ArticlePDF Available

Abstract and Figures

Introduced house mice Mus musculus have recently been discovered to be significant predators of chicks of Tristan albatrosses Diomedea dabbenena and several burrowing petrels at Gough Island. We summarize evidence for mouse attacks on albatross chicks at sub-Antarctic Marion Island, where mice are also the only introduced mammal following the eradication of feral cats Felis catus in the early 1990s. Wounds consistent with mouse attacks have been found on wandering albatrosses Diomedea exulans since 2003 and dark-mantled sooty albatrosses Phoebetria fusca in 2009. To date, attacks on wandering albatross chicks have been infrequent, affecting <1% of chicks in study colonies, and only about half of the attacks have been fatal. Small chicks may also die when mouse burrows collapse under chicks, trapping them. Mouse attacks appear to be a recent phenomenon, supporting the contention that mice pose a significant threat when they are the only introduced mammal species. Ongoing monitoring is needed to assess whether the impacts of mice increase over time. Our observations add impetus to calls for the eradication of mice from Marion Island.
Content may be subject to copyright. Downloaded: 11 Dec 2013 IP address:
Antarctic Science 22(1), 39–42 (2010) & Antarctic Science Ltd 2009 doi:10.1017/S0954102009990459
Evidence of mouse attacks on albatross chicks on sub-Antarctic
Marion Island
Percy FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa
Abstract: Introduced house mice Mus musculus have recently been discovered to be significant predators
of chicks of Tristan albatrosses Diomedea dabbenena and several burrowing petrels at Gough Island. We
summarize evidence for mouse attacks on albatross chicks at sub-Antarctic Marion Island, where mice are
also the only introduced mammal following the eradication of feral cats Felis catus in the early 1990s.
Wounds consistent with mouse attacks have been found on wandering albatrosses Diomedea exulans since
2003 and dark-mantled sooty albatrosses Phoebetria fusca in 2009. To date, attacks on wandering albatross
chicks have been infrequent, affecting ,1% of chicks in study colonies, and only about half of the attacks
have been fatal. Small chicks may also die when mouse burrows collapse under chicks, trapping them.
Mouse attacks appear to be a recent phenomenon, supporting the contention that mice pose a significant
threat when they are the only introduced mammal species. Ongoing monitoring is needed to assess whether
the impacts of mice increase over time . Our observations add impetus to calls for the eradication of mice
from Marion Island.
Received 29 June 2009, accepted 6 August 2009
Key words: alien species, conservation, Diomedea exulans, Mus musculus, Phoebetria fusca
Until recently, populations of house mice Mus musculus L.
introduced to oceanic islands were considered to have little
impact on breeding bird populations. However, recent
observations at Gough Island have shown significant
impacts on both seabirds and endemic landbirds (Cuthbert
& Hilton 2004, Wanless et al. 2007, 2009, Ryan &
Cuthbert 2008). Wanless et al. (2007) argued that mice are
likely to be mos t problematic at islands where they are the
only introduced mammal. In the absence of competition
and predation by other, larger introduced mammals, mice
attain high population densities that may trigger predatory
behaviour. Sub-Antarctic Marion Island is one such island.
Mice were introduced to Marion presumably by sealers
sometime before 1818, and cats Felis catus L.
were brought to the island in 1949 to control mice at
the weather station, resulting in a feral population (Cooper
2008) that decreased breeding success of burrowing petrel s
and caused local extinction of some species (De Villiers &
Cooper 2008). Cats were eventually eradicated from the
island by 1992/93 (Bester et al . 2002), leaving mice as the
only introduced mammal.
Marion Island supports significant breeding populations
of several threatened or near-threatened albatrosses: 22%
of the world’s wandering albatrosses Diomedea exulans
L. (Vulnerable), 9% of dark-mantled sooty albatrosses
Phoebetria fusca (Hilsenberg) (Endangered), 7% of grey-
headed albatrosses Thalassarche chrysostoma (Forster)
(Vulnerable) and 3% of light-mantled sooty albatrosses
P. palpebrata (Forster) (Near-Threatened; Ryan et al.
in press). These species are listed as threatened largel y
due to accidental mortality on fishing gear, especially
longlines (BirdLife Interna tional 2008 -
Both species of giant petrels Macronectes spp. (Near-
Threatened) are also common surface-nesters at the island,
and at least nine other species of petrels breed in burrows
on the island, including white-chinned petrels Procellaria
aequinoctialis L. (Vulnerable; Ryan & Bester 2008). In this
paper we report evidence of mouse attacks on seabird
chicks on Marion Island following the eradica tion of cats
from the island.
