ArticlePDF Available

Deciding when to lend a helping hand: a decision-making framework for seabird island restoration


Abstract and Figures

Following the removal of an introduced species, island restoration can follow two general approaches: passive, where no further intervention occurs and the island is assumed to recover naturally, and; active, where recovery of key taxa (e.g. seabirds) is enhanced by manipulating movement and demography. Steps for deciding between these techniques are: (1) outlining an explicit restoration goal; (2) building a conceptual model of the system; (3) identifying the most effective management approach; and (4) implementing and monitoring outcomes. After decades of island restoration initiatives, retrospective analysis of species’ responses to active and passive management approaches is now feasible. We summarize the advantages of incorporating these analyses of past restoration results as an initial step in the decision-making process. We illustrate this process using lessons learned from the restoration of seabird-driven island ecosystems after introduced vertebrate eradication in New Zealand. Throughout seven decades of successful vertebrate eradication projects, the goals of island restoration have shifted from passive to active enhancement of island communities, which are heavily dependent on burrow-nesting petrel population recovery. Using a comparative analysis of petrel response to past predator eradications we built a conceptual model of petrel recovery dynamics and defined key site and species characteristics for use in a stepwise decision tree to select between active or passive seabird population management. Active restoration techniques should be implemented when seabird populations are absent or declining; and on islands with no nearby source colony, small remnant colonies, highly altered habitat with shallow soil and slopes, and with competitive species pairs. As we continue to restore complex island communities, decision-making tools using a logical, step-wise framework informed by previous restoration successes and failures can aid in increasing understanding of ecosystem response.
This content is subject to copyright. Terms and conditions apply.
Deciding when to lend a helping hand: a decision-making
framework for seabird island restoration
Rachel T. Buxton
Christopher J. Jones
Philip O’Brien Lyver
David R. Towns
Stephanie B. Borrelle
Received: 21 August 2015 / Revised: 22 February 2016 / Accepted: 3 March 2016 /
Published online: 10 March 2016
ÓSpringer Science+Business Media Dordrecht 2016
Abstract Following the removal of an introduced species, island restoration can follow
two general approaches: passive, where no further intervention occurs and the island is
assumed to recover naturally, and; active, where recovery of key taxa (e.g. seabirds) is
enhanced by manipulating movement and demography. Steps for deciding between these
techniques are: (1) outlining an explicit restoration goal; (2) building a conceptual model of
the system; (3) identifying the most effective management approach; and (4) implementing
and monitoring outcomes. After decades of island restoration initiatives, retrospective
analysis of species’ responses to active and passive management approaches is now fea-
sible. We summarize the advantages of incorporating these analyses of past restoration
results as an initial step in the decision-making process. We illustrate this process using
lessons learned from the restoration of seabird-driven island ecosystems after introduced
vertebrate eradication in New Zealand. Throughout seven decades of successful vertebrate
eradication projects, the goals of island restoration have shifted from passive to active
enhancement of island communities, which are heavily dependent on burrow-nesting petrel
Communicated by Stephen Garnett.
Electronic supplementary material The online version of this article (doi:10.1007/s10531-016-1079-9)
contains supplementary material, which is available to authorized users.
&Rachel T. Buxton
Department of Zoology and Centre for Sustainability: Agriculture, Food, Energy, and Environment,
University of Otago, PO Box 56, Dunedin 9054, New Zealand
Present Address: Department of Fish, Wildlife and Conservation Biology, Colorado State
University, 1474 Campus Delivery, Fort Collins, CO 80523, USA
Landcare Research, P.O. Box 69040, Gerald Street, Lincoln 7640, New Zealand
School of Applied Sciences, Institute for Applied Ecology, Auckland University of Technology,
Private Bag 92006, Auckland 1142, New Zealand
Department of Conservation, Private Bag 68908 Newton, Auckland 1145, New Zealand
Biodivers Conserv (2016) 25:467–484
DOI 10.1007/s10531-016-1079-9
population recovery. Using a comparative analysis of petrel response to past predator
eradications we built a conceptual model of petrel recovery dynamics and defined key site
and species characteristics for use in a stepwise decision tree to select between active or
passive seabird population management. Active restoration techniques should be imple-
mented when seabird populations are absent or declining; and on islands with no nearby
source colony, small remnant colonies, highly altered habitat with shallow soil and slopes,
and with competitive species pairs. As we continue to restore complex island communities,
decision-making tools using a logical, step-wise framework informed by previous
restoration successes and failures can aid in increasing understanding of ecosystem
Keywords Adaptive management Decision tree Burrowing seabirds Eradication
New Zealand Prioritization Recovery
Islands hold a disproportionately large percentage by area of global biodiversity and are
increasingly important repositories for populations or ecosystems eliminated from the
mainland (Daugherty et al. 1990; Mittermeier et al. 1998; Kier et al. 2009). Unfortunately,
island ecosystems are also more susceptible to disturbance and have experienced high
extinction rates—primarily due to the introduction of alien species (King 1985; Cour-
champ et al. 2003). Although advancements have been made in alien species eradications
and ecosystem restoration, islands’ remote locations and limited infrastructure make
conservation efforts expensive (Donlan 2007; Helmstedt et al. 2016). Priority setting and
decision-making tools are thus especially important in allocating limited resources while
maximizing successful outcomes of island restoration.
Islands are particularly important for seabirds, typically providing terrestrial predator-
free nesting habitat in proximity to pelagic feeding areas. Similarly, seabirds are partic-
ularly important members of island ecosystems, where their presence drives ecological
processes (Mulder et al. 2011a). On islands where seabirds nest (henceforth ‘‘seabird
islands’’), seabird guano enriches the soil with marine-derived nutrients and nest-building
disturbs vegetation and aerates the soil (Mulder et al. 2011b; Smith et al. 2011). Fur-
thermore, seabirds play a special cultural role on islands around the world, providing
people with food (Circumpolar Seabird Working Group 2001), income (Duffy 1994), and
cultural cohesion and identity (Lyver et al. 2008). Because most seabirds have nested for
millennia on islands free of mammalian predators, they lack behavioural and life-history
adaptations to avoid ground-based predation (Milberg and Tyrberg 1993). Thus, seabirds
are vulnerable to alien predators, leading to species extirpation or severe population
reduction on invaded islands (Towns et al. 2011). Seabird population declines have
transformed entire island socio-ecological systems and their recovery is often integral to
successful restoration (Croll et al. 2005; Fukami et al. 2006; Young 2014).
Predator eradication has become a prevalent seabird island restoration technique
worldwide, with over 900 islands cleared of predators as of 2011 (Keitt et al. 2011; DIISE
2015). Following eradication of alien predators, restoration efforts can follow two basic
approaches: passive, where no further intervention occurs and seabird populations and
islands are assumed to recover naturally, and; active, where recovery of seabirds is
468 Biodivers Conserv (2016) 25:467–484
enhanced by manipulating distribution and demography (Hobbs et al. 2011). Passive
management operates under the ‘Field of Dreams’ hypothesis, assuming that removing a
stressor is sufficient to restore habitat and thus the capacity of seabirds to recover (‘‘if you
build it, they will come’’; Palmer et al. 1997). It is generally cheaper than active man-
agement, but relies exclusively on the unpredictable capacity of populations and ecosys-
tems to recover on their own (Scott et al. 2001; Jones and Schmitz 2009). Passive seabird
population recovery is assumed to be slow because of k-selected life history characteristics,
seemingly high philopatry, and intermittent breeding (Kappes and Jones 2014). Active
management can help overcome impediments to population recovery, but often has high
logistical and financial demands and variable success rates (Holl and Aide 2011; Jones and
Kress 2012). Despite their logical interdependency, passive and active seabird island
restoration techniques have evolved largely independently, so that few guidelines are
available to help managers decide when to support passive recovery with active techniques.
Like most restoration endeavors, seabird island restoration is complex, operating within
a dynamic network of ecological, cultural, social, and economic ideologies. Thus, deciding
whether to employ active techniques would benefit from using a structured decision-
making framework (Noss et al. 2009). Structured decision-making frameworks organize
information, define objectives, and identify outcome alternatives and uncertainty, allowing
restoration options to be weighted objectively (Wyant et al. 1995). A typical decision-
making process involves: (1) outlining an explicit restoration goal; (2) building a con-
ceptual model of the system; (3) identifying the most effective management approach; and
(4) implementing and monitoring outcomes (Possingham et al. 2001). Seabird island
restoration is unique in that there is an abundance of pre-existing passive and active
restoration projects (Jones and Kress 2012; DIISE 2015). This represents an extraordinary
opportunity to incorporate large-scale retrospective analyses of restoration outcomes
directly into the decision-making framework. In this way, the amount of information about
the recovery process is maximized, allowing for a more complete conceptual model of the
system, and specific decision criteria to guide the prioritization of passive versus active
management approaches before a project is implemented.
The objective of this study was to summarize how retrospective analyses of existing
restoration data enhance a typical decision-making process, in particular for guiding when
to invest additional time and money into active management. To illustrate this approach in
a seabird island restoration context, we use the New Zealand archipelago as a case study.
We focus on New Zealand due to the prevalence of burrowing seabirds, seabird-driven
island systems, the country’s rich history of predator eradications and island restoration,
and the cultural significance of seabirds to Ma¯ori, New Zealand’s indigenous peoples
(Moller et al. 2000; Taylor 2000; Mulder et al. 2011a; Towns 2011; Buxton et al. 2014).
