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Audubon's Shearwater Puffinus lherminieri lherminieri 


Audubon's Shearwater Adult

At a glance

  • Declining with 1600-3800 breeding pairs

  • Sub-tropical and tropical pelagic species
  • The only shearwater breeding in the region
  • Nocturnal, nests in cavities, is difficult to detect 
  • Highly vocal at night throughout breeding season
  • Often associated with pelagic Sargassum
  • Has declined from human consumption of adults, eggs and chicks, and introduced predators such as rats

Index


Identification:

Adults

Small, stocky, long-tailed black and white shearwater. Tube-nose. Tail appears longer than other small black and white shearwaters (Manx and Little) occurring in the North Atlantic. Amount of white in under tail coverts more variable than what is shown in most field guides. Legs dark bluish-black. Bill tip to tail length 12 inches (30 cm). Wingspan ~69 cm. Because of their nocturnal behavior around breeding sites they are unlikely to be detected by casual observation except by voice. Several recordings are below.

Vocalizations:

    Male
    Female
    Duet
    Another Male aiff
    Another Female aiff

Juveniles

As adult. Juveniles moult flight feathers the following spring. Downey chicks are small, grey, downy balls with dark eyes, bills and feet. Eggs are white.

Systematics

One of three small black and white shearwaters occurring in thee Atlantic. The relationship between Audubon’s and the smaller, more temperate Little Shearwater is not fully resolved. As a result of their rather sedentary nature and high fidelity to nest sites, limited genetic exchange exists between populations of Audubon’s Shearwaters. At least 12 subspecies, each with considerable variation in overall size, are recognized. Nominate subspecies endemic to our region of the western North Atlantic. P. l. loyemilleri is smaller and in the breeding season at least, is confined to western Caribbean. This subspecies is close to extinction but no recent population assessments are available. Lee (1988) provides comparative measurements of the black and while shearwaters of the Atlantic basin.

Likely locations

At and near breeding sites throughout the region, and in tropical and sub-tropical seas along oceanic fronts, near areas of upwelling. Regularly in the Gulf Stream off the Southeastern US in the warmer months.


Distribution

Nesting populations are widespread in tropical seas with a few populations extending into the sub-tropics. In the Atlantic, they breed throughout the West Indies region and in the Cape Verde Islands; in the Indian Ocean Audubon’s Shearwaters nest on islands in the Arabian Sea, Mascarene Is., Aldabra, Seychelles, Amirante, Maldives and Chagos Islands. In the Pacific they breed on the Galapagos Islands, Bonin and Volcano Islands, and also Banks and New Hebrides and throughout the central Pacific.

Nesting occurs in Bahamas, throughout the West Indies and on various islands in the Western Caribbean. Disperses to adjacent tropical and subtropical seas in non-breeding period. Follows Gulf Stream northward and is commonly encountered off the Carolinas, and regularly north to New Jersey and New York. Typically in deep waters over Outer Continental Shelf, with storm driven birds and vagrants occasionally found in other areas of the Atlantic basin.

There is very little information about the populations of the subspecies P. l. loyemilleri that once nested off the Caribbean coast of Panama.

Distribution of Audubon's Shearwater

Biology

At sea

Highly pelagic, seldom seen from land. Post breeding birds disperse widely from nesting areas moving mostly northward as the surface waters of warm summer tropical seas become less productive. Foraging both diurnal and nocturnal. Feeds along current edges and similar marine boundaries and over upwellings. Major food items small fishes (in 94.1%  of stomachs examined), squid (65.5%), and crustaceans (6.3%). Off North Carolina, this species is a Sargassum specialist; most of the prey items recovered from stomachs of birds collected at sea represent Sargassum associates. Feeds on the wing or while swimming. Birds observed in the Gulf Stream take only shallow dives, but adults feeding chicks in the Bahamas were found to dive to maximal depths of 29 m (median=7m; n=131; Mackin, 2004). Often feed in large mixed species flocks. Molting adult birds are common from July to September off NC coast.  

