Download - Abbie Ferrar Disseration

Eradication methods on invasive species on islands; is there an effect on seabird populations?

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Environment Department

University of York,

University Road,

York YO10 5DD

Acknowledgments

I would like to take this time to thank all of my lecturers in the Environmental

Department for being supportive when I’ve needed. Especially towards the end of the year. I

would also like to thank my Uncle Boris, because without his trust in me, I would not have

been able to write this. And as always, my parents, for still putting me and my brother before

anything else in this World.

Abstract

134 bird species have gone extinct in the last 500 years. 71 have been due to invasive

species.11.8% are marine birds. Due to marine birds breeding on Islands and being ground

nesters, they are more vulnerable. 80% of the world’s invasive species are found on islands.

Islands are open niches for invasive species as there are no natural predators. 20 years ago

eradication methods on these invasive species were developed. This study uses a systematic

review and Meta analyse approach to investigate what these eradication methods have on

seabird populations. Coefficient correlation (r) being the standardized measure.

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Introduction

Birds are the most diverse of the vertebrate family, having twice as many taxa as

mammals and ten times more species that fly (Sekercioglu 2006). Over the last 500 years,

134 species of birds have gone extinct (Bird Life International 1). It is believed that the recent

decline in bird populations is from invasions of non-native species, at least 71 of these

extinctions is due to invasive species (Bird Life International 1). An invasive species is a non-

native animal or plant that has a negative effect on the native species. They occur in

ecosystems that are similar to their natural environment (Howald et al 2007).

IUCN red list has agreed with this and it explains why 5.7% of terrestrial species, 2%

of freshwater species (mostly birds) and 11.8% of marine species (again mostly birds) have

become extinct recently. Out of the 21 recently extinct marine species, 11 of them have been

marine bird species. (Gurevitch and Padilla 2004). Most of the marine birds that have become

extinct, have been native island species. Island birds are more likely to be effected by alien

invasive species because majority of the time island birds have no predators so have not had

to evolve into fleeing when danger is near (Bird Life International 1 and 2).

Of all the invasive species that have become a problem over recent years, rodents

have become the most dangerous (Howald et al 2007). Unlike most other invasive mammals,

rodents are omnivores so can affect all species on the island, plant or animal. 80% of the

world’s major islands have invasive rodents and more are continuously invading the World’s

islands. Island ecosystems may be more prone to invasion because their species faced few

strong competitors and predators, or because their distance from colonizing species

populations makes them more likely to have "open" niches for invasion. Over 20 years ago

systematic techniques were developed into eradicating the invasive rodents due to the

negative impacts that were occurring (Howald et al 2007). Between n 1983 and 1984 the

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WWF poisoned and trapped Rattus rattus (Appendix; Table 2) on Cerro Pajas, Galapogas.

This is because the once abundant, now endangered, dark Pterdroma phaeopugia (Appendix;

Table 1) has been affected by the invasive R.rattus. The rat feeds on the eggs and chicks.

Before the eradication methods began, only 31% of the eggs that were laid fledged. In 1983,

46% fledged (104 nests were checked) and in 1984, 72% fledged (100 nests were checked)

(Cruz and Cruz 1996).

To prevent extinction, eradications have become a very important tool (Howald et al

2007). Howe Scientists believe that the best way to prevent an invasion (defined as when

none native species takes over an island) is to catch the alien species when it first arrives at

the island and has not affected anything on the island yet. This can be achieved when an alien

species has arrived on island but has not bred or taken over is known as incursion. This is the

critical time for the eradication of the alien species (Russel et al 2006). A good example of an

island that has managed to eradicate an invasive alien species problem is the Clipperton

Islands, which is located 1000km South West of Manzanillo, Mexico. Feral pigs were

introduced by settlers at the turn of the Centenary. Before this, the island was a sparsely

vegetated atoll and was home to a high density of plant eating land crabs and 10,000s nesting

marine birds. The pigs would feed on the crabs and the eggs of the nesting marine birds.