General decision-making framework
Decision-making frameworks are not new to prioritizing restoration interventions, but to
our knowledge, are rarely used in island restoration (Helmstedt et al. 2016). Moreover, the
formal use of previous restoration outcomes in decision frameworks when evaluating
active versus passive management options is rare, notably for animal communities (but see
Richardson et al. 2009 for decision-making framework for assisted colonization). We
outline how initial analyses of existing restoration project outcomes can make each step of
the decision-making process more efficient:
Biodivers Conserv (2016) 25:467–484 469
(1) Outline SMART project goals/objectives: Setting explicit goals and objectives is the
integral starting point of restoration planning. By defining ‘SMART’ (specific,
measurable, attainable, relevant, and time-bound) goals and assessing the likelihood
of achieving them at the outset of a restoration project, planning becomes efficient
and step-wise, and allows measurement of success and return on investment (Hobbs
et al. 2011). Assessing the effectiveness of previous restoration alternatives can help
refine more robust and widely-accepted current restoration objectives. For example,
by basing current objectives on past restoration efforts with high success rates,
restoration plans are more likely to be cost-effective and thus receive financial and
public support (Tunstall et al. 1999; Wilson and Bruskotter 2009; Kettenring and
Adams 2011);
(2) Generate a conceptual systems model: In a restoration context, conceptual models
outline a set of factors influencing the restoration target (i.e. population, community,
or ecosystem), providing a simple visual or mathematical means to examine how a
system may respond to management interventions (Heemskerk et al. 2003;
Margoluis et al. 2009). Studies of chronosequences or comparative analyses of
previous restoration outcomes can be used to gain insight into the mechanics of the
recovery process, namely the natural ability of species and ecosystems to recover
after passive restoration management;
(3) Project design– identify and prioritize management approaches: Restoration
management interventions range from removal of the primary stressor to construc-
tion of novel ecosystems (Hobbs and Cramer 2008). Passive management may
consist of little more than monitoring, as defined by the life histories of the system
components being monitored. Active management is becoming more common at
highly disturbed sites where the approach is feasible. Where more than one approach
is available, the choice of which management intervention should be used on each
species, site, or ecosystem requires a structured analysis of the probability of success
of each alternative approach (Tear et al. 2005). Attributes affecting the probability
of natural recovery can be identified and tested empirically to determine their
relative contribution to a restoration approach successfully achieving the desired
outcome (LoSchiavo et al. 2013). In many cases, collecting field data to model how
a system may respond to a management intervention is not possible, either because
the response to restoration is beyond the timescale of a current project or there are
few comparable reference sites. Thus, a retrospective study of the successes and
failures of similar projects, if available, can be a valuable source of information
from which a set of key management decision criteria can be identified;
(4) Implement project and monitor outcomes: Monitoring outcomes of a restoration
approach allows informed revision of project goals, conceptual models, and
prioritization of future activities (i.e. adaptive management; Westgate et al. 2013). A
project which is established as adaptive will be subject to fewer confounding factors
than one that uses retrospective analyses of restoration outcomes (Armstrong et al.
2007; Lindenmayer et al. 2011). However, given the time frames associated with
ecosystem recovery, adaptive management is likely to be less demonstrably
effective in the short-term, highlighting the value of examining data from previous
restoration projects (Lewis 2000; Jones and Schmitz 2009).
470 Biodivers Conserv (2016) 25:467–484
Applying the framework: New Zealand seabird island restoration
We illustrate a decision-making framework that incorporates retrospective analyses using
the restoration of seabird-dominated island ecosystems in New Zealand. With an abun-
dance of pre-existing restoration projects and a clear connection between seabird popu-
lations and island ecosystem functioning, a comparative analysis of seabird population
response to eradication around the New Zealand archipelago can provide information to
guide subsequent seabird island restoration management decisions.
New Zealand has over 700 islands larger than 1 ha and no native land mammals other
than two extant bat species (Parkes and Murphy 2003). Since human colonization, over
three-quarters of these islands have been modified substantially through burning, clearing,
and the introduction of alien vertebrate species (Parkes and Murphy 2003; Bellingham
et al. 2010). Seabirds were once abundant and widespread around New Zealand, which still
has the highest diversity of seabird species in the world (Taylor 2000). However, predator
introduction has resulted in the extinction, extirpation, or severe reduction of seabird
populations (Holdaway and Worthy 1994; Taylor 2000; Veitch et al. 2004). Marine
nutrient subsidies and in particular soil bioturbation by seabirds are central to island
ecosystem functioning, and the loss of seabird populations due to predation has trans-
formed ecosystem structure (Fig. 1; Mulder et al. 2011a; Orwin et al. 2015).
New Zealand is acknowledged internationally as a leader in island conservation and pest
eradication with over 100 islands around the archipelago cleared of all alien animals
(Towns et al. 2013). The country also has a long history of active restoration, including
nearly 260 species transfers since the 1960 s, 16 of which were seabird species (Craig et al.
2000; Miskelly and Powlesland 2013).
Because of the widely recognized damage caused by alien mammals in New Zealand,
the public is highly aware of conservation issues and community groups are increasingly
involved in eradication and restoration (Forgie et al. 2001). However, general under-
standing of the role and diversity of seabirds is low (Seabrook-Davidson and Brunton
2014). Moreover, increasing co-governance of natural resources by Ma¯ori in New Zealand
has led to greater consideration of their values, customary approaches, and practices within
island management systems (Newman and Moller 2005; Lyver et al. 2009; Lyver et al.
2015a). Some Ma¯ori tribes harvest the chicks of sooty shearwaters (Puffinus griseus)or
grey-faced petrels (Pterodroma gouldi), which are an important source of food, trade,
cultural identity, and social cohesion (Taiepa et al. 1997; Lyver et al. 2008; Moller 2009).
Historical relationships with the Pacific rat or kiore (Rattus exulans) add further com-
plexity to island restoration planning. Kiore were brought to New Zealand by Polynesians
c. 1280 (Wilmshurst et al. 2008), used by Ma¯ori as a food source, and feature prominently
in their traditions, proverbs, and prayer (Haami 1993). Evidence suggests that kiore sup-
press native flora and fauna and that their eradication results in recovery of threatened
species (e.g. Towns 2009). Yet for some Ma¯ori, the extinction of kiore would represent a
the loss of a cultural treasure (Chanwai and Richardson 1998).
New Zealand’s Department of Conservation (DOC) is charged with managing the
country’s biological and historic heritage. DOC’s mandates include active management
interventions, including restoration of island ecosystems; advocacy; and integrating the
rights of local Ma¯ori (Towns et al. 1990b). However, DOC has undergone repeated large-
scale restructures ever since its inception. The most recent, and most profound, was in
2011–2013, which included a structural model aimed at increased participation from
business, non-government agencies, and community groups (Bushnell and Pratt 2014). As
Biodivers Conserv (2016) 25:467–484 471
a result, DOC may delegate restoration projects to outside agencies more frequently than in
the past. Given the high cost of seabird island projects, this could have consequences for
the future financial security of island restoration.
Restoration goals
As the number of New Zealand islands from which alien predators have been eradicated
has increased, island restoration goal setting has evolved. To illustrate this shift, we col-
lated restoration goals from islands with predators eradicated around New Zealand from
1934 to 2011 (Table 1; Supplementary material S1). Using an updated list of predator
eradication projects (Buxton et al. 2014), we searched for goals in published literature,
restoration plans, threatened species plans, and eradication plans. The most common early
(prior to 2000) goals of eradication were to improve eradication techniques, protect key
species, or enable recovery of native species by removing predation pressure. Within the
past decade, goals such as working with Ma¯ori to promote and support cultural values and
aspirations (i.e. ‘bi-cultural management’ and ‘protect and conserve cultural aspects’;
Table 1), education and outreach, restoring ecosystem functioning, and creating self-
Fig. 1 Seabird island restoration in New Zealand to illustrate use of decision framework. The ecological,
social and cultural contexts of the proposed project are summarized at the outset, generating a long-term
SMART goal. A conceptual model of burrow-nesting seabird population recovery, constructed using models
of metapopulation dynamics and information on drivers of intrinsic population growth, guides key decision
criteria. To choose management approaches, these criteria predict whether natural recovery of burrow-
nesting seabirds is likely and, if not, which active management methods should be used. Alternative
approaches can then be compared for likely cost-effectiveness using a simple prioritisation metric. Both
short- and long-term outcomes should be monitored, using a robust sampling scheme to report progress and
to manage the project adaptively over time. (TEK =traditional ecological knowledge)
472 Biodivers Conserv (2016) 25:467–484
sustaining populations of rare plants and animals have become more prevalent. Generally,
we found few goals that conformed to SMART criteria.
In the earlier days of ecological restoration planning in New Zealand, goals were
dominated by a Eurocentric historical perspective, where the endpoint of a restoration
program was a biotic community that was assumed to represent the pre-human past
(Atkinson and Towns 1990; Towns et al. 1990b). However, palaeoecological investigations
indicate that, before human colonization, some offshore islands were dominated by
podocarp forests which have no modern analogue (Wilmshurst et al. 2014). This evidence,
and the cultural significance of islands for Ma¯ori, suggests that pre-human island
restoration targets may be neither feasible nor desirable (Bellingham et al. 2010; Lyver
et al. 2015b). Thus, contemporary post-eradication island restoration goals in New Zealand
include: maintaining ecosystem processes, preventing extinction, improving species and
functional diversity, forming partnerships with local Ma¯ori, preserving historic and cultural
Table 1 Summary of reported post-predator eradication goals of island restoration initiatives in New
Zealand in published literature and technical plans between 1936 and 2011. Among all years and islands
where the goal was reported, the ‘mean report date’ represents the average
Context Goal Total
Most recent
Mean report
Ecological None 10
Test eradication techniques 37 1978 2012 1994
Protect specific species 51 1970 2008 1995
Determine the impacts of predation 8 1979 2005 1996
Seabird recovery/restoration 21 1985 2014 1996
Reintroduce natural flora and fauna 44 1970 2014 1996
Restore communities 11 1990 2012 1997
Reintroduce functional groups 1 1999 1999 1999
Enable recovery by removing
predation pressure
63 1946 2014 2000
Research reintroductions 3 1996 2007 2000
Restore pre-human state 3 1999 2003 2000
Create a refuge for threatened
63 1970 2000
Reforestation 14 1982 2014 2003
Create self-sustaining population of
rare species
4 1999 2012 2007
Economic Ecotourism 6 1982 2012 2001
Restore ecosystem functioning 21 1990 2014 2003
Social Community participation 10 1990 2014 2001
Education outreach 29 1982 2013 2004
Bi-cultural management 22 1978 2013 2005
Reinstate sustainable cultural
harvest of seabirds
2 1998 2012 2005
Protect and conserve historic sites 22 1990 2014 2006
Protect and conserve cultural aspects 11 1978 2012 2009
Biodivers Conserv (2016) 25:467–484 473
values, and fostering community engagement, enjoyment, and recreational use (Table 1;
Lee et al. 2005; Department of Conservation 2010).
