Conservation of the fairy tern (Sternula nereis spp.) via subspecies level management
Marleen Baling How does one manage a species of concern when their distribution crosses geographic and political boundaries (i.e. countries)? The laws and legisla- tions of each country govern different levels of national management priori- Pacific Invasives Initiative ties, therefore resulting in unequal outcomes regarding the status of species’ (IUCN Invasive Species Spe- cialist Group), The Univer- conservation efforts. In most cases the general strategy, especially for widely sity of Auckland, Private Bag distributed species, focuses on management at a population level. This is par- 92019, Auckland, New Zea- ticularly true for species comprised of several subspecies distributed between land different countries. The fairy tern (Sternula neries) is an example of a wide geographically [email protected] ranging species, and it is distributed between Australia, New Zealand, and New Caledonia (Figure 1). The species’ phenotypic differences as well as ge- netic and geographical distances between three regions have resulted in the classification of three subspecies (Hitchcock 1959; Hitchcock 1967; Higgins and Davis 1996; Chambers and Coddington 1998; Baling and Brunton 2005). The fairy tern has just recently been uplisted to ‘Vulnerable C1’ (from ‘Least Concern’) under the IUCN Red List (Birdlife International 2008), however the population status of each subspecies differs due to variations in their lo- cal abundance (Table 1). Therefore, the priority status of this species varies across the countries where it occurs. The New Zealand (NZ) fairy tern (S. n. daviase) has the smallest popula-
Figure 1: Distribution of the fairy tern species (in grey) in the world. (Map modi- fied from Higgins & Da- vis 1996 p. 726).
86 Endangered Species UPDATE Vol. 25 No. 3 2008 Australian fairy tern New Caledonia fairy New Zealand fairy S. n. neresis tern tern S. n. exsul S. n. davisae
1 National Status Least Concern Threatened Acutely Threatened - Table 1: Nationally Critical Subspecific compari- Breeding pairs 2,000-3,000 c. 100 c. 10 son of the biology, Breeding adult mor- Posterior loral patches; Larger posterior loral Adults have largest ecology and manage- phology2 yellow beak sometimes patches than nominate posterior loral patches with black tip. subspecies but smaller (round to square); ment of the fairy tern than S. n. davisae; larg- black cap extends (Sternula nereis spp.). er black on tip of bill from lower hind- than nominate; short- neck to cap; whole est wing length. bill yellow; longest wing length; darker dorsally. Distribution3 Western Australia, and Islands or islets around North Island, only south-east Australia Grande Terre, Loyalty four known breeding (South Australia, Vic- Islands, and other is- sites (Waipu, Man- toria, Tasmania and lands in the Pacific gawhai, Papakanui, New South Wales). Ocean. Possible popu- and Pakiri). lation at Herald Island, Great Barrier Reef. Migratory behaviour4 Sedentary in Victoria Migratory between Within New Zealand and South Austra- islands in the Pacific, lia, Migratory within and possibly north- Western Australia and eastern part of Austra- Tasmania. lian Territory. Breeding season5 September to March June to October October to February Nesting behaviour6 Colonies between sev- Colonies of several No obvious ‘colonies,’ eral to hundreds of pairs, on dead coral nests are between 8 pairs. Nesting area banks or islands. Ag- m to several kilome- from sand to rocky gressive behaviour tres. Nesting area in substrate, both on the observed in pairs iwth sandspits. Aggression mainland and islands. chicks. Flushing be- (‘territorial’) behav- Aggressive behaviour haviour seen in the iour observed towards seen in smaller colo- rest of the colonies conspecifics and others nies; flushing behav- with eggs. in the vicinity. iour observed in larger colonies; aggression seen at aerial preda- tors. Aggression seen toward mixed pairs (little and fairy terns). Recovery plan? No No Yes Threats7 Human disturbance Human disturbance Human disturbance (including industrial (especially recreation- (especially urban de- pollution), mammalian al activities), mammal velopment), mamma- and avian predators, and avian predators, lian and avian preda- interbreeding with weather. tors, weather. little tern (Sternula albi- frons sinensis).8
Vol. 25 No. 3 2008 Endangered Species UPDATE 87 Conservation manage- No direct management No active manage- Colour banding ment9 (benefits via little tern ment. No banding scheme, nest areas and conservation manage- scheme. Status and nesting pair protec- ment), metal banded conservation efforts tion from human ac- according to general initiated by Soci- cess, pest and weather. shore-and seabird ete Caledonienne Flock counts and dis- banding scheme. d’Ornithologie. A ro- tribution by New Zea- dent eradication proj- land Department of ect on several islands Conservation and pub- in the New Caledonia lic volunteers for long- territory is underway, term database collec- and will also benefit tion. Public education the fairy tern. and participation. NZ Fairy Tern Charitable Trust formed in 2008.