Study area and methods
Marion Island (46854'S, 37 845'E, 290 km
) has a vegetated
coastal plain that rises to volcanic scoria peaks (highest
point 1243 m). The island is home to large breeding
populations of seabirds and pinnepeds, and ornithological
research has been conducted on the island since 1965
(Cooper & Brown 1990, Ryan & Bester 2008), with regular
monitoring of breeding success of three wandering
albatross (c. 195–270 nests per annum) and three northern
giant petrel (c. 70–135 nests per annum) colonies since the
1980s (Cooper et al. 2001, Nel et al. 2003), and one grey-
headed albatross (c. 90–140 nests per annum) colony since
1996 (Ryan et al. 2007). In these study colonies, breeding
attempts were monitored from egg laying to fledging. Once
the chicks were no longer brooded, they were checked
every 2–4 weeks, and any wounded chicks recorded.
39 Downloaded: 11 Dec 2013 IP address:
Ad hoc observations have also been made of albatross chicks
outside study colonies, including chicks of light-mantled and
dark-mantled sooty albatrosses, as well as small numbers
of white-chinned and great-winged petrel Pterodroma
macroptera (Smith) chicks observed in monitored burrows
of low intensity studies. Wounded chicks were photographed,
and where feasible, their fate was checked by repeated visits.
Since the mid-1980s, annual counts of the entire breeding
population of wandering albatrosses on Marion Island have
been conducted during early incubation (January), and counts
of large chicks have been made prior to fledging (October),
allowing crude estimates of breeding success around
the island.
Since 2003, 12 wandering albatross chicks have been found
on Marion Island with wounds on their backs, rumps and
flanks that were identical to those exhibited by Tristan
albatross Diomedea dabbenena Matthews chicks following
attacks by mice (Fig. 1). Six were recorded among
study colony chicks, with 0–2 records per year (0–2% of
Fig. 1. a. A well-feathered wandering albatross chick on Marion
Island exhibits wound on its lower back (photo: M.G.W.
Jones) very similar to b. those inflicted by mice on a Tristan
albatross chick on Gough Island (photo: P.G. Ryan).
Table I. Numbers of wandering albatross chicks attacked and killed by
mice in relation to breeding effort and success in study colonies at
Marion Island since the first record of a mouse attack in 2003.
2003 2004 2005 2006 2007 2008 Total
Eggs laid 268 197 242 199 257 249 1420
Chicks hatched 204 153 173 132 213 223 1098
Chicks attacked 201201 6
Chicks killed 101000 2
Breeding success (%) 80 71 79 77 72 64 74
Fig. 2. The head and neck wounds exhibited by one of nine
dark-mantled sooty albatross chicks near the south-western
point of Marion Island in April 2009 (photo: P.G. Ryan).
40 M.G.W. JONES & P.G. RYAN Downloaded: 11 Dec 2013 IP address:
chicks that hatch; Table I). The other six were observed
incidentally, mostly close to the research station, where
observer effort is greatest, but one attack occurred on the
island’s west coast, indicating that attacks occur around the
island. The fates of 11 wounded chicks were followed, of
which six (55%) died. Counts of incubating adults and large
fledglings showed no consistent regional differences in
breeding success around the island.
There has been no evidence of mouse attacks on grey-
headed albatross or northern giant petrel chicks, either
in the study colonies or from incidental observations.
However, in April 2009 localized attacks were recorded on
dark-mantled sooty albatross chicks at Marion Island.
Seven of 19 large chicks on two ledges of an inland cliff in
the south-west of the island (Old Sea Cliffs, Toffee Lava)
bore open wounds on the backs of their heads and/or necks
(Fig. 2) similar to wounds observed on some Tristan
albatross chicks on Gough Island (K. Cita, unpublished
photographs). Another dark-mantled sooty albatross chick
bearing similar wounds was observed on sea cliffs near
Bullard Beach on the eastern coast of the island during the
same period (Bo Bonnevie, personal communicatio n 2009).
There have been no incidental observations of attacks on
other seabirds. Mouse activity has been seen in many petrel
burrows, including mice running over and around chicks,
but no definite attacks have been recorded.
Mouse holes are frequently found in nests of wandering
albatrosses and, to a lesser extent, in grey-headed albatross
nests. Many such mouse holes lead into the base of the nest
cup where the mice may obtain a thermal advantage,
especially in winter (Sinclair & Chown 2006). In April 2009
two small wandering albatross chicks died under brooding
adults after they apparently were unable to extricate
themselves from large hollows (c. 10 cm in diameter) in the
nest cup. After death, their carcases required considerable
force to be pulled from these hollows. It is probable that mouse
nests had caved in under the chicks, indirectly killing them.
Although mice have not been observed attacking albatross
chicks on Marion Island, the nature of the chicks’ wounds
strongly suggests that mice were responsible. Based on our
observations, currently , 1% of wandering albatross chicks
at Marion Island are attacked by mice. At Gough Island,
mouse attacks on Tristan albatrosses were overlooked
previously because of spatial differences in the frequency
of attacks (Cuthbert & Hilton 2004), but this does not
appear to be the case at Marion Island. It is also probable
that the attacks at Marion only commenced in the last few
years, because monitoring of wandering albatross chicks
has been conducted at the same intensity since the study
colonies were established in the early 1980s without any
records of wounded birds.