Although seabird population recovery is likely to be a significant component of
attaining these modern island restoration goals (Moller 2010; Mulder et al. 2011a), few
early restoration initiatives acknowledged its importance (Table 1). Appropriate baseline
data were therefore rarely collected to allow seabird recovery outcomes to be assessed.
Because seabirds, especially petrels and shearwaters, exert a large influence on island
ecosystems in New Zealand, we propose that seabird re-colonization and colony growth
may be beneficial SMART post-eradication outcomes for many offshore islands (e.g. see
Imber et al. 2003). A project may select a particular species, the recovery of which is
measurable within the respective species’ generation time (approximately 15 years for
petrels and shearwaters; IUCN 2012). Longer-term (e.g. [30 years) outcomes for seabird-
driven island restoration could include re-establishing island ecosystem functioning and
community structure, and, on some islands, the re-instatement of cultural harvest (Fig. 1).
Conceptual systems model for the restoration of NZ’s seabird islands
Assuming that the restoration goal of seabird recovery is selected, reliable prediction of the
response of seabird populations to management interventions at breeding sites requires a
basic understanding of local seabird population dynamics (Margoluis et al. 2009). In this
way, a conceptual model of seabird recovery can be constructed by identifying the drivers
of population growth (Buxton et al. 2014).
Generally, seabirds form metapopulations, with breeding sites separated by water
barriers and where local population growth rates are affected by both intrinsic and extrinsic
dynamics (McCullough 1996; Matthiopoulos et al. 2005). Intrinsically, seabirds have low
annual reproductive output, fecundity is low, and intermittent breeding is common,
resulting in low rates of per capita growth (Warham 1990; Cubaynes et al. 2011). Intrinsic
negative density-dependence may result from limitations in breeding sites and food
(Croxall and Rothery 1991; Sandvik et al. 2012), while positive density dependence may
be associated with coloniality (Kildaw et al. 2005). Moreover, despite being highly mobile,
behavioral mechanisms associated with coloniality (e.g. philopatry and social attraction)
mean that the number of immigrants recruiting from other colonies is thought to be low
(Hamer et al. 2002). Thus, population dynamics are likely to be slow and characterized by
traits that may not conform to metapopulation theory (Matthiopoulos et al. 2005). When
predators are removed from an island, local seabird population growth (i.e. passive
recovery) will depend on a number of factors; for example, the size of the remnant
population at the time of eradication, species-specific life history traits (such as age of first
reproduction), local habitat quality, and density-mediated immigration rates. However,
because of seabirds’ slow population growth, evaluating how these parameters drive
population recovery is problematic within the time constraints of a restoration project.
Towns (2002) and Towns et al. (2012) recommend long term environmental monitoring
of islands that escaped predator invasion to build conceptual models of recovery. In the
absence of robust long-term monitoring data, chronosquence analyses or ‘space-for-time
substitutions’ have been used to compare ecosystem function or population dynamics
among islands with different periods since pest eradication (Fukami et al. 2006; Jones
2010a; Jones 2010b). Although caution must be taken when examining successional
processes using chronosequences (Johnson and Miyanishi 2008), if results can be validated
from data using other methods (e.g. monitoring before and after eradication), they could
represent a useful proxy for temporal recovery dynamics (Towns 2009). Given the
474 Biodivers Conserv (2016) 25:467–484
abundance of eradication projects around New Zealand, chronosequences have been useful
in identifying factors driving post-eradication seabird response (Buxton et al. 2014).
Generally, we have a poor understanding of how seabirds and ecosystems respond to
introduced predator eradication and active restoration (Mulder et al. 2009). In the past,
threatened species conservation has assumed greater urgency than consideration of the
impact of such species on the island’s existing biota. For example, the reintroduction of
natural seabird predators (e.g. tuatara Sphenodon sp.) at too early a stage in recovery may
result in reduced probability of the re-establishment of small seabird species (Atkinson and
Towns 1990; Towns et al. 1990a). Moreover, if seabird predators are introduced before the
recovery of their seabird prey, this may result in lower probability of establishing the
predator itself.
Management techniques
The most widespread and effective passive seabird island restoration technique in New
Zealand is the eradication of alien predators (Towns and Broome 2003; Clout and Russell
2006; Broome 2009). In some cases, abundant native avian predators may also prey on
breeding seabirds, and populations must be controlled to reduce their impact on threatened
seabirds (Miskelly 2013). The temporary cessation, ra
¯hui, of traditional harvest from
seabird islands where Ma¯ori are owners or have customary rights may also be employed to
assist population maintenance or recovery (Moller 2006; Kitson and Moller 2008; Lyver
et al. 2015a).
After eradication, a number of active techniques can be used to restore habitat and
encourage seabird population recovery. Both exotic weed control and revegetation of
indigenous plant communities can facilitate seabird recovery actively through habitat
enhancement (Towns et al. 1997; Forbes and Craig 2013). Chick translocation to a
restoration site, before the age where they imprint to their natal site, has been successful for
a number of seabird species (Jones and Kress 2012). However, because of the high cost and
labor requirements of transportation and feeding, plus an average lag time of five years
until birds return to a restoration site to breed, translocation is expensive and outcomes are
difficult to predict (Miskelly et al. 2009). Social attraction (e.g. playback of recorded
vocalizations or decoys; Kress 1998), where birds are lured to formerly-occupied or new
breeding habitat by mimicking social cues is emerging as a cost-effective alternative
technique on some islands in New Zealand (Sawyer and Fogle 2010). Because remnant
colonies of seabirds may have skewed species composition, resulting inter-specific com-
petition may require active management (Buxton 2014). For example, widespread inter-
ference competition between broad-billed prions (Pachyptila vittata) and endangered
Chatham petrels (Pterodroma axillaris) on South-east Island, New Zealand, poses the most
serious threat to the latter (Was et al. 2000). Restoration managers have intervened by
culling broad-billed prions and constructing Chatham petrel nest-boxes that exclude broad-
billed prions (Gummer et al. 2015). Similarly, an active technique used by some Ma¯ori
tribes has involved the splitting of existing burrows or drilling of new ones to increase
breeding habitat for burrowing petrels (Lyver et al. 2008).
Prioritizing management approaches
Assuming the goal of restoration is to encourage recovery of seabird populations, a series
of decisions will need to be made relating to how population recovery can best be
achieved. Managers will first need to consider a conceptual model of the key factors
Biodivers Conserv (2016) 25:467–484 475
influencing natural seabird population recovery. This includes factors influencing the
recruitment of individuals from other islands to the newly predator-free space as well as the
intrinsic rate of growth of any remnant colony. We used a previously published compar-
ative analysis of over 100 seabird population responses to predator eradication on 41
islands (Buxton et al. 2014) to identify key decision criteria in choosing between active and
passive management alternatives (Fig. 2). These criteria are:
Distance to source population
Colony growth and re-colonization after eradication is reliant on the size, distance, and
connectivity to nearby source populations (Hanski 1998). Evidence suggests that recruit-
ment probability decreases exponentially with distance from a source population, and that
re-colonization is unlikely without a colony within *25 km (Oro and Pradel 1999; Buxton
et al. 2014).
Fig. 2 Ecological decision tree to guide management interventions for burrow-nesting seabirds based on
the probability of natural recovery following predator eradication. Active (green) versus passive
management (yellow) can be chosen based on site- or species-specific characteristics. Asterisks indicate
that the majority of criteria are met (‘‘yes’’) or not met (‘‘no’’). Further considerations include cost and
stochastic events. (Color figure online)
476 Biodivers Conserv (2016) 25:467–484
Remnant colony size
seabird colony growth is regulated by both positive density dependence, where birds are
attracted to settle in larger pre-existing colonies, and negative density dependence, where
crowding decreases habitat quality at higher densities (Kildaw et al. 2005; Buxton et al.
2016b). Thus recovery is more likely in a mid-sized remnant colony (*25–100 breeding
pairs; Buxton et al. 2014).
Metapopulation status
Growth of a local population after eradication is more likely if the species’ overall
metapopulation is stable or increasing in size (Oro 2003).
Presence of other breeding seabird species
Not only are seabirds more likely to settle amongst colonies of conspecifics, colonies of
other species may also be attractive; re-colonization is more likely on islands with higher
seabird species richness (Parejo et al. 2005; Buxton 2014). This relationship may reflect
habitat quality, where recovery is more likely on islands with less habitat alteration (e.g. no
grazing by cattle), or heterospecific habitat copying, where prospecting individuals of one
species respond to the presence of other species with similar ecological needs (Wagner
et al. 2000).