At the nest

Audubon’s Shearwaters breed in a variety of situations. The only common denominator to all breeding sites is the absence, or near absence, of introduced terrestrial predators. Typically nest in natural cavities or under rocks, but will also dig their own burrows. The length of the burrow depends on the nature of the substrate. They also nest in the open spaces beneath rocks and coral rubble, under Agavi leaves, rock walls, and other forms of shelter. Nesting may be anywhere from just above the high tide line to higher elevations in the interior of islands (e.g. Saba, NWI). Where suitable nesting sites exists these shearwaters tend to form small colonies. Wind gaps in vegetation can result in dense sub colonies where conditions for entry to nest cavities is enhanced.

Females lay a single egg. Nests are simple depressions in the substrate. Both birds incubate with each incubation shift lasting several days. Breeding activity varies with location. Typically adults appear at nesting colonies in late winter. Eggs are laid in mid-spring (12 March - 23 May extreme egg dates for Bahamas). Most eggs hatch by the beginning of June. 

Most young and adults disperse from colonies by the beginning of August. Incubation lasts about 48 days, and fledging 62-100 days. This protracted breeding cycle increases the amount of time they are vulnerable to terrestrial predators.

Shearwaters will not fly over land during daylight or moonlit periods of the night. The best time to search for birds is the two-week period  around the new moon. Around the new moon, the colony will reach sufficient darkness for the greatest number of birds to visit.  


Current Population

Audubon's Shearwaters have been reported at 124 sites with 10 sites that have more than 26 pairs and 11 sites that have been extirpated including large islands such as Anegada, Eleuthera, Abaco, Bermuda, Mona, Monito, and Anguilla. Limestone sinkholes on Mona island are filled with shearwater subfossils, indicating a formerly huge population. Mona has become infested with rats, cats, feral pigs, and goats, all of which negatively affect shearwaters.

Location Colonies Low Estimate High Estimate
Antigua and Barbuda 2 0 10
Anguilla 2 0 10
Bahamas 43 1283 2383
Barbados 3 10 200
Bermuda 1 0 0
British Virgin Islands 5 2 50
Colombia 1 0 0
Cuba 1 2 2
St. Martin 1 0 1
Guadeloupe 3 2 30
Grenada 5 7 55
Haiti 1 0 10
Jamaica 1 5 14
Martinique 4 53 121
Navassa 1 1 10
St. Maarten 1 1 10
Puerto Rico 15 12 81
Saba 5 15 21
St. Barts 1 0 10
St. Eustatius 2 2 20
Tobago 2 200 500
Turks and Caicos 6 6 60
US Virgin Islands 5 27 75
Venezuela 13 13 130
Panama11100??
Total 125 1642 3903

Many of the colonies of both subspecies have not been visited at night and are in need of surveys during the breeding season. Sites in the Cay Sal Bank and out islands of the Bahamas Archipelago (Walker's Cay, Pelican Cays at Abaco, East and West Plana Cay, Ragged Islands, Long Cay near East Caicos) and in the Los Roques Archipelago are the most isolated from humans and the most likely to show larger populations of this species.

P. l. lherminieri (Most of the region)

The population estimates for this species show a persistent drop in numbers. Van Halewyn and Norton (1984) estimated about 5,000 pair in the region. A more detailed assessment fifteen years later indicated that the total population was between 3,000 and 5,000 pairs (Lee 2000). We currently suspect the total population to be 1600-3,800 pairs. While some of this ‘loss’ is a result of better information on colony sizes, historical records indicate that this was a much more common and widespread species in recent times.

P. l. loyemilleri (Central American Coast)

Western Caribbean subspecies believed to be close to extinction (van Halewyn and Norton 1984), although Olson (pers. comm.) reports: 

 "We collected 3 young on one of the Tiger Rocks on 24 April 1990 after no long search.  The islands are covered with dense vegetation that would inhibit much human exploitation of shearwaters so unless predators have been introduced in the last 19 years there would be no reason to consider that the population there is any more imperiled than at any time in the post-Columbian past. "

Conservation Status 

While in some areas of the world this shearwater appears to be quite common, the Atlantic population is small and the species has disappeared from a number of former breeding sites. These include Bermuda, various islands in the Bahamas, Puerto Rico, Culebra, Mona, Monito, the British Virgin Islands, the Grenadines, and islands in the Western Caribbean. Introduced predators, mostly rats and feral house cats are a major problem and populations on many islands continue to decline. The West Indies population regarded as near threatened by Schreiber and Lee (2000).

