Colony size and foraging range in seabirds

The reasons for variation in group size among animal species remain poorly understood. Using ‘Ashmole's halo’ hypothesis of food depletion around colonies, we predict that foraging range imposes a ceiling on the maximum colony size of seabird species. We tested this with a phylogenetic comparative study of 43 species of seabirds (28 262 colonies), and investigated the interspecific correlation between colony size and foraging ranges. Foraging range showed weak relationships with the low percentiles of colony size of species, but the strength of the association increased for larger percentiles, peaking at the maximum colony sizes. To model constraints on the functional relationship between the focal traits, we applied a quantile regression based on maximum colony size. This showed that foraging range imposes a constraint to species’ maximum colony sizes with a slope around 2. This second-order relationship is expected from the equation of the area of a circle. Thus, our large dataset and innovative statistical approach shows that foraging range imposes a ceiling on seabird colony sizes, providing strong support to the hypothesis that food availability is an important regulator of seabird populations.Peer Reviewe

Using globally threatened pelagic birds to identify priority sites for marine conservation in the South Atlantic Ocean

The Convention on Biological Diversity aspires to designate 10% of the global oceans as Marine Protected Areas (MPAs), but so far, few MPAs protect pelagic species in the high seas. Transparent scientific approaches are needed to ensure that these encompass areas with high biodiversity value. Here we used the distribution of all globally threatened seabirds breeding in a centrally located archipelago (Tristan da Cunha) to provide guidance on where MPAs could be established in the South Atlantic Ocean. We combined year-round tracking data from six species, and used the systematic conservation-planning tool, 'Zonation', to delineate areas that would protect the largest proportion of each population. The areas used most intensively varied among species and seasons. Combining the sites used by all six species suggested that the most important areas of the South Atlantic are located south of South Africa, around the central South Atlantic between 30 degrees S and 55 degrees S, and near South America. We estimated that the longline fishing effort in these intensively used areas is around 11 million hooks on average each year, highlighting the need for improved monitoring of seabird bycatch rates and the enforcement of compliance with bird bycatch mitigation requirements by fisheries. There was no overlap between the identified areas and any of the existing MPAs in the South Atlantic. The conservation of these highly mobile, pelagic species cannot be achieved by single countries, but requires a multi-national approach at an ocean-basin scale, such as an agreement for the conservation of biodiversity beyond national jurisdiction under the United Nation Convention on the Law of the Sea

Using globally threatened pelagic birds to identify priority sites for marine conservation in the South Atlantic Ocean

The Convention on Biological Diversity aspires to designate 10% of the global oceans as Marine Protected Areas (MPAs), but so far, few MPAs protect pelagic species in the high seas. Transparent scientific approaches are needed to ensure that these encompass areas with high biodiversity value. Here we used the distribution of all globally threatened seabirds breeding in a centrally located archipelago (Tristan da Cunha) to provide guidance on where MPAs could be established in the South Atlantic Ocean. We combined year-round tracking data from six species, and used the systematic conservation-planning tool, ‘Zonation’, to delineate areas that would protect the largest proportion of each population. The areas used most intensively varied among species and seasons. Combining the sites used by all six species suggested that the most important areas of the South Atlantic are located south of South Africa, around the central South Atlantic between 30°S and 55°S, and near South America. We estimated that the longline fishing effort in these intensively used areas is around 11 million hooks on average each year, highlighting the need for improved monitoring of seabird bycatch rates and the enforcement of compliance with bird bycatch mitigation requirements by fisheries. There was no overlap between the identified areas and any of the existing MPAs in the South Atlantic. The conservation of these highly mobile, pelagic species cannot be achieved by single countries, but requires a multi-national approach at an ocean-basin scale, such as an agreement for the conservation of biodiversity beyond national jurisdiction under the United Nation Convention on the Law of the Sea

Colony size and foraging range in seabirds

Trabajo presentado en el 4º Congreso Ibérico de Ecología, celebrado en coimbra, Portugal, del 16 al 19 de junio de 2015Understanding why group size varies among animals species is an open question in evolutionary ecology. Seabird colonies range from some few breeding pairs up to hundreds of thousands of nests. We have previously reported high colony size variation within species, but consistent median and maximum colony sizes when studying same species in different populations. Seabirds are central place foragers with species-specific foraging distances ranging from some few hundred meters from the colony to hundreds of kilometers to find food for their nestlings. Here we predicted that the foraging range of species imposes a ceiling on their maximum colony sizes; according to the mathematical equation of the area of the circle, we predicted a second-order relationship between (foraging) radius and (foraging) area. Accordingly, on a log-scale, maximum colony size would scale with slope 2 with foraging range. We performed a phylogenetic comparative study of 43 species. Foraging range showed weak relationships with the low percentiles of colony size, but the strength of the association increased for larger percentiles, peaking at the maximum colony sizes. In order to model constraints on the functional relationship between the focal traits, we applied a quantile regression based on maximum colony size, which showed that the slope of the correlation was around 2 for species that have the higher colony sizes given their foraging ranges. Our results provide a mechanistic explanation to seabird colony sizes, and pose strong support to the hypothesis that food availability is an important regulator of seabird populations.Peer Reviewe