If a potential restoration site does not meet these criteria for the focal species, active
methods should be considered. Some species and sites may be better candidates for a less
logistically demanding active approach (e.g. social attraction; Fig. 2). For example, grey-
faced petrels readily disperse from their natal site and will settle and breed at sites with
call-playback (Sawyer and Fogle 2010; Lawrence et al. 2014; Buxton et al. 2015b). For
grey-faced petrels and fluttering shearwaters (Puffinus gavia), responses to playback
increases if larger, denser colonies are closer to the restoration site. In instances where
species exhibit strong site fidelity, the restoration site is far removed from a source pop-
ulation, or species are critically threatened and require immediate intervention to prevent
extinction, chick translocation is more likely to achieve recovery objectives (Fig. 2;
Miskelly et al. 2009). Conversely, the biology of some species may inhibit the success of
active restoration (e.g. unfeasibly complex post-fledgling care or diet) and must also be
considered during prioritization.
The ability of a remnant colony to grow will also depend on local habitat suitability.
Although burrow-nesting seabirds’ nesting habitat selectivity can weaken as a colony
grows, birds use deeper soils, steeper slopes facing prevailing winds, and later-succession
vegetation types more readily than other habitat characteristics (Whitehead et al. 2014;
Buxton et al. 2015a). Some features of a proposed restoration site might preclude con-
sideration of restoration or demand intensive preparation (e.g. revegetation) prior to any
attempts at species manipulation. Once a species is established, the nature and intensity of
interactions between sympatric species in a community can vary, particularly if selective
predation pressure has skewed community structure (Buxton 2014). Some burrow-nesting
seabird species may competitively exclude others, especially when communities are re-
assembling after eradication (e.g. grey-faced petrel and little shearwater Puffinus assimilis
Pierce 2002; Buxton 2014). In this case, some species may remain rare because they cannot
withstand inter-specific competition, especially if the population of the dominant species
Biodivers Conserv (2016) 25:467–484 477
continues to increase (Oro et al. 2009). These factors must be considered in advance of any
decision to embark on a project (Fig. 2).
At this point in the planning process, the probability of restoration success should be
analyzed in a bioeconomic framework to weigh cost and benefit (see Joseph et al. 2009;
Jones and McNamara 2014 for details of accessible methods).
Implementation and monitoring
Although monitoring is an integral component of management activity, the outcomes of
eradication are rarely measured in New Zealand (Jones et al. 2011). If SMART project
outcomes are defined clearly, indicators of success at each stage should be easily identi-
fiable and monitoring can be included as part of the project planning. Without appropriate
monitoring it is impossible to determine whether or not the project has been a success or to
manage the project adaptively through time. Moreover, monitoring data can help validate
predictions made by analyzing recovery across chronosequences.
For seabirds, there are numerous logistical challenges that preclude simple monitoring
strategies, including cryptic nesting behavior (below-ground nesting and nocturnal colony
attendance; Warham 1990), high costs of getting to island breeding grounds, and high
interannual variability in breeding participation (Newman et al. 2009). However, new
technologies are being applied to seabird monitoring, including infra-red burrow camera
surveys (Hamilton 2000), automated acoustic sensors (Buxton and Jones 2012; Borker
et al. 2014), and radar (Gauthreaux and Belser 2003), while modern simulation techniques
allow greater refinement of monitoring data (Buxton et al. 2016a). Moreover, there is a
well-established tradition of community involvement in conservation in New Zealand
(Peters et al. 2015) and an increasingly strong recognition of the role of Ma¯ori traditional
knowledge in monitoring seabird populations (Kitson 2004; Moller et al. 2004). Partici-
patory approaches are also valuable, as public involvement enhances restoration accep-
tance, increases the capacity for active restoration through volunteering, and builds
capacity through education and outreach (Parkes and Panetta 2009; Hardie-Boys 2010).
Deciding which restoration techniques to implement on islands is complicated: restoration
goals are steeped in conflicting socio-political and cultural contexts, recovery trajectories
of species are difficult to predict, restoration is expensive, and budgets are limited.
Decision-making tools are well-suited to help managers decide objectively between
restoration alternatives under complex circumstances. When it comes to decision-making,
island systems are at a unique advantage– a wealth of previous restoration outcome
information exists that can be incorporated readily into decision-making frameworks.
Accordingly, the formal inclusion of retrospective analyses of species response to past
restoration approaches can contribute to several stages of a decision-making framework:
successes can increase the socio-economic acceptance of a project, while comparative
analyses can identify factors driving species recovery and determine the likelihood of the
success of alternative restoration approaches. Identifying a set of key criteria based on
previous restoration data can help create step-wise decision process to select among
restoration approaches, without the need for further field data to be collected.
478 Biodivers Conserv (2016) 25:467–484
Due to the prevalence and success of predator eradication around New Zealand, a
comparative analysis of seabird population responses after eradication revealed drivers of
recovery, site characteristics, and species where natural recovery is more likely. Con-
versely, this indicated situations where active intervention should be prioritized. Retro-
spective analyses require results from previous projects to be made available, even if those
projects were unsuccessful. Accordingly, this approach depended on the ‘grey’ literature,
given the bias in publishing only success stories (Csada et al. 1996). Decision-making
within the seabird island restoration process would be based, ideally, on assessment of
passive and active restoration outcomes planned initially as tests of alternative approaches
(i.e. adaptive management; Williams 2011). However, the timeframe required for this
adaptive approach may be unrealistic for restoration decisions involving long-lived sea-
birds. The existence of numerous pre-existing passive and active restoration projects means
that their outcomes can be incorporated into prioritizing current restoration approaches,
while monitoring outcomes of the current project can validate or refine predictions made
using previous projects. The seabird island decision framework outlined in this paper can
guide managers’ choice of tools to facilitate seabird recovery.
Since its inception as a discipline in conservation biology 60 years ago, island
restoration has evolved from a field that was dominated by removing threats and assuming
that populations will eventually recover, to one where the recovery of ecosystems and
wildlife can be facilitated actively and outcomes monitored. As we move forward with
restoring complex island communities, decision-making tools using a logical, step-wise
framework informed by previous restoration successes and failures will aid in increasing
understanding and reducing uncertainty of ecosystem response.
Acknowledgments We thank C. Stone, D. Hamon, and H. Moller for helpful discussions and editing.
P. Gaze, J. Greenman, E. Dunning for contributing restoration goals and unpublished data. This project was
funded by the New Zealand Ministry of Business, Innovation and Employment (Te Hiringa Tangata Ki Te
Tai Timu Ki Te Tai Pari—facilitating bicultural restoration of coastal forests using seabirds as ecosystem
engineers contract C09X0908) and the University of Otago.
Armstrong DP, Castro I, Griffiths R (2007) Using adaptive management to determine requirements of re-
introduced populations: the case of the New Zealand hihi. J Appl Ecol 44:953–962
Atkinson IAE, Towns DR (1990). Ecological restoration on islands: prerequisites for success. In Ecological
restoration of New Zealand islands. Conservation Sciences Publication No. 2. (Towns, D. R., C.
H. Daugherty, and I. A. E. Atkinson). Department of Conservation, Wellington, New Zealand 73–90
Bellingham P, Towns DR, Cameron EK, Davis JJ, Wardle DA, Wilmshurst JM, Mulder C (2010) New
Zealand island restoration: seabirds, predators, and the importance of history. New Zealand J Ecol
Borker AL, McKown MW, Ackerman JT, Eagles-Smith CA, Tershy BR, Croll DA (2014) Vocal activity as
a low cost and scalable index of seabird colony size. Conserv Biol 28:1100–1108
Broome K (2009) Beyond Kapiti—a decade of invasive rodent eradications from New Zealand islands.
Biodiversity 10:14–24
Bushnell P, Pratt M (2014). Performance review framework: review of the department of conservation
(DOC). State Services Commission, the Treasury, and the Department of the Prime Minister and
Cabinet. Wellington, New Zealand
Buxton RT (2014). Ecological drivers of seabird recovery after the eradication of introduced predators, PhD
Thesis, University of Otago, Dunedin, New Zealand
Buxton RT, Jones IL (2012) Measuring nocturnal seabird activity and status using acoustic recording
devices: applications for island restoration. J Field Ornithol 83:47–60
Biodivers Conserv (2016) 25:467–484 479
Buxton RT, Jones CJ, Moller H, Towns DR (2014) Drivers of seabird population recovery on New Zealand
islands after predator eradication. Conserv Biol 28:333–344
Buxton RT, Anderson D, Moller H, Jones CJ, Lyver POB (2015a) Release of constraints on nest-site
selection in burrow-nesting petrels following invasive rat eradication. Biol Invasions 17:1453–1470
Buxton RT, Jones CJ, Moller H, Lyver POB (2015b) One method does not suit all: variable settlement
responses of three procellariid species to vocalisation playbacks. Emu 115:126–136
Buxton RT, Gormley AM, Jones CJ, Lyver PO (2016a) Monitoring burrowing petrel populations: a sam-
pling scheme for the management of an island keystone species. J Wildlife Manag 80:149–161
Buxton RT, Taylor GA, Jones CJ, Lyver PO, Moller H, Cree A, Towns D (2016b) Spatio-temporal changes
in density and distribution of burrow-nesting seabird colonies after rat eradication. New Zealand J Ecol
Chanwai, K, Richardson B (1998) Reworking indigenous customary rights? The case of introduced species.
New Zealand J Environ Law 2:157–185
Circumpolar Seabird Working Group (2001) Seabird harvest regimes in the circumpolar nations. CAFF
Technical, Report No 9
Clout M, Russell JC (2006). The eradication of introduced mammals from New Zealand islands. In
Assessment and Control of Biological Invasion Risks (Koike, F., M. Clout, M. Kawamichi, M. De
Poorter, and K. Iwatsuki). IUCN and Shoukadoh Book Sellers, Gland, Switzerland and Kyoto, Japan
Courchamp F, Chapuis JL, Pascal M (2003) Mammal invaders on islands: impact, control and control
impact. Biol Rev 78:347–383
Craig J, Anderson S, Clout M, Creese B, Mitchell N, Ogden J, Roberts M, Ussher G (2000) Conservation
issues in New Zealand. Annu Rev Ecol Syst 31:61–78
Croll DA, Maron JL, Estes JA, Danner EM, Byrd GV (2005) Introduced predators transform subarctic
islands from grassland to tundra. Science 307:1959–1961
Croxall JP, Rothery P (1991). Population regulation of seabirds: implications of their demography for
conservation. In Bird population studies: relevance to conservation management (Perrins, C. M., J.
