Sievert Rohwer (Department of Biology and Burke Museum of Natural History, University of Washington, Seattle, USA) and colleagues have “pre-published” in the on-line open-access resource PeerJPrePrints on the link between hybridization and rape in Black-footed Phoebastria nigripes and Laysan P. immutabilis Albatrosses.

The paper’s abstract follows:

“Conspecific rape often increases male reproductive success.  However, the haste and aggression of forced copulations suggests that males may sometimes rape heterospecific females, thus making rape a likely, but undocumented, source of hybrids between broadly sympatric species.  We present evidence that heterospecific rape may be the source of hybrids between Black-footed and Laysan Albatrosses (Phoebastria nigripes, and P. immutabilis, respectively).  Extensive field studies have shown that paired (but not unpaired) males of both of these albatross species use rape as a supplemental reproductive strategy.  Between species differences in size, timing of laying, and aggressiveness suggest that Black-footed Albatrosses should be more successful than Laysan Albatrosses in heteropspecific [sic] rape attempts, and male Black-footed Albatrosses have been observed attempting to force copulations on female Laysan Albatrosses.  Nuclear markers showed that six hybrids we studied were F1s and mitochondrial markers shoed that male Black-footed Albatrosses sired all six hybrids.  The siring asymmetry found in our hybrids may have long persisted because an IM analysis suggests that long-term gene exchange between these species has been from Black-footed Albatrosses into Laysan Albatrosses.  If hybrids are sired in heterospecific rapes, they presumably would be raised and sexually imprinted on Laysan Albatrosses, and two unmated hybrids in a previous study courted only Laysan Albatrosses.

Laysan-Black-footed Albatross hybrid, photograph by Lindsay Young

Click here and here to read two previous postings in ACAP Latest News on hybrid Black-footed and Laysan Albatrosses.

Reference:

Rohwer, S., Harris, R.B. & Walsh, H.E. 2014.  Rape and the prevalence of hybrids in broadly sympatric species: a case study using albatrosses.  PeerJPrePrints  27 pp.

John Cooper, ACAP Information Officer, 21 May 2014

Lorna Deppe (School of Biological Sciences, Canterbury University, Christchurch, New Zealand) and colleagues have published in the journal Marine Ecology Progress Series on at-sea GPS tracking of Chatham Albatrosses Thalassarche eremita.

The paper’s abstract follows:

“The analysis of environmental characteristics to explain the distribution of endangered seabirds can aid in the identification of important areas at sea and lead to more effective conservation.  We used high resolution Global Positioning System (GPS) tracking data to study the at-sea patterns of chick-rearing Chatham albatrosses Thalassarche eremita across 3 years (2007, 2008 and 2009) in relation to bathymetry, slope, sea surface temperature (SST) and chlorophyll a (chl a) concentration. Birds mostly foraged within 400 to 600 km of their colony, located within the southeastern part of New Zealand’s continental shelf, the Chatham Rise.  Despite little spatial overlap across years, foraging areas were predominantly associated with waters of less than 2500 m depth, slopes of 1 to 4°, SST between 15 and 16°C, and chl a concentrations >1 mg m^-3 in all years.  According to boosted regression tree models, no single habitat variable particularly explained the spatial occurrence of foraging areas.  However, bathymetry was of higher relative importance in 2008 and 2009, while chl a was relatively more important in 2007, a year of increased primary productivity.  Our results suggest that chick-rearing Chatham albatrosses rely on resources that are generally predictable in location, but that they also respond to fine-scale changes within their foraging environment.  Incorporating such dynamics into conservation planning might be best addressed by mitigating incidental bycatch in fishing operations, as well as implementing a protected area southeast of the breeding site, which we identified as a key foraging zone.”

Chatham Albatrosses, photograph by Graham Robertson

For an ACAP Latest News item on Lorna’s PhD on Chatham and other albatrosses click here.