Wanless et al. (2007) hypothesized that mice have a greater
effect on native vertebrates when they are the sole introduced
mammal on an island. This is because their populations
increase when the comb ined effects of dominance,
competition and predation are removed. Our observations
lend further support to this hypothesis because the first mouse
attacks were recorded a decade after the eradication of feral
cats, the only other introduced mammal on the island. The
worrying conclusion is that mouse attacks might be expected
to increase at Marion Island, especially if mouse populations
benefit from global warming (de Villiers & Cooper 2008).
This would be cause for serious concern given the large
proportion of the global population of wandering albatrosses
that breeds on Marion Island (Ryan et al. in press). Given the
serious impacts of mice on insular populations when they are
the sole alien mammal, precautions should be taken if
competing aliens are eradicated. Every attempt should be
made to eradicate mice as well as other predatory mammals.
The apparent attacks on dark-mantled sooty albatrosses are
also cause for alarm. One sooty albatross chick has been
recorded killed by mice on Gough Island (Cuthbert et al.
unpublished), but this is the first occurrence of multiple
attacks on chicks in a single colony. Sooty albatrosses are
listed as Endangered (BirdLife International 2008), and are
the only albatross species whose population is decreasing at
Marion Island (Ryan et al. in press). It is also likely that
burrowing petrels are victims of mouse predation at Marion
Island, but that it goes undetected because they are less easily
observed and are not currently studied at this island. In the
1980s, blue petrel Halobaena caerulea (Gmelin) chicks were
apparently attacked by mice on Marion Island (Fugler
et al. 1987). South Africa is a party to the Agreement on
the Conservation of Albatrosses and Petrels (ACAP) and as
such has international obligations to ensure the conservation
of these birds. Continued monitoring of seabird chicks on
Marion Island for signs of mouse predation is required. Our
study provides further support for the need to attempt to
eradicate mice from Marion Island.
We thank Bo Bonnevie, Linda Clokie, Nico de Bruyn,
Quentin Hagens, Henk Louw, Edith Mertz, Cornelia
Niewenhuys, Samantha Petersen, Cheryl Tosh and Paul
Visser, for their observations. Research on Marion Island is
supported by the South African National Antarctic Programme
through the National Research Foundation, with logistical
support from the Directorate: Antarctica and Islands of the
former Department of Environmental Affairs and Tourism.
P.J.J., SKINNER,J.D.,HOWELL,P.G.&NAUDE,T.W.2002.Areviewofthe
successful eradication of feral cats from s ub-Antarctic Marion Island, southern
Indian Ocean. South African Journal of Wildlife Research, 32,6573.
COOPER, J. 2008. Human history. In CHOWN, S.N. & FRONEMAN,W.,eds.
The Prince Edward Islands: land-sea interactions in a changing
ecosystem. Stellenbosch: Sun Media, 331–350.
OOPER,J.&BROWN, C.R. 1990. Ornithological research at the sub-
Antarctic Prince Edward Islands: a review of achievements. South
African Journal of Antarctic Research, 20, 40–57.
&WILLIAMS, A.J. 2001. Aspects of the breeding biology of the
northern giant petrel (Macronectes halli) and the southern giant petrel
(M. giganteus) at sub-Antarctic Marion Island. International Journal of
Ornitholology, 4, 53–68.
UTHBERT,R.&HILTON, G. 2004. Introduced house mice Mus musculus:a
significant predator of endangered and endemic birds on Gough Island,
South Atlantic Ocean? Biological Conservation, 117, 483–489.
E VILLIERS,M.S.&COOPER, J. 2008. Conservation and management. In
HOWN,S.N.&FRONEMAN,W.,eds. The Prince Edward Islands: land-sea
interactions in a changing ecosystem. Stellenbosch: Sun Media, 301–324.
FUGLER, S.R., HUNTER, S., NEWTON, I.P. & STEELE, W.K. 1987. Breeding
biology of blue petrels Halobaena caerulea at the Prince Edward
Islands. Emu, 87, 103–110.
EL, D.C., TAYLOR, F., RYAN, P.G. & COOPER, J. 2003. Population
dynamics of wandering albatrosses Diomedea exulans at sub-Antarctic
Marion Island: long-line fishing and environmental influences. African
Journal of Marine Science, 25, 503–517.
YAN, P.G. & BESTER, M.N. 2008. Pelagic predators. In CHOWN,
S.N. & F
RONEMAN, W., eds. The Prince Edward Islands: land-sea
interactions in a changing ecosystem. Stellenbosch: Sun Media,
YAN, P.G. & CUTHBERT, R.J. 2008. The biology and conservation status of
the Gough bunting Rowettia goughensis. Bulletin of the British
Ornithology Club, 128, 242–253.
