Federal Register: December 17, 2007 (Volume 72, Number 241)
DOCID: fr17de07-30 FR Doc E7-24347
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
CFR Citation: 50 CFR Part 17
RIN ID: RIN 1018-AV21
DOCUMENT ID: [96100-1671-0000-W4]
NOTICE: PROPOSED RULES
DOCID: fr17de07-30
ACTION: Endangered and threatened species:
DOCUMENT ACTION: Proposed rule.
SUBJECT CATEGORY:
Endangered and Threatened Wildlife and Plants; Proposed Rule To List Six Foreign Bird Species Under the Endangered Species Act
DATES: We must receive comments and information from all interested parties by March 17, 2008. Public hearing requests must be received by January 31, 2008.
DOCUMENT SUMMARY:
We, the U.S. Fish and Wildlife Service (Service), propose to list three petrel species (order Procellariiformes), the Chatham petrel (Pterodroma axillaris), previously referred to as (Pterodroma hypoleuca axillaris); Fiji petrel (Pterodroma macgillivrayi); and the magenta petrel (Pterodroma magentae) as endangered, pursuant to the Endangered Species Act of 1973, as amended (Act). In addition, we propose to list the Cook's petrel (Pterodroma cookii); Galapagos petrel (Pterodroma phaeopygia), previously referred to as (Pterodroma phaeopygia phaeopygia); and the Heinroth's shearwater (Puffinus heinrothi) as threatened under the Act. This proposal, if made final, would extend the Act's protection to these species. The Service seeks data and comments from the public on this proposal.
SUMMARY:
Chatham petrel, etc. (six foreign bird species),
SUPPLEMENTAL INFORMATION
Background
In this proposed rule, we propose to list three foreign seabird species as endangered, pursuant to the Act (16 U.S.C. 1531, et seq.). These species are: the Chatham petrel (Pterodroma axillaris), Fiji petrel (Pterodroma macgillivrayi), and magenta petrel (Pterodroma magentae). We also propose to list the Cook's petrel (Pterodroma cookii), Galapagos petrel (Pterodroma phaeopygia), and Heinroth's shearwater (Puffinus heinrothi) as threatened species under the Act. All species are considered pelagic, occurring on the open sea generally out of sight of land, where they feed year round. They return to nesting sites on islands during the breeding season where they nest in colonies (Pettingill 1970, p. 206).
Chatham petrel (Pterodroma axillaris)
The Chatham petrel is also known by its Maori name, ranguru. Fossil evidence indicates that this species was once widespread throughout the Chatham Islands of New Zealand [New Zealand Department of Conservation (NZDOC) 2001b]. However, the species is currently only known to breed on South East Island (Rangatira) (BirdLife International 2007a) and, as a result of recent release efforts, on Pitt Island (BirdLife International News 2006) within the Chatham Islands. The population of this species is very small, estimated at 8001,000 birds based on recent research and banding studies (Taylor 2000), and is showing a decreasing population trend (BirdLife International 2007a). It is estimated that fewer than 200 pairs breed per year (NZDOC 2001b). The IUCN considers the Chatham petrel to be ``Critically Endangered'' (BirdLife International 2006a).
Banding studies have shown that young birds of this species remain at sea for at least two years before returning to land to breed and nest. Based on limited feeding habits data, the species preys on squid and small fish (Heather and Robertson 1997, as cited in BirdLife International 2000).
Fiji petrel (Pterodroma macgillivrayi)
Synonyms for the Fiji petrel include Pseudobulweria macgillivrayi and Thalassidroma macgillivrayi. Very little information is available on the Fiji petrel and its life history. There have only been 12 substantiated sightings of this species on land since 1965, and a total of 13 historically. These sightings have all been on Gau Island (BirdLife International 2000), a 52.55square mile (136.1 km\2\) island in Fiji's Lomaiviti archipelago (Wikipedia 2007f). The population of this species is very small, estimated at less than 50 birds and is showing a decreasing population trend (BirdLife International 2007c). The IUCN classifies the Fiji petrel as ``Critically Endangered'' (BirdLife International 2006c).
Magenta petrel (Pterodroma magentae)
The magenta petrel, or Taiko as it is known locally, is native to Chatham Island, New Zealand (BirdLife International 2000), the largest island in the Chatham Islands chain, covering 348 square miles (900 km\2\, Wikipedia 2007b). Based on fossil evidence and historical records, it is believed that the magenta petrel was once the most abundant burrowing seabird on Chatham Island (Bourne 1964, Sutton and Marshall 1977, as cited in NZDOC 2001a). It has been reported that prior to 1900, indigenous Moriori and Maori harvested thousands of petrel chicks for food (Crockett 1994). The limited feeding habits data show that the magenta petrel preys on squid (Heather and Robertson 1997, as cited in BirdLife International 2000).
The type specimen for the magenta petrel was first collected at sea
in 1867, and after 10 years of intensive searching the species was re discovered in 1978 in
[[Page 71299]]
the southeast corner of Chatham Island (Crockett 1994). Since then,
additional searches have resulted in the location and banding of 92
birds (BirdLife International 2007d). The IUCN considers this species
as ``Critically Endangered'' (BirdLife International 2006d). The
magenta petrel population is estimated at 120 individuals with a decreasing trend (BirdLife International 2007d).
Cook's petrel (Pterodroma cookii)
Cook's petrel is endemic to the New Zealand archipelago (del Hoyo, et al. 1992), which comprises two main islands, the North and South Islands, and numerous smaller islands. The total land area of the archipelago covers 103,700 square miles (268,680 km\2\, Wikipedia 2007i). Historically, Cook's petrels were harvested in large numbers as a food source by native Moriori (Oliver 1955).
Although the Cook's petrel was once considered a dominant species on these islands, the species' breeding and nesting activities are now restricted to islands at the northern and southern limits of its former breeding range, including Great Barrier (Aotea), Little Barrier (Hauturu), and Codfish (Whenua Hou) Islands (del Hoyo, et al. 1992). The species' diet consists primarily of cephalopods, fish, crustaceans, and bioluminescent tunicates that can be hunted at night (Imber 1996).
The IUCN classifies this species as ``Endangered'' (BirdLife International 2006b). Although the population on Little Barrier Island was thought to be about 50,000 pairs (BirdLife International 2007b), using GIS (Geographic Information System) technology, Rayner, et al. (2007b) determined that the population is around 286,000 pairs. In 2006, the Great Barrier Island population was considered to be in danger of extirpation because only four nest burrows had been located in recent years, and it was estimated that fewer than 20 pairs continued to breed on the island. However, the populations on Little Barrier and Codfish islands are likely to be increasing (BirdLife International 2007b).