The role of seabirds in Marine Protected Area identification, delineation, and monitoring: introduction and synthesis

Currently less than 1% of the world's seas are under any form of protected area designation, thus, there is an important and immediate need for tools to identify and delineate a network of ecologically representative Marine Protected Areas (MPAs). Although the role of seabirds in MPA identification and the importance of MPAs to seabird conservation have been discussed for more than a decade, the actual designation of MPAs using seabird data has lagged far behind. To synthesize the current state of knowledge regarding seabirds and the designation of MPAs, this special issue presents 14 papers resulting from the 1st World Seabird Conference, held in Canada in 2010. These papers present examples from around the world that show the important role seabirds can play in the identification, design, implementation, and monitoring of MPAs. Approaches to seabird MPA site identification consider single- versus multiple-species approaches, mapping of marine biological > hotspots>, and assessment of overlap with risks and threats. The delineation of MPA boundaries may further be refined with information on seabird foraging ranges, at-sea density estimates, and tools for ranking areas based on conservation priorities. Seabirds can also be used to evaluate the effectiveness of MPAs as conservation tools by monitoring changes in seabird foraging ranges, patterns of distribution and abundance, and population dynamics. To date, very few MPAs have been established specifically for the benefit of seabirds, however, many of the papers in this special issue suggest that this should become a growing trend in seabird conservation and marine spatial planning. © 2012 Elsevier Ltd.Peer Reviewe

Global priorities for marine biodiversity conservation.

In recent decades, many marine populations have experienced major declines in abundance, but we still know little about where management interventions may help protect the highest levels of marine biodiversity. We used modeled spatial distribution data for nearly 12,500 species to quantify global patterns of species richness and two measures of endemism. By combining these data with spatial information on cumulative human impacts, we identified priority areas where marine biodiversity is most and least impacted by human activities, both within Exclusive Economic Zones (EEZs) and Areas Beyond National Jurisdiction (ABNJ). Our analyses highlighted places that are both accepted priorities for marine conservation like the Coral Triangle, as well as less well-known locations in the southwest Indian Ocean, western Pacific Ocean, Arctic and Antarctic Oceans, and within semi-enclosed seas like the Mediterranean and Baltic Seas. Within highly impacted priority areas, climate and fishing were the biggest stressors. Although new priorities may arise as we continue to improve marine species range datasets, results from this work are an essential first step in guiding limited resources to regions where investment could best sustain marine biodiversity

Using globally threatened pelagic birds to identify priority sites for marine conservation in the South Atlantic Ocean

The Convention on Biological Diversity aspires to designate 10% of the global oceans as Marine Protected Areas (MPAs), but so far, few MPAs protect pelagic species in the high seas. Transparent scientific approaches are needed to ensure that these encompass areas with high biodiversity value. Here we used the distribution of all globally threatened seabirds breeding in a centrally located archipelago (Tristan da Cunha) to provide guidance on where MPAs could be established in the South Atlantic Ocean. We combined year-round tracking data from six species, and used the systematic conservation-planning tool, 'Zonation', to delineate areas that would protect the largest proportion of each population. The areas used most intensively varied among species and seasons. Combining the sites used by all six species suggested that the most important areas of the South Atlantic are located south of South Africa, around the central South Atlantic between 30 degrees S and 55 degrees S, and near South America. We estimated that the longline fishing effort in these intensively used areas is around 11 million hooks on average each year, highlighting the need for improved monitoring of seabird bycatch rates and the enforcement of compliance with bird bycatch mitigation requirements by fisheries. There was no overlap between the identified areas and any of the existing MPAs in the South Atlantic. The conservation of these highly mobile, pelagic species cannot be achieved by single countries, but requires a multi-national approach at an ocean-basin scale, such as an agreement for the conservation of biodiversity beyond national jurisdiction under the United Nation Convention on the Law of the Sea

Priority areas for marine biodiversity conservation

<p>for (<b>A</b>) species richness, (<b>B</b>) range rarity, and (<b>C</b>) proportional range rarity within EEZs and ABNJ. Orange areas denote priority areas with high human impacts and green denotes areas with low human impacts. Total area of priorities is 7,233,550 km² within EEZs and 9,894,560 km² within ABNJ (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082898#pone.0082898.s005" target="_blank">Tables S5</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082898#pone.0082898.s006" target="_blank">S6</a>).</p

Top 20 EEZ regions by total priority area (km²).

<p>Total priority area was determined through the union of priority areas based on richness, range rarity, and proportional range rarity (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082898#pone-0082898-g003" target="_blank">Fig. 3A–C</a>). Calculations for the United States do not include EEZ regions around Alaska or Hawaii, which are calculated separately. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082898#pone.0082898.s003" target="_blank">Table S3</a> has statistics for all EEZ areas and further statistics on priority areas by richness, endemism and proportional range rarity. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082898#pone.0082898.s004" target="_blank">Table S4</a> has statistics by FAO region for ABNJ priority areas.</p

Spatial patterns for (A) species richness, (B) range rarity, and (C) proportional range rarity and (D) cumulative human impacts within EEZs and ABNJ.

<p>The highest values for all diversity measures within 5% of EEZ or ANBJ area are also shown. Due to scale, not all values may be visible. EEZ boundaries are shown in white.</p