YAN, P.G., PHILLIPS, R.A., NEL, D.C. & WOOD, A.G. 2007. Breeding
frequency in grey-headed albatrosses. Ibis, 149, 45–52.
in press. Recent population estimates and trends in numbers of
albatrosses and giant petrels breeding at the sub-Antarctic Prince
Edward Islands. African Journal of Marine Science..
SINCLAIR, B.J. & CHOWN, S.L. 2006. Caterpillars benefit from thermal
ecosystem engineering by wandering albatrosses on sub-Antarctic
Marion Island. Biology Letters, 2, 51–54.
2007. Can predation by invasive mice drive seabird extinctions? Biology
Letters, 3, 241–244.
UTHBERT,R.&HILTON, G.M. 2009. From both sides: dire
demographic consequences of carnivorous mice and longlining for the
critically endangered Tristan albatrosses on Gough Island. Biological
Conservation, 142, 1710–1718.
... Rats are usually the focus of island restoration and conservation interventions, yet house mice also have ecosystem-altering ramifications (Crafford 1990;Fukami et al. 2006;Wanless et al. 2007;Angel et al. 2009). Initially thought to pose minimal risk to seabirds, mice recently entered the spotlight of island conservation when they were discovered depredating seabirds (adults and chicks alike), in some cases leading to a significant decline in species' breeding success (Cuthbert and Hilton 2004;Wanless et al. 2007Wanless et al. , 2009Wanless et al. , 2012Jones and Ryan 2009;Duhr-Schultz et al. 2018;Jones et al. 2019). Starting in 2015, house mice (Mus musculus) were discovered to depredate breeding albatross on Midway Atoll National Wildlife Refuge (MANWR, Pihemanu and Kuaihelani in Hawaiian), a subtropical atoll in the north Pacific Ocean (Duhr-Schultz et al. 2016). ...
... Since USFWS currently applies a low-grade rodenticide (Agrid3-cholecalciferol) in the fall months (when albatross return to breed), we do not necessarily expect to detect albatross DNA in mouse fecal samples. However, given that mice are opportunistic omnivores and are known to consume seabirds in various island ecosystems (e.g., Jones and Ryan 2009;Davies et al. 2015), ...
Full-text available
Invertebrates are key to island ecosystems, but impacts from invasive mammalian predators are not well documented or understood. Given this knowledge gap, we studied terrestrial arthropod communities in the presence of a common invasive rodent (house mice, Mus musculus) on a subtropical atoll—Midway Atoll National Wildlife Refuge (MANWR). Here, invasive mice recently began to attack and depredate nesting seabirds, prompting a mouse eradication. Although eradication planning efforts are underway, uncertainty remains regarding the ecosystem’s response to mouse removal. As part of a pre-eradication investigation, we conducted a baseline survey of MANWR’s arthropod community structure and diversity, comparing islands with and without mice. From April 2018 to February 2020, we used pitfall traps to monitor ground-dwelling arthropods on MANWR’s Sand Island (mice present) and Eastern Island (mice absent). During our study, we captured over 450,000 specimens from 24 taxonomic units. Arthropods on MANWR form six community clusters and differ between islands and habitats. Richness is relatively similar among clusters and islands, but diversity of common and dominant taxa is significantly higher on Sand Island, as well as in anthropogenically built habitats. Arthropod communities and diversity vary marginally throughout the year; temperature and rainfall are minor environmental drivers. Additionally, anthropomorphic landscape-level alteration of MANWR may still influence arthropod communities today. Continued monitoring and research will provide better insight into how arthropod communities recover following invasive mouse eradications. Our study contributes to the body of knowledge of arthropods in the Northwestern Hawaiian Islands, arthropod community ecology, and potential mouse impacts on islands.
... Mice are known to scavenge dead seabirds and prey on live birds, but until recently, their effect was thought to be limited to smaller burrowing seabirds (Bolton et al. 2014). However, findings in the South Atlantic have revealed mouse predation on three species of albatross chicks on Gough (Cuthbert and Hilton 2004) and Marion Islands (Jones and Ryan 2010). Here, we show that, in addition to chicks, house mice (Mus musculus) prey on adult nesting LAAL on Midway Atoll. ...
... We are unaware of reports of mice acting as predators on adult nesting albatross. All other instances of mouse predation on albatross in the South Atlantic have involved smaller, downy chicks Hilton 2004, Jones andRyan 2010) or relatively larger fledgling chicks (Dilley et al. 2016). Interestingly, our necropsy sample was heavily biased toward females. ...
Full-text available
Invasive rodents on islands have adverse effects on native birds in island ecosystems, and rats are the most common culprits. Recently, house mice (Mus musculus) in the South Atlantic were found preying on three species of albatross chicks. Here, we show that house mice can also prey on nesting adult Laysan Albatross (Phoebastria immutabilis) on Midway Atoll National Wildlife Refuge (US). In contrast to mouse attacks on albatross in the South Atlantic, where mice targeted the rump and crown of chicks, on Midway, mice targeted nesting adults mainly on the back. For both regions, the outcome was similar with reduced nesting success. In the case of Midway, reduced nesting success was due to nest abandonment or mortality of one or both parents because of secondary bacterial infections. Mouse-induced mortality of adult albatross has the potential to have a more potent demographic effect because of their much higher natural survivorship once they reach adulthood.