Causing a massive decrease in marine birds. It was reported that only 150 Scula dactylatra

and 500 Scula leycogasta (Appendix; Table 1) were now on the island. In 1958, all of the

pigs were shot. By 1968, the breeding pairs of seabird population had increased to 25,000

(Birdlife International 3)

Using a systematic review approach and a Meta analysis on independent and primary

research studies on marine bird species after eradication of invasive species this study will

discuss the impacts invasive mammals are having on island marine birds and how eradication

techniques can help prevent declines in species population or eventual extinction in species.

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Systematic reviews and Meta analysis have been used in health care for a number of

years now, however in recent year’s conservationists and ecologists have been using the

methods. A systematic review is considered the best way to synthesis the findings of several

studies that have investigated the same question. They are defined as an overview of

scientific strategies that limit bias to the regular association, critical assessment and synthesis

of all relevant studies on a specific topic. They are designed to locate, appraise and synthesize

the evidence relating to the same scientific question to provide informative and evidence-

based answers (Cook et al 1995; Dickson et al 2014). This type of review requires the

following to be successful; definition of the question/problem, identification and critical

assessment of the evidence that’s available, synthesis of the findings and finally the drawing

of a relevant conclusion (Dickson et al 2014). A Meta analysis is a quantitative overview of

the systematic review. Statistical methods from primary and independent research are used to

combine and summarize the results of several relevant studies all asking the same question.

(Cook et al 1995).

The aim of this study is to see if the eradication of predatory invasive species on

islands has an effect on the native marine bird populations. This will be achieved by using a

systematic review and a Meta analysis on previous primary and independent studies.

Methods

There are nine steps to follow whilst doing a systematic review (Table 1). Fig 1 shows

these steps as a flow chart, and how many studies were found/removed within reason during

this study. Step 1 is to perform a scoping search to help determine the aim of the project.

Once the aim of the project had been determined the inclusion criteria (Table 3) and search

terms (Table 2) were developed to help with the following steps. Step 2 was achieved by

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using Web of Science (WoS) and Scopus were the search engines used to find the initial

studies of this review (Over 22,000 studies). All of the studies were imported into an endnote

software where the duplicates were removed.

Table 1: - Table showing what the 9 steps are when doing a systematic review (Edited from Dickson et al 2014)

Step 1 Performing scoping searches identifying the aim

Step 2 Literature Searching and removing duplicates

Step 3 Screening titles and abstracts

Step 4 Obtaining studies

Step 5 Selecting full text studies

Step 6 Quality assessment

Step 7 Data extraction

Step 8 Analysis and synthesis

Step 9 Writing up and editing

Once the duplicates had been removed, the inclusion criteria (established from the

aim of the study; Table 3) was used to screen the abstract and titles of each of the remaining

studies (over 10,000 studies), the studies that were not relevant to the aim were then removed.

Successful eradication in this study was defined as the main invasive species of a study being

removed from the island completely and no trace of the invasive species had be seen in over a

year. 41 studies (Appendix; Table 3) remained after steps 1, 2 and 4 (Table 1) had been

completed (Fig 1).

The studies were then obtained for full text screening (Table 1) (Appenndix; Table 3).

Full text screening of the text is the step in which appropriate data needs to be scoped for the

Meta analyse software. The software used in this study was Meta Win 2.0 (Rosenberg et al

2000). 9 studies (Fig 1) had enough data that could be extracted for a quantitative analyse.

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However, some of these studies had different statistical methods or data was written in

different formats. For a summary analyse to be performed, the data needs to be in the same

statistical format. This study required the data to be measured in effect size. An effect size is

an objective and standardized measure of the magnitude of observed effect between two or

more variables. The observed effect for this study is the population changes for marine birds

after successful eradication (Ferguson 2009).

Effect size is ideal to use in a Meta analyse because different variables can be

compared and different statistical data can be extracted and converted depending on the

availability of data within a study. For this study coefficient correlation (r) was the

measurement used for effect size as a correlation between seabird population changes and

successful eradications needs to be established to reach the aim. Using the “effect size

calculator” provided within the meta-win software and inputting the sample size and the

statistical data (Chi-squared or t test) extracted from the 9 studies the data could be convert to

an r value. The studies that did not have enough data, i.e. no sample size or studies that did

not have full eradication of species, were excluded, leaving only 7 studies that could be used

(Fig 1).

