear whether a CTI change is due to an increase in the abundance of warm‐dwelling species or a decrease in the abundance of cold‐dwelling species.…”

“…For the second question, we expected that the positive temporal changes in CTI have occurred inside and outside PAs (Curley et al., 2022; Gaget et al., 2021; Santangeli et al., 2017) because the ambient average temperatures increased during the study period (Devictor et al., 2008; Lindström et al., 2013). However, we considered two competing hypotheses about differences in CTI change between PAs and unprotected lands.…”

“…This could cause reduced CTI changes compared with unprotected areas. Second, warm‐dwelling species speed up the increase in CTI because abundances of warm‐dwelling species increased in North America during the study period following recent climate warming (Curley et al., 2022; Princé & Zuckerberg, 2015).…”