Ecological “bright spots” and the challenge of residuals-based assessment

The bright spots approach aims to assess the performance of managed ecosystems by comparing certain ecological outcomes, while controlling for other known drivers of the outcome via a statistical model; in effect, ranking sites based on their residuals from the fitted model. While the method has the potential to reduce bias in comparing different sites, the resulting assessment may come with high variance.

Reflections on Papers Past: Revisiting Estes et al. 1998

This is a series of posts entitled “Reflections on the Past”, a series by Hari Sridhar.

“In 1998, James Estes, Tim Tinker, Terrie Williams and Dan Doak published a paper in Science providing evidence to suggest that killer whales were behind the sudden declines in sea otter populations in western Alaska in the 1990s. Estes and colleagues also showed in this paper that the otter decline had, in turn, led to an increase in sea urchin numbers and consequent deforestation of kelp forests. Eighteen years after the paper was published, I spoke to James Estes about the observations that motivated this study and what we have learnt since about the killer whale’s role in this system.”

Posts in this series are archived at

The conservation value of migration bottlenecks: A case study from the Strait of Messina

Migration bottlenecks provide researchers with fascinating opportunities to study animal movement ecology. Advances in technology enable the dissemination of migratory ground-speed data in relation to independent variables such as weather conditions and time of day. I spent a week in the region of Calabria, Italy monitoring raptor migrations over the Strait of Messina bottleneck. In a single field day over 1,382 migratory raptors were counted; approximately 80% of these were European Honey Buzzards (Pernis apivorus). This post identifies Europe’s most important migratory raptor bottlenecks and highlights the threats facing migratory avifauna.