Although all of the data was converted to an r value, the data from larger studies still

had skew compared to the smaller studies. Using the Fisher’s r-to-Z transformation, the effect

size was converted to Zr and the effect size variance (Var(Zr)) were worked out for each. The

r value and sample size are the only forms of data that are needed for this conversion. Using

the category method in the summary analyse, Zr and Var(Zr) were used to plot. Category

method was used as it compared all of the variables (Appendix; Table 3) extracted from the 7

studies. The 7 individual authors were also categorised together to show the mean effect size

and to show what the overall effect has shown. For a Meta analyse to be performed, two

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variables need to be present (Rosenburg et al 200). Some of the studies only had one variable,

due to this they were not included within this analyse.

Table 2: - Table showing the entire search terms typed into Web of Science (WoS) and Scopus for the scoping search.

An asterisk (*) searches for a word with different spellings.

Search Terms WoS Scopus

Invasive and egg* and eradication 41 28

Invasive and egg* and human* 443 380

Invasive and egg* and island* 107 97

Invasive and egg* and mammal* 338 56

Invasive and egg* and plant* 579 326

Invasive and egg* and predator* 208 175

Invasive and egg* and rodent* 116 21

Invasive and nest* and eradication 77 66

Invasive and nest* and human* 1262 1199

Invasive and nest* and island* 220 186

Invasive and nest* and mammal* 911 68

Invasive and nest* and plant* 386 226

Invasive and nest* and predator* 148 114

Invasive and nest* and rodent* 144 46

Island* and Eradication and Human* 381 358

Island* and Eradication and Mammal* 598 139

Island* and Eradication and Plant* 301 170

Island* and Eradication and Predator* 196 125

Island* and Eradication and Rodent* 278 185

Marine bird* and Island* and Conservation 645 158

Marine bird* and Island* and Human* 293 114

Marine bird* and Island* and Invasive 42 21

Marine bird* and Island* and Mammal* 637 163

Marine bird* and Island* and Plant* 356 94

Marine bird* and Island* and Predator* 556 154

Marine bird* and Island* and Rodent* 90 22

Sea bird* and Island* and Conservation 632 231

Sea bird* and Island* and Human* 335 168

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Sea bird* and Island* and Invasive 30 20

Sea bird* and Island* and Mammal* 560 141

Sea bird* and Island* and Plant* 391 121

Sea bird* and Island* and Predator* 426 182

Sea bird* and Island* and Rodent* 97 25

Seabird* and Island* and Conservation 871 231

Seabird* and Island* and Human* 342 336

Seabird* and Island* and Invasive 131 124

Seabird* and Island* and Mammal* 626 267

Seabird* and Island* and Plant* 349 208

Seabird* and Island* and Predator* 685 594

Seabird* and Island* and Rodent* 179 130

Total: - 23,141

Table 3: - Table showing all of the inclusion criteria used to cut down the studies found.

Inclusion Criteria

Predators only

Mammals only

Effects to productivity

Effects to clutch size

Only studies with full eradication (defined in text)

Native island birds only

Marine birds only

No plants, diseases or humans

Sample size needed to be present

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Figure 1- Flow chart showing how many studies that were found in the search, how many were left once duplicates had been removed, once studies that weren't within the inclusion criteria, how many were left once the full-text had been assessed for eligibility. The last part of the flow chart is showing how many studies were included in qualitative synthesis and quantitative synthesis. (Diagram is a template from Moher et al 2009)

Studies included in quantitative synthesis

(meta-analysis) (n = 7)

Full-text articles excluded, with reasons

(n =2)

Full-text articles assessed for eligibility

(n = 9)

Records excluded (n = 10,764)

Records screened (n = 41)

(Appendix; Table 3)

Records after duplicates removed (n = 10,805)

Identification

Eligibility

Included

Screening

Records identified through database searching

(n = 23,141)

Results and Discussion

As stated before the effect size in this study is the observation in population changes

for marine birds after eradication of invasive species. If the effect size is at 0, no effect has

been seen and if the value is a negative number, then a negative effect size has been see

(Rosenburg et al 2000). All of the variables found in this study have a positive effect size

(Table 4), which shows successful eradication of invasive species has a positive effect on

marine bird populations. Fig 2 is a funnel plot showing the positive effect observed for 5

variables. It also shows the larger the effect size, the more of the total variance the effect

accounts for.

