Introduced Mammal Species Research Articles

Small mice create big problems: Why Predator Free New Zealand should include house mice and other pest species

AbstractPredator Free 2050 (PF2050) is a government initiative aiming to eradicate selected invasive mammals (mustelids, rats, and possums) from New Zealand (NZ) by 2050. Selecting which of 32 introduced mammal species to include has received little evaluation, yet targeting a few species often results in perverse ecological outcomes given interactions within the invasive guild. We explore how PF2050 could be improved strategically by focusing on biodiversity outcomes instead of selectively targeting invasives, using rodents as an example. Current PF2050 targets include all rat species (Rattus exulans, R. norvegicus, and R. rattus), but not the house mouse (Mus musculus). Mice can be as damaging as rats when competition and predation are removed, negating benefits of rat removal. Multirodent eradications are more cost‐effective and prevent mesopredator release. Using a case study, we show adding mice to a rat eradication would raise costs modestly, comparing favorably to independent mouse eradication later, which would be riskier and more socially and economically costly than the preceding rat eradication. Missing the opportunity to tackle all rodents simultaneously, leaving mice to multiply in numbers and impacts, could have serious environmental and socioeconomic consequences. Naïve eradication strategies neglecting ecological expertise risk biodiversity outcomes and NZ's eradication science reputation.

First evidence of mouse predation killing adult great albatrosses

AbstractInvasive rodents threaten native species in numerous ecosystems, especially oceanic islands. The House Mouse Mus musculus is the only introduced mammal species on sub-Antarctic Gough and Marion Islands. Ample evidence exists of mice preying upon seabird chicks on these two islands, but there have been only a few reports of attacks on adult seabirds, none of which has been fatal. We report the first deaths of adult great albatrosses due to mouse attacks. On Gough Island, three Tristan Albatrosses Diomedea dabbenena (Critically Endangered) brooding small chicks were observed with wounds typical of mouse attacks in March–April 2021; two likely abandoned their chick, causing breeding failure, and the third was found dead eight days after discovery with large blowfly larvae in the wound. On Marion Island, two wounded and eight dead adult Wandering Albatrosses D. exulans (Vulnerable) were found in April 2023. Inspection of the wounded individuals, as well as the injuries on the fresh carcasses strongly suggest that mouse predation was the cause of death. Gough Island is home to virtually all Tristan Albatrosses, and Marion Island is the single most important breeding site for Wandering Albatrosses, home to about a quarter of all breeding birds. The death of breeding adults of these long-lived species emphasizes the urgent need to eradicate introduced mice from these islands.

DAMA: the global Distribution of Alien Mammals database.

We developed the DAMA (Distribution of Alien Mammals) database, a comprehensive source reporting the global distribution of the 230 species of mammals that have established self-sustaining and free-ranging populations outside their native range due to direct or indirect human action. Every alien range is accompanied by information on its invasion stage, pathway, method of introduction, and date of introduction. We collected information from 827 different sources (scientific literature, books, risk assessments, reports, online biodiversity databases and websites), and used it to draw alien range maps for these species following the IUCN mapping framework. DAMA comprises 2,726 range polygons, covering 199 countries, 2,190 level 1 administrative areas, and 11 zoogeographic realms for the period 21500 BC-AD 2017. The most represented orders among introduced mammal species are Rodentia (n = 58, 25.22%), Cetartiodactyla (n = 49 species, 21.30%), Carnivora (n = 30 species, 13.04%), Diprotodontia (n = 28, 12.17%), and Primates (n = 26, 11.30%). Mammal species have been frequently introduced for hunting (n = 100), pet trade (n = 57), conservation (n = 51), and fauna improvement (n = 42). The majority of range polygons are placed on islands (n = 2,196, 80.56%), encompass populations that have moved beyond establishment and into the invasion stage (n = 1,655, 60.71%), and originated from 1500 AD to the present (n = 1,496, 54.88%). Despite inheriting literature biases towards more studied regions (e.g., developed countries), DAMA is the most up-to-date picture of alien mammal global distribution and can be used to investigate their invasion ecology across different biogeographical regions. There are no copyright or proprietary restrictions; IUCN range maps were modified into a derivative work according to the IUCN's terms of service.