Galapagos petrel (Pterodroma phaeopygia)
The Galapagos petrel is endemic to the Galapagos Islands, Ecuador (BirdLife International 2000), and is currently known to occur on the archipelago's islands of Santa Cruz, Floreana, Santiago, San Crist[oacute]bal, and Isabela, which cover a total land area of 2,680 square miles (6,942 km\2\, Cruz and Cruz 1987; Vargas and Cruz 2000, as cited in BirdLife International 2000). This species feeds mostly on squid, fish, and crustaceans (Castro and Phillips 1996, as cited in BirdLife International 2000), and has been observed foraging near the Galapagos Islands, as well as east and north of the islands (Spear, et al. 1995).
The IUCN classifies the Galapagos petrel as ``Critically Endangered'' (BirdLife International 2006e). The total population is estimated to be 20,00060,000 birds with a decreasing population trend (BirdLife International 2007e).
Heinroth's shearwater (Puffinus heinrothi)
Very little information is available on the Heinroth's shearwater and its life history. The species' nesting grounds have not been located, but observations of the species indicate that the species breeds on Bougainville Island in Papua New Guinea, and Kolombangara and Rendova Islands in the Solomon Islands (Buckingham, et al. 1995, Coates 1985, 1990, as cited in BirdLife International 2000).
The IUCN categorizes this species as ``Vulnerable'' (BirdLife International 2006f). The population is estimated at 250999 birds, with an unknown population trend; however, there is no substantial evidence of a decline (BirdLife International 2007f).
Previous Federal Action
Section 4(b)(3)(A) of the Act requires the Service to make a finding known as a ``90day finding'' on whether a petition to add, remove, or reclassify a species from the list of endangered or threatened species has presented substantial information indicating that the requested action may be warranted. To the maximum extent practicable, the finding shall be made within 90 days following receipt of the petition and published promptly in the Federal Register. If the Service finds that the petition has presented substantial information indicating that the requested action may be warranted (referred to as a positive finding), Section 4(b)(3)(A) of the Act requires the Service to commence a status review of the species if one has not already been initiated under the Service's internal candidate assessment process. In addition, Section 4(b)(3)(B) of the Act requires the Service to make a finding within 12 months following receipt of the petition on whether the requested action is warranted, not warranted, or warranted but precluded by higherpriority listing actions (this finding is referred to as the ``12month finding''). If the listing of a species is found to be warranted but precluded by higherpriority listing actions, then the petition to list that species is treated as if it is a petition that is resubmitted on the date of the finding and is, therefore, subject to a new 12month finding within one year. The Service publishes an Annual Notice of Resubmitted Petition Findings (annual notice) for all foreign species for which listings were previously found to be warranted but precluded.
On November 24, 1980, we received a petition (1980 petition) from Dr. Warren B. King, Chairman, United States Section of the International Council for Bird Preservation (ICBP), to add 79 native and foreign bird species to the list of Threatened and Endangered Wildlife (50 CFR 17.11). The species covered by the 1980 petition comprised 19 native species and 60 foreign species, including the six seabird species of the family Procellariidae that are the subject of this proposed rule. In response to the 1980 petition, we published a notice to announce a positive 90day finding on May 12, 1981 (46 FR 26464) for 77 species, as two of the foreign species identified were already listed under the Act. On January 20, 1984, we published a 12 month finding within an annual review on pending petitions and description of progress on all ESA listing amendments (49 FR 2485). In this notice, we found that listing all 58 foreign bird species on the 1980 petition was warranted but precluded by higherpriority listing actions, however, the species were not listed by name. On May 10, 1985, we published the first annual notice (50 FR 19761) in which we continued to find that listing all 58 foreign bird species on the 1980 petition was warranted but precluded by higherpriority listing actions. In our next annual notice (51 FR 996), published on January 9, 1986, we found that listing 54 species from the 1980 petition, including the six species that are the subject of this proposed rule, continued to be warranted but precluded by higherpriority listing actions, whereas new information caused us to find that listing the four remaining species was no longer warranted. We published additional annual notices of findings on July 7, 1988 (53 FR 25511), December 29, 1988 (53 FR 52746), April 25, 1990 (55 FR 17475), November 21, 1991 (56 FR 58664), and May 21, 2004 (69 FR 29354). In addition, on September 28, 1990, we published a final rule (55 FR 39858) to list six species from the 1980 petition to the List of Threatened and Endangered Wildlife.
Per the Service's listing priority guidelines that were published
on September 21, 1983 (48 FR 43098), in our April 23, 2007, Annual Notice on
[[Page 71300]]
Resubmitted Petition Findings for Foreign Species (72 FR 20184), we determined that listing the six seabird species of family
Procellariidae was warranted. The six species were selected from the
list of warranted but precluded species for two reasons. First, this
family grouping includes more high priority species than any other
taxonomic family group in our list of warranted but precluded species;
and, second, because of the significance and similarity of the threats
to the species. Combining taxonomically related species that face
similar threats into one proposed rule allows us to maximize our
limited staff resources and thus increases our ability to complete the listing process for warrantedbutprecluded species.
Summary of Factors Affecting the Species
Section 4(a)(1) of the Act (16 U.S.C. 1533 (a)(1)) and regulations
promulgated to implement the listing provisions of the Act (50 CFR part
424) set forth the procedures for adding species to the Federal lists
of endangered and threatened wildlife and plants. A species may be
determined to be an endangered or threatened species due to one or more
of the five factors described in section 4(a)(1) of the Act. These
factors and their application to the Chatham petrel, Cook's petrel,
Fiji petrel, Galapagos petrel, magenta petrel, and Heinroth's shearwater follow.
Chatham petrel (Pterodroma axillaris)
A. The Present or Threatened Destruction, Modification, or Curtailment of the Habitat or Range
The range of this species changes intraannually based on an established breeding cycle. During the breeding season (November to June) (NZDOC 2001b), breeding birds return to breeding colonies to breed and nest. During the nonbreeding season, birds migrate far from their breeding range where they remain at sea until returning to breed. Therefore, our analysis of Factor A is separated into analyses of: (1) The species' breeding habitat and range, and (2) the species' non breeding habitat and range.
BirdLife International (2007a) estimates the range of the Chatham petrel to be 436,000 km\2\ (168,300 mi\2\); however, BirdLife International (2000) defines ``range'' as the ``Extent of Occurrence, the area contained within the shortest continuous imaginary boundary which can be drawn to encompass all the known, inferred, or projected sites of present occurrence of a species, excluding cases of vagrancy.'' Because this reported range includes a large area of non breeding habitat (i.e., the sea), our analysis of Factor A with respect to the Chatham petrel's breeding range focuses on the islands where the species is known to breed.
