Building trust in science and evidence-based decision-making depends heavily on the credibility of studies and their findings. Researchers employ many different study designs that vary in their risk of bias to evaluate the true effect of interventions or impacts. Here, we empirically quantify, on a large scale, the prevalence of different study designs and the magnitude of bias in their estimates. Randomised designs and controlled observational designs with pre-intervention sampling were used by just 23% of intervention studies in biodiversity conservation, and 36% of intervention studies in social science. We demonstrate, through pairwise within-study comparisons across 49 environmental datasets, that these types of designs usually give less biased estimates than simpler observational designs. We propose a model-based approach to combine study estimates that may suffer from different levels of study design bias, discuss the implications for evidence synthesis, and how to facilitate the use of more credible study designs.

Research in remote locations is more expensive than similar activities at sites with easier access, but these costs have rarely been compared. Using examples from seabird research, we show that conducting research in the Arctic is typically eight times more expensive than pursuing similar studies at a southern location. The differences in costs are related principally to the much higher expenses of travel and shipping (typically 4–10× higher for Arctic work), as well as the good practice of meaningful engagement with northern communities (4%–25% of project costs). Although there is some variation in costs among Arctic countries, we hope that the consistent pattern of relatively higher Arctic costs allows policy-makers and funding agencies to better plan for research support, especially for this region that is experiencing rapid environmental change.

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The presence of introduced Norway rats Rattus norvegicus has raised concerns for the fate of the large least auklet Aethia pusilla colony situated at Sirius Point, Kiska Island, Alaska. Previous studies have documented extreme interannual variation in least auklet reproductive success and potential drastic population declines, both of which have been attributed to the varying abundance of, and predation by, Norway rats. A diet study would resolve the uncertainty that remains about the role of rats in the auklet's reproductive failure and the colony's decline. Our main objectives here were to quantify the variation in diet of introduced Norway rats and assess predation on least auklets. Using stable isotope analysis we document wide variability in rat diet dependent on location and provide direct evidence that Norway rats are preferentially preying on least auklets at Sirius Point. In conclusion, we hypothesize that the observed wide variability in rat diet will contribute to the persistence of rats on Kiska long after auklets have been extirpated. The persistence of rats enabled by their foraging plasticity will increase their effects by creating ecological traps within which prospecting individuals will fall and be depredated. This has large conservation consequences as it suggests that when seabirds are extirpated recolonization by prospecting birds is virtually impossible and island ecosystems will continue to be negatively affected and altered as long as introduced predators, such as rats, remain within them.

Growing evidence indicates relationships between seabird demography and both largeand small-scale variation in climate and oceanography, yet few studies have examined multiple species and locations simultaneously. As secondary consumers, least, whiskered, and crested auklets (Aethia pusilla, A. pygmaea, and A. cristatella, respectively), congeneric planktivorous seabirds endemic to the Bering and Okhotsk seas, are expected to respond to changes in ocean climate due to their low trophic positioning. From 1990 to 2008, we measured reproductive success (productivity) and breeding phenology (mean hatching date) of auklets on Buldir, Kiska, and Kasatochi, 3 islands spanning 585 km across the Aleutian Islands, Alaska, USA. A model including Island, Species, and Winter Aleutian Low Pressure Index (ALPI) best explained productivity, with reproductive success decreasing among all species with increasing ALPI (β = -0.273 ± 0.0263 [SE]), likely through control of water temperature and prey (zooplankton) availability. Auklet productivity also increased with increasing winter sea surface temperature (SST) in the western North Pacific and western Bering Sea (and correspondingly decreased with increasing SST in the Gulf of Alaska), and was correlated negatively with spring sea-level air pressure in the North Pacific. These responses are reflective of positive values of the Aleutian low pressure system. Though our datasets cover only 19 yr or less, we found similar correlations between climate and auklet productivity among all species and islands. Together, our results suggest that ocean climatic conditions and reproductive success of planktivorous auklets are significantly related.KEY WORDS: Productivity · Oceanography · Demography · Aethia spp. · Least auklet · Crested auklet · Whiskered auklet · Aleutian Islands 424: 205-218, 2011 Pacific and Bering Sea, this shift resulted in greater climatic variability (Bond et al. 2003, Hunt & Elliott 2004, Rodionov et al. 2005, greater stratification of the water column, and increased primary productivity (Trenberth & Hurrell 1994, Iida & Saitoh 2007. Other purported ecosystem shifts have occurred in 1989-1990 and 1998-1999, but these putative shifts in system state have not been well documented (Overland et al. 1999, Hare & Mantua 2000, Mueter et al. 2007. Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerSeabirds, as conspicuous, generally unexploited, secondary and tertiary consumers in marine systems, provide a unique opportunity to investigate coupled climate-ecosystem variation (Durant et al. 2009). Indeed, the relationship between ocean climate, ranging from direct measures of SST to multivariate climate indices, e.g. Pacific Decadal Oscillation (PDO) (Mantua & Hare 2002), and seabird breeding performance has been investigated frequently in the North Pacific (e.g. Gjerdrum et al. 2003, Abraham & Sydeman 2004) and elsewhere (e.g. Harris et al. 2005, Durant et al. 2006, Møller et al. 2006, Lavers et al. 2008, Jenouvrier et ...