Chick mortality (Zr = 0.46; df = 2; CI = 0.29 to 0.63) (Table 4) and breeding success

(Zr = 0.53; df = 20; CI = 0.49 to 0.48) (Table 4) are strongly related to eradication of invasive

predators and showed to be significant (p < 0.05). Predation, egg-stage survival and nest

failure all have a small but positive effect size (Fig 2), it shows that eradication has a positive

effect on these variables but other factors could still be affecting them. Predation and egg

stage survival do not show to be significant (p < 0.05; CI = -0.36 to 0.49; -0.06 to 0.28;

respectfully).

In this study, predation is defined as chick, egg or adult predation that has occurred

after eradication of the main invasive species that has been defined as fully eradicated from

the island. Fig 2 shows predation on the marine birds has a slight positive (Zr = 0.06; Table

4) effect even after successful eradication has been achieved. Some studies stated that there

were more than one predator present on the island and no or failed attempts of eradication

had occurred for them (Appendix; Table 3).

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Table 4: - Table showing the number of studies for 5 different variables measured to represent how seabird populations change after eradication of invasive species, the effect size of these studies, the degrees of freedom and the 95% confidence interval. Table also shows the mean effect size and confidence interval.

Class Number of Studies

Effect Size (zr)

Degrees of Freedom (df)

95% Confidence Interval (CI)

Breeding Success

21 0.53 20 0.49 to 0.58

Egg-Stage Survival

3 0.11 2 -0.06 to 0.28

Nest Failure 3 0.18 2 0.04 to 0.32Predation 2 0.06 1 -0.36 to 0.49

Chick Mortality

3 0.46 2 0.29 to 0.63

Mean 0.33 0.30 to 0.36

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Although there is a positive effect of the removal of the invasive species on nest

failure (Zr = 0.18; Table 4), other factors can affect marine birds’ nests and how successful

they are at breeding. Where marine birds select to have their nests has a correlation with

failure. Marine birds that nest in burrows select appropriate nesting sites on soil and thermal

properties which are going to give them the least chance of nest failure and the best chance of

breeding success. Soil depth is the most important factor for a successful burrow, as it keeps

the nest warm allowing both parents to leave the egg or chick to feed (Buxton et al 2015).

Studies have shown that because of direct consumption by the invasive species there is a

negative effect on the island ecosystems (Caut et al 2005; Le Corre et al 2015). Rattus spp are

particularly damaging on the islands environment because they are opportunistic feeders, they

will feed on the vegetation with or without marine birds breeding on the island. They

continue to feed on vegetation until that vegetation is no longer available and move on (Caut

et al 2005). Fig 3 shows that even after eradication of an invasive species the islands

ecosystem takes at least 15 years to recover (Jones et al 2010, Kappas and Jones 2015). As

soil depth is an important factor in nest and breeding success and islands ecosystems take

time to recover, this could explain why nest failure has a small effect size compared to

breeding success and chick mortality (Buxton et al 2015; Kappas and Jones 2014).

Chick mortality shows to have a high correlation with eradication (Z = 0.46) (Fig 2;

Table 4). However in 2008, Hughes et al found that Onychoprion fustcata populations

(Appendix; table 1) increased after successful eradication in 2003 of Felis silvestris on

Ascension Island (Appendix; table 2), but high chick mortality still occurred due to starvation

and Rattus spp predation. With F.silvestris successfully eradicated Rattus spp have become

the top predator on the island. The rodents were not observed at predating on chicks until

after the eradication of F.silvestris had occurred.

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Table 5: - Table showing three individual studies of the same island at different years after successful eradication in 2002 and how it was observed to effect the native bird and what variable it affected – Full table 3 in Appendix

Author Island Invasive Spp

Native Spp Variable Observation

Jones et al 2005

Anacapa Island

R. rattus Synthliboramphus hypoleucus

Predation 97% of chicks survived

Whitworth et al2005

Anacapa Island

Rattusrattus

S. hypolecucus Nest Site Selection

Increased from 36% to 51% in 2

yearsHatching Success

Increased from 42% to 80% in 2

yearsPredation Decreased from

52% to 7% in 2 years

Whitworth et al 2013

Anacapa Island

Felis catus

Rattus spp

Synthliboramphus scrippsi

S. hypolecucus

Hatching Success

First 8 years had a gradually increase

Anacapa Island (11 miles off the coast of California) has steep, lava rock cliff holds

numerous crevices that are particular important for breeding marine birds. These marine birds

ave become increasingly rare due to invasive species (R. rattus and F. catus) since the 1940s.