Mammal responses to moderate-intensity planned burning in a small, isolated woodland reserve

Abstract Context Fire management advice for fauna conservation in protected areas must often be based on expert opinion and extrapolation from very few scientific studies. More monitoring and research are needed to better inform land managers tasked with both managing for biodiversity and managing the threat of bushfires. Aims To document changes in the activity of native and introduced mammal species in response to planned burns in a small, isolated woodland reserve in Tasmania. Methods Over a 10-year period, mammal activity was monitored before and after two separate moderate-intensity planned burns in 20-ha management blocks and in unburnt blocks of similar size by using live-trapping and camera-trapping. Vegetation density was monitored concurrently, and we also searched burnt areas for animals killed by fire. Key results The activity of most mammal populations was largely unaffected by the two planned burns. However, during one of the burns, over 20 rufous-bellied pademelons were directly killed as a result of a need to conduct a backburn. The population recovered after 3 years. The activity of red-necked wallabies, common brushtail possums and short-beaked echidnas generally increased across the whole study area during the 10-year monitoring period. Limited evidence suggests that eastern barred bandicoot and European rabbit activity increased after fire. No swamp rat activity was recorded in burnt areas following the planned burns. Unexpectedly they did not recolonise burnt areas and also ceased to be active in control areas for the last 3 years of the study; we hypothesise that this may be due to the increased dryness and thinning of vegetation. Conclusions We found that most of the mammal populations within this small, isolated reserve were resilient to the planned burning program, with no or limited short-term effect for all but one species. The absence of swamp rats from burnt or unburnt areas for the last 3 years of our study suggests that factors other than fire are also affecting this species. Implications Planned burning is an important tool for biodiversity conservation, but its use needs to be underpinned by empirical data because mammal fire responses are likely to be site-, time- and context-specific.

Effects of introduced sika deer (Cervus nippon) and population control activity on the distribution of Haemaphysalis ticks in an island environment.

The effects of introduced mammal species on the ecology of parasites are often under investigated. The sika deeer, Cervus nippon, is host species of many hard ticks. We collected 8348 ticks on an island where sika deer were introduced. The most representative species was Haemaphysalis megaspinosa (n = 4198; 50.3%), followed by H. longicornis (n = 1945; 23.3%), H. cornigera (n = 1179; 14.1%), H. flava (n = 713; 8.5%), Ixodes turdus (n = 289; 3.7%), I. granulatus (n = 22; 0.3%), and H. hystricis (n = 2; <0.1%) on an island where sika deer were introduced. H. megaspinosa and H. hystricis have not previously been recorded on the Izu islands. The high abundance of H. megaspinosa indicated that the tick species may have been introduced with the sika deer. Furthermore, H. megaspinosa larvae were more abundant at collection sites 21–40 days after sika deer were caught by foot snare traps indicate that engorged female of this tick species were forced to drop off in a very limited area near the foot snare trap. This represented a risk for hunters and people associated with wildlife control visiting the area.

Camera trapping of Grey-faced Petrel (Pterodroma gouldi) breeding burrows reveals interactions with introduced mammals throughout the breeding season

ABSTRACTGrey-faced Petrels (Pterodroma gouldi) are burrow-nesting seabirds endemic to New Zealand. They usually breed on mammal-free offshore islands along the North Island coast. Mechanisms by which breeding colonies can persist on the North Island with introduced mammals present are still uncertain. Motion-sensing video cameras were used in the Waitakere Ranges to determine the types of interaction between resident introduced mammal species and petrel breeding burrows. Existing predator control is reducing the total count of recorded interactions by predators, with rabbits (Oryctolagus cuniculus) entering burrows dominating interactions. The interaction of ship rats (Rattus rattus) or rabbits with breeding burrows had no influence on egg-laying or chick-hatching success. Grey-faced Petrels remained in breeding burrows, despite high interaction frequencies of introduced mammals prior to the egg-laying stage. Whilst our data show no impact of mammalian visit rates on Grey-faced Petrel breeding success, other published studies suggest that population recovery might be enhanced by site-specific trapping and baiting methods which also target rabbits.