1Garnett and Crowley 2000a; Hitchmoughet al. 2007. 2Hitchcock 1959; Higgins and Davis 1996. 3Napier 1972; Rancurel 1976; de Naurois and Rancurel 1978; Lane 1981; Willig 1982; Roun- sevell 1983; Higgins and Davis 1996; Burbidge and Fuller 2000; Garnett, and Crowley 2000c; Tarburton 2001; Benoit and Bretagnolle 2002; Baling et al. 2008; Birdlife Interna- tional 2008. 4Storr 1960; Hill et al. 1988; Parrish and Pulham 1995b; Carter and Mustoe 2007. 5Parrish and Pulham 1995b; Paton and Paltridge 2001; Baling et al. 2009. 6Lane 1984; Hill et al. 1988. Parrish and Pulham 1995a; Baling et al. 2009; pers. obs. 7Lane 1981; Hill et al. 1988. 8Cox, and Close 1977; Benoit and Bretagnolle 2002; Taylor et al. 2004. 9NSW National Parks and Wildlife Service 2003; Ferreira et al. 2005; Cranwell 2009. tion size in the species (c. 10 breeding nesting areas (Higgins and Davis 1996) pairs), with their lowest record of c. 3 are absent of the nominate subspecies. breeding pairs in 1983. This popula- For example, my 2004 survey for nest- tion is regarded as one of the rarest and ing Australian fairy terns (S. n. nereis) in most threatened bird populations in the the state of Victoria, resulted in the lo- country (Hitchmough et al. 2007). The cation of only two nesting colonies out other small population, the New Cale- of 12 previously recorded areas, listed donian (NC) fairy tern (S. n. exsul) has by Higgins & Davis (1996). In addi- a slightly higher number of estimated tion, the absence of nesting colonies in breeding pairs than NZ (c. 100, (Wet- a well-known breeding area in NC be- lands International 2002)), and is also tween 1991 and 1996, followed by their considered to be nationally threatened. appearance again in 1997 until pres- Despite the low densities of fairy terns ent, may indicate extreme fluctuations in these areas, the overall species status in population numbers (Benoit and on the IUCN Red List is less severe than Bretagnolle 2002; Baling and Brunton expected due to the overwhelming c. 2008). The current population size and 2,000 – 3,000 breeding pairs in Australia status of this subspecies is being re-as- (Birdlife International 2000; Wetlands sessed (N. Barré, unpub. data). The NZ International 2002), which have a na- fairy tern population size has varied be- tional listing of ‘Least Concern’ (Garnett tween 20 - 40 individuals over the last and Crowley 2000a). 15 years (Ferreira et al. 2005; Hansen However, the overall population 2006). These current information justi- trend, including Australia, is seen to be fies the uplisting of the fairy tern in the decreasing (Birdlife International 2008), IUCN Red List, however also highlights and many of the previously recorded the issue of why these populations are
88 Endangered Species UPDATE Vol. 25 No. 3 2008 decreasing or in constantly in low den- vegetation to nesting areas have also sities. benefited other shorebird and seabird All subspecies are threatened at the species nesting in the same area, includ- breeding stage, where increasing hu- ing the fairy tern (Vincent 1983; NSW man disturbance (direct and indirect), National Parks and Wildlife Service mammalian and avian predators, and 2003). unpredictable weather events are iden- The priority for conservation of tified as key factors affecting breed- NC fairy tern has been expressed in ing success (Hill et al. 1988; Benoit and previous surveys showing low local Bretagnolle 2002; Hansen 2006; Baling population abundance, and increasing et al. 2009). It is unfortunate that breed- threats to breeding colonies (Benoit and ing areas selected by fairy terns are also Bretagnolle 2002; Spaggiari et al. 2007a; preferred sites for urban development Baling et al. 2009). However a govern- and human recreational activities. These mental-based management plan for this activities also indirectly introduce po- species has yet to be established. The re- tential predators, such as domestic pets cent publication of Important Bird Ar- (e.g dogs and cats). Other introduced eas (IBA) for New Caledonia (Spaggiari mammalian pests (e.g. hedgehogs, Eri- et al. 2007b) has identified several areas naceus europaeus, in NZ; or foxes, Vulpes that are significant for colonial seabirds, vulpes, in Australia) and birds (e.g. sil- which includes breeding populations of ver gull, Larus novaehollandiae, and kelp bobbies, frigatebirds, tropicbirds, and gull, L. dominicanus) are also threats to terns. The recognition of these areas eggs and chicks (Hulsman 1977; Secomb was considered an initial but important 1994; Rose 2001); pers. obs). Large