The Chatham petrel breeds primarily on one island (BirdLife International 2000; NZDOC 2001b), the 0.84 square mile (2.18 km\2\, Wikipedia 2007k) South East Island in the Chatham Islands (BirdLife International 2000; NZDOC 2001b). In 2002, the NZDOC began efforts to expand the species' breeding range by releasing chicks onto Pitt Island, an island approximately 2.5 km (1.55 mi) northwest of South East Island. Over a fouryear time period, 200 chicks were transferred to the 40 ha (98.8 acre) Ellen Elizabeth Preece Conservation Covenant (Caravan Bush), a fenced, predatorfree enclosure on Pitt Island. As of 2006, four adult birds had returned to the island from the sea to breed, and in June, 2006, a pair successfully reared a chick. This represents the first time in more than a century that a Chatham petrel chick has fledged on Pitt Island (BirdLife International News 2006).
The Chatham petrel breeds on coastal lowlands and slopes in habitats with low forest, bracken, or rank grass (del Hoyo, et al. 1992). It nests in burrows on flat to moderately sloping ground among low vegetation and roots (Marchant and Higgins 1990, as cited in BirdLife International 2000). Since the arrival of European explorers, this breeding habitat has contracted extensively, largely as a result of its conversion to agricultural purposes (NZDOC 2001b; Tennyson and Millener 1994).
We are not aware of any present or threatened destruction or modification of the Chatham petrel's habitat on South East Island. This island is currently uninhabited by humans (Wikipedia 2007k), and since 1954, it has been managed as a reserve for the Chatham petrel. Access to this island is restricted by permit. In addition, since 1961, all livestock has been removed from the island, allowing the natural vegetation to regenerate (Nilsson, et al. 1994). The Chatham petrel's fenced, 40 ha (98.8 acre) release area on Pitt Island is protected by a conservation covenant, and we are unaware of any present or threatened destruction or modification of any of the species' habitat on Pitt Island. Therefore, we find that the present or threatened destruction or modification of the species' breeding habitat is not a threat to the species.
The Chatham petrel's range at sea is poorly known; the species has
been recorded on several occasions at sea near South East Island, and
has been recorded once 12 km (7.5 mi) south of the island (West 1994).
It is believed that the species migrates to the North Pacific Ocean in
the nonbreeding season, based on the habits of closely related
species; however, no sightings have been recorded in the Northern
Hemisphere (Taylor 2000). We are unaware of any present or threatened
destruction, modification, or curtailment of this species' current sea habitat or range.
B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
We are unaware of any commercial, recreational, scientific, or educational purpose for which the Chatham petrel is currently being utilized.
C. Disease or Predation
The Chatham petrel's breeding range was reduced extensively following the arrival of European explorers, largely due to predation by introduced species such as rats (Rattus spp.), feral cats (Felis catus), and weka (Gallirallus australis), an introduced bird (Heather and Robertson 1997, as cited in BirdLife International 2000; NZDOC 2001b; Taylor 2000). Although no introduced predators are currently present on South East Island, there is an ongoing risk that predators will be introduced to the island by boats transporting conservation and research staff to the island. Given this risk, combined with the devastating impact introduced predators had on Chatham petrel populations historically, we find that predation by introduced species is a threat to the Chatham petrel on South East Island, the species' primary breeding location.
On Pitt Island, Chatham petrel chicks were released within a 40 ha (98.8 acre) fenced, predatorfree breeding habitat. Although this area is fenced, and the threat of predation on nesting Chatham petrels is reduced, introduced predators, such as feral cats and weka, are present on this island (BirdLife International News 2002) and could potentially get inside the fenced area or prey on Chatham petrels that leave the fenced area. Therefore, we find that predation by introduced species is a threat to the Chatham petrel on Pitt Island.
We are unaware of any threats due to predation on Chatham petrels during the nonbreeding season while the species is at sea.
The information available suggests that petrels in general are
susceptible to a variety of diseases and parasites, particularly during the breeding season, when large numbers of seabirds
[[Page 71301]]
congregate in relatively small areas to breed and nest (BirdLife
International 2007a; Carlile, et al. 2003). However, there are no
documented records of diseases impacting the persistence of the Chatham
petrel. Therefore, we find that the threat of diseases is not a significant threat to this species.
D. The Inadequacy of Existing Regulatory Mechanisms
The Chatham petrel is protected from disturbance and harvest under New Zealand's Wildlife Act of 1953 and its Reserves Act of 1977. The petrel is designated as a Category A species by the NZDOC, which signifies the species is of the highest priority for conservation management (Molloy and Davis 1999). As such, the NZDOC developed a ten year recovery plan for the Chatham petrel in 2001, with the goals of protecting the species' breeding burrows on South East Island from the broadbilled prion (Pachyptila vittata) (see Factor E below) and establishing a reintroduced population elsewhere within the species' historic breeding range (NZDOC 2001b). A measure of the success of this recovery plan is the successful establishment of breeding individuals on Pitt Island (see Factor A above) in 2006, thereby increasing the breeding range of the species. These efforts are beginning to show some success (see Factor E below), but it is too early to know the level of success, because it can take fledged seabirds years to return to their breeding colony to breed and nest (Taylor 2000). Similarly, protection of Chatham petrel burrows has reduced the population impacts resulting from competition with the broadbilled prion (see Factor E below), however, this threat remains the greatest threat to the species.
New Zealand ratified the Agreement on the Conservation of Albatrosses and Petrels (ACAP) in November 2001, which is designed to reduce impacts of fishing operations on populations of Procellariids (ACAP 2001), however the Chatham petrel is not listed in Annex 1 to this Agreement and, therefore, is not protected under this Agreement. Therefore, implementation of this Agreement has not reduced the threat of incidental take of this species in longline fisheries (see Factor E below).
Therefore we find that existing regulatory protections have not significantly reduced or removed the threats to the Chatham petrel. E. Other Natural or Manmade Factors Affecting the Continued Existence of the Species
Based on the information available, the predominant threat to the Chatham petrel is nest burrow competition between this species and the more abundant broadbilled prion, which numbers around 300,000 individuals. The prion not only occupies potential Chatham petrel burrows, but has been observed actively evicting or lethally attacking eggs, nestlings, and occasionally adults of the Chatham petrel. Such competition has resulted in a high rate of pair bond disruption and a low rate of breeding success in Chatham petrels, despite the high percentage of eggfertility (BirdLife International 2000; NZDOC 2001b).
To reduce the threat posed by competition with the broadbilled prion on South East Island, the NZDOC has implemented nest site protection efforts for the Chatham petrel, including placement of artificial nest sites and the blockage of burrows to prevent occupation by the broadbilled prion (NZDOC 2001b). During the 20052006 breeding season, out of 155 known breeding pairs, 83 percent of the pairs successfully fledged one chick per pair (Wikipedia 2007d). Although these actions are improving the petrel's breeding success (NZDOC 2001b; Taylor 1999, as cited in BirdLife International 2000), only a small proportion of breeding burrows occupied by Chatham petrels have been located and, therefore, protected (Taylor 1999, as cited in BirdLife International 2000). Therefore, we consider nest burrow competition between this species and the broadbilled prion to be a significant threat to the Chatham petrel.