40% of Synthliboramphus scrippsi (Appendix, Table 1) nests showed signs of Rattus spp

predation. In the mid 1990s conservation groups looked into how these invasive species could

be eradicated from the island. In 2001, the eradication methods started, by autumn 2002 the

eradication methods had been successful (Whitworth et al 2009). Since then the marine bird

colonies have been monitored (Table 5 – Full table found in Appendix; Table 3). After the

eradication predation on Synthliboramphus hypoleucus eggs and chicks took 2 years to

decrease from 52% of eggs and chicks, to only 7% of the juvenile populations being predated

on (Whitworth et al 2005). Predation still occurred on the island as only R. spp had been fully

eradicated, F. catus numbers had decreased but were still observed on the island.

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Due to this decrease in predation, hatching success increased from 43% to 80% over

the same 2 years and 95% of these hatchlings successfully fledged the nest (Whitworth et al

2005, Jones et al 2005). However, frequency of nests observed did not increase as rapidly as

these variables. There was only a 15% increase in frequency of nests found on the island

(Whitworth et al 2005). In 2013, Whitworth et al observed the same gradually incline in

marine bird species as discussed previously (Fig 3). They observed that in the first 8 years

after the successful eradication of R. spp there was a gradually increase in the marine bird

populations and nests. However in the first 2 years a higher percentage of chicks survived to

fledging due to the lack of predation.

These studies show that eradication methods do have a positive effect on marine

bird’s chicks and eggs in the first stages after eradication as there is less predation but over

time has a positive effect on the breeding population.

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Figure 2: - Forrest Plot showing each variable plotted using its effect size (Zr - FIsher Z-Test) and it's error bars (N = How many studies were included in the Forrest Plot).

During this study, limitations were met, the main whilst extracting the data for

analyse being that not all studies write the results into the same format or provide sufficient

data (i.e. sample size or statistical analyse) to convert. Due to this, more studies were used in

a qualitative manner than a quantitative (Appendix; Table 3), although both show that there is

a positive effect to seabird populations after successful eradication methods of invasive

species.

Another limitation whilst looking through studies for available data, was that although

some of the studies used the same variables, they were described in a different matter. Cooper

et al (1995) defined breeding success as the percentage of burrows that were still occupied at

the end of breeding season, whereas Ratcliffe et al 2010 defines breeding success as the mean

percentage of hatchlings that fledged successfully. Some of the studies with multiple variable

measurements also stated that there were more than one invasive species on the island,

however that made it clear if these species were still present and what effect they were having

on the native species. Due to this, those studies were removed from this study as this was not

classed as a full eradication.

Although these limitations were met, all of the studies showed that the successful

eradication of invasive species from islands had a positive effect on the native seabird

populations. Although there is a positive effect, they do not recover immediately. In 2014

Kappas and Jones theorised that seabird populations would need to recover passively and

actively for the islands ecosystem to restore itself (Fig 3).

The aim of this study was to see if the eradication of predatory invasive species on

islands has an effect on the native seabird populations by conducting a Meta analyse on

primary and independent studies. The mean effect size of all 7 studies was 0.53, this showed

to be significant (p < 0.05; Mean CI = 0.49 to 0.58). This shows that there is an overall

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positive effect on seabird populations after invasive species have been eradicated from the

island. In Meta win, a fail-safe analyse was performed in order to see how many unpublished

studies would need to be out there in order to invalidate the conclusions drawn about the

overall significance of the results. This was analysed using Rosenthal’s method. 12486

(variable analyse) and 7999 (individual studies) unpublished studies are unlikely, further

showing the overall significance of these results is valid (Rosenberg et al 2000) and the aim

of the study has been met.