storm step for applying conservation actions events are unavoidable threats for these in the field and acquiring community low-lying nest areas where eggs or support for New Caledonian birds chicks are exposed to strong winds and (Spaggiari 2007). Two of these identi- high tides. fied ‘important areas’ are known fairy So how do conservation efforts for tern breeding sites, therefore any con- each subspecies differ between coun- servation efforts directed at those sites tries? There is little species manage- will be beneficial to the species. ment in Australia and NC. In Australia, A rodent eradication project started the majority of the efforts have been in 2003 on several important breeding indirectly influenced by management seabird islands located north-west of of eastern little ternS. ( albifrons sinen- NC (Cranwell 2009), will also assist in sis), a sympatric species breeding in securing the breeding success of the the south-eastern region of the country fairy terns. This rodent eradication (Vincent 1983; Hill et al. 1988). The little project, led by the Société Calédonienne tern is listed as ‘Endangered’ in two states d’Ornithologie (SCO) and BirdLife In- (Queensland and New South Wales), ternational (supported by the Packard ‘Threatened’ in Victoria, and ‘Vulnerable’ Foundation), aims to protect and re- in South Australia (Garnett and Crow- store selected islands of ecological sig- ley 2000b; NSW National Parks and nificance to seabirds. This ongoing proj- Wildlife Service 2003; Department of ect included several stages of process: Environment Water Heritage and the ecological island surveys and selection; Arts 2007). Protection of the little terns’ eradication planning, training and ap- nesting habitat by fencing off nesting plication; and finally monitoring for full colonies from public access, predator- eradication confirmation. control, and removal of encroaching Between the three countries, only
Vol. 25 No. 3 2008 Endangered Species UPDATE 89 and Brunton 2001; Ferreira et al. 2005; Pred- New Zealand fairy dey 2008). This tern. Photo credit: information has Sioux Plowman. been used to re- view the prog- ress of current m a n a g e m e n t and guide fu- ture manage- ment decisions (Taylor et al. 2004). Despite in- tensive manage- ment assisted in fledgling suc- cess, two sig- nificant issues were identified; overall hatch- ing rate (38%) and breeding attempts by New Zealand has produced a recovery adults (43%) were plan for the fairy tern (Parrish and Hon- still low (Ferreira et al. 2005). The hatch- nor 1997; Hansen 2006), with goals to ing rate in NZ is similar to the rates for increase population size by active man- fairy terns (34%) at unmanaged sites in agement, public relations, and research. New Caledonia (Baling et al. 2009). This Since 1983, the population has under- suggests that influences other than ex- gone colour banding for identification, ternal factors (e.g. human, predator and DNA-sexing, nest and nesting pair pro- weather disturbance) may be affecting tection, predator-control, and database the low hatching rates. Hatching rate collection via flock-counting and other is generally considered as a measure of sightings (Taylor et al. 2004). Addition- reproductive fitness; when population ally, the NZ Fairy Tern Charitable Trust fitness decreases along with low abun- was formed in 2008 to encourage pub- dance, inbreeding depression is said lic participation in tern advocacy and to be occurring (Frankham et al. 2002; monitoring, alongside NZ Department Jamieson et al. 2006). High failures in of Conservation (DOC). Public aware- hatching rates have also been associated ness and support are very important for to high levels of severity in population minimising and preventing the grow- genetic bottleneck (Briskie and Mack- ing urban development around nesting intosh 2004). Therefore, the very low sites. Long-term monitoring and re- number of breeding pairs in 1983 (i.e. search revealed detailed life history, be- high genetic bottleneck) and the record- haviour, and distribution information ed infertility in several eggs (i.e. high on the NZ fairy tern (Parrish and Pul- hatching failure) may indicate inbreed- ham 1995b; Parrish and Pulham 1995a; ing depression within the NZ fairy tern Jeffries 2000; Treadgold 2000; Jeffries