Conservation Needs

In the Antilles, the fat young are still prized for food and patrolling of colonies and pro-active protection of the larger ones is warranted. Closure of major nesting islands during the breeding season is highly recommended. In addition to poaching by island residents, there are additional problems associated with boat refugees from Cuba and Haiti. Stranded refugees have been documented to devastate Audubon's Shearwater colonies when they are stranded on remote cays for weeks on end (Bahamas, Cay Sal Bank 1999; >200 adult shearwaters killed by Cuban refugees) and it can be assumed that similar events have gone undocumented.

Predators, especially rats and house cats, are the major problem. Rats and house mice are particularly troublesome. Not only do they affect nesting success, but their presence also helps sustain other predators such as house cats, and native ones like Barn Owls (Mackin 2008).

David Wingate (pers comm.) believes that lights disoriented the last surviving Audubon’s Shearwaters in Bermuda. This seems likely as all known extant colonies are on remote islands away from any permanent light source.

It would be a most worth while project to reintroduce Audubon's Shearwaters to Bermuda. There are protected island sites that are free from house cats and Rattus, and the methodologies for translocating and inprinting seabird chicks to new sites are well established. Not only would such a program return an extirpated native species to Bermuda, but the documentation the methodologies of a successful regional transplant of this shearwater to a former nesting location would be useful for creating guide lines for future conservation efforts for this and other seabirds. Perhaps as importantly it would create a tremendous opportunity to educate the people of the region about the plight of seabirds and be a pioneering program for conservation agencies of two regional governments in addressing issues regarding formerly shared faunas.

A systematic inventory of known and suspected nesting sites is needed. The problem is that these birds are difficult to census and results from different researchers might provide results that would not be comparable. Their cavity nesting behavior is only part of the problem, for most populations we do not have a clear understanding of their local breeding synchronization. Of specific interest would be surveys of the islands off the northern coast of Cuba. While there are no reports from this area it would be surprising if these shearwaters were not present. With the exception of the endemic West Indian petrels (Pterodroma), our knowledge is less complete for this species than any other of the seabirds of the region. These baseline surveys are important in that they would provide both a better understanding of the current population as well as allowing us to measure population changes in the future as they relate to local management and protection efforts.

The extent of regional laws, regulations and enforcement is unclear. Until recently fat salted chicks were sold openly in local markets, and this practice may still go on in some places. Local education programs are needed and enforcement personnel need to be in tune with regional conservation issues.  

Specifically the Bahamas needs to step up education, monitoring, and patrols of its larger Audubon’s Shearwater colonies. Local wardens and others concerned with conservation of marine resources need to be aware of site locations, nesting seasons, and various aspects of the bird’s biology in order to better protect the species. Other enforcement agencies present in the area could also help with patrolling the nesting islands and cays. A number of islands should be closed to all unauthorized visitation from January through July.

Issues at sea are limited and at least at the moment not of major concern. There is no evidence that this shearwater is part of the by-catch of pelagic commercial fisheries operations in the Atlantic. Compared to other Procellariiforms, foraging Audubon’s Shearwaters had slightly lower amounts of plastic ingestion, but it was still high. In a study of gizzards in collected specimens, 83.3% of birds had floating plastics and 16.7% had pieces of styrofoam (studies off North Carolina over a 14 year period; total sample N= 119).

The potential for mortality from oil spills is high. Up to 75% of the region's population summers off Cape Hatteras where a discussion continues about offshore oil exploration in the very area occupied by the shearwaters. In warmer months, 68% of the birds foraging off North Carolina are adults.

It has also been suggested that wing energy farms be placed off the North Carolina coast. Periodically local and federal agencies are asked for permission to harvest the pelagic Sargassum from waters off the SE coast of the United States. Harvesting could have a tremendous negative impact on this shearwater as well as other species that are dependent on these alga mats for foraging.