D. Lebreton, and G. J. M. Hirons). Oxford University Press, Oxford
Csada RD, James PC, Espie RHM (1996) The ‘‘file drawer problem’’ of non-significant results: does it apply
to biological research. Oikos 76:591–593
Cubaynes S, Doherty JPF, Schreiber EA, Gimenez O (2011) To breed or not to breed: a seabird’s response to
extreme climatic events. Biol Lett 7:303–306
Daugherty CH, Towns D, Atkinson IAE, Gibbs GW (1990). The significance of the biological resources of
New Zealand islands for ecological restoration. In Ecological restoration of New Zealand islands
(Towns, D., C. H. Daugherty, and I. A. E. Atkinson). Department of conservation, Wellington
Department of Conservation (2010) The island strategy: guidelines for managing islands administered by the
Department of Conservation (unpublished). Department of Conservation, Ecosystem Management
DIISE (2015). The Database of Island Invasive Species Eradications. developed by Island Conservation,
Coastal Conservation Action Laboratory UCSC, IUCN SSC Invasive Species Specialist Group,
University of Auckland and Landcare Research New Zealand.
Donlan CJ (2007) The complexities of costing eradications. Anim Conserv 10:156–158
Duffy DC (1994). The guano islands of Peru: the once and future management of a renewable resource In
Seabirds on Islands, Threats, Case Studies and Action Plans, vol. Birdlife Conservation Series 1
(Nettleship, D. N., J. Burger, and M. Gochfield). Birdlife International and Smithsonian Institute Press,
Cambridge, UK Birdlife Conservation Series 168-76
Forbes AR, Craig JL (2013) Assessing the role of revegetation in achieving restoration goals on Tiritiri
Matangi Island. New Zealand J Ecol 37:343–352
Forgie VP, Horsley, Johnston J (2001). Facilitating community based conservation initiatives. Sci Conserv
Fukami T, Wardle DA, Bellingham PJ, Mulder CPH, Towns DR, Yeates GW, Bonner KI, Durrett MS,
Grant-Hoffman MN, Williamson WM (2006) Above- and below-ground impacts of introduced
predators in seabird-dominated island ecosystems. Ecol Lett 9:1299–1307
Gauthreaux SA, Belser CG (2003) Radar ornithology and biological conservation. Auk 120:266–277
Gummer H, Taylor G, Wilson K-J, Rayner MJ (2015) Recovery of the endangered Chatham petrel
(Pterodroma axillaris): A review of conservation management techniques from 1990 to 2010. Global
Ecol Conserv 3:310–323
Haami B (1993). Cultural knowledge and traditions relating to the kiore rat in Aotearoa. Part 1: a Maori
perspective. Science and Mathematics Education Papers. Hamilton: University of Waikato
480 Biodivers Conserv (2016) 25:467–484
Hamer KC, Schreiber EA, Burger J (2002). Breeding biology, life histories, and life history-environment
interactions in seabirds. In Biology of Marine Birds (Schreiber, E. A., and J. Burger). CRC Press, Boca
Raton, FL
Hamilton S (2000) How precise and accurate are data obtained using an infra-red scope on burrow-nesting
sooty shearwaters Puffinus griseus. Mar Ornithol 28:1–6
Hanski I (1998) Metapopulation dynamics. Nature 396:41–49
Hardie-Boys N (2010). Valuing community group contributions to conservation. Sci Conserv 299
Heemskerk MK, Wilson M, Pavao-Zuckerman (2003). Conceptual models as tools for communication
across disciplines. Ecol Soc 7
Helmstedt KJ, Shaw JD, Bode M, Terauds A, Springer K, Robinson SA, Possingham HP (2016). Prioritizing
eradication actions on islands: it’s not all or nothing. Journal of Applied Ecology:n/a-n/a
Hobbs RJ, Hallett LM, Ehrlich PR, Mooney HA (2011) Intervention ecology: applying ecological science in
the twenty-first century. Bioscience 61:442–450
Holdaway R, Worthy T (1994) A new fossil species of shearwater Puffinus from the late quaternary of the
South Island, New Zealand, and notes on the biogeography and evolution of the Puffinus gavia
superspecies. Emu 94:201–215
Holl KD, Aide TM (2011) When and where to actively restore ecosystems. For Ecol Manage
Imber M, West JA, Cooper WJ (2003) Cook’s petrel (Pterodroma cookii): historic distribution, breeding
biology and effects of predators. Notornis 50:221–230
IUCN (2012)
Johnson EA, Miyanishi K (2008) Testing the assumptions of chronosequences in succession. Ecol Lett
Jones HP (2010a) Prognosis for ecosystem recovery following rodent eradication and seabird restoration in
an island archipelago. Ecol Appl 20:1204–1216
Jones HP (2010b) Seabird islands take mere decades to recover following rat eradication. Ecol Appl
Jones HP, Kress SW (2012) A review of the world’s active seabird restoration projects. J Wildlife Manag
Jones C, McNamara L (2014) Usefulness of two bioeconomic frameworks for evaluation of community-
initiated species conservation projects. Wildlife Res 41:106–116
Jones HP, Schmitz OJ (2009) Rapid recovery of damaged ecosystems. PLoS ONE 4:e5653
Jones HP, Towns DR, Bodey T, Miskelly CM, Ellis JC, Rauzon MJ, Kress SW, McKown MW (2011).
Recovery and restoration on seabird islands. In Seabird Islands: Ecology, Invasion and Restoration
(Mulder, C., W. Anderson, D. R. Towns, and P. Bellingham). Oxford University Press, New York, NY
Joseph LN, Maloney RF, Possingham HP (2009) Optimal allocation of resources among threatened species:
a project prioritization protocol. Conserv Biol 23:328–338
Kappes P, Jones H (2014) Integrating seabird restoration and mammal eradication programs on islands to
maximize conservation gains. Biodivers Conserv 23:503–509
Keitt BS, Campbell A, Saunders A, Clout M, Wang YW, Tershy B (2011). The global islands invasive
vertebrate eradication database: a tool to improve and facilitate restoration of island ecosystems. In
Island invasives: Eradication and Management (Veitch, C. R., M. Clout, and D. R. Towns). IUCN,
Gland, Switzerland 74–77
Kettenring KM, Adams CR (2011) Lessons learned from invasive plant control experiments: a systematic
review and meta-analysis. J Appl Ecol 48:970–979
Kier G, Kreft H, Lee TM, Jetz W, Ibisch PL, Nowicki C, Mutke J, Barthlott W (2009) A global assessment
of endemism and species richness across island and mainland regions. Proc Natl Acad Sci
Kildaw SD, Irons DB, Nysewander DR, Buck CL (2005) Formation and growth of new seabird colonies: the
significance of habitat quality. Marine Ornithology 33:49–58
King WB (1985). Island birds: will the future repeat the past? In Conservation of Island Birds, vol. 3 (Moors,
P. J.). International Council for Bird Preservation Technical Publication 33–15
Kitson JC (2004) Harvest rate of sooty shearwaters (Puffinus griseus) by Rakiura Maori: a potential tool to
monitor population trends. Wildlife Res 31:319–325
Kitson JC, Moller H (2008) Looking after your ground: resource management practice by Rakiura Maori
Titi harvesters. Papers Proc Royal Soc Tasmania 142:161–167
Kress SW (1998). Applying research for effective management: case studies in seabird restoration. In Avian
Conservation (Marzluff, J. M., and R. Salabanks). Island Press, Washington, DC 141–154
Biodivers Conserv (2016) 25:467–484 481
Lawrence HA, Lyver POB, Gleeson DM (2014) Genetic panmixia in New Zealand’s grey-faced petrel:
implications for conservation and restoration. Emu 114:249–258
Lee WM, McGlone, Wright E (2005) Biodiversity inventory and monitoring: a review of national and
international systems and a proposed framework for future biodiversity monitoring by the Department
of Conservation. Landcare Res Contract Report: LC0405/122
Lewis RR III (2000) Ecologically based goal setting in mangrove forest and tidal marsh restoration. Ecol
Eng 15:191–198
Lindenmayer DB, Likens GE, Haywood A, Miezis L (2011) Adaptive monitoring in the real world: proof of
concept. Trends Ecol Evol 26:641–646
Lyver POB, Jones CJ, Doherty J (2009). Flavor or forethought: Tuhoe traditional management strategies for
the conservation of kereru (Hemiphaga novaeseelandiae novaeseelandiae) in New Zealand. Ecol
Lyver POB, Ngamane L, Anderson A, Clarkin P (2008) Hauraki Ma¯ori ma¯tauranga for the conservation and
harvest of ¯tı¯, Pterodroma macroptera gouldi. Pap Proc R Soc Tas 142:149–160
Lyver PO, Jones CJ, Belshaw N, Anderson A, Thompson R, Davis J (2015a) Insights to the functional
relationships of Ma¯ori harvest practices: customary use of a burrowing seabird. J Wildlife Manag
Lyver POB, Wilmshurst JM, Wood JR, Jones CJ, Fromont M, Bellingham PJ, Towns DR, Stone C, Sheehan
M, Moller H (2015b) Looking back for the future: local knowledge and paleoecology inform bio-
cultural restoration of New Zealand coastal ecosystems. Human Ecol 43:691–695
Margoluis R, Stem C, Salafsky N, Brown M (2009) Using conceptual models as a planning and evaluation
tool in conservation. Eval Program Plan 32:138–147
Matthiopoulos J, Harwood J, Thomas L (2005) Metapopulation consequences of site fidelity for colonially
breeding mammals and birds. J Anim Ecol 74:716–727
McCullough DR (1996) Metapopulations and wildlife conservation. Island Press, Washington, DC
Milberg P, Tyrberg T (1993) Naive birds and noble savages—a review of man-caused prehistoric extinctions
of island birds. Ecography 16:229–250
Miskelly CM (2013). Southern black-backed gull. In New Zealand Birds Online (Miskelly, C. M.). www.