... Most commonly, increased mortality among native vertebrate populations has been caused directly or indirectly by rats (Rattus rattus), mice (Mus musculus), cats and rabbits (Oryctolagus cuniculus). Rodents inflict significant injury and mortality among seabirds, including albatross chicks (Wanless et al., 2007;Jones and Ryan, 2010;Dilley et al., 2016). As the birds evolved without the presence of natural terrestrial predators, they are ill suited to defend themselves (Frenot et al., 2005). ...
... At Marion Island, they reached densities of >150 mice ha −1 (Matthewson et al., 1994). Cats were eradicated here in the 1990s (Jones and Ryan, 2010;Jones et al., 2019). Since 2003, mouse attacks on albatrosses (including fatally) have been noted. ...
Full-text available
The massive number of seabirds (penguins and procellariiformes) and marine mammals (cetaceans and pinnipeds) – referred to here as top predators – is one of the most iconic components of the Antarctic and Southern Ocean. They play an important role as highly mobile consumers, structuring and connecting pelagic marine food webs and are widely studied relative to other taxa. Many birds and mammals establish dense breeding colonies or use haul-out sites, making them relatively easy to study. Cetaceans, however, spend their lives at sea and thus aspects of their life cycle are more complicated to monitor and study. Nevertheless, they all feed at sea and their reproductive success depends on the food availability in the marine environment, hence they are considered useful indicators of the state of the marine resources. In general, top predators have large body sizes that allow for instrumentation with miniature data-recording or transmitting devices to monitor their activities at sea. Development of scientific techniques to study reproduction and foraging of top predators has led to substantial scientific literature on their population trends, key biological parameters, migratory patterns, foraging and feeding ecology, and linkages with atmospheric or oceanographic dynamics, for a number of species and regions. We briefly summarize the vast literature on Southern Ocean top predators, focusing on the most recent syntheses. We also provide an overview on the key current and emerging pressures faced by these animals as a result of both natural and human causes. We recognize the overarching impact that environmental changes driven by climate change have on the ecology of these species. We also evaluate direct and indirect interactions between marine predators and other factors such as disease, pollution, land disturbance and the increasing pressure from global fisheries in the Southern Ocean. Where possible we consider the data availability for assessing the status and trends for each of these components, their capacity for resilience or recovery, effectiveness of management responses, risk likelihood of key impacts and future outlook.
... The global population of Wandering Albatross is declining, mainly as a result of bycatch in longline fishing, and the species is currently listed as Vulnerable (Poncet et al. 2017, Birdlife International 2018. Several threats to Wandering Albatross populations are well documented and understood (see Jones & Ryan 2010, Pardo et al. 2017, Jones et al. 2019, but factors affecting nest-site selection, and what this would mean for the distribution and availability of future breeding sites, have not been investigated. Wandering Albatross foraging patterns, breeding success and survival are affected by wind in different ways (Weimerskirch et al. 2000, Cornioley et al. 2016, Pardo et al. 2017. ...
Full-text available
Several factors may drive bird nest‐site selection, including predation risk, resource availability, weather conditions, and interaction with other individuals. Understanding the drivers affecting where birds nest is important for conservation planning, especially where environmental change may alter the distribution of suitable nest sites. This study investigates which environmental variables affect nest‐site selection by the Wandering Albatross Diomedea exulans, the world’s largest pelagic bird. Here, wind characteristics are quantitatively investigated as a driver of nest‐site selection in surface nesting birds, in addition to several topographical variables, vegetation, and geological characteristics. Nest locations from three different breeding seasons on sub‐Antarctic Marion Island were modelled to assess which environmental factors affect nest‐site selection. Elevation was the most important determinant of nest‐site selection, with Wandering Albatrosses only nesting at low elevations. Distance from the coast and terrain roughness were also important predictors, with nests more generally found close to the coast and in flatter terrain, followed by wind velocity, which showed a hump‐shaped relationship with the probability of nest occurrence. Nests occurred more frequently on coastal vegetation types, and were absent from polar desert vegetation (generally above ~ 500 m elevation). Of the variables that influence Wandering Albatross nest location, both vegetation type and wind characteristics are likely to be influenced by climate change, and have already changed over the last 50 years. As a result, the availability of suitable nest sites needs to be considered in light of future climatic change, in addition to the impacts that these changes will have on foraging patterns and prey distribution. More broadly, these results provide insights into how a wide range of environmental variables, including wind, can affect nest‐site selection of surface nesting seabirds.