Figure 3: Theoretical trajectories island ecosystems could take following eradication. 1. Solid line shows island conditions improve to pre-invasion conditions passively. 2. Hatched line shows islands are locked into a degraded state until seabird restoration is initiated after which the systems recover. 3. Box shows the island does not recover passively and since no furhter restorationis initiated is remains in a invasive species free but degraded state. (Kappas and Jones 2014)

WORD COUNT = 3120

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Disclaimer

The views in this dissertation are those of the others and do not reflect in anyway of

studies used or the opinions of the University of York

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34) Matias, R. and P. Catry (2008). The diet of feral cats at New Island, Falkland Islands, and impact on breeding marine birds. Polar Biology 31(5) 609-616.

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35) Medina, F. M., et al. (2011). A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology 17(11) 3503-3510.

36) Meek, P. D., et al. (2011). Eradication of Black Rats Rattus rattus L. from Bowen Island, Jervis Bay NSW. Australian Zoologist 35(3) 560-568.

37) Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews andMeta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed1000097

38) Olivera, P., et al. (2010). Successful eradication of the European rabbit (Oryctolagus cuniculus) and house mouse (Mus musculus) from the island of Selvagem Grande (Macaronesian archipelago), in the Eastern Atlantic. Integrative Zoology 5(1) 70-83.

39) Oppel, S., et al. (2014). Habitat-specific effectiveness of feral cat control for the conservation of an endemic ground-nesting bird species. Journal of Applied Ecology 51(5) 1246-1254.

40) Ratcliffe, N., et al. (2010). The eradication of feral cats from Ascension Island and its subsequent recolonization by marine birds. Oryx 44(1) 20-29.

41) Ringler, D., J. C. Russell and M. Le Corre (2015). Trophic roles of black rats and seabird impacts on tropical islands: Mesopredator release or hyperpredation? Biological Conservation 185 75-84.

42) Robinson, S. A. and G. R. Copson (2014). Eradication of cats (Felis catus) from subantarctic Macquarie Island. Ecological Management & Restoration 15(1) 34-40.

43) Rosenberg, M. S., D. C. Adams, and J. Gurevitch. 2000. MetaWin: Statistical Software for Meta-Analysis. Version 2.0. Sinauer Associates, Sunderland, Massachusetts

44) Russell, J. C. and N. D. Holmes (2015). Tropical island conservation: Rat eradication for species recovery. Biological Conservation 185 1-7.

45) Russell, James Charles, David Robert Towns, and Michael Norman Clout. "Review of rat invasion biology: implications for island biosecurity." Science for conservation 286 (2008).

46) Sekercioglu, C. H. (2006). Increasing awareness of avian ecological function. Trends in Ecology & Evolution 21(8) 464-471.

47) Tabak, M. A., et al. (2015). Rat eradication and the resistance and resilience of passerine bird assemblages in the Falkland Islands. Journal of Animal Ecology 84(3) 755-764.

48) VanderWerf, E. A., et al. (2014). Increase in Wedge-tailed Shearwaters and Changes in Soil Nutrients following Removal of Alien Mammalian Predators and Nitrogen-fixing Plants at Kaena Point, Hawaii.Restoration Ecology 22(5) 676-684.

49) Wanless, R. M., et al. (2012). Predation of Atlantic Petrel chicks by house mice on Gough Island. Animal Conservation 15(5) 472-479.

50) Whitworth, D. L., et al. (2005). Initial recovery of Xantus's Murrelets following rat eradication on Anacapa Island, California. Marine Ornithology 33(2) 131-137.

51) Whitworth, D. L., Carter, H. R., Koepke, J. S., & Gress, F. (2008). Nest monitoring of Xantus’s Murrelets at Anacapa Island, California: 2007 annual report. Unpublished report, California Institute of Environmental Studies, Davis, California.

52) Whitworth, D. L., H. R. Carter and F. Gress (2013). Recovery of a threatened seabird after eradication of an introduced predator: Eight years of progress for Scripps's murrelet at Anacapa Island, California.Biological Conservation 162 52-59.

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54) Zino, F., et al. (2008). Was the removal of rabbits and house mice from Selvagem Grande beneficial to the breeding of Cory's shearwaters Calonectris diomedea borealis? Oryx 42(1) 151-154.