Miskelly CM, Powlesland R (2013) Conservation translocations of New Zealand birds, 1863-2012. Notornis
Miskelly CM, Taylor GA, Gummer H, Williams R (2009) Translocations of eight species of burrow-nesting
seabirds (genera Pterodroma, Pelecanoides, Pachyptila and Puffinus: Family Procellariidae). Biol
Conserv 142:1965–1980
Mittermeier RA, Myers N, Thomsen JB, Da Fonseca GAB, Olivieri S (1998) Biodiversity hotspots and
major tropical wilderness areas: approaches to setting conservation priorities. Conserv Biol
Moller H (2006) Are current harvests of seabirds sustainable. Acta Zoologica Sinica 52:649–652
Moller H (2009) Matauranga Maori, science and seabirds in New Zealand. New Zealand J Zool 36:203–210
Moller H (2010). Cross-cultural partnership for seabird conservation and restoration. Talk at Island Inva-
sives: Eradication and Management Conference. Center for Biodiversity and Biosecurity
Moller H, Frampton C, Hocken AG, McLean IG, Saffer V, Sheridan L (2000) The importance of seabird
research for New Zealand. New Zealand J Zool 27:255–260
Moller H, Berkes F, Lyver PO, Kislalioglu M (2004) Combining science and traditional ecological
knowledge: monitoring populations for co-management. Ecol Soc 9:2
Mulder C, Grant-Hoffman M, Towns D, Bellingham P, Wardle D, Durrett M, Fukami T, Bonner K (2009)
Direct and indirect effects of rats: does rat eradication restore ecosystem functioning of New Zealand
seabird islands. Biol Invasions 11:1671–1688
Mulder CW, Anderson DR, Towns, Bellingham P (2011a). Seabird Islands: Ecol Invasion Restor
Mulder CPH, Jones HP, Kameda K, Palmborg C, Schmidt S, Ellis JC, Orrock JL, Wait DA, Wardle DA,
Yang L, Young H, et al (2011b). Impact of seabirds on plant and soil properties. In Seabird Islands:
Ecology, Invasion and Restoration (Mulder, C. P. H., W. Anderson, D. R. Towns, and P. Bellingham).
Oxford University Press, New York, NY
Newman J, Moller H (2005) Use of matauranga (Maori traditional knowledge) and science to guide a
seabird harvest: getting the best of both worlds. Senri Ethnol Studies 67:303–321
Newman J, Fletcher D, Moller H, Bragg C, Scott D, McKechnie S (2009) Estimates of productivity and
detection probabilities of breeding attempts in the sooty shearwater (Puffinus griseus), a burrow-
nesting petrel. Wildlife Res 36:159–168
482 Biodivers Conserv (2016) 25:467–484
Noss RS, Nielsen, Vance-Boland K (2009). Chapter 12—prioritizing ecosystems, species, and sites for
restoration. In Spatial Conservation Prioritisation: Quantitative Methods and Computational Tools
(Moilanen, A., K. A. Wilson, and H. P. Possingham). Oxford University Press, Oxford, UK 158–170
Oro D (2003) Managing seabird metapopulations in the Mediterranean: constraints and challenges. Scientia
Marina 67:13–22
Oro D, Pradel R (1999) Recruitment of Audouin’s gull to the Ebro Delta colony at metapopulation level in
the western Mediterranean. Mar Ecol Prog Ser 180:267–273
Oro D, Pe
´gueza A, Martı
´nez-Vilaltab A, Bertolero A, Vidal F, Genovart M (2009) Interference
competition in a threatened seabird community: a paradox for a successful conservation. Biol Conserv
Orwin KH, Wardle DA, Towns DR, St MG, John PJ, Bellingham C, Jones BM, Fitzgerald RG, Parrish,
Lyver POB (2015) Burrowing seabird effects on invertebrate communities in soil and litter are
dominated by ecosystem engineering rather than nutrient addition. Oecologia 180:217–230
Palmer MA, Ambrose RF, Poff NL (1997) Ecological theory and community restoration ecology. Restor
Ecol 5:291–300
Parejo D, Danchin E, Avile
´s JM (2005) The heterospecific habitat copying hypothesis: can competitors
indicate habitat quality. Behav Ecol 16:96–105
Parkes J, Murphy E (2003) Management of introduced mammals in New Zealand. New Zealand J Zool
Parkes JP, Panetta D (2009). Eradication of invasive species: progress and emerging issues in the 21st
century. In Invasive Species Management (Clout, M. N., and P. A. Williams). Oxford University Press,
Oxford, UK 47–62
Peters MA, Hamilton D, Eames C (2015) Action on the ground: a review of community environmental
groups’ restoration objectives, activities and partnerships in New Zealand. New Zealand J Ecol
Pierce RJ (2002). Kiore (Rattus exulans) impact on breeding success of Pycroft’s petrels and little
Possingham HP, Andelman SJ, Noon BR, Tromblak S, Pulliam HR (2001). Making smart conservation
decisions. In Conservation Biology: Research Priorities for the Next Decade (Soule, M. E., and G.
H. Orians). Island Press, Washington, DC 225–244
Richardson DM, Hellmann JJ, McLachlan JS, Sax DF, Schwartz MW, Gonzalez P, Brennan EJ, Camacho A,
Root TL, Sala OE, Schneider SH et al (2009) Multidimensional evaluation of managed relocation. Proc
Natl Acad Sci USA 106:9721–9724
Sandvik H, Erikstad KE, Sæther BE (2012) Climate affects seabird population dynamics both via repro-
duction and adult survival. Mar Ecol Prog Ser 454:273–284
Sawyer SL, Fogle SR (2010) Acoustic attraction of Grey-faced Petrels (Pterodroma macroptera gouldi) and
Fluttering Shearwaters (Puffinus gavia) to Young Nick’s Head, New Zealand. Notornis 57:166–168
Scott TA, Wehtje W, Wehtje MA (2001) The need for strategic planning in passive restoration of wildlife
populations. Restor Ecol 9:262–271
Seabrook-Davidson MNH, Brunton DH (2014) Public attitude towards conservation in New Zealand and
awareness of threatened species. Pac Cons Biol 20:286–295
Smith JL, Mulder CPH, Ellis JC (2011). Seabirds as ecosystem engineers: nutrient inputs and physical
disturbance. In Seabird Islands: Ecol Invasion Restor (C. P. H. Mulder, W. A., D. R. Towns, and P.
Bellingham). Oxford University Press, New York, NY
Taiepa T, Lyver P, Horsley P, Davis J, Brag M, Moller H (1997) Co-management of New Zealand’s
conservation estate by Maori and Pakeha: a review. Environ Conserv 24:236–250
Taylor GA (2000). Action plan for seabird conservation in New Zealand, part A. in Threatened Species
Occasional Publication. Department of Conservation, Wellington, NZ
Towns DR (2002) Korapuki Island as a case study for restoration of insular ecosystems in New Zealand.
J Biogeogr 29:593–607
Towns DR (2009) Eradications as reverse invasions: lessons from Pacific rat (Rattus exulans) removals on
New Zealand islands. Biol Invasions 11:1719–1733
Towns DR (2011). Eradication of vertebrate pests from islands around New Zealand: what have we
delivered and what have we learned? In Island Invasives: Eradication and Management (Veitch, C. R.,
M. Clout, and D. R. Towns). IUCN, Gland, Switzerland 364–371
Towns DR, Broome KG (2003) From small Maria to massive Campbell: forty years of rat eradications from
New Zealand islands. New Zealand J Zool 30:377–398
Towns D, Atkinson IAE, Daugherty CH (1990a). The potential for ecological restoration in the mercury
islands. In Ecological restoration of New Zealand islands. Conservation Sciences Publication No. 2
Biodivers Conserv (2016) 25:467–484 483
(Towns, D., C. H. Daugherty, and I. A. E. Atkinson). Department of Conservation, Wellington, New
Towns D, Daugherty CH, Atkinson IAE (1990b). Ecological Restoration of New Zealand Islands.
Department of Conservation, Conservation Sciences Publication No. 2, Wellington, New Zealand
Towns D, Simberloff D, Atkinson IAE (1997) Restoration of New Zealand islands: redressing the effects of
introduced species. Pac Conserv Biol 3:99–124
Towns DR, Byrd GV, Jones HP, Rauzon MJ, Russell JC, Wilcox C (2011). Impacts of introduced predators
on seabirds. In Seabird Islands: Ecology, Invasion and Restoration (Mulder, C., W. Anderson, D.
R. Towns, and P. Bellingham). Oxford University Press, New York, NY 56–90
Towns DR, Bellingham PJ, Mulder CPH, Lyver POB (2012) A research strategy for biodiversity conser-
vation on New Zealand’s offshore islands. New Zealand J Ecol 36:1–20
Towns DR, West CJ, Broome KG (2013) Purposes, outcomes and challenges of eradicating invasive
mammals from New Zealand islands: an historical perspective. Wildlife Res 40:94–107
Tunstall SM, Tapsell SM, Eden S (1999) How stable are public responses to changing local environments?
A ‘before’ and ‘after’ case study of river restoration. J Environ Plan Manage 42:527–545
Veitch CR, Miskelly CM, Harper GA, Taylor GA, Tennyson AJD (2004) Birds of the Kermadec Islands,
south-west Pacific. Notornis 51:61–90
Wagner RH, Danchin E, Boulinier T, Helfenstein F (2000) Colonies as byproducts of commodity selection.
