Abstract: The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life-history stages even though they can represent a substantial proportion of the total population. Here we develop a methodological framework for estimating population-level density distributions of seabirds, integrating tracking data across the main life-history stages (adult breeders and non-breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life-history stage. We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non-breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population-level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all life-history stages. Synthesis and applications. Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data-poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at-sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations.

Abstract: A Geographic Information System (GIS)-based investigation into the interannual variability of sea ice concentration was conducted in the Dumont dUrville Sea off the Terre Adélie coastline, south of 65°S and between 139 and 146°E. Sea ice concentration data derived from Advanced Microwave Scanning Radiometer-EOS (AMSR-E) data were analysed for the period 2003 to 2009. Sea ice concentration was found to be least variable in three regions, namely the Buchanan Bay/Watt Bay region (143145°E), along 65.5°S (west of 144.5°E), and the Adélie Bank northeast of Dumont dUrville near 66°S, 140.5°E. The remaining areas had relatively high interannual variability, in particular the Adélie Basin (66°S, 140°E) and the outer fringe of the Mertz Glacier Polynya (MGP). In general, higher sea ice concentration conditions were experienced in the west of the study area (i.e., where annual fast ice recurs), and open water dominated in the MGP and in the northeast. The years 20072009 experienced greater persistence of higher sea ice concentration than earlier years. This study provides a baseline for assessing changes in the regional sea ice regime that may occur since the calving of the Mertz Glacier in February 2010.