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Appendix

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Table 1: - List of Latin names and common names of marine birds

Latin Names Common NamesPterdroma phaeopugia Dark Rumped Petrel Scula dactylatra Masked BoobyScula leycogasta Brown BoobySynthliboramphus hypolecucus

Guadalupe murrelet

Synthliboramphus scrippsi Scripps’s murreletOnychoprion fustcata Sooty terns

Table 2: - List of Latin names and common names of invasive predators

Latin Names Common NamesRattus rattus Black rat

Felis silvestris / catus Feral cat

Acridotheres tristis Common Mynas

Table 3: - Table showing the 41 studies that were full text screened for data. (NB = what results the study found without showing with statistics, S = Statistical analysis used, U = studies included in this study, Y = Included/Yes, N = Not included/No, S.s = If sample size was stated in the study or not, S.E = If the invasive species was fully eradicated from the island or not)

AuthorYear

Island Invasive Species

S.E

Native Species

Variable S.s

S NB U

Algar et al

(2011)

Rottnest Felis catus

Y Mammal Breeding Population

N N Increase in population

N

Bolton et al

(2014)

Steeple Jason

Grand Jason

M.musculus

N Garrodia nereis

Oceanites oceanicus

Predation N N High rates of egg and chick loss.

N

Bourgeois et al

(2013)

Zembra Rattus rattus

Y Puffinus yelkonan

Breeding Population

N N Increase in population

N

Brodier et al

(2011)

Kerguelen

Archipelago

Oryctolagus

cuniculus

Y Halobaena caerulea

Pachyptila desolata

Pelecanides georgicus

Breeding Population

N Y Increase in population

N

Buxton et 92 None Y 132 Species Breeding N Y - Increase in N

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al(2014)

Specified Population Models

population

Buxton et al

(2015)

5 New Zealand

Rattus exulans

Y Pterodroma macroptera

Puffinus gavia

Puffinus carneipes

Puffinus assimilis

Pelecanides urinatrix

Puffins griseus

Pterodroma pycrofti

Nest Site Selection

N N A distinct patternof high

nestdensities

afterrat

eradicationMore chicks

Ringed.

N

Capizzi et al

(2010)

Italian R.rattus Y Calonectris diomedea

P.yelkonan

Breeding Pairs

N Y Increase in breeding

pairs

N

Caut et al (2008)

Surprise R.rattus Y Sula leucogaster

Sula dactylatra

Puffinus pacificus

Predation Y N 20% of eggs and chicks were

predated on

NRattus

Norvegicus

Y

R.exulans YMus

musculusN

Cooper et al

(1995)

Marion Felis silvestris

Y P.macroptera

Procellaria aequinctialis

H.caerulea

Breeding Success

Y Y See text for more details

Y

Girardet et al

(2001)

Little Barrier

F.silvestris

Y 14 species Bird Population

N N 3 species had

increased, 2 species

had decreased

and 9 N

changes

N

R.exulans N

Hervias et al

(2013)

Corvo Rattus spp

Y C.diomedea Breeding Success

Y N Low breeding Success,

F.silvertus most

N

Mus domesticu

s

N

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destructiveFelis catus

Y

Howald et al

(2010)

Anacapa R.rattus Y S.hypolecus None N N Eradication proved

positive in other

areas, this study had a

theory it would

improve here too

Hughes et al

(2008)

Ascension

F.silvestris

Y Onychoprion fustcata

Breeding Success

Incubation Success

Egg-Stage Survival

Nest Failure

Predation


Y

R.rattus NAcridoth-eres tristis

N

Breeding Population

N N Population Increased over time

N

Igual et al(2008)

Congreso R.rattus Y C.diomedea Breeding Success

Egg-Stage Survival

Chick Mortality


Y

Imber et al

(2000)

Whale - 2

colonies

R.rattus Y P.macroptera

Breeding Success


Y

Jones et al

(2005)

Anacapa R.rattus Y Synthliboramphus

hypoleucus

Predation N Y Predation reduced

and 97%of chicks

survived

N

Jones et al

(2010)

15 New Zealand

Rattus exulans

N None Soil, plant and spider

ratio

N N No recovery

for 15 years and then

rapid recovery

N

Jouventin et al

Crozet R.rattus Y P.aequinoctialis

Breeding Success

Y Y See text for more

Y

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(2003)Nest

Failure

details

Kappes and Jones

(2014)