Behav Ecol 11:572–573
Warham J (1990) The petrels: their ecology and breeding systems. Academic Press, San Diego
Was NW, Sullivan WJ, Wilson KJ (2000). Burrow competition between broad-billed prions (Pachyptila
vittata) and the endangered Chatham petrel (Pterodroma axillaris)
Westgate MJ, Likens GE, Lindenmayer DB (2013) Adaptive management of biological systems: a review.
Biol Conserv 158:128–139
Whitehead A, Lyver POB, Jones CJ, Macleod C, Bellingham PJ, Coleman M, Karl BJ, Drew K, Pairman D,
Gormley AM, Duncan RP (2014) Establishing accurate baseline estimates of breeding populations of a
burrowing seabird, the Grey-faced Petrel (Pterodroma macroptera gouldi) in New Zealand. Biol
Conserv 169:106–116
Williams BK (2011) Adaptive management of natural resources—framework and issues. J Environ Manage
Wilmshurst JM, Anderson AJ, Higham TFG, Worthy TH (2008) Dating the late prehistoric dispersal of
Polynesians to New Zealand using the commensal Pacific rat. Proc Natl Acad Sci 105:7676–7680
Wilmshurst JM, Moar NT, Wood JR, Bellingham PJ, Findlater AM, Robinson JJ, Stone C (2014) Use of
pollen and ancient DNA as conservation baselines for offshore islands in New Zealand. Conserv Biol
Wilson RS, Bruskotter JT (2009) Assessing the impact of decision frame and existing attitudes on support
for wolf restoration in the United States. Human Dimens Wildlife 14:353–365
Wyant J, Meganck R, Ham S (1995) A planning and decision-making framework for ecological restoration.
Environ Manage 19:789–796
Young RC (2014). Behavior, physiology, biological age, and cultural role of long-lived Bering Sea seabirds.
PhD, PhD thesis, University of Alaska Fairbanks, Fairbanks, USA
484 Biodivers Conserv (2016) 25:467–484
... In their global review, Jones and others (2016) identipopulation size or colonization of a location) from the eradication of invasive mammals from islands. Other programmes to restore or improve habitat for seabirds have also been reforestation, weed control, enhancing or providing nesting opportunities and erosion control (Beck and others, 2015;Bried and Neves, 2015;Buxton and others, 2016). provides that marine and coastal ecosystems should be sustainably managed verse impacts; and impacts on biodiversity will need to be taken into account in order to make progress towards Goal 12. Efforts to reduce increasing, including through the adoption or updating of national plans of action by some methods, in which by-catch is most commonly an issue. ...
... ery by-catch and invasive species, in particular in island habitats, will likely continue, as their importance for the conservation of biodiversity and seabirds is increasingly recognized and prioritized (Buxton and others, 2016;Jones -with associated potential detrimental impacts on some seabird populations, even though the empirical evidence for a consistent effect is not strong (Hilborn and others, 2017). The impacts of potentially increasing competition may be exacerbated by any decreases in prey abundance related to changes in oceanographic conditions driven by climate change (Grémillet and Boulinier, 2009). ...
Full-text available
A summary of information about seabirds for the second world ocean assessment published in August 2021
... Further research can be undertaken to combine this dataset with other evidence-based threat and conservation datasets (e.g., refs. 22, 23, and 34-36) and incorporate information into frameworks for active seabird restoration decision-making (7,37,38). ...
The global loss of biodiversity has inspired actions to restore nature across the planet. Translocation and social attraction actions deliberately move or lure a target species to a restoration site to reintroduce or augment populations and enhance biodiversity and ecosystem resilience. Given limited conservation funding and rapidly accelerating extinction trajectories, tracking progress of these interventions can inform best practices and advance management outcomes. Seabirds are globally threatened and commonly targeted for translocation and social attraction ("active seabird restoration"), yet no framework exists for tracking these efforts nor informing best practices. This study addresses this gap for conservation decision makers responsible for seabirds and coastal management. We systematically reviewed active seabird restoration projects worldwide and collated results into a publicly accessible Seabird Restoration Database. We describe global restoration trends, apply a systematic process to measure success rates and response times since implementation, and examine global factors influencing outcomes. The database contains 851 active restoration events in 551 locations targeting 138 seabird species; 16% of events targeted globally threatened taxa. Visitation occurred in 80% of events and breeding occurred in 76%, on average 2 y after implementation began (SD = 3.2 y). Outcomes varied by taxonomy, with the highest and quickest breeding response rates for Charadriiformes (terns, gulls, and auks), primarily with social attraction. Given delayed and variable response times to active restoration, 5 y is appropriate before evaluating outcomes. The database and results serve as a model for tracking and evaluating restoration outcomes, and is applicable to measuring conservation interventions for additional threatened taxa.
... Seabirds tend to breed on islands free of mammalian predators and, as a result, may lack anti-predator defense mechanisms (e.g., Buxton et al. 2016). Therefore, seabirds are highly vulnerable if mammalian predators are introduced to a colony (Borrelle et al. 2018), and they rarely coexist with introduced mammalian predators (De . ...
Full-text available
2023. Experts' opinions on threats to Leach's Storm-Petrels (Hydrobates leucorhous) across their global range. Avian Conservation and Ecology 18(1):11. https://doi. ABSTRACT. Seabirds are declining globally, though the threats they face differ among and within species and populations. Following substantial population declines at several breeding colonies, Leach's Storm-Petrel (Hydrobates leucorhous) was uplisted from Least Concern to Vulnerable by the International Union for Conservation of Nature (IUCN) in 2016. Reasons for these declines are unclear, and it is important to identify threats the species faces across its global breeding range to guide research directions and inform conservation efforts. We solicited feedback from 37 Leach's Storm-Petrel scientific experts from eight countries on the importance of different threats facing the species on land and at sea. Perceived threats to extant colonies varied spatially, with a consensus within regions for main threats. Most researchers agreed that the main threats at or near colonies are avian and mammalian predators and onshore light attraction. At-sea threats have been less studied and were harder to identify and rank, but include offshore lights and structures, spatial shifts in prey, and contaminants. Climate change was not listed specifically because of its multifaceted repercussions, but several perceived threats are linked to climate change. Globally, introduction of mammalian predators is an overarching driver of seabird colony decline or extirpation; thus biosecurity must be considered an important measure for the conservation of storm-petrels. In addition, filling knowledge gaps and implementing a series of regionally relevant and targeted strategies that lead to small but cumulative conservation successes may be the best approach for this species.
... Feral pigs (Sus scrofa) are omnivores and opportunistic feeders, as such they have a wide range of impacts on agricultural, biodiversity and environmental resources (Parkes 2006;Bengsen et al. 2017). Islands are biodiversity hotspots and eradication of invasive species, such as feral pigs, is often necessary to prevent extinctions of native species (Hutton et al. 2007;Buxton et al. 2016;Holmes et al. 2019). Internationally, management of pig populations commonly uses poison baiting, trapping, aerial and ground shooting (Reddiex et al. 2006;West & Saunders 2007). ...
... Feral pigs (Sus scrofa) are omnivores and opportunistic feeders, as such they have a wide range of impacts on agricultural, biodiversity and environmental resources (Parkes 2006;Bengsen et al. 2017). Islands are biodiversity hotspots and eradication of invasive species, such as feral pigs, is often necessary to prevent extinctions of native species (Hutton et al. 2007;Buxton et al. 2016;Holmes et al. 2019). Internationally, management of pig populations commonly uses poison baiting, trapping, aerial and ground shooting (Reddiex et al. 2006;West & Saunders 2007). ...
Full-text available
A feasibility study for removing feral pigs (Sus scrofa) from Auckland Island trialled feeders monitored by trail cameras to determine their effectiveness for detecting and attracting feral pigs. Ten automatic feeders were installed during January–February 2019 (summer) and again in August–September 2019 (winter) on Auckland Island. They delivered kibbled maize daily for a period ranging from 25 to 37 days. Sites selected for feeder installation needed to be of appropriate relief and area to allow feeder and trap installation, as would occur during an eradication operation. Feeder success varied across sites during the trial. Site selection where there was evidence of fresh pig presence improved the rate of visitation. Feeders offer significant efficiencies to lethal techniques such as trapping by automatically dispensing feed to allow constant supply over a long period. This automation reduces operator effort, but is also advantageous as consistent feed times train pigs to condition their visits so they can be more effectively targeted. In this trial, most visiting pigs returned to the feeder daily from around 15 days after installation. Automated feeders will be an integral component of the proposed methodology for Auckland Island pig eradication to target nocturnal individuals and family groups, and, importantly, reduce the risk of education through non-lethal engagement.
... The largest global population of White-chinned Petrels is at South Georgia, where the main island was recently cleared of invasive rodents in the world's largest aerial baiting campaign to date (Martin and Richardson 2017). Despite the potential opportunity for showcasing the benefits to wildlife of this huge restoration effort, there has been little or no monitoring of the response of burrowing petrels, partly related to the logistical difficulties of covering such a large and remote region by field teams (Buxton et al. 2016;Brooke et al. 2018). However, acoustic recorders have the potential to provide a viable long-term monitoring tool that, if validated, could be scaled up across widespread breeding sites. ...
