Search

Invasive mammalian predators have devastating effects on seabird nesting colonies. A census was conducted on breeding Wedge-tailed Shearwaters Ardenna pacifica in 2016 and 2021 on D'Arros Island, Seychelles, which has been rat-free since 2003. Results were compared with an earlier population estimate to assess population growth following the rat eradication. Compared to counts in 2009, we estimated a 10-fold increase in breeding population size, with 2768 (95% confidence interval (CI) 2424-3112) and 2406 (95% CI 2143-2667) breeding pairs in 2016 and 2021, respectively. While the estimated increase is partly attributable to differences in the timing of the conducted census between the two studies, we also observed an increase in the areal extent of the population, from 3.00 to 3.85 ha (0.0300-0.0385 km2), and an increase in nesting density. Cumulatively, this indicates a true population increase. [ABSTRACT FROM AUTHOR]

Bycatch risk assessments typically rely on spatial overlaps between seabirds and fishing vessels but should also consider seabirds' position in the attraction spectrum. Investigating seabird-fishery interactions in relation to habitat use is vital for species-specific risk assessments. To address this, we studied interactions between sooty albatrosses (SA) and white-chinned petrels (WCP) with fisheries. GPS data from 20 SA and 18 WCP individuals from Marion Island were analysed alongside Automatic Identification System-derived boat locations over two breeding seasons. We calculated encounter and attraction rates and correlated them with marine habitat characteristics. SA interactions occurred in deeper, warmer waters compared to their foraging habitat when vessels were absent, with 20% of individuals encountering and only 5% being attracted to boats. In contrast, WCP interactions occurred in shallow, warm South African shelf waters, consistent with their typical foraging habitats, with 72% encountering and 56% attracted to boats. These results highlight the need for continued reinforcement of mitigation measures for WCP. Despite the low attraction rates for SA, ongoing vigilance is required due to their smaller population size, which heightens the potential impact of illegal fisheries. The comparison of species along an attraction spectrum contributes to refining risk assessments and informs species-specific conservation strategies. [ABSTRACT FROM AUTHOR]