Flexibility in migratory strategy contrasts with reliance on restricted staging and overwintering grounds for Sabine’s gulls from the Canadian High Arctic

Abstract Sabine’s gulls (Xema sabini) undertake the longest migration of any gull, a trans-equatorial journey between Arctic breeding and southern hemisphere wintering areas. For such long-distance migrants, quantifying within- and between-individual variation in migratory strategy is key towards understanding resilience to environmental variability encountered over migration. We tracked 22 birds on 32 migrations from the Canadian Arctic to evaluate strategies and quantify flexibility among individuals and years. All birds undertook extended stopovers in a geographically-restricted staging area halfway through migration in the California Current System in both directions. Individuals were otherwise flexible in most aspects of migration but were repeatable in arrival date and duration of the southbound staging phase. Routes taken during southbound migration and overlap in overwintering areas were significantly larger within the same year than among years. Overall, birds showed high individual flexibility in migratory strategies but made similar decisions to one another in the same years. Every year, all birds showed repeatable, consistent reliance on the staging grounds as a key stopover site in both directions. This suggests Sabine’s gulls adjust to environmental change in many aspects of their migration but may be vulnerable to climate change and other anthropogenic influences during critical stages of the journey.

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Dynamic geography of small pelagic fish populations in the California Current System on the regime time scale (19311997)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f02-142 ◽

2002 ◽

Vol 59 (12) ◽

pp. 1980-1988 ◽

Cited By ~ 30

Author(s):

Rubén Rodríguez-Sánchez ◽

Daniel Lluch-Belda ◽

Héctor Villalobos ◽

Sofia Ortega-García

Keyword(s):

Time Scale ◽

Large Scale ◽

Environmental Variability ◽

Current System ◽

California Current ◽

Regime Shifts ◽

Population Changes ◽

California Current System ◽

Geographical Variations ◽

Sardine Population

Climate regime shifts in the Northeast Pacific appear to have forced population size changes associated with major geographical variations in the position of the center of distribution and bulk of biomass of Pacific sardine (Sardinops caeruleus). These findings help explain the disappearance of sardines around 60 years ago at the northern part of the California Current System and their return following the 1980s. The spatial processes described here differ from those suggesting that environmental regime shifts lead to progressive increasedecrease of stock abundance associated with homogeneous expansioncontraction of its distribution range around a fixed geographical center. Sardine population changes are seemingly related to environmental variability, whereas the spatial pattern of abundance for the northern anchovy (Engraulis mordax) appears to be inversely related to sardine population abundance. Anchovies increased where and when sardines were either absent or at a low population level. Thus, from the long-term and large-scale perspective, neither sardine nor anchovy populations conform to the simple homogeneous geographical range changes usually assumed. The sardine population changes its location within the ocean habitat in an evolving progression over a multidecadal time scale.

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Diet dichotomy between two migrant seabirds breeding near a high Arctic polynya

Royal Society Open Science ◽

10.1098/rsos.160982 ◽

2017 ◽

Vol 4 (3) ◽

pp. 160982 ◽

Cited By ~ 3

Author(s):

Isabeau Pratte ◽

Kelly A. Boadway ◽

Shanti E. Davis ◽

Mark Maftei ◽

Mark L. Mallory

Keyword(s):

Open Water ◽

High Arctic ◽

Canadian High Arctic ◽

Long Distance ◽

Sterna Paradisaea ◽

Xema Sabini ◽

Reliable Source ◽

Dietary Niche ◽

Sabine’S Gull ◽

Ground Nesting

High Arctic polynyas are predictable areas of open water, which offer long-distance migrant seabirds a reliable source of food during a period when they have to replenish and accumulate energy for reproduction. Investigating the interaction between species nesting sympatrically in the vicinity of polynyas should provide insights into the role that such oceanographic features play for pre-breeding seabirds. We used stable isotopes (δ 13 C and δ 15 N) to compare the diet of two ground-nesting seabirds, Sabine's gull ( Xema sabini ) and Arctic tern ( Sterna paradisaea ), nesting on an island adjacent to a recurring polynya in the Canadian high Arctic in 2008 and 2009. We show that, unlike Arctic terns, the diet of Sabine's gulls appears to include a non-negligible amount of terrestrially derived prey during early incubation, and that overall both species segregate their dietary niche during pre-laying and early incubation.

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Faculty Opinions recommendation of Rapid progression of ocean acidification in the California Current System.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717953148.793458716 ◽

2012 ◽

Author(s):

Russell Moll

Keyword(s):

Ocean Acidification ◽

Current System ◽

California Current ◽

Rapid Progression ◽

California Current System

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Improved Ecosystem Predictions of the California Current System via Accurate Light Calculations

10.21236/ada557196 ◽

2011 ◽

Author(s):

Curtis D. Mobley

Keyword(s):

Current System ◽

California Current ◽

California Current System

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Reconstruction of Diffusion Coefficients and Power Exponents from Single Lagrangian Trajectories

Fluids ◽

10.3390/fluids6030111 ◽

2021 ◽

Vol 6 (3) ◽

pp. 111

Author(s):

Leonid M. Ivanov ◽

Collins A. Collins ◽

Tetyana Margolina

Keyword(s):

Black Sea ◽

Diffusion Coefficients ◽

Current System ◽

Mean Square Displacement ◽

California Current ◽

The Black Sea ◽

Mean Square ◽

California Current System ◽

The Mean ◽

Non Gaussian

Using discrete wavelets, a novel technique is developed to estimate turbulent diffusion coefficients and power exponents from single Lagrangian particle trajectories. The technique differs from the classical approach (Davis (1991)’s technique) because averaging over a statistical ensemble of the mean square displacement (<X2>) is replaced by averaging along a single Lagrangian trajectory X(t) = {X(t), Y(t)}. Metzler et al. (2014) have demonstrated that for an ergodic (for example, normal diffusion) flow, the mean square displacement is <X2> = limT→∞τX2(T,s), where τX2 (T, s) = 1/(T − s) ∫0T−s(X(t+Δt) − X(t))2 dt, T and s are observational and lag times but for weak non-ergodic (such as super-diffusion and sub-diffusion) flows <X2> = limT→∞≪τX2(T,s)≫, where ≪…≫ is some additional averaging. Numerical calculations for surface drifters in the Black Sea and isobaric RAFOS floats deployed at mid depths in the California Current system demonstrated that the reconstructed diffusion coefficients were smaller than those calculated by Davis (1991)’s technique. This difference is caused by the choice of the Lagrangian mean. The technique proposed here is applied to the analysis of Lagrangian motions in the Black Sea (horizontal diffusion coefficients varied from 105 to 106 cm2/s) and for the sub-diffusion of two RAFOS floats in the California Current system where power exponents varied from 0.65 to 0.72. RAFOS float motions were found to be strongly non-ergodic and non-Gaussian.

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