Monitoring of population sizes and trends using conventional surveys is challenging for nocturnal, burrow-nesting seabirds. The White-chinned Petrel is the most commonly killed species in Southern Ocean fisheries and its breeding success at many sites is reduced because of predation by invasive cats and rodents. As adaptive management of such threats requires cost-effective and reproducible protocols for monitoring populations, we examined the potential of automated bioacoustic techniques for measuring colony attendance patterns (relative number of birds visiting at a given time) using data from acoustic recorders deployed over a breeding season at Bird Island, South Georgia. Generic recognition software was of limited utility, but a suite of acoustic indices in a random forest model reliably predicted the occurrence of vocalisations. Vocal activity showed clear temporal patterns, despite high day-to-day variability, and was lowest during the pre-laying period, in the early evening, and on moonlit nights. To facilitate estimation of population density using acoustic recorders, we determined the mean vocalisation rate of individuals (2.3 min⁻¹), mean call length (~15.3 sec), and detection distance (~15 m based on signal to noise ratios of playbacks). Our results indicate that acoustic indices are a useful measure of colony attendance. If these indices can be linked to density, acoustic monitoring would provide a powerful and cost-effective census method for White-chinned Petrels and other nocturnal species.
... behaviour, ecology, and the broader management context. Social attraction (e.g., decoys, acoustic lures) is recommended for surface nesters that exhibit post-fledging parental care, (Gummer 2003;Jones & Kress 2012), when there is a nearby colony (< 25 km) to attract birds from, or the source population is increasing (Gummer 2003;Buxton et al. 2016 Feare (1975); Brown (1976)). In this period, they spend the day at sea and return to be fed at night (Brown 1976a). ...
Decision making for threatened species recovery can be complex: there is often a diverse range of stakeholders holding values that may be conflicting, data are typically deficient and imperfect, and there is uncertainty about the outcomes of proposed actions. Yet in this pressured and challenging context, decisions must still be made. Conservationists therefore need the right tools to address these complexities, and structured decision making (SDM) is effective in this space. Here, I demonstrate the utility of SDM and its component tools to assist recovery planning for Aotearoa-New Zealand’s rarest indigenous breeding bird, tara iti (New Zealand fairy tern, Sternula nereis davisae). My PhD aims to advance (i) the way we approach decisions via inclusivity and expression of values, (ii) the way we make decisions by recognising objectives, creating alternatives and making explicit trade-offs, and (iii) the way we use data to support these decisions by analysing and interpreting biased or imperfect datasets. Values drive decisions, and I first demonstrate how SDM, a values-focused approach, can be used to meaningfully integrate stakeholder values such as mātauranga Māori (Māori [indigenous New Zealander] knowledge/perspective) into conservation decisions and provide a basis for co-management between different peoples. Second, I analyse a seabird translocation trial, showing how creative thinking about alternatives can help better achieve conservation objectives. Third, I show how the application of SDM resulted in a new management recommendation that balanced across multiple objectives and was evidence-based. This was the first action after a decade of inaction and communication breakdown between stakeholders. Finally, I use a decision tree and counterfactuals to analyse the efficacy of tara iti egg management, showing how these tools can help navigate complex and biased monitoring data sets to improve future decisions. This thesis provides a detailed real-world example of how SDM can be applied effectively to a complex conservation problem, and highlights the importance of clear, values-focused thinking and inclusive approaches in species recovery.
The U.S. Tropical Pacific (USTP) is a globally important area for seabirds with tens of millions of individuals of 32 species breeding in the region. The two greatest threats to breeding seabirds in the USTP are inundation of colonies caused by global climate change and non-native predators. We assessed the status of seabird species breeding in the USTP and which species would benefit most from restoration activities. We scored each species for nine criteria that reflected their extinction risk and vulnerability to climate change and invasive predators, then summed the scores of all criteria to obtain an overall score and ranked the species in terms of overall conservation need. The top five species at risk (in order) were Hawaiian Petrel (Pterodroma sandwichensis), Newell's Shearwater (Puffinus newelli), Polynesian Storm-Petrel (Nesofregetta fuliginosa), Phoenix Petrel (Pterodroma alba), and Black-footed Albatross (Phoebastria nigripes). We also assessed 86 locations in the USTP as potential source and restoration sites for seabirds to mitigate the impacts of sea level rise and invasive predators. Some restoration actions are underway for three of the top five species in the USTP, but more actions are needed. Two of the top species (Polynesian Storm-petrel and Phoenix Petrel) occur primarily outside the USTP. Actions within the USTP are needed to complement existing conservation measures underway elsewhere in the Pacific and should be prioritized for future management actions.
Full-text available
The eastern slope of the abandoned mine in the Zhoujiayuan Mountain Island area has been seriously damaged by local quarrying, which often triggers visual pollution, soil erosion, and landslides during rainfall. This paper carries out an ecological restoration of the abandoned mine based on indoor experiments and field investigation data. The paper also quantitatively analyzes the stability evolution laws of the soil-covered slope before and after the ecological restoration in the rainfall process, putting forward further slope reinforcement and ecological restoration measures. The results showed that the stability safety factor of the covered slope decreased to 0.92 after raining for 18 h, and the instability risk was very high. When the vegetation had recovered, the stability of the soil-covered slope with root system was significantly improved, and its safety factor was close to 1.15 after 64 h of continuous rainfall. Throughout the field observation conducted from 2019 to 2022, the slope of abandoned rock mines was found to be lush with restored plant diversity. After several continuous rainfall processes, neither soil erosion nor instability phenomena were found there. The study has certain reference significance for the ecological restoration of abandoned rock mines in rainy regions.
Invasive species pose the highest overall threat to seabirds, affecting the most species and the greatest impact based on the timing, scope, and severity. Invasive mammals have been proven the most harmful on seabird breeding islands, and important advances have been made towards solutions to prevent, control, or eradicate these impacts to seabirds. Biosecurity aims to prevent new invasive species from arriving, and as the most cost-effective strategy considered is a cornerstone for island restoration. Great strides have been made in eradicating invasive mammals from islands, with more than 1500 efforts on nearly 1000 islands worldwide and clearly documented benefits for seabirds. Considerable synergy exists for implementing seabird solutions on islands to achieve conservation goals for other biotas and benefits for human communities. For many seabird species, implementing tractable invasive species solutions will be a critical component of boosting resilience to projected climate change impacts.
Full-text available
Introduced species of mammals have now been removed from many islands around New Zealand, thus providing singular opportunities for ecological restoration. If island restoration is to be attempted, the way island biota originate and the precise effects of introduced organisms must be identified. Plants introduced to the New Zealand archipelago may have transitory effects, but others may modify forest structure and disrupt succession. Goats have been the most destructive introduced herbivore on islands. Among introduced predators, cats have extirpated colonies of seabirds, and rats (depending on species) affect invertebrates, lizards, and birds. Ecological theories and concepts that may help with island restoration projects include: the keystone species concept, in which the effects of one species on others is disproportionate relative to its abundance; the "intermediate predator" hypothesis, where removal of the top introduced predator may lead to rebound effects of intermediate predators; and ecological chain reactions, where local extinction of some species can cause complicated multiple effects. Problems with restoration of islands may be encountered because of meagre data on the previous effects of pests (such as predators), use of non-seral species in revegetation projects, proliferations of indigenous or introduced species that have unforeseen community effects, and inexplicable difficulties with some translocations. A restoration case study in the continental Mercury Islands and on Cuvier Island showed success with removal of introduced mammals and demonstrates the various effects of introduced browsers, grazers, and predators. A contrasting case study is provided by oceanic Mangere Island in the Chatham Islands where 22 species of avifauna have been lost, seven as permanent extinctions. Restoration targets for some New Zealand islands can be clarified by palaeoecological studies of Maori (Polynesian) middens and natural deposits. Understanding the role of disturbance in island systems may also help clarify restoration targets. When exotic keystone species are introduced, physical disturbance may be overridden by biotic disturbance. This replacement in turn has implications for trophic structure. With high levels of biotic disturbance, continental islands may be changed from relatively species-rich bottom-up food webs to species-poor top-down trophic cascades. These possibilities can be tested with an experimental approach to restoration, although such experiments may be hard to interpret because of difficulties with replicates and controls. Ecological restoration en New Zealand islands has potential to replace damaged or lost communities, expand the ranges of relict populations, reduce the selective influence of exotic (keystone) species on indigenous species, help in understanding how the systems are formed, provide opportunities for educational and scientific investigation, and act as a testing ground for new technologies against pests.
A survey was conducted amongst a sample (n = 3 000) of the New Zealand public to gauge their perception of government spending on conservation. The survey also obtained an understanding of the level of awareness the public has of New Zealand threatened species. Respondents ranked eight areas of government spending, namely health, education, superannuation, law and order, defence, conservation of native species, primary industry research & development and tourism. From a response rate of n = 131 (4.5%), health and education were ranked the highest, followed by law and order with conservation in fourth position. Except for conservation of native species, these rankings by respondents closely aligned with priorities of average annual government spending. Awareness was the highest for endemic species such as kiwi Apteryx spp, Hector’s dolphin Cephalorhynchus hectori, kokako Callaeas cinerea cinerea, kakapo Strigops habroptilus, takahe Porphyrio mantelli, Maui’s dolphin Cephalorhynchus hectori maui and tuatara Sphenodon punctatus. The awareness for these prominent species may suggest that the Department of Conservation is achieving some success in its advocacy role to increase the public’s awareness of species threatened with extinction. With awareness of threatened species and the moderate ranking given to conservation expenditure, it is evident there is a level of public support for expenditure on protection of biodiversity and natural heritage.
Islands with large colonies of seabirds are found throughout the globe. Seabird islands provide nesting and roosting sites for birds that forage at sea, deposit marine nutrients on land, and physically alter these islands. Habitats for numerous endemic and endangered animal and plant species, seabird islands are therefore biodiversity hotspots with high priority for conservation. Successful campaigns to eradicate predators from seabird islands have been conducted worldwide. However, removal of predators will not necessarily lead to natural recovery of seabirds or other native species. Restoration of island ecosystems requires social acceptance of eradications, knowledge of how island food webs function, and a long-term commitment to measuring and assisting the recovery process. This book provides a large-scale cross-system compilation, comparison, and synthesis of the ecology of seabird island systems.