Differential population trends align with migratory connectivity in an endangered shorebird

Abstract

Migratory connectivity describes the extent to which migratory species' populations are connected throughout the annual cycle. While recognized as critical for understanding the population dynamics of migratory species and conserving them, empirical evidence of links between migratory connectivity and population dynamics are uncommon. We analyzed associations between spatiotemporal connectivity and differential population trends in a declining and endangered migratory shorebird, the far eastern curlew (Numenius madagascariensis), with multiyear tracking data from across the Australian nonbreeding grounds. We found evidence of temporal and spatial segregation during migration and breeding: curlew from southeast Australia initiated northward migration earlier, arrived at breeding sites earlier, and bred at lower latitudes than curlew from northwest Australia. Analysis of land modification intensity revealed that populations from southeast Australia face greater human impacts compared to those from northwest Australia at both the breeding and nonbreeding grounds, a pattern that aligns with steeper population declines in southeast Australia. This alignment between migratory † Clive D. T. Minton was deceased.

Migratory network reveals unique spatial-temporal migration dynamics of Dunlin subspecies along the East Asian-Australasian Flyway

“…Constructing a migratory network from animal tracking data is one approach to assess spatial and temporal connections among flyway areas and the migrants that use them [16][17][18][19]. Adapted from network theory, a migratory network combines movement data from multiple individuals to graphically summarize how breeding and nonbreeding areas (i.e., network nodes) are interconnected via immigration and emigration (i.e., network edges; [20].…”

“…Once constructed, a migratory network is a powerful framework for evaluating how populations use a flyway in space and time [13,21], estimating the tradeoffs associated with various conservation actions [6,7], and helping to understand drivers of population trends [16,22]. However, there are comparatively few examples where spatially and temporally explicit migratory networks have been constructed to evaluate the migration dynamics of a bird population across its entire annual cycle [e.g., 18, 19,23].…”

Connectivity between countries established by landbirds and raptors migrating along the African–Eurasian flyway

“…If instead the birds spread across multiple African countries, they establish multiple links of lower strength. This measure of strength is directional (e.g., Morrick et al, 2021): it reflects the degree of importance of an African country to the population breeding in a European country. We did not calculate the reverse (the extent to which the European country is important to the non-breeding population of the African country) because tracking studies were initiated in Europe and representativeness of African countries' non-breeding populations is therefore too low for broad inference.…”

“…However, much more detailed information could be obtained from reanalyses of full tracks, including distributions across the annual cycle (Carneiro et al, 2020), stopover sites along migration routes (Knight et al, 2021), and identification of key sites for conservation Morrick et al, 2021), mortality hotspots (Klaassen et al, 2014), and threats along the flyway (Oppel et al, 2021) across species and populations. Repositories such as Movebank (https://www.movebank.org/) and the Seabird Tracking Database (http://seabirdtracking.…”

Conservation planning for threatened marine megafauna: Moving forward with a better approach

“…Challenges in conservation planning for threatened marine megafauna in coastal and estuarine waters come not only from the intensification of coastal development and engineering activities (Huang et al, 2022), but also from the complexity of conservation planning and implementation. Marine megafauna generally have broad distribution ranges spanning national, ecoregional, or even continental regions (Sequeira et al, 2019; Morrick et al, 2021), and these are often difficult to survey completely (Hammond et al, 2021) and protect (Wang et al, 2021; Huang et al, 2022). For threatened marine megafauna, such as the Indo‐Pacific humpback dolphin ( Sousa chinensis ), sound conservation planning needs to ensure the identification of special areas for conservation (SACs) that can provide sufficient space to accommodate a viable population (Karczmarski, Huang & Chan, 2017b).…”