Patterns of selectivity in introductions of mammal species worldwide

Humans have an extremely long history of transporting and introducing mammal species outside their native geographic range. The characteristics of the species introduced (taxonomy, life-history, ecology, environment) can all influence which traits are available (and selected) for establishment, and subsequent invasive spread. Understanding the non-randomness in species introductions is therefore key to understanding invasions by alien species. Here, we test for selectivity in the identities and traits of mammal species introduced worldwide. We compiled and analysed a comprehensive database of introduced mammal species, including information on a broad range of life history, ecological, distributional and environmental variables that we predicted to differ between introduced and non-introduced mammal species. Certain mammal taxa are much more likely to have been introduced than expected, such as Artiodactyls in the families Bovidae and Cervidae. Rodents and bats were much less likely to have been introduced than expected. Introduced mammal species have significantly larger body masses, longer lifespans and larger litter sizes than a random sample of all mammal species. They also have much larger native geographic ranges than expected, originate from significantly further north, from cooler areas, and from areas with higher human population densities, than mammal species with no recorded introductions. The traits and distributions of species help determine which have been introduced, and reflect how the evolutionary history of mammals has resulted in certain species with certain traits being located in the way of human histories of movement and demands for goods and services. The large amount of unexplained variation is likely to relate to the intrinsically stochastic nature of this human-driven process.

Le renouvellement récent des faunes de vertébrés sur l’île de Cavallo (archipel des Lavezzi, Corse)

We present a recent survey of the vertebrate fauna of Cavallo, a small island belonging to the Lavezzi archipelago located between Corsica and Sardinia. This island is the only inhabited one off the coast of Corsica and underwent deep landscape and ecosystem changes in the past 50 years induced by touristic development. The herpetofauna of the Cavallo island has changed with two recent colonisations, one green frog and one gecko. Two amphibian species and four reptiles live nowadays on this island. Concerning the breeding landbirds, this island has been visited by ornithologists more or less regularly since 1955. Several species have colonized the island while others have left. These changes are due to important modifications of the habitats, such as urbanization, the decline of high matorral and grasslands, but also the development of gardens and the creation of a permanent wetland. Today, 13 species of landbirds breed on Cavallo. Several introduced mammal species recorded in the 1980s seem to have vanished, and today the list is restricted to the introduced Black rat and two or three bat species.

Can recreational hunting contribute to pest mammal control on public land in Australia?

Abstract Natural resource management agencies in many countries take advantage of recreational hunting to manage the impacts or abundance of mammal populations that damage biodiversity or environmental, economic, or social values. In Australia, public lands are increasingly being made available for recreational hunters to pursue introduced mammals that can cause substantial damage to important resources. There is fervent debate over the role that recreational hunting might play in controlling introduced mammals in Australia, and scant evidence to build management strategies upon. In this review, we combine information from Australia and elsewhere in a systematic examination of the potential for recreational hunting to contribute to the control of introduced mammals on public lands in Australia. We examine the traits of introduced mammal species and populations, geographical settings, hunters, and management agencies to propose situations where hunting might be most useful, and suggest how current practice could be improved. We find there is insufficient evidence to support or disprove arguments that contemporary recreational hunting programs are effective at controlling introduced mammal populations on public lands. Moreover, current hunting management programs offer little potential for clarifying the situation or optimizing the value of recreational hunting as a pest animal control tool. To resolve this problem, we outline a framework of competing models and diagnostic criteria for assessing the effects of recreational hunting on introduced mammal populations. We contend that hunting will continue to be an under‐utilized and over‐politicized resource until management strategy is informed by transparent monitoring based on rational strategic objectives that provide mutual benefits to hunters and public resource managers.

The good, the bad, and the ugly: which Australian terrestrial mammal species attract most research?

Abstract The Australian mammalian fauna is marked by high endemism and evolutionary distinctiveness and comprises monotreme, marsupial, and eutherian (‘placental’) native species. It has suffered the highest extinction rate of any mammalian fauna in any global region; surviving species are threatened by competition and predation from a range of introduced mammal species, and receive low levels of conservation‐oriented funding compared with species in many other countries. We investigated research foci on this unique fauna by using species h‐indices (SHI), and identified both taxonomic bias and subject bias in research effort and research impact for 331 Australian terrestrial mammal species. Species broadly fell into categories we labelled as the ‘good’, the ‘bad’, and the ‘ugly’. The majority of studies on monotremes and marsupials (the ‘good’) are directed towards their physiology and anatomy, with a smaller ecological focus. By contrast, introduced eutherians (the ‘bad’) have attracted greater attention in terms of ecological research, with greater emphasis on methods and technique studies for population control. Despite making up 45% of the 331 species studied, native rodents and bats (the ‘ugly’) have attracted disproportionately little study. While research on invasive species is directed towards problem solving, many Australian native species of conservation significance have attracted little research effort, little recognition, and little funding. Current global and national conservation funding largely overlooks non‐charismatic species, and yet these species may arguably be most in need of scientific and management research effort.