... The disease, caused by the bacterium Pasteurella multocida, appears to be responsible for the death of a large proportion of albatross chicks . Introduced rodents likely also contribute to the low breeding success of the population , as observed in other seabird populations worldwide (Cuthbert & Hilton 2004, Jones & Ryan 2009, Caravaggi et al. 2019, Holmes et al. 2019. ...
Full-text available
L’Albatros à nez jaune de l’océan indien (Thalassarche carteri) est une espèce menacée d’extinction dont la population principale, qui se reproduit sur l’île Amsterdam (Terres Australes et Antarctiques Françaises), connait un déclin et une très forte mortalité des jeunes individus depuis plusieurs décennies. La bactérie responsable du choléra aviaire, Pasteurella multocida, est suspectée comme étant à l'origine de ces mortalités et notre équipe évalue depuis plusieurs années maintenant l'utilisation d'un vaccin pour protéger les poussins, via leur vaccination directe, mais aussi celle des femelles reproductrices susceptibles de transmettre des anticorps protecteurs à leur poussin. Le vaccin utilisé est un vaccin autologue (autovaccin) spécifiquement développé par Ceva-Biovac contre une souche de la bactérie Pasteurella multocida isolée sur cadavre d’albatros. Suite à l’obtention de premiers résultats prometteurs, les objectifs de la thèse étaient d’ajuster le protocole de vaccination, mais également de mieux appréhender et décrire les processus éco-épidémiologiques en jeu au sein des populations de vertébrés de l’île Amsterdam. Ceci a reposé sur l'analyse fine du suivi de couples reproducteurs année après année, mais aussi sur l'utilisation de données éco-épidémiologiques expérimentales complémentaires, notamment une nouvelle formulation du vaccin. Une diversité de pathogènes responsables de mortalités a pu être caractérisée. L’âge optimal de vaccination des poussins parait être vers 10 jours et la vaccination des femelles reproductrices semble pouvoir protéger les poussins pendant plusieurs années, mais la forte densité de rats (Rattus norvegicus) actifs dans les colonies a rendu difficile l’identification d’un effet protecteur fort du vaccin. Les résultats obtenus améliorent la compréhension des mécanismes de circulation d'agents infectieux chez des espèces à reproduction coloniale et permettront de comparer les bénéfices relatifs attendus de différents scénarios de vaccination. Le travail montre l’importance d’intégrer des approches complémentaires, notamment du domaine biomédical et de l’écologie des populations, pour aborder la problématique de l’émergence de maladies infectieuses dans le contexte des changements environnementaux actuels.
... The disease, caused by the bacterium Pasteurella multocida, appears to be responsible for the death of a large proportion of albatross chicks . Introduced rodents likely also contribute to the low breeding success of the population (Micol & Jouventin 1995) as observed in other seabird populations worldwide (Cuthbert & Hilton 2004, Jones & Ryan 2010, Caravaggi et al. 2019, Holmes et al. 2019. ...
Breeding failure is expected to induce behavioural changes in central place foragers. Indeed, after a failed reproductive attempt, breeding individuals are relieved from having to return to their breeding site for reproductive duties and thus are less constrained than successful breeders in their movements during the remainder of the breeding season. Accordingly, they are expected to adjust their behaviour, travelling longer in distance and/or time to reach foraging grounds. They are also expected to use different foraging areas to decrease local intra-specific competition with successful breeders. We compared the at-sea behaviour and habitat use of successful and failed Indian yellow-nosed albatrosses nesting in Amsterdam Island, Southern Indian Ocean, during 2 chick-rearing seasons. Failed breeders exhibited the same at-sea foraging behaviour, travelling as far and as long as successful breeders. They also spent the same amount of time on their nest between at-sea trips. Nevertheless, habitat models revealed partial spatial segregation of failed breeders, which used specific foraging areas characterized by deeper and colder waters in addition to the areas they shared with successful breeders. Our study shows the importance of combining a range of analytical methods (spatial analysis, behavioural inferences with advanced movement models and habitat models) to infer the at-sea behaviour and habitat use of seabirds. It also stresses the importance of considering individual breeding status when aiming to understand the spatial distribution of individuals, especially when this information may have conservation implications.
Full-text available
Ego net analysis is a well-known practice in social sciences, where an ego net (EN) consists of a focal node, the ego, and its links to other nodes, called alters, and alter-alter links may also be included. An EN describes how a focal node is embedded in its interaction context. Here, I introduce EN analysis to ecology in a study of the trophic network of a sub-Antarctic land bird, Lesser Sheathbill (Chionis minor). Data originate from the sheathbill population on Marion Island in the Southern Ocean. The bird is ego and its enemies and food are alters. The EN is organized along three dimensions: habitat, interaction type, and time (from before human arrival in 1803 and until a future year 2100). Ten EN descriptors are defined, estimated, and used to track the 300 years of change in sheathbill EN structure. Since 1803, the EN has passed two major, but reversible shifts-seal exploitation in the 19th century and presence of cats from 1949 to 1991. These shifts can be read as structural changes in the sheathbill EN. In the future, a third, perhaps irreversible change is predicted, driven by climate change and a surprising, recent shift to seabird predation by House Mouse, the most detrimental of all extant invaders on Marion. In a warmer and drier future, the mouse will proliferate, and if this forces seabirds to abandon the island, their accumulation of detritus runs dry, starving a rich invertebrate detritivore fauna, which also is a key food source to sheathbills. These detritivores together with plants have also constituted the main food sources of mice. The EN descriptors quantify that story. In the future, these events may lead to a collapse of the island ecosystem, including extinction of the sheathbill-unless plans for mouse eradication are implemented.
