Spring Stopover Ecology of Migrant Western Sandpipers

The presence of top predators can affect prey behaviour, morphology and life history, and thereby can produce indirect population consequences greater and further reaching than direct depredation would have alone. Raptor species in the Americas are recovering since restrictions on the use of dichlorodiphenyltrichloroethane (DDT) and the implementation of conservation measures, in effect constituting a hemisphere-wide predator-reintroduction experiment, and profound effects on populations of their prey are to be expected. Here, we document changes in the behaviour of western sandpipers (Calidris mauri ) at migratory stopover sites over two decades. Since 1985, migratory body mass and stopover durations of western sandpipers have fallen steadily at some stopovers in the Strait of Georgia, British Columbia. Comparisons between years, sites and seasons strongly implicate increasing danger from the recovery of peregrine falcons (Falco peregrinus) as a causal factor. A decade-long ongoing steep decline in sandpiper numbers censused on our study site is explained entirely by the shortening stopover duration, rather than fewer individuals using the site. Such behavioural changes are probably general among migratory shorebird species, and may be contributing to the widespread census declines reported in North America.

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“…= 0.66, n = 10 ( Iverson et al 1996); 1995/1996: 2.2 days, s.e.m. = 0.23, n = 25 (Warnock & Bishop 1998)). …”

Section: Resultsmentioning

confidence: 94%

Western sandpipers have altered migration tactics as peregrine falcon populations have recovered

Ydenberg

Butler

Lank

et al. 2004

Proc. R. Soc. Lond. B

148

171

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“…Under both hypotheses, birds in better condition should have shorter stopover durations. However, the majority of empirical studies have found little evidence supporting the conditionstopover duration relationship (Gudmunsson et al 1991, Holgren et al 1993, Skagen and Knopf 1994, Lyons and Haig 1995, Warnock and Bishop 1998, Pfister et al 1998, Dinsmore and Collazo 2003, Warnock et al 2004). Other researchers have suggested that predation risk (Ydenberg et al 2004) and wind (Butler et al 1997; but see Weber et al 1998) strongly influence stopover duration.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Body Condition on the Stopover Ecology of Least Sandpipers in the Lower Mississippi Alluvial Valley during Fall Migration

Lehnen¹,

Krementz²

2007

ACE

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ABSTRACT. Many shorebirds are long-distance migrants and depend on the energy gained at stopover sites to complete migration. Competing hypotheses have described strategies used by migrating birds; the energy-selection hypothesis predicts that shorebirds attempt to maximize energy gained at stopover sites, whereas the time-selection hypothesis predicts that shorebirds attempt to minimize time spent at stopover sites. The energy-and time-selection hypotheses both predict that birds in better condition will depart sites sooner. However, numerous studies of stopover duration have found little support for this prediction, leading to the suggestion that migrating birds operate under energy and time constraints for only a small portion of the migratory season. During fall migration 2002, we tested the prediction that birds in better condition depart stopover sites sooner by examining the relationship between stopover duration and body condition for migrating Least Sandpipers (Calidris minutilla) at three stopover sites in the Lower Mississippi Alluvial Valley. We also tested the assumption made by the Lower Mississippi Alluvial Valley Migratory Bird Science Team that shorebirds stay in the Mississippi Valley for 10 d. The assumption of 10 d was used to estimate the amount of habitat required by shorebirds in the Mississippi Valley during fall migration; a period longer than 10 d would increase the estimate of the amount habitat required. We used multiple-day constancy models of apparent survival and program MARK to estimate stopover duration for 293 individually color-marked and resighted Least Sandpipers. We found that a four-day constancy interval and a site x quadratic time trend interaction term best modeled apparent survival. We found only weak support for body condition as a factor explaining length of stopover duration, which is consistent with findings from similar work. Stopover duration estimates were 4.1 d (95% CI = 2.8-6.1) for adult Least Sandpipers at Bald Knob National Wildlife Refuge, Arkansas, 6.5 d (95% CI = 4.9-8.7) for adult and 6.1 d (95% CI =4.2-9.1) for juvenile Least Sandpipers at Yazoo National Wildlife Refuge, Mississippi, and 6.9 d (95% CI = 5.5-8.7) for juvenile Least Sandpipers at Morgan Brake National Wildlife Refuge, Mississippi. Based on our estimates of stopover duration and the assumption made by the Lower Mississippi Alluvial Valley Migratory Bird Science Team, there is sufficient habitat in the lower Mississippi Valley to support shorebirds during fall migration.RÉSUMÉ. De nombreux oiseaux de rivage migrent sur de longues distances et dépendent de l'énergie accumulée aux haltes migratoires pour compléter leur migration. Il existe deux hypothèses concurrentes pour définir les stratégies utilisées par les oiseaux en migration : l'hypothèse énergétique suppose que les oiseaux tentent de maximiser leurs gains énergétiques sur les haltes migratoires, tandis que l'hypothèse temporelle avance qu'ils tentent de minimiser leur durée de séjour à ces endroits. Ces hypothèses prédisent toutes d...

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“…The availability and quality of resources during spring migration may have implications for success during subsequent stages of the annual cycle (Ankney & MacInnes 1978, Alisauskas & Ankney 1992, Warnock & Bishop 1998, Smith & Moore 2003, Morrison & Hobson 2004). Several researchers have described cross-seasonal effects of spring habitats on reproductive performance by migratory waterfowl (Anteau & Afton 2004, Reed et al 2004, Schmutz et al 2006, and because these events provide the energy and nutrients required for reproduction, it follows that population dynamics might be influenced by habitat conditions during spring migration.…”

Section: Discussionmentioning

confidence: 99%

“…Resale or republication not permitted without written consent of the publisher migratory birds acquire energy and nutrient reserves at spring stopover sites, and the availability and quality of resources at these sites can have implications for success during subsequent stages of the annual cycle (Ryder 1970, Ankney & MacInnes 1978, Alisaus kas & Ankney 1992, Warnock & Bishop 1998, Smith & Moore 2003, Morrison & Hobson 2004. Therefore, the timing of migration and the choice of stopover habitat can have population-level demographic consequences.…”

Section: Abstract: Habitat Use · Herring Spawn · Melanitta Perspicilmentioning

confidence: 99%

Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis

Lok

Esler²,

Takekawa³

et al. 2012

Mar. Ecol. Prog. Ser.

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Spring Stopover Ecology of Migrant Western Sandpipers

Cited by 114 publications

References 29 publications

Western sandpipers have altered migration tactics as peregrine falcon populations have recovered

Western sandpipers have altered migration tactics as peregrine falcon populations have recovered

The Influence of Body Condition on the Stopover Ecology of Least Sandpipers in the Lower Mississippi Alluvial Valley during Fall Migration

Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis

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