Mapping shifts in spatial synchrony in grassland birds to inform conservation planning

Abstract

Spatial synchrony, defined as the correlated fluctuations in abundance of spatially separated populations, can be caused by regional fluctuations in natural and anthropogenic environmental population drivers. Investigations into the geography of synchrony can provide useful insight to inform conservation planning efforts by revealing regions of common population drivers and metapopulation extinction vulnerability. We examined the geography of spatial synchrony and decadal changes in these patterns for grassland birds in the United States and Canada, which are experiencing widespread and persistent population declines. We used Bayesian hierarchical models and over 50 years of abundance data from the North American Breeding Bird Survey to generate population indices within a 2°latitude by 2°longitude grid. We computed and mapped mean local spatial synchrony for each cell (mean detrended correlation of the index among neighboring cells), along with associated uncertainty, for 19 species in 2, 26-year periods, 1968-1993 and 1994-2019. Grassland birds were predicted to increase in spatial synchrony where agricultural intensification, climate change, or interactions between the 2 increased. We found no evidence of an overall increase in synchrony among grassland bird species. However, based on the geography of these changes, there was considerable spatial heterogeneity within species. Averaging across species, we identified clusters of increasing spatial synchrony in the Prairie Pothole and Shortgrass Prairie regions and a region of decreasing spatial synchrony in the eastern United States. Our approach has the potential to inform continental-scale conservation planning by adding an additional layer of relevant information to species status assessments and spatial prioritization of policy and management actions. Our work adds to a growing literature suggesting that global change may result in shifting patterns of spatial synchrony in population dynamics across taxa with broad implications for biodiversity conservation.

Drivers and spatial patterns of population synchrony of fish species in a floodplain

“…We have found that sites associated with the Baia River have higher contribution to the mean synchrony network, whereas a lake associated with the Paraná River contributed the most to mean anti‐synchrony network. These hubs of synchrony and anti‐synchrony could receive management attention to increase metacommunity stability and persistence of several floodplain fish populations (Allen & Lockwood, 2020; Dallas et al., 2020). For example, decreasing populations in the Baia River sites have the potential to overspill to the entire floodplain, especially for those species with high spatial synchrony, leading to generalised population declines.…”

“…This is already partially done by the Long‐Term Ecological Research Project in the study area, stressing the importance of this type of study. Nonetheless, some native species may need special attention (Allen & Lockwood, 2020), such as P. lineatus , which had high levels of spatial synchrony across the floodplain and is also of great socioeconomic and conservation value (Agostinho et al., 2007). By contrast, any effort to control the populations of the invasive Loricariichthys platymetopon should consider its spatially independent dynamics across the floodplain.…”

“…Mapping spatial synchrony levels can be useful to identify sites that are important to synchrony (Allen & Lockwood, 2020; Dallas et al., 2020; Gouveia et al., 2016) and to study their potential correlates at local scales (Dallas et al., 2020; Gouveia et al., 2016). We have found that sites associated with the Baia River have higher contribution to the mean synchrony network, whereas a lake associated with the Paraná River contributed the most to mean anti‐synchrony network.…”

“…Considering the threats to freshwater biodiversity, such as habitat fragmentation and hydrological regulation (Bezerra et al., 2019; Liermann et al., 2012; Reid et al., 2019; Winemiller et al., 2016), studying spatial synchrony is particularly important because there is evidence that synchrony increases metapopulation extinction risk (Earn et al., 2000; Engen et al., 2002; Heino et al., 1997; Palmqvist & Lundberg, 1998), with potential effects on metacommunity (Wang et al., 2019; Wilcox et al., 2017) and ecosystem stability (Patrick et al., 2021). In fact, some recent studies have considered spatial synchrony as a criterion for assessing species extinction risk (Allen & Lockwood, 2020; Stowe et al., 2020). In addition, synchrony levels can inform population monitoring programmes by demonstrating the need to increase or the possibility to reduce the number of sites monitored, in case of low or high spatial synchrony, respectively (Rhodes & Jonzén, 2011).…”

Interspecific variation in fish spatial synchrony relates to reproductive traits in a highly fragmented river

“…The levels of spatial synchrony may be related to regional extinction risk (Heino et al, 1997) because rescue effects are less likely to occur when different local populations decline simultaneously (Akçakaya, 2000; Earn et al, 2000; Palmqvist & Lundberg, 1998), so in the case of alterations in environmental conditions that negatively affect population dynamics, species with high spatial synchrony could suffer from simultaneous declines across the region (Allen & Lockwood, 2020; Palmqvist & Lundberg, 1998). Therefore, finding trait‐based correlates of spatial synchrony may provide useful insights for management purposes (Bino et al, 2020; Chevalier et al, 2014; Hsieh et al, 2021).…”