Modelled niche of little auks during winter.

<p>Modelled niche of little auks during winter (expressed as log10 (x+1)) as a function of air temperature and abundance of <i>Calanus finmarchicus</i> (expressed as log10 (x+1)) for the months of December and January and the 12∶00–14∶00 period (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041194#s2" target="_blank">methods</a> for details). Open circles represent the observed distribution of little auks in relation to air temperature and abundance of <i>C. finmarchicus</i> (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0041194#pone-0041194-g002" target="_blank">Figure 2A</a>).</p

Bathymetric and oceanographic characteristics within the kernel density distribution of male and female Sooty Shearwaters during the pre-breeding, pre-laying exodus, incubation, chick-rearing and non-breeding periods.

<p>Representative middle months were chosen for environmental extractions within the extended incubation, chick-rearing and non-breeding period.</p

Characteristics of the pre-laying exodus of Sooty Shearwaters tracked using GLS loggers from Kidney Island, Falkland Islands, prior to the 2009 breeding season.

<p>Characteristics of the pre-laying exodus of Sooty Shearwaters tracked using GLS loggers from Kidney Island, Falkland Islands, prior to the 2009 breeding season.</p

Activity patterns of Sooty Shearwaters, recorded by BAS GLS loggers, throughout the annual cycle.

<p>Data for migration and the period of non-breeding residence are from Hedd et al. (2012). Values are means of individual bird means ±1 SD, with the range for individuals in parentheses.</p

Percentage of core foraging habitat shared by male and female Sooty Shearwaters.

<p>Percentage of core foraging habitat shared by male and female Sooty Shearwaters.</p

Spatial distribution of Sooty Shearwaters throughout the year.

<p>Kernel density distribution of male and female Sooty Shearwaters from Kidney Island, Falkland Islands (star) during the pre-breeding period (i.e., prior to the pre-laying exodus; A,B), the pre-laying exodus (C, D), the incubation (E, F) and chick-rearing periods (G, H), and the period of non-breeding residence (I, J). Place names mentioned in the text are indicated.</p

Influence of environmental factors on little auk winter distribution.

<p>(A) Occurrence of little auks (December 2009 and January 2010) in relation to <i>Calanus finmarchicus</i> densities (12∶00–14∶00 period, average for 1958–2007 – expressed as log10 (x+1)) and to air temperature (average for 1960–2009). (B) Correlation between little auk occurrence (number per grid cell) and abundance of <i>C. finmarchicus</i> (12∶00–14∶00 period, average for 1958–2007 – expressed as log10 (x+1)). The data were obtained by reducing the 3D euclidean space in panel a as a 2D euclidean space by averaging the number of little auk occurrence as a function of air temperature. (C) Thermal habitat preference of little auks. The data were obtained by reducing the 3D euclidean space in panel a as a 2D euclidean space by averaging the number of little auk occurrence as a function of <i>C. finmarchicus</i> densities.</p

Foraging trip durations of Sooty Shearwaters during the pre-breeding and breeding periods.

<p>Males are depicted in white and females in grey. Box plots show the median and 25^th and 75^th percentiles, whiskers indicate values within 1.5 times the interquartile range and circles represent outliers.</p

Distribution of little auks, <i>Calanus finmarchicus</i>, and air temperature during winter in the North Atlantic Ocean.

<p>(A, B) Number of occurrences of little auks per grid cell in December 2009 and January 2010, respectively. (C, D) Abundance of <i>C. finmarchicus</i> in December and January, respectively (average for 1958–2007), for the 12∶00–14∶00 period (expressed as percentage of abundance compared to the annual maximum abundance). (E, F) Air temperatures above sea surface (average for 1960–2009) in December and January, respectively.</p

At sea activity patterns.

<p>Percent time spent flying by male and female Sooty Shearwaters during daylight and darkness in different stages of the annual cycle. Values are LME model fits ±95% confidence intervals.</p