Abstract: Long-term studies are essential to determine demographic parameters and population trends in seabirds. However, studies to date have focused mainly on the larger and accessible species. While small seabirds (< 200 g) play a major role in marine ecosystems, their nesting habitat, which is typically fragile convoluted burrows, largely preclude long-term surveys. This study evaluated the installation of artificial burrows as a tool to facilitate ongoing long-term research on small burrowing seabirds. We tested the use and acceptance of artificial burrows during the chick-rearing period of common diving petrels (Pelecanoides urinatrix) on Mayes Island, Kerguelen Archipelago, southern Indian Ocean. The growth rate, mass at fledging and fledging rate of chicks were similar between artificial and natural burrows. Similarly, there was no difference in occupancy rate 1 and 2 years after artificial burrows were installed. The installation of artificial burrows during the chick-rearing period of a small burrowing seabird appears to be an effective way to facilitate ongoing monitoring and research and, therefore, we recommend the wider use of artificial burrows to facilitate monitoring and research of other small burrow-nesting procellariiform species.

Abstract: The Minamata Convention On Mercury (Hg) Entered Into Force In 2017, Committing Its 116 Parties (As Of January 2019) To Curb Anthropogenic Emissions. Monitoring Of Atmospheric Concentrations And Trends Is An Important Part Of The Effectiveness Evaluation Of The Convention. A Few Years Ago (In 2017) We Reported An Increasing Trend In Atmospheric Hg Concentrations At The Cape Point Global Atmosphere Watch (Gaw) Station In South Africa (34.3535∘ S, 18.4897∘ E) For The 2007–2015 Period. With 2 More Years Of Measurements At Cape Point And The 2012–2017 Data From Amsterdam Island (37.7983∘ S, 77.5378∘ E) In The Remote Southern Indian Ocean, A More Complex Picture Emerges: At Cape Point The Upward Trend For The 2007–2017 Period Is Still Significant, But No Trend Or A Slightly Downward Trend Was Detected For The Period 2012–2017 At Both Cape Point And Amsterdam Island. The Upward Trend At Cape Point Is Driven Mainly By The Hg Concentration Minimum In 2009 And Maxima In 2014 And 2012. Using Ancillary Data On 222rn, Co, O3, Co2, And Ch4 From Cape Point And Amsterdam Island, The Possible Reasons For The Trend And Its Change Are Investigated. In A Companion Paper This Analysis Is Extended For The Cape Point Station By Calculations Of Source And Sink Regions Using Backward-trajectory Analysis.

Abstract: Optimal foraging theory predicts that diving predators should maximise their energy intake while minimizing the costs of their foraging activities at depth. This hypothesis was tested in two breath-hold divers that foraged in the pelagic waters off Kerguelen Island, southern Indian Ocean. Macaroni penguins (Eudyptes chrysolophus) feed predominately on crustaceans at moderate depths (ca. 50 m), while king penguins (Aptenodytes patagonicus) feed on mesopelagic fish at deep depths (ca. 100–150 m). We instrumented 22 penguins with time-depth recorders during the breeding season of the 2014 southern summer, just before they went to sea. Birds were recaptured after one to five foraging trips and the dive data were analysed on the level of single dive cycles and entire dive bouts. Both species adjusted their diving behaviour and modulated their foraging activity in accordance with their experience in their previous dives. Foraging activity during a dive (in terms of number of wiggles per dive) was greater if birds targeted the same depth as the previous dive. The penguins spent less time at the surface between two prey capture attempt dives than when a prey capture attempt dive was preceded by a non-prey capture attempt dive. Dive bout analyses showed that foraging activity increased with bout duration, while transit time during dives decreased with bout duration. Our findings are in general agreement with predictions based on optimal foraging models. The results suggest that penguins anticipated the depth of their next dive based on their encounter of a prey patch in the previous dive and optimized their chances of feeding success by spending minimal time at the surface and in transit to the patch depth. Once penguins detected a prey patch, these behavioural adjustments allowed them to rapidly return to that patch, increasing their chances of feeding again before the prey disperses.