The Chatham petrel's restricted breeding range puts the species at a greater risk of extinction. Breeding colonies were once widespread throughout the Chatham Islands (NZDOC 2001b), a group of about 10 islands within a 24.85 mile [40kilometer (km)] radius covering a total land area of 373 square miles (966 km\2\, Wikipedia 2007c). Currently, however, breeding of this species is restricted to South East Island (BirdLife International 2007a) and, as a result of recent release efforts, Pitt Island (BirdLife International News 2006), a total land area of less than 1 mi\2\ (Wikipedia 2007j,k). This habitat area is insufficient for the longterm survival of the Chatham petrel, particularly since breeding pairs, eggs, and nestlings on South East Island, the primary breeding area of this species, face the pervasive threat of nestsite competition with the broadbilled prion. It is estimated that the selfsustainability of the breeding population on Pitt Island as a result of the release program will take longer than four more years to achieve (NZDOC 2001b).
The Chatham petrel's restricted breeding range combined with its colonial nesting habits and small population size of 8001,000 birds (Taylor 2000) makes the species particularly vulnerable to the threat of adverse random, naturally occurring events (e.g., cyclones, fire) that destroy breeding individuals and their breeding habitat. Fire is a high risk in the Chatham Islands because the climate is very dry during the summer, and the vegetation becomes tinder dry. If fires do occur, the remoteness of the islands renders the fires unlikely to be exterminated by human intervention. Burrownesting species such as the Chatham petrel are at a high risk because they are likely to suffocate from smoke inhalation or to be lethally burned inside or while attempting to escape from their burrows (Taylor 2000).
Another natural disaster, severe storms, has impacted New Zealand historically, and so the likelihood of future impacts of storms is high. A severe storm in 1985 stripped two islands in the Chatham Islands chain bare of vegetation and soil cover, causing high increases in egg mortality of nesting albatrosses (Taylor 2000). Considered the worst recorded cyclone in New Zealand's history, Cyclone Giselle hit New Zealand April 10, 1968, with wind speeds of 275 km/h (Wikipedia 2007). Although we are unaware of the impact of this cyclone on the Chatham petrel's population numbers or breeding habitat, the severity of the wind or waves created by such a storm has potential to significantly damage Chatham petrel burrows. These burrows are particularly vulnerable because they are located on coastal lowlands (del Hoyo, et al. 1992), and they are extremely fragile, occurring in soft soils (Taylor 2000).
While species with more extensive breeding ranges or higher population numbers could recover from adverse random, naturally occurring events such as fire or storms, the Chatham petrel does not have such resiliency. Its very small population size and restricted breeding range puts the species at higher risk for experiencing the irreversible adverse effects of random, naturally occurring events. Therefore, we find that the combination of factorsthe species' small population size, restricted breeding range, and likelihood of adverse random, naturally occurring eventsto be a significant threat to the species.
We are unaware of any documented cases of incidental take of
Chatham petrels by commercial longline fishing operations or entanglement in marine
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debris; however, it is generally recognized that all seabirds are at
high risk of injury or mortality when they attempt to take bait from
longline fishing gear. The lack of data on these impacts could be a
result of the species' low population number. Dr. Michael Rands,
Director and Chief Executive of BirdLife International, has reported
that the number of seabirds killed in longline fishery operations
continues to increase, and the longline fishery, especially operations
by unlicensed ``pirate'' vessels, is the single greatest threat to all
seabirds [Australian Antarctic Division (AAD) 2007; BirdLife
International News 2003]. Therefore, we consider the incidental take of
Chatham petrels by commercial longline fishing operations to be a significant threat to the species.
Conclusion
Predation by introduced species is an ongoing threat to the Chatham petrel, which historically reduced the species' population numbers. Nest burrow competition between the Chatham petrel and the more abundant broadbilled prion is a current, ongoing threat to the Chatham petrel that is of high magnitude that has not been controlled by human intervention. The broadbilled prion occupies Chatham petrel burrows, actively evicting or lethally attacking eggs, nestlings, and occasionally adults of the Chatham petrel, and as a result is reducing the Chatham petrel's population which is already very small, estimated at 8001000 individuals. Although the NZDOC has been actively working to protect Chatham petrel nest sites from the broadbilled prion, only a small proportion of Chatham petrel breeding burrows have been located and protected (Taylor 1999, as cited in BirdLife International 2000). This threat is magnified by the fact that the impacted area is the Chatham petrel's primary breeding location, and the breeding area is extremely small, less than 1 mi\2\ in size. The only other location where the species has been documented to breed is the 40 ha (98.8 acre) enclosed area on Pitt Island where Chatham Petrels were reintroduced. It is currently uncertain whether the species will maintain this portion of its range as a breeding area; as of 2006, only one pair breeding in this area had successfully reared a chick.
Once a population is reduced below a certain number of individuals, it tends to rapidly decline towards extinction (Franklin 1980; Gilpin and Soule 1986; Soule 1987). The Chatham petrel's small population, combined with its restricted breeding range and colonial nesting habits makes the species particularly vulnerable to the threat of random, naturally occurring events. These catastrophic events, such as cyclones and fire, are known to occur in New Zealand and have the potential to destroy breeding individuals and their breeding habitat.
The threats within the species' breeding range are compounded by
the threat posed by longline fishing in the species' nonbreeding
range. Although New Zealand implements measures to protect other
seabird species from this threat under the Agreement on the
Conservation of Albatrosses and Petrels, the Chatham petrel is not
currently offered protection by this Agreement. We are unaware of any
documentation on the level of Chatham petrel mortality caused by long
line fisheries; however, the number of seabirds killed in longline
fishery operations continues to increase, and the longline fishery,
especially operations by unlicensed ``pirate'' vessels, is the single
greatest threat to all seabirds (AAD 2007; BirdLife International News
2003). Therefore, the magnitude of this threat to the species in its
nonbreeding range is significant. Because the survival of this species
is dependent on recruitment of chicks from its breeding range, the
severity of threats to the Chatham petrel within its breeding range
puts the species in danger of extinction throughout its range.
Therefore, we find the Chatham petrel to be in danger of extinction
throughout all of its range. Because we find that the Chatham petrel is
endangered throughout all of its range, there is no reason to consider its status in a significant portion of its range.
Fiji petrel (Pterodroma macgillivrayi)
A. The Present or Threatened Destruction, Modification, or Curtailment of the Habitat or Range
Although little is known about the Fiji petrel and its life history, based on general information common to all other Procellariid species, we know that the range of the Fiji petrel changes intra annually based on an established breeding cycle. During the breeding season, breeding birds return to breeding colonies to breed and nest. During the nonbreeding season, birds migrate far from their breeding range where they remain at sea until returning to breed. Therefore, our analysis of Factor A is separated into analyses of: (1) The species' breeding habitat and range, and (2) the species' nonbreeding habitat and range.