Impact of introduced house mice (Mus musculus) on burrowing seabirds on Steeple Jason and Grand Jason Islands, Falklands, South Atlantic

Whilst there is good evidence for negative impacts of introduced rat species on island ecosystems, the effects of house mice (Mus musculus) are generally less well documented. In some situations, introduced house mice can exert severe impacts, particularly where this is the only introduced mammal. Here, we examine the distribution, relative abundance and breeding success of small burrowing seabirds on Steeple Jason Island, Falklands, in relation to habitat types and the distribution of house mice which is the sole introduced mammal species, and we make comparisons with seabird distribution and densities on the neighbouring island of Grand Jason where mice are absent. Grey-backed storm-petrel (Garrodia nereis) and Wilson’s storm-petrel (Oceanites oceanicus), which due to their extremely small size are likely to be the most vulnerable to mouse predation, were considerably more abundant on mouse-free Grand Jason than on Steeple Jason. Grey-backed storm-petrel, which are typically associated with tussac grass, avoided this habitat on Steeple Jason where it is associated with high levels of house mouse activity (assessed from the proportion of wax baits gnawed overnight), whereas on mouse-free Grand Jason, there was no such avoidance. Wilson’s storm-petrel nesting on Steeple Jason suffered high rates of egg and chick loss. Whilst we found evidence for detrimental impacts of house mice on the two small storm-petrel species, there was no relationship between relative mouse activity levels and the distribution or abundance of the larger thin-billed Prion (Pachyptila belcheri).

Diversification of an emerging pathogen in a biodiversity hotspot: Leptospira in endemic small mammals of Madagascar.

Biodiversity hotspots and associated endemism are ideal systems for the study of parasite diversity within host communities. Here, we investigated the ecological and evolutionary forces acting on the diversification of an emerging bacterial pathogen, Leptospira spp., in communities of endemic Malagasy small mammals. We determined the infection rate with pathogenic Leptospira in 20 species of sympatric rodents (subfamily Nesomyinae) and tenrecids (family Tenrecidae) at two eastern humid forest localities. A multilocus genotyping analysis allowed the characterization of bacterial diversity within small mammals and gave insights into their genetic relationships with Leptospira infecting endemic Malagasy bats (family Miniopteridae and Vespertilionidae). We report for the first time the presence of pathogenic Leptospira in Malagasy endemic small mammals, with an overall prevalence of 13%. In addition, these hosts harbour species of Leptospira (L. kirschneri, L. borgpetersenii and L. borgpetersenii group B) which are different from those reported in introduced rats (L. interrogans) on Madagascar. The diversification of Leptospira on Madagascar can be traced millions of years into evolutionary history, resulting in the divergence of endemic lineages and strong host specificity. These observations are discussed in relation to the relative roles of endemic vs. introduced mammal species in the evolution and epidemiology of Leptospira on Madagascar, specifically how biodiversity and biogeographical processes can shape community ecology of an emerging pathogen and lead to its diversification within native animal communities.

Non-invasive multi-species monitoring: real-time PCR detection of small mammal and squirrel prey DNA in pine marten (Martes martes) scats

DNA identification of mammal species occurring in the diet of a predator is potentially a useful approach to remotely monitor the distribution of multiple species. This is important in Ireland, where it has been shown that the combined presence of the introduced bank vole and greater white-toothed shrew impact the distribution of the indigenous small mammals, the wood mouse and pygmy shrew. Direct monitoring of these species and their interactions requires trapping, a labour-intensive and costly approach. In this study, we applied an indirect method by genetically testing the presence of small mammals in pine marten scats collected during the National Pine Marten Survey (2005–2007) to map their distribution. We also included additional scats to investigate if less common prey items, the red squirrel and grey squirrel, could also be detected. This study demonstrates that all target species were genetically detected from pine marten scats. This strategy could be implemented as a monitoring programme for indigenous and introduced mammal species.

10.1007/s11184-008-2010-8

The functioning of two foci of helminth diseases caused by trematodes Apophallus muehlingi and Rossicotrema donicum has been studied in the Volga Delta. The origin of these foci is related to the expansion of species ranges of Lithoglyphus snails, intermediate hosts of trematodes. Introduced mammal species, the raccoon dog Nyctereutes procyonoides and American mink Mustela vision, are involved in the circulation of the invasion.