90 Endangered Species UPDATE Vol. 25 No. 3 2008 population (Parrish and Honnor 1997; tially benefit by enforcing similar man- Ferreira et al. 2005). Although conserva- agement protocols as NZ. In particular, tion efforts have been primarily focused the implementation of colour-banding on minimising the ecological risks (e.g. schemes to accurately monitor local (or predator-control), issues regarding the potential international) movements and effects of inbreeding depression in the individual breeding stages (e.g. first or long-term should not be neglected; and second clutches), public access restric- consequently investigation of the popu- tions during breeding period, and pest- lation’s genetic structure is suggested to controls on targeted breeding areas. monitor this potential additional factor. These direct management efforts will be The low number of NZ fairy terns capable of reducing or even eliminating attempting to breed is also of concern, some of external factors that negatively despite increasing fledgling success influence the fairy tern’s breeding suc- rate in the 16 years of management. An cess. average of only 43% of all identified New Zealand’s fairy tern conserva- adults attempt to breed each season tion efforts are also highly dependent which raises concerns that limitations to on local community volunteer and sup- breeding site access and habitat quality port. The large number of hours spent may exist (Ferreira et al. 2005). The lack by many unpaid volunteers - reporting of recruitment in breeding adults is also sightings, behavioural observations, noted. This includes several occurrenc- and advocating for fairy tern conserva- es of NZ fairy tern fledglings or adults tion has provided valuable information disappearing from the known breeding for the DOC database. This may also be sites for several years, after which they considered for the NC fairy tern man- would appear again and breed success- agement plan: to invest in local educa- fully thereafter (Ferreira et al. 2005). It tion, promote interest, participation and is unknown where these individuals go adherence to island restrictions during during these periods, and the possibil- the seabird breeding season. The con- ity of movement or migration out of stant communication between research- the country is raised. However, due to ers, NGO’s, governmental departments, the lack of, or very little, banding and and the public will also provide long- monitoring schemes for fairy terns in term benefits for fairy tern conserva- NC and Australia, the probability of tion. detecting colour-banded NZ fairy terns Finally, the importance of communi- is very low. There is currently a call for cation and collaboration between coun- NZ public to record sightings of fairy tries will also be crucial for the species’ tern foraging to determine seasonal conservation as a whole. Greater sharing movement and foraging patterns. of information on sightings, breeding Can New Caledonia learn from the biology, and conservation techniques conservation efforts of New Zealand? should be encouraged between the The logistics of accurate estimation of three countries. Lessons learned from population abundance and trends is lim- one case, may prove to be invaluable to ited by frequency of access to some of the another similar management plan. more remote small coral islets, islands and atolls. This frequency is highly de- Acknowledgment pendent on weather, labour and finan- I would like to thank Gwenda Pulham for cial aspects (Cranwell 2009; pers. obs.). information on the New Zealand fairy terns, Dy- lan van Winkel, Luis Ortiz Catedral, and ESU Once their conservation status has been editorial staff for their input in the earlier drafts. reviewed and more funding approved, the NC fairy tern population may ini-
Vol. 25 No. 3 2008 Endangered Species UPDATE 91 References Baling, M. and Brunton, D. 2005. Conservation genetics of the New Zealand fairy tern. Unpublished report to the New Zealand Department of Conservation, Auckland. 32 pp. Baling, M.; Brunton, D.H. and Jeffries, D. 2008. Marine and coastal bird survey of islands in the Southern Lagoon, New Caledonia. Notornis 55: 111-113. Baling, M.; Jeffries, D.; Barré, N. and Brunton, D.H. 2009. A survey of fairy tern Sterna( nereis) breed- ing colonies in the Southern Lagoon, New Caledonia. Emu 109: 57-61. Benoit, M.P. and Bretagnolle, V. 2002. Seabirds of the Southern Lagoon of New Caledonia, distribu- tion, abundance and threats. Waterbirds 25 (2): 202-213. Birdlife International 2000. Threatened birds of the world. Barcelona and Cambridge, Lynx Edi- cions and Birdlife International. Birdlife International 2008 Sterna nereis. In: IUCN 2009. IUCN Red List of Threatened Species. Ver- sion 2009.1.
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