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Efforts to conserve biodiversity comprise a patchwork of international goals, national-level plans, and local interventions that, overall, are failing. We discuss the potential utility of applying the mitigation hierarchy, widely used during economic development activities, to all negative human impacts on biodiversity. Evaluating all biodiversity losses and gains through the mitigation hierarchy could help prioritize consideration of conservation goals and drive the empirical evaluation of conservation investments through the explicit consideration of counterfactual trends and ecosystem dynamics across scales. We explore the challenges in using this framework to achieve global conservation goals, including operationalization and monitoring and compliance, and we discuss solutions and research priorities. The mitigation hierarchy’s conceptual power and ability to clarify thinking could provide the step change needed to integrate the multiple elements of conservation goals and interventions in order to achieve successful biodiversity outcomes.

Many animal taxa exhibit sex‐specific variation in ecological traits, such as foraging and distribution. These differences could result in sex‐specific responses to change, but such demographic effects are poorly understood. Here, we test for sex‐specific differences in the demography of northern (NGP, Macronectes halli) and southern (SGP, M. giganteus) giant petrels – strongly sexually size‐dimorphic birds that breed sympatrically at South Georgia, South Atlantic Ocean. Both species feed at sea or on carrion on land, but larger males (30% heavier) are more reliant on terrestrial foraging than the more pelagic females. Using multi‐event mark‐recapture models, we examine the impacts of long‐term changes in environmental conditions and commercial fishing on annual adult survival and use two‐sex matrix population models to forecast future trends. As expected, survival of male NGP was positively affected by carrion availability, but negatively affected by zonal winds. Female survival was positively affected by meridional winds and El Niño–Southern Oscillation (ENSO), and negatively affected by sea ice concentration and pelagic longline effort. Survival of SGPs did not differ between sexes; however, survival of males only was positively correlated with the Southern Annular Mode (SAM). Two‐sex population projections indicate that future environmental conditions are likely to benefit giant petrels. However, any potential increase in pelagic longline fisheries could reduce female survival and population growth. Our study reveals that sex‐specific ecological differences can lead to divergent responses to environmental drivers (i.e. climate and fisheries). Moreover, because such effects may not be apparent when all individuals are considered together, ignoring sex differences could underestimate the relative influence of a changing environment on demography. Giant petrels (Macronectes spp.) are the most sexually size‐dimorphic of all seabirds. The author's study reveals that the resulted sex‐specific ecological differences can lead to divergent responses to environmental drivers. Moreover, because such effects may not be apparent when all individuals are considered together, ignoring sex differences could underestimate the relative influence of a changing environment on demography.

Wading birds are key components of wetlands, transporting matter, energy, contaminants and associated organisms among limnetic, estuarine, terrestrial and coastal ecosystems. The role of cocoi herons (Ardea cocoi) in connecting these ecosystems was studied in the only known estuarine and limnetic colonies in coastal plains of southern Brazil. Food obtained by parents around colonies when foraging for chicks and themselves was used to assess diet, by the analysis of 50 pellets, gastrointestinal contents and spontaneous regurgitated samples, as well as the analysis of stable isotopes (δ¹³C and δ¹⁵N) in the whole blood of 25 chicks. Cocoi herons were predominantly piscivorous in both environments, relying mainly on whitemouth croaker (Micropogonias furnieri) in the estuarine colony (47 % of samples and 36–56 % in the isotope mixing model), followed by Callinectes blue crabs and on trahira (Hoplias aff. malabaricus), in the limnetic colony (60 % of the dietary samples). However, for the limnetic colony, terrestrial and aquatic potential food sources contributed evenly to the isotopic mixing model. Furthermore, stable isotopes suggested that marine food sources, available on the coast 15 km away, were part of the diet of chicks in the limnetic colony. Complementary approaches used in the current study demonstrate that widely distributed, large-sized Ardea herons and other waterbirds are important for the connectivity of terrestrial and a range of aquatic environments. These birds contribute to the flow of matter and energy between wetlands and adjacent habitats and are key species for linking different food webs through complex and still poorly understood lateral subsides.

