David Hyrenbach (Department of Natural Sciences, Hawai'i Pacific University, Honolulu, Hawai'i, USA) and Wendy Johnson write in 'Elepaio, newsletter of the Hawai‘i Audubon Society, on their monitoring and management efforts with Wedge-tailed Shearwaters Puffinus pacificus over five years in a colony on the Hawaiian island of Oahu.

Their results show the Freeman Seabird Preserve colony has increased by 25% per year since 2009 from around 75 to 200 breeding pairs:  “[t]his trend suggests that the ongoing revegetation efforts and the increasing number of available nesting sites continue to support an unprecedented growth of this Wedge-tailed Shearwater colony…”.

“From January through March 2013, while the birds were at sea, Hawai'i Audubon Society members and other volunteers worked to remove alien plant species from the preserve and to maintain wedge-tailed shearwater burrows and nesting sites.  Weekly fieldwork opportunities attracted a wide variety of participants, ranging from wildlife conservationists and scientists, to gardening enthusiasts, neighbors and young student groups.  These efforts support the work done in 2011 and 2012 by professional native plant landscapers from Hui Ku Maoli Ola, who transformed a vacant house-lot into a unique example of pre-contact Hawaiian dryland coastal habitat with multiple shearwater nesting sites.  Repeat volunteers have found it extremely satisfying to witness, and contribute to, the resurgence of native Hawaiian coastal plants at the Freeman Seabird Preserve.”

A pair of Wedge-tailed Shearwaters

Constructed shearwater burrow in the Freeman Seabird Preserve

Photograph by David Hyrenbach

Click here for an earlier ACAP Latest News item on the Freeman Seabird Preserve.

Reference:

Hyrenbach, K.D. & Johnson, W. 2014.  Five years of Wedge-tailed Shearwater monitoring and habitat restoration at the Freeman Seabird Preserve: 2009 – 2013.  'Elepaio 74(2): 5-6.

See also:

Hyrenbach, K.D. 2011. Tale of two years: monitoring Wedge-tailed Shearwaters at Freeman Seabird Preserve in Black Point, O'ahu. ‘Elepaio 71(3): 17-20.

Hyrenbach, K.D. 2012. 2011: a mixed year at the Freeman Seabird Preserve. ‘Elepaio 72(2): 13-14.

Hyrenbach, K.D. & Johnson, W. 2013. 2012: record breeding shearwater count at the Freeman Seabird Preserve. ‘Elepaio 73(2): 14-15.

Young, L., VanderWerf, E.A. & Lohr, M.E. 2012. Freeman Seabird Preserve predator control. ‘Elepaio72(1): 6.

John Cooper, ACAP Information Officer, 26 April 2014

Burrowing petrels typically fly to and from, and their chicks fledge from, their breeding sites at night, presumably so as to avoid predators as they pass over land to and from the sea.  In inhabited areas where outside artificial lighting at night prevails, such birds can be dazzled by, or even attracted to, artificial lights, leading to collisions with buildings and vehicles on roads, “downings”, fatal injuries and enhanced risk of capture by predators, such, as in the southern hemisphere, by skuas.

Conservation efforts at a number of breeding sites world-wide have concentrated on both collecting downed fledglings, notably of shearwaters Puffinus and Calonectris and gadfly petrels Pterodroma, for later release to sea and reducing the numbers and strength of artificial lights.

A downed Newell's Shearwater fledgling is released after rescue

Photograph by Elizabeth Ames

At one locality, the Barking Sands Pacific Missile Range Facility (PMRF) on the USA’s Hawaiian island of Kauai, green lights have been tried with success, leading to a reduced number of downed birds being recorded.  “The 2013 fledging season for Newell’s shearwater [Puffinus newelli] and Hawaiian Petrels [Pterodroma sandwichensis] ended … with zero injuries or casualties at the base”.