Managing ecosystems in the face of complex species interactions, and the associated uncertainty, presents a considerable ecological challenge. Altering those interactions via actions such as invasive species management or conservation translocations can result in unintended consequences, supporting the need to be able to make more informed decisions in the face of this uncertainty. We demonstrate the utility of ecosystem models to reduce uncertainty and inform future ecosystem management. We use Phillip Island, Australia, as a case study to investigate the impacts of two invasive species management options and consider whether a critically endangered mammal is likely to establish a population in the presence of invasive species. Qualitative models are used to determine the effects of apex predator removal (feral cats) and invasive prey removal (rabbits, rats, and mice). We extend this approach using Ensemble Ecosystem Models to consider how suppression, rather than eradication influences the species community; and consider whether an introduction of the critically endangered eastern barred bandicoot is likely to be successful in the presence of invasive species. Our analysis revealed the potential for unintended outcomes associated with feral cat control operations, with rats and rabbits expected to increase in abundance. A strategy based on managing prey species appeared to have the most ecosystem‐wide benefits, with rodent control showing more favourable responses than a rabbit control strategy. Eastern barred bandicoots were predicted to persist under all feral cat control levels (including no‐control). Managing ecosystems is a complex and imprecise process. However, Qualitative Modelling and Ensemble Ecosystem Modelling address uncertainty and are capable of improving and optimising management practices. Our analysis shows that the best conservation outcomes may not always be associated with the top –down control of apex predators, and land managers should think more broadly in relation to managing bottom‐up processes as well. Challenges faced in continuing to conserve biodiversity mean new, bolder, conservation actions are needed. We suggest that endangered species are capable of surviving in the presence of feral cats, potentially opening the door for more conservation translocations.
Full-text available
Introduced mammals have devastated island nesting seabird populations worldwide. Declines in breeding seabirds on St Kilda, UK, have been linked to climate change and predation from great skuas Stercorarius skuas, but the introduced St Kilda field mouse Apodemus sylvaticus hirtensis may also play a role by feeding on adults, chicks or eggs. Here, we use stable isotopes in St Kilda mouse blood and potential dietary items to investigate their foraging ecology, specifically focussing on the importance of seabirds and marine foods in their diet. Mice were seasonally sampled at three sites on Hirta, St Kilda over three consecutive years (2010–2012). The δ13C and δ15N ratios were used in analyses, including isotope niche and dietary source mixing models, to examine foraging behaviour among locations and between seabird breeding seasons. Mice sampled in Carn Mor – where the majority of the island’s seabirds nest - had consistently higher δ13C than other locations throughout the year, with δ15N also being significantly higher for all but one comparison. The isotopic niche width (SEAs) of Carn Mor mice in each season were distinct from the other locations, and became smaller during the seabird breeding season. Dietary mixing models revealed that seabirds made up a large proportion of the diet for mice from Carn Mor, particularly during the seabird breeding season. In conclusion, our work reveals that seabird-derived foods are likely to form a significant part of the diet of St Kilda mice populations located in and around breeding colonies. It is unclear however, whether this is from scavenging or predation of seabirds, or through their discarded food items. Given that mice have had significant effects on seabird populations elsewhere, it is important to carry out further work to determine whether mice are a significant cause of seabird mortality in this island ecosystem.
Full-text available
Ecological interactions, especially those that are beneficial (i.e. mutualism) or detrimental (i.e. parasitism), play important roles during the establishment and spread of alien species. This chapter explores the role of these interactions during biological invasions in South Africa, covering a wide range of taxonomic groups and interaction types. We first discuss the different ways in which interactions can be reassembled following the introduction of alien species, and how these depend on the eco-evolutionary experience of the alien species. We then discuss documented examples of parasitism and mutualism associated with invasions in South Africa and how these relate to various ecological and evolutionary hypotheses aimed at explaining species invasiveness. Selected examples of how invasive species impact on native species interactions are provided. A diverse array of biotic interactions (e.g. pollination, fish and mollusc parasitism, plant-soil mutualistic bacteria, seed dispersal) have been studied for various invasive species in South Africa. Surprisingly, only a few of these studies explicitly tested any of the major hypotheses that invoke biotic interactions and are commonly tested in invasion ecology. We argue that many invasions in South Africa are promising candidates for testing hypotheses related to species interactions and invasiveness.