None specified

None specified

N Fractercula arctica

Breeding Pairs

N N Took 27 years

to reach 100 pairs

N

Kazuto et al

(2010)

Bonin , Japan

R.rattus Y Bulweria bulwerii

Predation N Y No local extinction

due to prompt

eradication

N

Latorre et al

(2013)

Mediterranean

R.rattus N Gulls Egg predation

N N Rats predate on

all sized eggs

N

Lavers et al

(2010)

None specified

None Specified

Y Birds Bird Population

N Y On average all populations increase by 25.3%

N

Le Corre et al

(2015)

Tromelin R.Norvegicus

Y S.dactylatra

Sula sula

Breeding Pairs

N Y Slow increase

then rapid

increase after 8

years of eradication

of R.rattus

N

M.musculus

N

Marie et al

(2014)

Moku'auia

R.rattus N P.pacificus Breeding Population

N Y Chicks were

higher in years

with N

predators (3,127)

than years with

predators (1,275)

N

Masuda and

Jamieson(2013)

New Zealand

Rattus spp

N Terrestrial Bird

Breeding Success

N N 31.5% decline in 12

months

N

Matias and Catry

(2008)

New , Falkland

F.catus N P.aequiNctialis

Breeding Success

Y Y 2005 breeding success -

48%. 2006

breeding success -

N

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44%Meek et

al(2001)

Bowen R.rattus Y Burrowing Marine birds

Predation N N R.rattus were

observed feeding at the

seabird burrows before

eradication

N

Medina et al

(2011)

120 F.silvestris

N/A

123 Birds IUCN Red List

N N 14% of global

extinctions is

due to cats and

threat 8% of birds

N

Olivera et al

(2010)

Great Salvage

M.musculus

O.cuniculus

Y C.diomedea

B.bulweria

Puffinus assimilis

Pelagodroma marina

Oceanodroma castro

Breeding Population

N N N

Oppel et al

(2014)

St Helena

F.catus N Charadrius sanctaehelen

ae

Nest Survival

N N Eradication had

a positive effect

on nest survival

N

Ratcliffe et al

(2010)

Ascension

F.silvestris

N S.dactylatra

F.aquila

Breeding Success

N Y Less adult carcasses found - 4,500

per year to negligible

levels

N

Ringer et al

(2015)

Europa

Juan de Nva

R.rattus Y Phaethon rubricasuda

Breeding Success

Predation


Y

Robinson and

Copson (2014)

Macquarie

F.catus Y Procellaria cinerea

Breeding Population

N N Not been recorded breeding

on the for 100 years but returned

N

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after eradication

Russel and

Holmes(2015)

Tropical Rattus spp

Y None Populations N N Few decades to recover

populations

N

Tabak et al

(2015)

Falkland R.norvegicus

Y Terrestrial Bird

Relative abundance

N N Abundances were lower on with rats

than those

without

N

Vanderwerf et al(2014)

Kaena Point,

Hawaii

Canis familiaris

F.cattus

Herpestes auropunc

tatus

Rattus spp

Y Puffins pacificus

Populations N N Maps showing satellite

images of population

s growing over time

N

Wanless et al

(2012)

Gough M.musculus

N Pterodroma incerta

Nest Survival

N Y In 2007, only one

chick fledge

Successfully

N

Whitworth et al(2005)

Anacapa R.rattus Y S.hypolecus Nest Site Selection

N N Increased from

36% to 51% in 2

years

N

Hatching Success

N N Increased from 42%to 80% in

2 years

N

Predation N N Decreased from

52% to 7% in 2 years

N

Whitworth et al (2013)

Anacapa F.catus

Rattus spp

Y Synthliboramphus scrippsi

Hatching Success

N N After 8 years,

success rate

gradually increased

N

Wiles(2003)

Guam, Mariana

None Specified

Y 27 marine birds

Breeding Population

N N Decrease in

populations have

N

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prompted conservati

on actsZino et al

(2008)Selvage

m Grande

O.cuniculus

Y C.diomedea Breeding Success


Y

M.musculus

N N Y 23% more successful fledglings

5 years after

eradication

N

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