Photos

        (Add sketches from Lee 1988 under photos)

Selected References:

Harris, M.P. 1969. Food as a factor controlling breeding of Puffinus lherminieri. Ibis 111:139-155,

Lee, D. S. 1988. The Little Shearwater (Puffinus assimilis) in the Western North Atlantic. American Birds 42(2):213-220.


Lee, D. S. 2000. Status and Conservation priorities for Audubon’s Shearwaters in the West Indies. Pages 25-39 In E. A. Schreiber and D. S. Lee (eds) Status and Conservation of West Indian Seabirds. Society of Caribbean Ornithology, Special Publication Number 1.225 pp.

Mackin, W. A. 2007. Conservation of Audubon's Shearwater in the Bahamas: Status, Threats, and Practical Solutions. Proceedings of the 11th Symposium on the Natural History of the Bahamas (K. Sealey, K and E. Freid, eds.). Pp. _-_+8.

Mackin, W. A. 2005. Neighbor-stranger discrimination in Audubon’s Shearwater (Puffinus l. lherminieri) explained by a “real enemy” effect. Behavioral Ecology and Sociobiology 59(2):326-332. 

Mackin, W. A. 2004. Communication and breeding behavior of Audubon’s Shearwater. PhD Dissertation. Chapel Hill: The University of North Carolina Pp. i-xxiv, 1-200.  


Sprunt, A. 1984. The status and conservation of seabirds of the Bahama Islands. Pages 157-168 in J. P. Croxall, P. G. Evans and R. W. Schreiber (eds). Status and Conservation of the World’s Seabirds. ICBP Tech. Publ., No. 2. 778 p.

van Halewyn, R. and R. Norton. 1984.The status and conservation of seabirds in the Caribbean. Pages 169-222 in J. P. Croxall, P. G. Evans and R. W. Schreiber (eds). Status and Conservation of the World’s Seabirds. ICBP Tech. Publ., No. 2. 778 p.

Trimm, N.A. 2001. Ecology of Audubon’s Shearwaters (Puffinus lherminieri) at San Salvador, Bahamas. MS thesis, Loma Linda University.

Trimm, N.A. 2004.  Behavioral Ecology of Audubon’s Shearwaters at San Salvador, Bahamas.  Diss. Loma Linda University. 

Trimm, N. A., Jr., and W. K. Hayes. 2005. Distribution of nesting Audubon’s shearwaters (Puffinus lherminieri) on San Salvador Island, Bahamas. Pages 138-146 in S. D. Buckner and T. A. McGrath (Eds.), Proceedings of the 10th Symposium on the Natural History of the Bahamas. Gerace Research Center, San Salvadaor, Bahamas.

Acknowledgements

Storrs Olson, Haven Wiley, Mary Kay Clark, Rick and Kathy Oliver, Chuck Knapp, David Wingate, Eric Carey, Nathan Wheeler, Jon Micancin, Ted Uyeno, Tiffany Kiernan, Burke Cathey, Jason Prichett, Kim and Chris Brand, Matthew Mckown, Twyla Harrington, Claire Campbell, Zach Ewart, Jessica Goshen, Predensa Moore, Minna Wiley, John Rothchild, Lou Roth, Renee Birk, Rachel Gross, Shedd Aquarium, Ray and Evelyn Darville, Blew Bayou, Larry Dougan, Judy and Tom Barbernitz, Exuma Park Volunteers, Stefan Payton, Bill Hayes, Tony Trimm, Georgia Ornithological Society, Cooper Ornithological Society, UNC Biology Department, Animal Behavior Society, American Museum of Natural History, and Conservation, Research, and Education Opportunities.
West Indian Breeding Seabird Atlas by Will Mackin and David Lee is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.Based on work at www.wicbirds.net.Permissions beyond the scope of this license may be available at www.wicbirds.net.

Suggested Citation: Lee, D. S., W. A. Mackin. 2009. Audubon's Shearwater. West Indian Breeding Seabird Atlas <http://www.wicbirds.net/aush.html>. Last Updated: _____. Date accessed: ______.

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