BirdLife International (2007c) estimates the range of the Fiji petrel to be 154,000 km2 (59,460 mi2); however, BirdLife International (2000) defines ``range'' as the ``Extent of Occurrence, the area contained within the shortest continuous imaginary boundary which can be drawn to encompass all the known, inferred, or projected sites of present occurrence of a species, excluding cases of vagrancy.'' Because this reported range includes a large area of non breeding habitat (i.e., the sea), our analysis of Factor A with respect to the Fiji petrel's breeding range focuses on the island where the species breeds.
Although the nesting area of this species has not been located (Priddel, et al. draft), the information available indicates that the species breeds on Gau Island, Fiji, where the few recorded sightings of this species on land have occurred (Priddel, et al. draft; RARE Conservation 2006a; Watling and Lewanavanua 1985). The species was originally known from just one specimen collected in 1855 on Gau Island. There were no additional confirmed sightings of the species until 1984 when an extensive, 16month search on Gau Island revealed one additional sighting. The researchers used spotlights and recorded collared petrel calls in an attempt to attract petrels to the highlands area where the researchers were searching. On the first night of spotlighting, a single Fiji petrel flew into the researchers' light. No additional birds were found on this search expedition (Watling 1986; Watling and Lewanavanua 1985). There have been an additional 16 reported sightings of this species on land, all on Gau Island, and ten additional sightings at sea, however, many of these reports have not been substantiated (Priddel, et al. draft). In 2007, Priddell, et al. (draft) summarized all these records, specifying which records were credible. The researchers determined that of the 17 recorded sightings on land between 1965 and 2007, 12 were highly credible based on researchers' identification of dead specimens, photographs of specimens, or live specimens. In addition to the sightings on land, there have been ten sightings at sea, all since 1960. However, none of these reports have been substantiated. Based on researcher observation or detailed descriptions, three of these reports are considered by Priddel, et al. (draft) to be credible.
We consider the evidence sufficient to conclude that the Fiji
petrel breeds on Gau Island because: (1) all 12 substantiated sightings
of the species on land have been on Gau Island; (2) Procellariids
return to land only for breeding purposes, and (3) the original specimen of this species collected in
[[Page 71303]]
1855 was determined to be an immature bird, based on its feathers and
skull morphology (Bourne 1981, as cited in Priddel, et al. draft; Imber
1985b; Priddel, et al. draft); so it is reasonable to believe that its nest was in the vicinity.
Based on the locations of Fiji petrel sightings on Gau Island, the species' breeding habitat is most likely to be undisturbed mature forest on rocky, mountainous ground within the island's cloud forest highlands (del Hoyo, et al. 1992; RARE Conservation 2006a). Based on the nesting habits of other colonial seabirds, it has been suggested that Fiji petrels nest in close proximity to collared petrels (Pterodroma leucoptera), which nest on the ground in this rugged terrain of interior Gau Island (Watling and Lewanavanua 1985).
In 1985, it was estimated that over 27 square miles (70 km\2\) of forest habitat up to 2,346 feet (715 meters) in elevation is potentially suitable for breeding and nesting of Fiji petrels on Gau Island (Watling and Lewanavanua 1985). Unlike the lowlands of Gau Island which have been cleared to a large extent for settlement, agriculture, and forest plantations, the upland interior forests where the species is believed to breed, has not been logged (Priddel, et al. draft; Veitayaki 2006). The only maintained inland trail leads to a telecommunication tower on a mountain peak just below Delaco. The 3,115 inhabitants of Gau Island live in coastal villages, where the majority live by subsistence fishing and farming, maintaining gardens up to 300 m in elevation. Although lowlevel forestry activities occur in lowland areas, no other intensive industry or agriculture is practiced on the island (Priddel, et al. draft). Veitayaki (2006) noted that the practice of shifting cultivation on Gau Island using improved machinery and the indiscriminant use of fire is rapidly progressing toward the cloud forests within the interior of the island. However, no information was provided to show this is actually occurring.
Veitayaki (2006), described a communitybased conservation project on Gau Island that has been in place since 2001, whereby villagers in the district of Vanuaso Tikina are collaborating with the University of the South Pacific to sustainably manage their environmental resources. Goals of the project include preservation of the upland cloud forest, adoption of sustainable land use practices, protection of drinking water, and development of alternative sources of livelihood. The success of this project has provided momentum beyond the Vanuaso Tikina district, as there is interest in incorporating the same sustainable use practices in the other villages on Gau Island (Veitayaki 2006).
In 2003, the World Resources Institute (WRI) reported that less than 1% (.88%) of Fiji's total land area is protected to such an extent that it is preserved in its natural condition (Earth Trends 2003a). Gau Island, however, is relatively pristine compared to most areas of Fiji due to the semisubsistence lifestyle (Veitayaki 2006). The Fiji people show great pride in the Fiji petrel, making it the emblem of the national airline (Air Fiji) and presenting it on the Fijian Fifty dollar banknote (Priddel, et al. draft). Legislation has been drafted to protect the Fiji petrel's habitat on Gau Island, once nesting colonies have been located (RARE Conservation 2006a) (see Factor D, below). Because Gau Island's upland forest habitat, where the species is most likely to breed, remains in a pristine condition and does not appear to be threatened with destruction or modification, we find that the present or threatened destruction, modification, or curtailment of this species' breeding habitat or range is not a threat to the species.
The Fiji petrel's range at sea is poorly known; the species has
been recorded once at sea near Gau Island and once at sea 200 km (124.3
mi) north of Gau Island (Watling 2000, as cited in BirdLife
International 2000; Watling and Lewanavanua 1985). We are unaware of
any present or threatened destruction, modification, or curtailment of this species' current sea habitat or range.
B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
We are unaware of any commercial, recreational, scientific, or educational purpose for which the Fiji petrel is currently being utilized.
C. Disease or Predation
The greatest threat to the longterm survival of the Fiji petrel is thought to be predation on breeding birds and their eggs and chicks by introduced predators such as rats and feral cats on Gau Island (BirdLife International 2000). Since nesting colonies of Fiji petrels have not been located, predation on the Fiji petrel has not been directly observed. However, cats and Pacific rats (R. exulans) have been found in the highland forests of Gau Island, where this species is most likely to breed (Imber 1986, as cited in Priddel, et al. draft; Watling and Lewanavanua 1985). The path to the telecommunications transmitter on the summit of Gau Island may have facilitated the movement of feral cats and Pacific and brown rats (R. norvegicus) into the Fiji petrel's breeding habitat (Watling 2000, as cited in BirdLife International 2000).
