Hanna Granroth-Wilding (Department of Biosciences Division of Ecology and Evolution, University of Helsinki, Finland) and Richard Phillips have an accepted paper in the journal Ibis that considers segregation within and between the two species of ACAP-listed giant petrels Macronectes spp.

The paper’s abstract follows:

“Biological communities are shaped by competition between and within species. Competition is often reduced by inter- and intra-specific specialization on resources, such as differences in foraging areas or time, allowing similar species to coexist and potentially contributing to reproductive isolation. Here, we examine the simultaneous role of temporal and spatial foraging segregation within and between two sympatric sister species of seabirds, Northern Macronectes halli and Southern M. giganteus Giant Petrels. These species show marked sexual size dimorphism and allochrony (with earlier breeding by Northern Giant Petrels), but this is the first study to test for differences in foraging behaviours and areas across the entire breeding season both between the two species and between the sexes. We tracked males and females of both species in all breeding stages at Bird Island, South Georgia, to test how foraging distribution, behaviour and habitat use varies between and within species in biological time (incubation, brood-guard or post-brood stages) and in absolute time (calendar date). Within each breeding stage, both species took trips of comparable duration to similar areas, but due to breeding allochrony they segregated temporally. Northern Giant Petrels had a somewhat smaller foraging range than Southern Giant Petrels, reflecting their greater exploitation of local carrion and probably contributing to their recent higher population growth. Within species, segregation was spatial, with females generally taking longer, more pelagic trips than males. Both sexes of both species showed unexpectedly plastic foraging behaviour, and there was little evidence of inter-specific differences in habitat use. Thus, in giant petrels, temporal segregation reduces inter-specific competition and sexual segregation reduces intra-specific competition. These results demonstrate how both specialization and dynamic changes in foraging strategies at different scales underpin resource division within a community.”

Southern Giant Petrel, photograph by Greg Hofmeyr

Feeding Northern Giant Petrel, photograph by Marienne de Villiers

Reference:

Granroth-Wilding, H.M.V. & Phillips^, R.A. 2018. Segregation in space and time explains the coexistence of two sympatric sub-Antarctic petrels. Ibis doi: 10.1111/ibi.12584.

John Cooper, ACAP Information Officer, 05 March 2018

Henri Weimerskirch (Centre d'Etudes Biologiques de Chizé, Villiers-en-Bois, France) has published in the Journal of Animal Ecology on linking population dynamics and foraging ecology of globally Vulnerable Wandering Albatrosses Diomedea exulans.

The paper’s summary follows:

“1.Population dynamics and foraging ecology are two fields of the population ecology that are generally studied separately. Yet foraging determines allocation processes and therefore demography. Studies on Wandering albatrosses Diomedea exulans over the past 50 years have contributed to better understand the links between population dynamics and foraging ecology. This paper reviews how these two facets of population ecology have been combined to better understand ecological processes, but also have contributed fundamentally for the conservation of this long-lived threatened species.

2.Wandering albatross research has combined a 50 year long-term study of marked individuals with two decades of tracking studies that have been initiated on this species, favoured by its large size and tameness.

3.At all stages of their life history the body mass of individuals plays a central role in allocation processes, in particular in influencing adult and juvenile survival, decisions to recruit into the population or to invest into provisioning the offspring or into maintenance.

4.Strong age-related variations in demographic parameters are observed and are linked to age-related differences in foraging distribution and efficiency. Marked sex specific differences in foraging distribution, foraging efficiency and changes in mass over life time are directly related to the strong sex specific investment in breeding and survival trajectories of the two sexes, with body mass playing a pivotal role especially in males.

5.Long-term study has allowed determining the sex specific and age specific demographic causes of population decline, and the tracking studies have been able to derive where and how these impacts occur, in particular the role of long line fisheries”.

Wandering Albatross, photograph by Kate Lawrence

Reference:

Weimerskirch, H. 2018. Linking demographic processes and foraging ecology in wandering albatross - conservation implications.  Journal of Animal Ecology doi: 10.1111/1365-2656.12817.

John Cooper, ACAP Information Officer, 02 March 2018

Jorge Pereira (MARE – Marine and Environmental Sciences Centre, University of Coimbra, Portugal) and colleagues have published in the journal Marine Biology on sexual segregation in  globally Vulnerable Wandering Albatrosses Diomedea exulans while foraging.