Barking Sands supports a breeding population of Laysan Albatrosses

“While none of last year’s incidents resulted in fatalities, all were attributed to high-wattage light sources, which were immediately switched, according to PMRF.  Those physical changes include the implementation of a “Dark Sky” program, which improved lighting conditions so the birds would be less distracted.  Conventional lamps were converted to LEDs, and full-cut-off fixtures prevent the light source from being seen by the birds from above.  Another technology being utilized at the base are “green lights,” a spectrum first tested [in] 2010, which seems to also work in the birds’ favour” (click here).

Green lights have also been installed on the other side of the World at South Africa’s weather and research station on sub-Antarctic Marion Island.  A strict policy of no outside lights, closing of black-out blinds at dusk and switching off unnecessary inside lights has led to the incidence of locally-known “night bird attacks” by burrowing petrels, most especially the abundant Salvin’s Prion Pachyptila salvini, being reduced over the years.

 Marion Island's weather and research station

Sky corridors from the outside

Sky corridor during the day

A sky corridor at night with its green footlights just discernable

Photographs of the corridor by Mariette Wheeler

The construction of a new base at Marion in the last decade gave the opportunity to install low-wattage green footlights to guide inhabitants in safety along glassed “sky corridors” between buildings at night.  Although experimental evidence is lacking it seems that the green lights are playing their part in reducing bird strikes and subsequent mortality of burrowing petrels when they fly close to the buildings on moonless and foggy nights.

With thanks to Mariette Wheeler for the photographs. 

Selected Literature: 

Imber, M.J. 1975.  Behaviour of petrels in relation to the moon and artificial lights.  Notornis 22: 302-306. 

Le Corre, M., Ollivier, A., Ribes, S. & Jouventin, P. 2002.  Light-induced mortality of petrels: a 4-year study from Réunion Island (Indian Ocean).  Biological Conservation 95: 93-102.

 Poot, H., Ens, B.J., de Vries, H., Donners, M.A.H., Wernand, M.R. & Marquenie, J.M. 2008.  Green light for nocturnally migrating birds.  Ecology & Society 13: 1-14.

Reed, J.R., Sincock, J.L. & Hailman, J.P. 1985.  Light attraction in endangered procellariiform birds: reduction by shielding upward radiation.  Auk 102: 377-383.

Rodríguez, A.& Rodríguez, B. 2009.  Attraction of petrels to artificial lights in the Canary Islands: effects of the moon phase and age class.  Ibis 151: 299-310.

Telfer, T.C., Sincock, J.L., Bryd, G.V. & Reed, J.R. 1987.  Attraction of Hawaiian seabirds to lights: conservation efforts and effects of moon phase.  Wildlife Society Bulletin 15: 406-413.

John Cooper, ACAP Information Officer, 25 April 2014

Stefano Focardi (Istituto dei Sistemi Complessi, Sesto Fiorentino, Italy) and Jacopo Cecere write in the Journal of Animal Ecology on flight patterns in Scopoli’s Shearwater Calonectris diomedea.

The paper’s summary follows:

1. “Lévy flight foraging represents an innovative paradigm for the analysis of animal random search by including models of heavy-tailed distribution of move length, which complements the correlated random walk paradigm that is founded on Brownian walks.  Theory shows that the efficiency of the different foraging tactics is a function of prey abundance and dynamics with Lévy flight being especially efficient in poor prey fields.
2. Lévy flights have been controversial in some quarters, because they previously have been wrongly ascribed to many species through the employment of inappropriate statistical techniques and by misunderstanding movement pattern data.  More recent studies using state-of-the-art statistical tools have, however, provided seemingly compelling evidence for Lévy flights.  In this study, we employ these maximum-likelihood methods and their Bayesian equivalents by analysing both turning angles and move length distributions.
3. We tested, for compliance with Lévy flight foraging, a set of 77 independent foraging trajectories of Cory's shearwaters Calonectris diomedea diomedea.  Birds were tagged with high-resolution GPS loggers in two Mediterranean colonies (Linosa and Tremiti) during both incubation and chick rearing.
4. We found that the behaviour of six birds was fitted by a correlated random walk; the movement of 32 birds was better represented by adaptive correlated random walks by switching from intensive to extensive searches; and the trajectories of 36 birds were fitted by a Lévy flight pattern of movement.  The probability of performing Lévy flights was higher for trips during chick provisioning when shearwaters were forced to forage in suboptimal areas.  This study supports Lévy flight foraging as an appropriate framework to analyse search tactics in this pelagic bird species and highlights that the adoption of a given search strategy is a function of biological and ecological constraints.