The remains of collared petrels have been found in feral cat scats and killings in the highland forests of Gau Island, where the Fiji petrel is also believed to breed. It is suggested that the collared petrel nests successfully despite this predation threat because its synchronized nesting during the first half of the year swamps cat predation. The collection of a firstflight young of the Fiji petrel on Gau Island in the month of October, however, indicates that this species has a more extended or later breeding season, putting this more sparsely populated species at greater risk of predation (Watling 1986). Cats and rats are known to have caused many local extirpations of other petrel species (Moors and Atkinson 1984, as cited in Priddel, et al. draft). According to Priddel, et al. (draft) there do not appear to be any inaccessible cliffs or mountainous ledges where Fiji petrels could nest out of the reach of cats or rats.
A feral pig (Sus scrofa) population has recently established in southern areas of Gau Island and is considered an emerging threat to the Fiji petrel (Priddel et al. draft). Feral pigs have caused the local extinction of other species of seabirds on numerous islands (Moors and Atkinson 1984, as cited in Priddel, et al. draft).
Protecting Fiji petrel nest sites from introduced predators by creating barriers around the nests is not possible at this time because the exact location of the nesting sites is unknown. There is no information indicating that predator eradication has been attempted on Gau Island. Even if a predator eradication program were to be implemented, protection of the nest sites would be difficult due to the permanent habitation of humans on the island. Even if cats were prohibited as pets, there is still a high potential for cats and rats to be transported to Gau Island in boats transporting humans or other shipments.
Because the threat of predation by introduced cats and rats has severely impacted closely related petrel species, and there are records of these introduced predators on Gau Island, especially feral cats and rats in the highland forests of Gau where the Fiji petrel is most likely to breed, we find that predation is a significant threat to the Fiji petrel.
We are unaware of any threats due to predation on Fiji petrels during the nonbreeding season while the species is at sea.
[[Page 71304]]
Although several diseases have been documented in other species of petrels (see Chatham petrel Factor C), disease has not been documented in the Fiji petrel. Therefore, the significance of this threat to the Fiji petrel is unknown.
D. The Inadequacy of Existing Regulatory Mechanisms
Although the Fiji petrel is protected from international trade under Fijian law (Government of Fiji 2002, 2003), this protection has not significantly reduced or removed the threat of predation within the species' breeding range, nor has it reduced the threat posed by long line fisheries (see Factor E below) within its range at sea.
Community awareness of the conservation significance of the Fiji petrel has been promoted in Fiji. From 20022004, Milika Rati, a local conservationist on Gau Island, led a ``Pride campaign'' (RARE Conservation 2006a), a constituencybuilding program developed by the conservation organization RARE (RARE Conservation 2006b). Ms. Rati chose the Fiji petrel as the flagship mascot for this movement and used a series of highprofile activities to raise awareness of the conservation urgency of the species. This campaign resulted in a confirmed sighting of a Fiji petrel (RARE Conservation 2006a). A followup survey to the campaign revealed that 99 percent of the participants believed natural resource protection to be important, and 94 percent were aware that the Fiji petrel is at risk of extinction.
Based on increased public awareness of the Pride campaign, a formal agreement supporting the creation of a bird sanctuary for the species was signed by all 16 of Fiji's village chiefs (RARE Conservation 2006a).
The Australian Regional National Heritage Programme continues to fund the Pride campaign on Gau Island. The Wildlife Conservation Society, BirdLife International, and the National Trust of the Fiji Islands are collaborating to work towards implementation of conservation recommendations made by Ms. Rati, including minimizing predators (RARE Conservation 2006a).
Although the Fiji petrel is protected from international trade
(Government of Fiji 2002, 2003) by Fijian law and public awareness and
support for the species' protection on Gau Island is strong, these
conservation measures have not significantly reduced the threats to the species.
E. Other Natural or Manmade Factors Affecting the Continued Existence of the Species
Because of the paucity of recorded sightings of this species (see discussion of Factor A above), the population is apparently very small. The IUCN estimates the population to be less than 50 individuals, with a decreasing trend due to predation by introduced predators (BirdLife International 2007c). Species with such small population sizes are at greater risk of extinction. Once a population is reduced below a certain number of individuals, it tends to rapidly decline towards extinction (Franklin 1980; Gilpin and Soule 1986; Soule 1987).
This species' risk of extinction is further compounded by its restricted current breeding range, which according to the best available information is limited to Gau Island, where an estimated 27 square miles (70 km\2\) of potential breeding habitat is available. However, based on what is known about the species, this is considered a relatively small amount of appropriate habitat for breeding, particularly since breeding pairs, eggs, and nestlings on Gau Island face the pervasive threat of predation by introduced species such as feral cats and rats.
The Fiji petrel's restricted breeding range combined with its colonial nesting habits and small population size of less than 50 birds (BirdLife International 2007c) makes the species particularly vulnerable to the threat of adverse random, naturally occurring events (e.g., cyclones, flooding, and landslides) that destroy breeding individuals and their breeding habitat. Fiji is vulnerable to the devastating affects of cyclones interannually between November and April. On average, 15 cyclones affect this country each decade (World Meteorological Organization 2004). The most severe cyclone in within the past 100 years was cyclone Kina in January, 1993, with wind speeds of 120 knots spanning an area 180 miles (289.7 km) from its center. The Government of Fiji declared the area a disaster, because virtually all areas of Fiji were impacted by this cyclone and the associated flooding (UN Department of Humanitarian Affairs 1993). Landslides are common in Fiji's mountainous areas during these severe weather conditions (World Meteorological Organization 2004), and would be particularly threatening to breeding Fiji petrels and their breeding habitat.
While species with more extensive breeding ranges or higher population numbers could recover from adverse random, naturally occurring events such as cyclones, the Fiji petrel does not have such resiliency. Its very small population size and restricted breeding range puts the species at higher risk for experiencing the irreversible adverse effects of random, naturally occurring events. One such event could destroy the entire known breeding population on Gau Island.
Therefore, we find that the combination of factorsthe species' small population size, restricted breeding range, and likelihood of adverse random, naturally occurring eventsto be a significant threat to the species.
Although we are unaware of any documented cases of incidental take of Fiji petrels by commercial longline fishing operations or entanglement in marine debris, these longline fishing operations have been identified as a threat to all seabird species (see analysis under Chatham petrel, Factor E). Moreover, the lack of data on these impacts to the Fiji petrel could be a result of the species' low population number. Therefore, we find the incidental take of Fiji petrels by commercial longline fishing operations to be a significant threat to the species.
Conclusion
The primary threat to the Fiji petrel is most likely predation by introduced feral cats and rats within the species' breeding range. The probability of introduced predators preying on this species is high given that introduced feral cats are documented to prey upon the closely related collared petrel in the interior forests of Gau Island where the Fiji petrel is most likely to nest. Furthermore, the devastating impact of predation by introduced species has been documented in several closelyrelated species. There is no information indicating that predator eradication has been attempted on Gau Island. This threat is magnified by the fact that the threat likely threatens the species throughout its breeding range, the interior forests of Gau Island. Although the Fiji petrel is legally protected from international trade, to our knowledge Fiji has not successfully implemented measures to protect the species from the threat of predation.
