April Hedd (Cognitive and Behavioural Ecology Program, Psychology Department, Memorial University, St. John’s, Canada) and colleagues have published open-access in PLoS ONE on differences in foraging areas by breeding male and female Sooty Shearwaters Puffinus griseus in the South Atlantic.

The paper’s abstract follows:

“Tracking technology has revolutionized knowledge of seabird movements; yet, few studies have examined sex differences in distribution and behavior of small to medium-sized, sexually-monomorphic seabirds.  Application of bird-borne geolocation-immersion loggers revealed seasonal segregation in the sexually-monomorphic Sooty Shearwater Puffinus griseus, mainly in the pre-laying period, when there were clear differences in reproductive roles.  Shearwaters first returned to the Falkland Islands on 27 Sept±8 d; males, on average, 8 d earlier than females.  Prior to egg-laying, distribution at sea, colony attendance and behaviour depended on sex.  Males foraged locally over the southern Patagonian Shelf and Burdwood Bank, spending mainly single days at sea and intervening nights in the burrow.  Females, who flew for more of the day during this time, foraged in more distant areas of the northern Patagonian Shelf and Argentine Basin that were deeper, warmer and relatively more productive.  Attendance of females at the colony was also more variable than that of males and, overall, males were present for significantly more of the pre-laying period (38 vs. 19% of time).  Sex differences were reduced following egg-laying, with males and females using similar foraging areas and making trips of similar mean duration in incubation (7.6±2.7 d) and chick-rearing (1.4±1.3 d).  Congruence continued into the non-breeding period, with both sexes showing similar patterns of activity and areas of occupancy in the NW Atlantic.  Thus, seasonal changes in reproductive roles influenced patterns of sexual segregation; this occurred only early in the season, when male Sooty Shearwaters foraged locally, returning regularly to the colony to defend (or maintain) the burrow or the mate, while females concentrated on building resources for egg development in distant and relatively more productive waters.”

Sooty Shearwater at sea, photograph by John Graham

With thanks to April Hedd for information.

Reference:

Hedd, A., Montevecchi, W.A., Phillips, R.A. & Fifield, D.A. 2014.  Seasonal sexual segregation by monomorphic Sooty Shearwaters Puffinus griseus reflects different reproductive roles during the pre-laying period.  PLoS ONE.

John Cooper, ACAP Information Officer, 19 January 2014

Australia’s South East Trawl Fishing Industry Association (SETFIA) has received an Australian Government grant of A$360 000 to continue work on protecting seabirds from fishing boats.  The Caring for our Country grant will be used to reduce collisions that occur between seabirds and the cables used to tow trawl nets (click here).

"All trawl vessels in South East Australia and the Great Australian Bight operate with regulated Seabird Management Plans to limit interactions with seabirds.  These plans incorporate measures like managing their offal by batching or retaining it (to avoid attracting the seabirds) and using a device that protects seabirds from bumping into trawl cables.

Most vessels currently use large inflatable buoys attached to the vessel to ensure that seabirds do not collide with trawl cables.  Although the buoys are effective, they are very difficult to use, and don’t work as well, because they tangle.  So we’re keen to use the grant to develop alternative mitigation measures that are at least as effective as the buoys, but are more practical for use on trawl vessels.

The grant will be spent on trials of new methods to avoid harming seabirds, and will be monitored by scientific observers.  Observers will be used to monitor and validate the use of water sprayers as seabird deterrents.

Additional scientific observer coverage will be used to test a yet-to-be identified approach to mitigation.  Fishermen will be asked to nominate concepts for devices and a panel of experts will select a second device that will be tested.

The grant will also allow several young fishermen from South East Australia and the Great Australian Bight to travel to New Zealand to learn about New Zealand seabird mitigation measures.  We hope to that an expert from New Zealand can travel to Australia to help Australian trawl fishermen develop more methods to avoid any harm to seabirds.”

John Cooper, ACAP Information Officer, 18 January 2014

Elizabeth (Biz) Bell (Marlborough, New Zealand) and colleagues have written in the New Zealand ornithological journal Notornis on the numbers of ACAP-listed Grey Petrels Procellaria cinerea existing on Antipodes Island.

The paper’s abstract follows:

“Aspects of the breeding biology of the grey petrel (Procellaria cinerea) were studied on Antipodes Island between April and June 2001.  The island was surveyed to determine grey petrel distribution and four 2500 m2 census grids were established.  The survey suggested that the distribution of grey petrels was restricted to steep, well-draining areas dominated by Poa litorosa tussock (approximately 510 ha of the 2025 ha island).  Occupied burrow density within the 4 census grids ranged from 31 to 44 burrows (0.01 burrows per square metre).  Extrapolating from the census grid density to the total grey petrel habitat resulted in a population estimate of 114,730 birds: 53,000 breeding pairs (range = 32,000-73,000) and 8,670 non-breeding-birds (range = 4,000-16,320) were present on Antipodes Island.  Aspects of the behaviour of the species were recorded.  Comparisons are made with other members of the genus Procellaria.”

Grey Petrel, photograph by Peter Ryan

With thanks to Richard Phillips for information.

Reference:

Bell, E.A., Bell, B.D., Sim, J.L. & Imber, M.J. 2013.  Notes on the distribution, behaviour and status of grey petrel (Procellaria cinerea) on Antipodes Island, New Zealand.  Notornis 60: 269-278.

John Cooper, ACAP Information Officer, 17 January 2014

Luke Einoder (School of Earth and Environmental Sciences, Adelaide University, Australia) and colleagues have written in the ornithological journal, The Condor on feeding strategies of the Short-Tailed Shearwater Puffinus tenuirostris.

The paper’s abstract follows:

“To understand how animals cope with environmental variability it is necessary to identify the degree of flexibility in a species' diet and foraging mode and the consequences of this flexibility for reproduction.  We examined rates of feeding and energy delivery to chicks by a long-lived pelagic seabird, the Short-tailed Shearwater (Puffinus tenuirostris).  Individual adults alternated between foraging trips of short and long duration in a dual foraging strategy, but the allocation of time on those trips varied significantly from year to year.  In two years when sea-surface temperatures of feeding grounds exploited during short trips were cooler (2005, 2006) adults initially fed their chick more often, then feeding decreased through the chick-rearing period.  In the following year of warmer sea-surface temperature (2007), the number of feedings per day was initially low but increased through chick rearing.  Despite varied feeding patterns, breeding success was consistently high, yet in 2006 the chicks' poor condition indicates the capacity for buffering chicks from these effects was lower than in other years.  The relative contribution of short and long trips to the amount of energy delivered to chicks also varied by year.  During local food shortages, shearwaters appeared to deliver more oil from long trips and increased the frequency of short trips.  Yet in 2006, low-calorie prey from short trips coincided with low volume of stomach oil from long trips, resulting in chicks' poorer condition.  Oil volume and increased short-trip foraging provide potential mechanisms of flexibility enabling adults to buffer prey delivery to chicks during food shortages.”

Short-tailed Shearwater, photographed by Mark Carey

Reference:

Einoder, L.D., Page, B. & Goldsworthy, S.D. 2013.  Feeding strategies of the Short-Tailed Shearwater vary by year and sea-surface temperature but go not affect breeding success.  The Condor 115: 777-787.

John Cooper, ACAP Information Officer, 16 January 2014