Is there sexual segregation in habitat selection by Black-browed Albatrosses wintering in the south-west Atlantic?

Abstract

Oceanographic variables are important to determine oceanographic processes such as the distribution of water bodies, identification of marine fronts, areas of high primary productivity and/or high availability of prey (Pereira et al. 2018). Anomalies and gradients are used for identifying marine fronts at various temporal and spatial scales. Anomalies are used to identify mesoscale fronts as eddies, while the gradients allow for the identification of the confluence zones where the larger scale fronts are generated. Anomalies of Sea Surface Temperature (SSTa), Cholorophyll-a concentration (CHLORa) and Sea Surface Hight (SSHa) for each month were calculated as the difference between the average value for a given month and year, and the average for that month over a 8-year (for Sea Surface Temperature [SST] and Cholorophyll-a concentration [CHLOR]) and 4-year (for Sea Surface Hight [SSH]) period in each grid cell. Gradients were generated by calculating the standard deviation of each cell in relation to the adjacent cell values (Sidhu et al. 2012;Li et al. 2015). For identifying fronts, eddies with values of SSHa < -10 cm were considered as a cyclone (cold core eddy), SSHa > +10 cm as anticyclone (warm core eddy), and SSHa between < 10 cm and > -10 cm as confluence zones (Davis et al. 2002). Habitat selection modellingThe platform BIOMOD allows the use different modelling techniques, their evaluation, and the construction of different averaged outputs of the single-model predictions (Thuiller et al. 2009;Ducci et al. 2015). The outstanding features of this modelling technique are: the generation of random pseudo-absences (when data are presence-only), the use of different statistical methods (highly recommended because the prediction discrepancies between modelling techniques can be very large) (Araujo et al. 2005;Thuiller et al. 2009), and the use of data-splitting procedures, whereby a set of the original data are used of training the models and the remainder for model evaluation.

Individual-level differences in size drive movements and spatial segregation of a pelagic seabird

“…Therefore, females seemed to be more e cient in the usage of wind. That is consistent to what is known for the species [14,15] and also for other dimorphic seabird species [50][51][52][53], where females, for being smaller, are lighter, have a lower wing load and therefore are able to increase speed and distance in response to wind.…”

Foraging habitat suitability of black‐browed albatrosses Thalassarche melanophris wintering in the South‐west Atlantic Ocean: Acknowledging age class to improve conservation management

“…Oceanographic variables were obtained from satellite images for the studied period (from July to September of 2011–2013 and 2015) with a monthly resolution of composite rasters (see Paz et al, 2021). Five satellite images were downloaded from online free services including Depth (DEPTH), Sea Salt Surface Mass Concentration (SAL), Sea Surface Temperature (SST), Chlorophyll‐ a concentration (CHLOR) and Sea Surface Height (SSH), and six other variables were post‐processed from those including Sea Surface Temperature gradient (SSTg) and anomaly (SSTa), Chlorophyll‐ a concentration gradient (CHLORg) and anomaly (CHLORa) and Sea Surface Height gradient (SSHg) and anomaly (SSHa) (Table S2).…”

“…The median age at first breeding is 10 years (range: 8–13) (Prince et al, 1994). The distribution and habitat selection of the species in the South‐west Atlantic Ocean have been widely studied for adult birds (Catry et al, 2013; Copello, Seco Pon & Favero, 2013; Grémillet et al, 2000; Phillips et al, 2004, 2005; Ponchon et al, 2019; Wakefield et al, 2011) with little information about immature individuals (however, see Paz et al, 2021). During the non‐breeding season, the birds from the Malvinas Islands mainly forage in the South‐west Atlantic Ocean including Argentinian, Uruguayan and Brazilian waters (Catry et al, 2013; Grémillet et al, 2000; Ponchon et al, 2019), and those breeding in Georgias del Sur Islands predominantly migrate to rich Benguela waters off South Africa, Namibia and Angola, with a small proportion moving to the South‐west Atlantic Ocean (Phillips et al, 2005).…”

“…Information about the use of foraging areas by age will be relevant both locally and globally to better understand the dynamics of albatross-fisheries interactions and the inherent risk of incidental mortality by age. This information will help avoid biassed estimates of overlap with fisheries and other threats and consequent misdirected management and conservation efforts (Carneiro et al, 2020;Paz et al, 2021). Tool to download the data (Coyne & Godley, 2005).…”