The paper’s abstract follows:

“Sexual segregation in foraging habitat occurs in many marine predators and is usually attributed to competitive exclusion, different parental roles of each sex or niche specialisation associated with sexual size dimorphism. However, relatively few studies have attempted to understand the patterns and underlying drivers of local-scale sexual segregation in marine predators. We studied habitat use, diet and feeding ecology of female and male wandering albatrosses Diomedea exulans, fitted with GPS and stomach-temperature loggers during the chick-rearing period (austral winter) at South Georgia in 2009. During this period, when oceanographic conditions were anomalous and prey availability was low in waters near the breeding colony, the tracked wandering albatrosses showed high consistency in their foraging areas at a large spatial scale, and both males and females targeted sub-Antarctic and subtropical waters. Despite consistency in large-scale habitat use, males and females showed different foraging behaviours in response to oceanographic conditions at a smaller scale. Males appeared to be more opportunistic, scavenging for offal or non-target fish discarded by fishing vessels in less productive, oceanic waters. They exhibited sinuous movements, feeding mostly on large prey and consuming similar amounts of food during the outbound and return parts of the foraging trip. In contrast, females targeted natural productivity hotspots, and fed on a wide variety of fish and cephalopods. They commuted directly to these areas; most prey were ingested on the outbound part of the trip, and they often started their return after ingesting large prey at the farthest point from the colony. Together, these results indicate that sexual segregation in core foraging areas of wandering albatrosses is driven by sex-specific habitat selection due to the low availability of prey in local Antarctic waters. This segregation results in different feeding behaviour at local scales which may be explained by differing breeding roles and degree of parental investment by each sex, with females investing more than males in reproduction. Further investigations are necessary to confirm the existence of this pattern through time under contrasting environmental conditions and to identify the drivers responsible for local-scale sexual segregation in wandering albatrosses.

Wandering Albatross at sea, photograph by John Chardine

With thanks to Richard Phillips.

Reference:

Pereira, J.M., Paiva, V.H., Phillips, R.A. & Xavier, J.C. 2018. The devil is in the detail: small-scale sexual segregation despite large-scale spatial overlap in the wandering albatross. Marine Biology 165: 55.  doi.org/10.1007/s00227-018-3316-0.

John Cooper, ACAP Information Officer, 01 March 2018

The project “Sustainable Management of Tuna Fisheries and Biodiversity Conservation in the Areas Beyond National Jurisdiction (ABNJ)”, (also known as the “Common Oceans Tuna Project”) aims to achieve responsibility, efficiency and sustainability in tuna production and biodiversity conservation in the ABNJ. The Food and Agriculture Organization of the United Nations (FAO) is the overall implementing agency of the project, and BirdLife International, through its local partner, BirdLife South Africa, is implementing the seabird bycatch component. This component has a number of separate, but aligned, areas of work. These include increasing awareness and capacity of observer programmes regarding seabird bycatch mitigation, and building capacity of national scientists from key countries in the areas of bycatch data collection and analysis, and facilitating a collaborative approach to the assessment of seabird bycatch. The first stage of the seabird bycatch assessment process involved two regional pre-assessment workshops, one in South Africa in March 2017, and the second in Vietnam in April 2017 (click here).

Attendees at the ABNJ workshop in Cusco, photograph courtesy of BirdLife South Africa

Building on the outcomes of these regional workshops, and to progress planning for the collaborative assessment of bycatch associated with southern hemisphere tuna fisheries, country representatives, and members of BirdLife and ACAP participated in a data preparation workshop from 20-24 February this year in Cusco, Peru. Discussions at the workshop focused on the data that are available for estimating seabird bycatch and assessing the effectiveness of mitigation measures, how best to address data gaps, and methodological approaches for estimating seabird bycatch in southern hemisphere tuna fisheries. An Action Plan was developed to help guide further work in preparation for the final assessment workshop, which is planned for February 2019. ACAP was represented at the workshop by Anton Wolfaardt, ACAP Seabird Bycatch Working Group Co-convenor.

Yellowfin Tuna

Anton Wolfaardt, Co-Convenor, ACAP Seabird Bycatch Working Group, 28 February 2018