Evidence of mouse attacks on albatross chicks on sub-Antarctic Marion Island

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 &lt;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.

Genesis of epizootics involving introduced species of helminths, mammals, and mollusks

The functioning of two foci of helminth diseases caused by trematodes Apophallus muehlingi and Rossicotrema donicum has been studied in the Volga Delta. The origin of these foci is related to the expansion of species ranges of Lithoglyphus snails, intermediate hosts of trematodes. Introduced mammal species, the raccoon dog Nyctereutes procyonoides and American mink Mustela vision, are involved in the circulation of the invasion.

FUNCTIONAL DIVERSITY OF MAMMALIAN PREDATORS AND EXTINCTION IN ISLAND BIRDS

The probability of a bird species going extinct on oceanic islands in the period since European colonization is predicted by the number of introduced predatory mammal species, but the exact mechanism driving this relationship is unknown. One possibility is that larger exotic predator communities include a wider array of predator functional types. These predator communities may target native bird species with a wider range of behavioral or life history characteristics. We explored the hypothesis that the functional diversity of the exotic predators drives bird species extinctions. We also tested how different combinations of functionally important traits of the predators explain variation in extinction probability. Our results suggest a unique impact of each introduced mammal species on native bird populations, as opposed to a situation where predators exhibit functional redundancy. Further, the impact of each additional predator may be facilitated by those already present, suggesting the possibility of “invasional meltdown.”

The conservation value of small woodland remnants on the New South Wales South Western Slopes: a case study from Wagga Wagga

A survey of the bird and non-flying mammal fauna in Pomingalarna Park, a small woodland remnant near Wagga Wagga, on the New South Wales South Western Slopes, recorded 91 native bird species and five native mammal species. Three introduced bird species and eight introduced mammal species were also recorded. The woodland is an association of Western Grey Box Eucalyptus microcarpa, Biakely's Red Gum E. blakelyi and White Cypress Pin0 Callitris glaucophylla. The results highlight the significance of small remnants for the conservation of biological diversity in the New South Wales South Western Slopes region.

Ecology of the rufous hare-wallaby, Lagorchestes hirsutus Gould (Marsupialia : Macropodidae) in the Tanami Desert, Northern Territory. III Interactions with introduced mammal species.

This paper reports a study of the interactions between a remnant population of the rufous hare-wallaby, Lagorchestes hirsutus, and populations of several introduced mammal species in a region of the Tanami Desert. Transect counts of faecal pellets and tracks were used to determine the local distributions of all species and analysis of faeces from both predators and competitors of hare-wallabies was undertaken. Six species of introduced mammals were recorded within the study area: dingoes, rabbits, camels, foxes, feral cats and cattle. The local distributions for a number of these species were found to be significantly correlated with that of L. hirsutus during some seasons. Analysis of dingo scats collected from fire trails within the study area identified a total of 12 different food classes including harewallabies which occurred in 6.9% of the scats. Foxes and feral cats appear to be more important predators as demonstrated by their impacts on natural and reintroduced populations of hare-wallabies. Comparison of the diets of the rabbit and L. hirsutus identified significant overlap in utilised plant species, particularly during drier times. Competition between rabbits and L. hirsutus seems probable, given the overlap of their diets and their similar body sizes and metabolic requirements. Cattle and camels are potentially as important at densities above present levels. The complex web of interactions between L. hirsutus and these introduced species have important implications for management of remnant and reintroduced hare-wallaby populations.

The Food of Fox, Dog and Cat in Croajingalong National Park, South-Eastern Victoria.

The diet of foxes, dogs and cats living in Croajingalong National Park in extreme south-easten Victoria was studied during 1979 and 1980. From 1397 scats collected over 20 months, remains of 22 indigenous and 7 introduced mammal species were identified. Remains of ringtail possums Pseudocheirus peregrinus predominated in the scats from all three predators (fox 58%, cat 56% and dog 38%). Other main prey species for the fox and cat were Antechinus spp.(24% and 15% respectively) and Rattus spp. (15% and 19%) and for the dog two species of wallabies, Macropus rufogriseus and Wallabia bicolor (34%), wombat Vombatus ursinus (11%), Antechinus spp.(l5%) and Rattus spp.(10%). Nonmammalian items for the three predators were birds, reptiles, fish, insects, crustaceans, molluscs and plant material.