Cory's/Scopoli's Shearwater, photograph by John Graham

Reference:

Focardi, S. & Cecere, J.G. 2014.  The Lévy flight foraging hypothesis in a pelagic seabird.  Journal of Animal Ecology 83: 353-364.

John Cooper, ACAP Information Officer, 24 April 2014

The ground-baiting campaign to remove Norway or Brown Rats Rattus norvegicus from the inhabited islands of St. Agnes and Gugh (connected by a tombolo) in the United Kingdom’s Isles of Scilly appears to have met with success.  Rat removal in the Scilly Isles will help protect small populations of Manx Shearwaters Puffinus puffinus and European Storm Petrels Hydrobates pelagicus that have been reported breeding on both islands.

The bait station sites on St Agnes (left) and Gugh (right) that led to the eradication of the rats

The latest issue (No. 3 of March 2013) of the Isles of Scilly Seabird Recovery Project’s newsletter The Shearwater reports “[w]e are delighted to update you to say there has been no sign of rats on St Agnes and Gugh for the last 16 weeks at the time of writing this newsletter.”  However, a formal announcement that the rats are definitely gone will only follow the accepted two-year rat-free period in 2016.

The rat-removal phase of the eradication project was undertaken by Elizabeth (Biz) Bell and colleagues of New Zealand’s Wildlife Management International Ltd (WMIL), which previously undertook the feasibility study into rat removal from the Isles of Scilly.  They used 1036 commercial lockable and tube stations carrying poison bait distributed over both islands.  These stations alomg with "all the pieces of wire, flagging tape [and] bamboo cane" have now been removed.

Plans are now in place to ensure that biosecurity protocols are adequate to ensure rats do not reinvade the islands, with training workshops being run for the islands’ inhabitants.  As part of post-eradication monitoring, permanent stations have been set up around the coasts of St Agnes and Gugh.  They house pieces of chocolate wax known to be attractive to rats.

Manx Shearwater at sea

Photograph by Nathan Fletcher

The newsletter also reports that the first “Manxies” have been sighted offshore on 21 March as the new breeding season approaches; hopefully one without the risk of breeding attempts being depredated by rodents.

The Isles of Scilly consist of five inhabited islands and numerous other small rocky islets off Cornwall in the south of England.  The project has been run by a partnership of organisations: RSPB, Isles of Scilly Wildlife Trust, Natural England, Duchy of Cornwall and the Isles of Scilly Area of Outstanding Natural Beauty.

For the European Storm Petrel, the Isles of Scilly represent the sole breeding site in England, with 1398 pairs.  The islands are also one of only two breeding sites for the Manx Shearwater in England with 171 pairs; the other being the island of Lundy in the Bristol Channel.

Click here for earlier reports in ACAP Latest News on the eradication attempt.

Selected Literature:

Bell, E. 2011.  Isles of Scilly Seabird Recovery Project: Summary Report: Improving rodent control on uninhabited islands, assessment of the feasibility of rat removal across the Isles of Scilly Archipelago and feasibility of rat removal from St Agnes and Gugh.  Blenheim: Wildlife Management International Ltd.  40 pp.

Brooke, M. de L. 1990.  The Manx Shearwater.  London: T & AD Poyser.  246 pp.

Lock, L., Brown, A., Webber, J., Mawer, D. & St. Pierre, P. 2009.  Isles of Scilly Seabird Conservation Strategy 2009-2013.

Mitchell, P.I., Newton, S.F., Ratcliffe, N. & Dunn, T.E. 2004.  Seabird Populations of Britain and Ireland.  Results of the Seabird 2000 Census (1998-2002).  London: Christopher Helm.  511 pp.

John Cooper, ACAP Information Officer, 23 April 2014