The Fiji petrel's low population size of less than 50 individuals
puts the species at a high risk of extinction. The low population size
combined with its restricted breeding and colonial nesting habits,
typical of all Procellariid species, makes the species particularly
vulnerable to the threat of random, naturally occurring events (e.g., cyclones) that are known to occur in Fiji
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and have the potential to destroy breeding individuals and their breeding habitat.
The threats within the species' breeding range are compounded by
the threat posed by longline fishing in the species' nonbreeding
range. There is no information indicating that Fiji has implemented
measures to protect the species from longline fishery activities.
However, because the survival of this species is dependent on
recruitment of chicks from its breeding range, the severity of threats
to the Fiji petrel within its breeding range puts the species in danger
of extinction throughout all of its range. Therefore, we find the Fiji
petrel to be in danger of extinction throughout all of its range.
Because we find that the Fiji petrel is endangered throughout all of
its range, there is no reason to consider its status in a significant portion of its range.
Magenta petrel (Pterodroma magentae)
A. The Present or Threatened Destruction, Modification, or Curtailment of the Habitat or Range of the Magenta Petrel
The range of this species changes intraannually based on an established breeding cycle. During the breeding season (September to May) (Imber, et al. 1994b; Taylor 1991), breeding birds return to breeding colonies to breed and nest. During the nonbreeding season, birds migrate far from their breeding range where they remain at sea until returning to breed. Therefore, our analysis of Factor A is separated into analyses of: (1) The species' breeding habitat and range, and (2) the species' nonbreeding habitat and range.
BirdLife International (2007d) estimates the range of the magenta petrel to be 1,960,000 km\2\ (7,568,000 mi\2\); however, BirdLife International (2000) defines ``range'' as the ``Extent of Occurrence, the area contained within the shortest continuous imaginary boundary which can be drawn to encompass all the known, inferred, or projected sites of present occurrence of a species, excluding cases of vagrancy.'' Because this reported range includes a large area of non breeding habitat (i.e., the sea), our analysis of Factor A with respect to the magenta petrel's breeding range focuses on the islands where the species is known to breed.
The magenta petrel breeds exclusively on Chatham Island, New Zealand, within relatively undisturbed inland forests (Crockett 1994; Imber, et al. 1994a). At least 23 breeding burrows have been discovered, all located near the TukuaTamatea River (BirdLife International 2007d; Brooke 2004, Hilhorst 2000, Taylor 2005, as cited in BirdLife International 2007d). Although some breeding burrows are on private land (Taylor 2000), the majority of known breeding burrows are located within the Tuku Nature Reserve (Reserve) (Chatham Island Taiko Trust 2007). This Reserve was established in 1984 to protect 5 square miles (12 km\2\) of magenta petrel breeding habitat. In 1993, 1 square mile (2 km\2\) of contiguous forested land was added to the Reserve by covenant, and a second covenant expected to be approved in the near future will protect an additional 4 square miles (11 km\2\) of contiguous habitat to the Reserve (Chatham Island Taiko Trust 2007).
As a result of New Zealand's Biodiversity Strategy, initiated in the year 2000, all logging of indigenous forests on government land has been halted, and logging on private land is required to be sustainable (Green and Clarkson 2005). Breeding burrows have been found on private land (Taylor 2000), and sustainable logging practices would not necessarily protect these magenta petrel nest sites. The significant loss of magenta petrel burrows and colonies historically due to the alteration of habitat on Chatham Island for livestock grazing purposes (Crockett 1994) demonstrates the severe impacts that habitat alteration has on magenta petrel populations. Besides logging, fire is a threat to the magenta petrel's breeding habitat. Although the species' recovery plan identifies accidental fire as a threat to the magenta petrel, it does not address mitigation of this threat (NZDOC 2001a). The NZDOC deals with an average of 160 fires in New Zealand each year, suggesting that fires are relatively common in New Zealand (NZDOC n.d.). Taylor (2000) identifies flooding of burrows as a threat, given that most known burrows are in wet areas in valley floors. He also notes that destruction of nestsites by pigs and dogs accompanying pighunters near the burrows threatens the magenta petrel's breeding habitat. These threats to the magenta petrel's breeding habitat are magnified by the species' restricted habitat area on Chatham Island. Because of the very small number of breeding pairs, any loss of breeders from the population would increase the species' threat of extinction. Therefore, we find that the present and threatened destruction of the habitat of this species to be a significant threat to the species.
The magenta petrel's range at sea is poorly known; however,
research has documented foraging behavior south and east of the Chatham
Islands (Imber, et al. 1994a). In addition, because the original
specimen of this species was shot at sea eastwards in the temperate
South Pacific Ocean, it is believed birds disperse there during the
nonbreeding season. We are unaware of any present or threatened
destruction, modification, or curtailment of this species' current sea habitat or range.
B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
We are unaware of any commercial, recreational, scientific, or educational purpose for which the magenta petrel is currently being utilized.
C. Disease or Predation
The available information suggests that the most serious threat to the magenta petrel is predation on all life stages (eggs, chicks, and adults) of the species by introduced predators, including feral cats, pigs, weka, and rats. It is reported that periodically the species' entire annual breeding production is lost due to predation of eggs and chicks (BirdLife International 2007d). Permanent eradication of these introduced predators from Chatham Island is difficult due to the permanent habitation of humans on the island. Since the early 1990's, however, the NZDOC has monitored known breeding burrows and has implemented an intensive predator control program, including setting extensive trap lines and poisoning to remove introduced predators from the magenta petrel's breeding areas (Taylor 2000). This effort has significantly reduced the threat of predation on adult petrels, with only two being found dead in 20 years, as of the year 2000. However, a number of chicks are still lost in some seasons (Imber, et al. 1998). As additional burrows have been located and protection from predation expanded over the years, breeding has increased and breeding success has improved. In 1994, only four breeding pairs were known, but in 2004, 15 breeding pairs were observed (Brooke 2004, Hilhorst 2000, Taylor 2005, as cited in BirdLife International 2007d). Sixteen chicks were known to have fledged from 19872000 (Taylor 2000), and within a single year, 2002, a total of seven chicks fledged (BirdLife International 2007d). Eight birds fledged in the 2005 season, and a record 11 magenta petrel chicks fledged in the 2006 season (Chatham Island Taiko Trust 2006).
Even though the predator control program has decreased the threat
of predation to the magenta petrel, birds, especially chicks, are still
killed by introduced predators, and only areas where petrels are known to breed are
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protected. Therefore, we find predation by introduced species to be a significant threat to the species.
We are unaware of any threats due to predation on magenta petrels during the nonbreeding season while the species is at sea.
Although several diseases have been documented in other species of petrels (see Chatham petrel Factor C), disease has not been documented in the magenta petrel. Therefore, the significance of this threat to this species is unknown.