Full-text available
This paper reviews the history of the feral cat eradication programme on sub-Antarctic Marion Island based on unpublished minutes of meetings, reports, letters, theses and published scientific papers; and reflects on the outcome of the eradication campaign. The 19-year programme comprised seven phases, commencing with a description of the effect of the cats on the Marion Island ecosystem, the characteristics of the cat population and the formulation of a management policy (phase 1: 1974-1976). Methods for control were selected and preparations were made for the implementation of the primary control measure, biological control with the feline panleucopaenia virus (phase 2: 1976/77). The virus was released in 1977 (phase 3: 1977), followed by the determination of its effects (phase 4: 1977-1980). Monitoring of the effects of the virus continued, and the secondary control measure of hunting at night was tested (phase 5: 1981-1983). Full-scale implementation of hunting and continued monitoring of the effects of both the disease and hunting followed (phase 6: 1986-1989). The inclusion of intensive trapping and poisoning as tertiary control measures culminated in the final eradication of cats from Marion Island in 1991 (phase 7: 1989-1993).
Full-text available
Blue Petrels breed in dense, often large, colonies at the Prince Edward Islands. They are summer-breeding burrowing petrels and are absent from the islands during June to August. Moult occurs at sea after breeding and takes 83- 13 1 days. The mean laying and hatching dates were 23 October and 9 December respectively; chicks fledged between 25 January and 14 February. Wing, culmen and tarsus length growth curves are described for 43 chicks. The mean peak mass of the nestlings was c. 210 g at about 40 days of age. The distributions of Blue Petrel colonies are given for both Marion and Prince Edward Islands; the species is more abundant at the latter island, which is free of cats. Burrowing petrels have suffered severely from cat predation at Marion Island and the future of the Blue Petrel population is discussed.
Full-text available
The subantarctic Prince Edward Islands (Marion and Prince Edward) support the largest breeding population of the Vulnerable wandering albatross Diomedea exulans. The number of birds breeding at Marion Island has fluctuated over the past three decades apparently as a result of both real changes in the size of the population and changes in the proportion of the population that attempts to breed in a given year. Changes in several demographic parameters that appear to be influenced by both environmental and anthropogenic effects are described. From 1994–2001, the proportion of first-time breeders in the population was positively correlated with the maximum ENSO (Niño 3) index, whereas from 1984–2000 the annual survival rates of breeding adults were negatively correlated with Japanese pelagic longline fishing effort in the southern Indian Ocean. Adult survival rates were significantly correlated with those on neighbouring Possession Island, Crozet Islands, but differed from those at South Georgia, suggesting common factors operating at an ocean-basin scale. The average survival rate of adult females was lower than that of males. Males who lost partners took 40% longer than females to find a new mate, suggesting a male-biased population. Survival rates of juvenile males and females did not differ. The age distribution of first-time breeders shifted progressively towards younger birds during the 1990s. Higher than expected survival rates of breeding adults during the late 1990s may be linked to large amounts of supplementary food being made available by the initiation of a longline fishery for Patagonian toothfish Dissostichus eleginoides close to the islands at this time. Overall, breeding success was better than recorded at other localities, indicating that breeding conditions at Marion Island were comparatively favourable. The early implementation of both international and national conservation initiatives to reduce the impact of longline fishing on this species and improve its conservation status is encouraged.
The IUCN recently uplisted the Tristan albatross (Diomedea dabbenena) to Critically Endangered. Here we present new data indicating negative population trends on Gough Island arising from low adult survival (∼91%, ascribed to accidental mortality on fishing gear) and low breeding success (averaging 32%, due to mouse predation). Fledgling production from 1979 to 2007 and numbers of incubating adults from 1956 to 2007 have both decreased by ∼1% p.a. Consecutive annual counts of incubating adults and a population model permit the first reliable estimates of the Tristan albatross population, presently 5400 breeding adults and 11,300 birds in all age- and stage-classes. Population models explore scenarios of likely demographic trends using combinations of hypothetical best-case estimates vs. observed estimates for two key parameters: adult survival and breeding success. These scenarios highlight the relative benefits to the species of eradicating mice or mitigating bycatch. The model scenario using observed estimates predicts annual growth rate at −2.85%. Adult survival rates have probably decreased in recent years, concomitant with increased longline fishing effort, which might explain the discrepancy between counts and modelled trends. Negative trends cannot be reversed by improving breeding success alone, and adult survival must exceed an improbable 97% to balance the current chick production. A worst-case scenario including a fixed number of adult deaths annually predicted a catastrophic 4.2% p.a. decrease and extinction in ∼30years. Population growth was most sensitive to adult survival, but even using an adult survival estimate without fishery mortality, current breeding success is insufficient to maintain the population. These findings do not support the ‘compensatory mitigation of bycatch’ model (offsetting bycatch impacts by eradicating invasive species), and the impacts of both fishery mortality and mouse predation must be addressed to improve the conservation status of the Critically Endangered Tristan albatross.