For nine days, the number of sally lightfoot crabs (Grapsus grapsus) in a 300 m² area within the brown booby (Sula leucogaster) colony and the activity of each crab were recorded in the morning (5:30-7:30 h), at midday (11:30-13:30 h), and in the afternoon (15:30-17:30 h). The average number of individuals was 80.2 plus or minus 15.5 (59-111) in the morning, 3.1 plus or minus 2.3 (0-7) at midday, and 65.3 plus or minus 15 (49-92) in the afternoon. A total of 1338 activity records were made, with the crabs standing still or walking in 844 records and handling material or feeding in 494 records. In the latter records, 53% of the crabs were handling detritus (pieces of dry bird excrement and sediment), 12.2% were handling feathers, 12.8% were feeding on regurgitated fish, 8.9% were feeding on dead Sula leucogaster, 8.1% were feeding on crab, 4.7% were feeding on material adhered to egg shells, and 0.6% were feeding on live nestlings of S. leucogaster. The low frequency of crabs in the colony around noon shows that the crabs avoid insolation, hiding in shady places and tidal pools. In the Sao Pedro and Sao Paulo Archipelago, the presence of S. leucogaster represents an important food source for G. grapsus. This crab plays the role of a cleaner in the S. leucogaster colony, consuming food remains, broken eggs, and dead birds.Original Abstract: Durante nueve dias se registro el numero de cangrejos costeros (Grapsus grapsus) en una area de 300 m² dentro de la colonia de piquero cafe (Sula leucogaster) y la actividad de cada uno de los individuos durante la manana (5:30-7:30 h), mediodia (11:30-13:30 h) y tarde (15:30-17:30 h). La media de individuos en la manana fue 80,2 plus or minus 15,5 (59-111), en el mediodia 3,1 plus or minus 2,3 (0-7) y en la tarde 65,3 plus or minus 15 (49-92). Del total de 1.338 registros de comportamiento, 844 fueron de cangrejos detenidos o caminando y 494 manipulando algun material o alimento. De estos, 53% fueron de manipulacion de detrito (excremento seco de ave y sedimento); 12,2% de manipulacion de plumas; 12,8% alimentandose de peces regurgitados; 8,9% de un Sula muerto; 8,1% de cangrejo; 4,7% de material adherido a las cascaras de huevos y 0,6% de cria de Sula viva. La baja frecuencia de los cangrejos en la colonia durante el mediodia es una evidencia que los mismos se protegen de la insolacion, permaneciendo en la sombra y en pozas de marea. En el archipielago de Sao Pedro y Sao Paulo la presencia de S. leucogaster representa una importante fuente de alimentacion para G. grapsus, que desempena un papel de limpiador en la colonia de esta ave, consumiendo restos de comida, huevos quebrados y aves muertas.

Understanding how populations and communities will respond to global changes is a major focus of modern ecology, and demographic studies are crucial for understanding the dynamic of wild populations and their responses to change. Here, I first conducted an analytically robust literature to demonstrate that seabird mortality in global fisheries (bycatch) tends to be biased by sex and age, mainly related to differential at-sea distributions, underpinning the population level effect bycatch on the most threatened group of birds. Next I performed a comprehensive longitudinal study, to address effects of fisheries, environmental variability and climate oscillation on population dynamics of northern (NGP, Macronectes halli) and southern giant petrel (SGP, M. giganteus) at Bird Island, South Georgia. I showed that annual survival and breeding success of NGP and SGP was influenced mainly by climatic oscillation and oceanographic conditions, including fisheries, and that the responses varied by sex and age. Giant petrels survived and reproduced better in warmer years, contrasting with the negative effects of warmer conditions on a range of marine land-based vertebrates in the same ecosystem. Differential accessibility to food resources during chick-rearing due to allochrony have contributed for the NGP breeding success and delayed reproductive senescence compared to SGP, supporting empirical evidence for role of allochrony on their divergent population trajectories. Finally, the findings in this thesis sheds a new light on how phenological mismatch can influence demographic process and on the role of environmental conditions on reproductive senescence, which are among the poorest understood processes in population ecology.

For nine days, the number of sally lightfoot crabs (Grapsus grapsus) in a 300 m? area within the brown booby (Sula leucogaster) colony and the activity of each crab were recorded in the morning (5:30-7:30 h), at midday (11:30-13:30 h), and in the afternoon (15:30-17:30 h). The average number of individuals was 80.2 ± 15.5 (59-111) in the morning, 3.1 ± 2.3 (0-7) at midday, and 65.3 ± 15 (49-92) in the afternoon. A total of 1338 activity records were made, with the crabs standing still or walking in 844 records and handling material or feeding in 494 records. In the latter records, 53% of the crabs were handling detritus (pieces of dry bird excrement and sediment), 12.2% were handling feathers, 12.8% were feeding on regurgitated fish, 8.9% were feeding on dead Sula leucogaster, 8.1% were feeding on crab, 4.7% were feeding on material adhered to egg shells, and 0.6% were feeding on live nestlings of S. leucogaster. The low frequency of crabs in the colony around noon shows that the crabs avoid insolation, hiding in shady places and tidal pools. In the São Pedro and São Paulo Archipelago, the presence of S. leucogaster represents an important food source for G. grapsus. This crab plays the role of a cleaner in the S. leucogaster colony, consuming food remains, broken eggs, and dead birds. [PUBLICATION ABSTRACT]