D. The Inadequacy of Existing Regulatory Mechanisms
The magenta petrel is protected from disturbance and harvest under New Zealand's Wildlife Act of 1953 and its Reserves Act of 1977. The petrel is designated as a Category A species by the NZDOC, which signifies the species is of the highest priority for conservation management (Molloy and Davis 1999). As such, the NZDOC developed a ten year recovery plan for the magenta petrel in 2001, with the goals of preventing further loss of known breeding pairs, maximizing productivity at known breeding burrows, locating and protecting additional burrows, and establishing an additional predatorproof breeding area in southern Chatham Island (NZDOC 2001a). A measure of success of the recovery plan has been demonstrated by the successful protection of breeding pairs and increased productivity resulting from predator control efforts (see Factor C above). However, the threat of predation on magenta petrels by introduced species remains the greatest threat to the species. In 2006, a second protected area was established near the southern coast of Chatham Island at a location where magenta petrels were known to have bred in reasonable numbers 90 years ago. This 7.5ha area, protected by landowner covenant, has been fenced to exclude livestock in an effort to allow the forest to recover. Within this area, 3 ha are enclosed by a predatorproof fence. Loudspeakers were placed on the site, and prerecorded magenta petrel calls are being played to attract young males to the ground where it is hoped they will begin to dig burrows and eventually find a mate to breed. It is too early to know the success of this effort because it is anticipated that it will take several years for breeding to begin once young males start digging burrows. Captive rearing studies of the closely related greyfaced petrel (P. macroptera) have been undertaken, and its diet analyzed, to develop methods for captive rearing of magenta petrels in captivity should it ever be necessary to `rescue' abandoned or malnourished magenta petrel chicks (NZDOC 2001a; Taylor 2000).
New Zealand ratified the Agreement on the Conservation of Albatrosses and Petrels in November 2001, which is designed to reduce impacts of fishing operations on populations of Procellariids (ACAP 2001), however the magenta petrel is not listed in Annex 1 to this Agreement and, therefore, is not protected under this Agreement. Therefore, implementation of this Agreement has not significantly reduced or removed the threat of incidental take of this species in longline fisheries (see Factor E below).
Therefore, we find that regulatory protections have not significantly reduced the threats to the magenta petrel.
E. Other Natural or Manmade Factors Affecting the Continued Existence of the Species
The magenta petrel population is extremely small, estimated at 120 individuals based on population surveys (Brooke 2004, Hilhorst 2000, Taylor 2005, as cited in BirdLife International 2007d) and is believed to be decreasing due to predation by introduced species (BirdLife International 2007d). The fact that it took 10 years of intensive searching to rediscover the species in 1978 is an indication of the rarity of the species. Species with such small population sizes are at greater risk of extinction. Once a population is reduced below a certain number of individuals, it tends to rapidly decline towards extinction (Franklin 1980; Gilpin and Soule 1986; Soule 1987).
This species' risk of extinction is compounded by its restricted breeding range, which is limited to Chatham Island. Based on what is known about the species, the breeding habitat available on Chatham Island is a relatively small amount of appropriate habitat for breeding, particularly since breeding pairs, eggs, and nestlings on Chatham Island continue to be threatened by introduced species such as feral cats and rats.
The magenta petrel's restricted breeding range combined with its colonial nesting habits and small population size of less than approximately 120 birds makes the species particularly vulnerable to the threat of adverse random, naturally occurring events (e.g., storms, fire) that destroy breeding individuals and their breeding habitat (NCDOC 2001b). Fire is a high risk in the Chatham Islands because the climate is very dry during the summer, and the vegetation becomes tinder dry. Burrownesting species such as the magenta petrel are at a high risk because they are likely to suffocate from smoke inhalation or to be lethally burned inside or while attempting to escape from their burrows (Taylor 2000).
Another natural disaster, severe storms, has impacted New Zealand historically (see Chatham petrel discussion of Factor E), and so the likelihood of future impacts of storms is high. Although we are unaware of the impact of previous cyclones on the magenta petrel's population numbers or breeding habitat, the severity of the wind or waves created by such storms or flooding associated with storms has potential to significantly damage magenta petrel burrows. These known burrows are particularly vulnerable to flooding because they are located on valley floors (NZDOC 2001a).
While species with more extensive breeding ranges or higher population numbers could recover from adverse random, naturally occurring events such as fire or storms, the magenta petrel does not have such resiliency. Its very small population size and restricted breeding range puts the species at higher risk for experiencing the irreversible adverse effects of random, naturally occurring events. One such event could destroy the entire known breeding population on Chatham Island. Therefore, we find that the combination of factorsthe species' small population size, restricted breeding range, and likelihood of adverse random, naturally occurring eventsto be a significant threat to the species.
Although we are unaware of any documented cases of incidental take of magenta petrels by commercial longline fishing operations or entanglement in marine debris, these longline fishing operations have been identified as a threat to all seabird species (see analysis under Chatham petrel, Factor E). Moreover, the lack of data on these impacts to the magenta petrel could be a result of the species' low population number. Therefore, we find the incidental take of magenta petrels by commercial longline fishing operations to be a significant threat to the species.
Conclusion
Predation by introduced species such as rats, weka, and feral cats
and pigs is a current, ongoing threat to the magenta petrel that is of
high magnitude that has not been controlled by human intervention.
These introduced predators are known to destroy magenta petrel eggs,
chicks, and adults, reducing the species' population (NZDOC 2001a), which is already very small, estimated
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at 120 individuals. Although the NZDOC has been actively working to
protect magenta petrel nest sites from predation by introduced species,
a number of chicks are still lost in some seasons (Imber, et al. 1998),
and the breeding burrows that have not yet been located are not
protected. This threat is magnified by the fact that a limited amount
of breeding habitat is protected from habitat alteration or
destruction. The breeding habitat that is protected remains at risk from accidental fires and flooding.
The magenta petrel's low population size of approximately 120 individuals puts the species at a high risk of extinction. The low population size combined with its restricted breeding habitat and colonial nesting habits makes the species particularly vulnerable to the threat of random, naturally occurring events (e.g., cyclones, fire) that are known to occur in New Zealand and have the potential to destroy breeding individuals and their breeding habitat. One such event, such as a cyclone during the nesting season could destroy the entire breeding population on Chatham Island.
The threats within the species' breeding range are compounded by the threat posed by longline fishing in the species' nonbreeding range. Although New Zealand implements measures to protect other seabird species from this threat under the Agreement on the Conservation of Albatrosses and Petrels, the magenta
FOR FURTHER INFORMATION CONTACT
Mary M. Cogliano, PhD, Division of Scientific Authority, U.S. Fish and Wildlife Service, 4401 N. Fairfax Drive, Room 110, Arlington, VA 22203; telephone 7033581708; fax, 703 3582276; or email, ScientificAuthority@fws.gov.