Antje Chiu Werner (Departamento de Ornitología, Museo de Historia Natural “Javier Prado,” Universidad Nacional Mayor de San Marcos, Lima, Peru) and colleagues have published in the ornithological journal Auk on differences in the at-sea foraging behaviour of male and female Cory's Shearwater Calonectris borealis in relation to nest quality.

The paper’s abstract follows:

“An extended reproductive period and high variability in food resource availability at sea make good quality nest sites particularly important for the survival of pelagic seabird chicks.  Despite high philopatry during the early pre-laying period, males compete strongly for nests, making this period a unique opportunity to independently assess the influence of nest-site characteristics and individual quality on the foraging behavior of Cory's Shearwater (Calonectris diomedea borealis) individuals.  We found significant differences in the at-sea foraging behavior of males and females at temporal (trip duration) and spatial (foraging areas, trip distance, and trip sinuosity) scales, both of which are greater in females.  Furthermore, we suggest that nests of higher quality are deeper and closer to the nest of a conspecific neighbor because both variables were associated with males foraging closer to the colony.  Finally, we showed that during the early pre-laying period the influence exerted by nests on males' behavior at sea is independent from the individual's quality.  Our study links nest-site features with the at-sea behavior of pelagic male seabirds during a period of nest competition and suggests that nest-site characteristics are important to explain foraging patterns of central-place foraging birds.”

A pair of Cory's Shearwaters, photograph by Paulo Catry

Reference:

Chiu Werner, A., Paiva, V.H. & Ramos, J.A. 2014.  On the “real estate market”: individual quality and the foraging ecology of male Cory's Shearwaters.  Auk 131:  265-274.

John Cooper, ACAP Information Officer, 02 May 2014

North Foreland is an ice-free headland on the northern coast of King George Island, the largest of the South Shetland Islands off the Antarctic Peninsula.  It forms the northernmost extremity of the island.

The headland has been identified as an Important Bird Area (IBA) with an area of 151 ha by BirdLife International for its large colony of c. 23 000 pairs of Chinstrap Penguins Pygoscelis antarctica.

ACAP-listed Southern Giant Petrels Macronectes giganteus breed on the headland on rocky ice-free ground.  A visit on 13 February 2012 by Tobias Guetter yielded a count of 279 nests thought to have been used in the current season and 128 chicks in 23 breeding groups (range 1-50 nests).  Of these totals five nests with one chick were recorded as being on an island.

A total of 248 pairs was recorded in 1966, suggesting a level of stability for this Least Concern species.

With thanks to Christina Braun and Tobias Guetter, both of the University of Jena, Germany, for information and photographs.

Selected Literature:

Patterson, D.L., Woehler, E.J., Croxall, J.P., Cooper, J., Poncet, S., Peter, H.-U., Hunter, S. & Fraser, M.W. 2008.  Breeding distribution and population status of the Northern Giant Petrel Macronectes halli and Southern Giant Petrel M. giganteus.  Marine Ornithology 36: 115-124 and appendix.

Peter, H.-U., Kaiser, M. & Gebauer, A. 1991.  Breeding ecology of the southern giant petrels Macronectes giganteus on King George Island (South Shetland Islands, Antarctic).  Zoologisches Jahrbuch Systematik 118: 465-477.

John Cooper, ACAP Information Officer, 01 May 2014

Maite Louzao (Instituto Español de Oceanografía, Xixón, Spain) and colleagues have published open-access in the journal Movement Ecology on foraging strategy of the Wandering Albatross Diomedea exulans.

The paper’s abstract follows:

“How foragers move across the landscape to search for resources and obtain energy is a central issue in ecology. Direct energetic quantification of animal movements allows for testing optimal foraging theory predictions which assumes that animals forage so as to maximise net energy gain.  Thanks to biologging advances, we coupled instantaneous energy-budget models and behavioural mode analysis to test optimal foraging theory predictions on wandering albatross Diomedea exulans during the brooding period.   Specifically, the instantaneous energy-budget model considered the energetic balance (i.e., the difference between empirical energy gain data and modelled energy expenditure via heart rate values) along the trajectory of a given individual.  Four stereotypic instantaneous behavioural modes were identified based on trajectory properties (e.g., speed and turning angle) by applying a new algorithm called Expectation Maximization Binary Clustering.  Previous studies on this species have shown that foraging-in-flight is the optimal foraging strategy during the incubation period when albatrosses undertake long-distance movements but no specific foraging strategy has been determined for shorter foraging movements (e.g., brooding period).”

A Wanderer at sea, photograph by John Chardine

With thanks to Maite Louzao for information.

Reference:

Maite Louzao, M., Wiegand, T., Bartumeus, F. & Weimerskirch, H. 2014.  Coupling instantaneous energy-budget models and behavioural mode analysis to estimate optimal foraging strategy: an example with wandering albatrosses.  Movement Ecology doi:10.1186/2051-3933-2-8.

John Cooper, ACAP Information Officer, 30 May 2014

Sylvia Zakkak (Department of Ecology, Aristotle University of Thessaloniki, Greece) and colleagues write in the open-access journal Marine Ornithologyon at-sea densities and extrapolated numbers of Scopoli’s Calonectris diomedea and Yelkouan Puffinus yelkouan Shearwaters (both potential candidates for ACAP listing) in the Aegean Sea.

The paper’s abstract follows:

“We estimate the population size of the three most abundant seabird species in the north Aegean Sea (Calonectris diomedea, Larus michahellis and Puffinus yelkouan), along with their distribution patterns. Sampling was carried out from May to September 2009 in line transects 300 m or 600 m wide and with a total length of 3 007 km. The sampling was opportunistic, using a variety of ships. After the data were corrected for movement bias, populations were estimated by using two types of stratification method:  novel fractal–based method as well as generalized additive models, which yielded the most conservative estimate of the population, although all estimates were quite similar. Overall, taking the mean estimate of the three most credible methods, we estimate the density of birds for the area to be 0.46 birds/km² for the three species together (C. diomedea 0.10 birds/km², L. michahellis 0.11 birds/km² and P. yelkouan 0.26 birds/km²). These densities of seabirds in the north Aegean are smaller than observed in studies in other parts of the world, but not surprisingly so, given the low productivity of the north Aegean. In view of the widespread and growing threats to seabird populations, the results of this study provide a useful basis for further scientific studies and for applied research including the designation of marine Important Bird Areas for the region.”

Yelkouan Shearwaters at sea

Reference:

Zakkak, S., Panagiotopoulou, M., & Halley, J.M. 2013.  Estimating the abundance of seabirds in the north Aegean Sea.  Marine Ornithology 41: 141-148.

John Cooper, ACAP Information Officer, 23 March 2014