Reference:

Deppe, L., McGregor, K.F., Tomasetto, F., Briskie, J.V. & Scofield, R.P. 2014.  Distribution and predictability of foraging areas in breeding Chatham albatrosses Thalassarche eremita in relation to environmental characteristics. Marine Ecology Progress Series 498: 287-301.

John Cooper, ACAP Information Officer, 20 May 2014

Hisashi Sugawa (Bird Banding Association, c/o Bird Migration Research Center, Yamashina Institute for Ornithology, Chiba, Japan) and colleagues have published in the open-access journal Marine Ornithology on breeding site fidelity in Streaked Shearwaters Calonectris leucomelas.

The paper’s summary follows:

“Site fidelity of Streaked Shearwater Calonectris leucomelas on Kanmurijima Island, Sea of Japan (35°40’N, 135°26’E) was analyzed based on a 27-year banding record from 1984 to 2010.  Two study sites were set in this colony, and return fidelity to the initial release site was assessed.  Most returns occurred at sites where they had been released.  Only small percentages (0.7% and 0.2%) of the returns were recorded in the other study sites.  Site fidelity was further analyzed using a 10 m × 10 m grid at one study site.  Returning birds showed high site fidelity.  The rate of returns within 10 m of the release place among the total returns was defined as the site fidelity index.  Based on a total of 4154 returns, the index was calculated to be 0.73.  The index was almost unchanged with increasing duration between the first release and the return.  Even after 20 years, birds returned to the vicinity of the initial release site.  The annual change in the index fluctuated from 0.54 to 0.81, with a slight increase during the most recent study period.”

Streaked Shearwater

Reference:

Sugawa, H., Karino, K., Ohshiro, A. & Hirai, M. 2014.  Long-term trends in breeding site fidelity of Streaked Shearwater Calonectris leucomelas.  Marine Ornithology 42: 11-15.

John Cooper, ACAP Information Officer, 19 May 2014

Peter Pyle (The Institute for Bird Populations, Point Reyes Station, California, USA) and colleagues write in the open-access journal Marine Ornithology on the little-known Bryan’s Shearwater Puffinus bryani.

The paper’s summary follows:

“Little is known about the conservation requirements of Bryan’s Shearwater Puffinus bryani, first described in 2011 based on a specimen collected in February 1963 near an area containing concrete rubble at Midway Atoll.  Here we document a second Bryan’s Shearwater observed on Midway during the winters of 1990/91 and 1991/92.  It was vocalizing from a 0.5–0.7 m crevice within an accumulation of artificial concrete and coral rubble.  Recent winter specimens of Bryan’s Shearwaters from the Bonin (Ogasawara) Islands, Japan, were also collected in areas with rocky crevices, possibly burrows they co-utilize with summer-breeding Bulwer’s Petrels Bulweria bulwerii.  This habitat is not found naturally on low-lying atolls in the Northwestern Hawaiian Islands; however, it does occur on Nihoa and Necker Islands, where Bulwer’s Petrels breed abundantly.  Digitized video and vocalization recordings from 1991 on Midway, detailed here and available at http://www.birdpop.net/index.php/en/brys, are currently being used to locate breeding Bryan’s Shearwaters in the Bonin Islands.  Similar monitoring should be considered for Nihoa and Necker Islands.  None of five at-sea records of small shearwaters in the central and eastern North Pacific Ocean can be confirmed as Bryan’s Shearwater; thus, nothing is currently know of its life history or requirements at-sea.”

The Midway Bryan's Shearwater, photograph by Reginald David

Click here to access three previous ACAP Latest News postings on Bryan's Shearwater.

Reference:

Pyle, P., David, R., Eilerts, B.D., Amerson, A.B., Borker, A. & Mckown, M. 2014.  Second record of Bryan’s Shearwater Puffinus bryani from Midway Atoll, with notes on habitat selection, vocalizations and at-sea distribution.  Marine Ornithology 42: 5-8.

John Cooper, ACAP Information Officer, 18 May 2014