title: Migratory connectivity magnifies the consequences of habitat loss from sea-level rise for shorebird populations.
abstract: Sea-level rise (SLR) will greatly alter littoral ecosystems, causing habitat change and loss for coastal species. Habitat loss is widely used as a measurement of the risk of extinction, but because many coastal species are migratory, the impact of habitat loss will depend not only on its extent, but also on where it occurs. Here, we develop a novel graph-theoretic approach to measure the vulnerability of a migratory network to the impact of habitat loss from SLR based on population flow through the network. We show that reductions in population flow far exceed the proportion of habitat lost for 10 long-distance migrant shorebirds using the East Asian-Australasian Flyway. We estimate that SLR will inundate 23-40% of intertidal habitat area along their migration routes, but cause a reduction in population flow of up to 72 per cent across the taxa. This magnifying effect was particularly strong for taxa whose migration routes contain bottlenecks-sites through which a large fraction of the population travels. We develop the bottleneck index, a new network metric that positively correlates with the predicted impacts of habitat loss on overall population flow. Our results indicate that migratory species are at greater risk than previously realized.
authors.affiliation: Australian Research Council Centre of Excellence for Environmental Decisions, School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia. takuya@stanford.edu
authors.forename: Takuya
authors.initials: T
authors.lastname: Iwamura
authors.forename: Hugh P
authors.initials: HP
authors.lastname: Possingham
authors.forename: Iadine
authors.initials: I
authors.lastname: Chadès
authors.forename: Clive
authors.initials: C
authors.lastname: Minton
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Murray
authors.forename: Danny I
authors.initials: DI
authors.lastname: Rogers
authors.forename: Eric A
authors.initials: EA
authors.lastname: Treml
authors.forename: Richard A
authors.initials: RA
authors.lastname: Fuller
mesh_terms: D025041:Animal Migration; D000818:Animals; D044362:Australasia; D001717:Birds; D017753:Ecosystem; D008962:Models, Theoretical; D009792:Oceans and Seas; D011157:Population Dynamics
keywords: East Asian–Australasian Flyway; ecological networks; graph theory; maximum flow; migratory shorebirds; sea-level rise