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Tree squirrel species that are successful invaders may modify their behaviour according to the characteristics of the invaded community. We studied the use of space by Callosciurus erythraeus in the main invasion focus established in Argentina, where suitable habitat is highly fragmented and immersed in a rural–urban landscape of the Pampas region. We evaluated habitat use in relation to the dominant arboreal vegetation (evergreen vs. deciduous) based on seasonal trapping data throughout two years and home range size and overlap based on seasonal radio-tracking data in two consecutive years. We captured 476 squirrels with a higher trapping success in areas dominated by evergreen vegetation. Effective home ranges were smaller for females (0.10–0.77 ha, n = 12) than for males (0.9–3.78 ha, n = 3). We observed home range overlap between and within both sexes, suggesting no or low territoriality. Our results support the two working hypotheses on the relatively higher use of areas dominated by evergreen vegetation and on the relatively small home range sizes and large overlapping areas associated to high squirrel density. The flexibility in the use of different type of arboreal patches would be another attribute linked to the invasion success of this species. [ABSTRACT FROM AUTHOR]

Squirrels have been traded in the pet market for several decades, and numerous species have established in the wild. The Asiatic speciesCallosciurus erythraeusandCallosciurus finlaysoniihave been introduced into other parts of Asia, in Europe and South America. In this study, (1) we conducted a genetic characterization ofC. erythraeusintroduced into Argentina and compared them with native and introduced populations in Asia, and (2) we analyzed genetic variation among the four invasion foci in Argentina in order to corroborate that the pathway of invasion was a single introduction event in the country and subsequent translocations. We analyzed mitochondrial (cytochrome b, Cyt b; cytochrome oxidase c subunit I, COI and D-loop) and nuclear (recombination activating gene I, RAGI) DNA markers using the classical method (DNA barcoding gap analysis) and also the Automatic Barcode Gap Discovery method (ABGD). The markers D-loop, COI, and RAG1 indicated that the introduced squirrels from the different invasion foci formed a monophyletic group that, together with only one haplotype for the D-loop and COI markers, supported the hypothesis of one introduction event into Argentina followed by subsequent translocations. Unexpectedly, sequences from squirrels captured in Argentina were more related toC. finlaysoniithan toC. erythraeusfor D-loop and Cyt b markers. However, intraspecific variation among sequences ofC. erythraeusbelonging to different subspecies or collected in different regions was large and comparable with the distance to the sequences from Argentina. The ABGD method also indicated large genetic variability withinC. erythraeusand close proximity between squirrels from Argentina andC. finlaysonii. The complex taxonomy ofCallosciurus, as occurs with the sister speciesC. erythraeusandC. finlaysonii, requires a thorough systematic revision. A simultaneous analysis of diagnostic morphological characters and genetic markers is needed and will provide new insight regarding the worldwide invasion of Asiatic squirrels. [ABSTRACT FROM AUTHOR]

We isolated Leptospira strains from renal tissue samples of Asiatic red-bellied squirrels Callosciurus erythraeus, captured in Argentina. In December 2008, we captured 34 squirrels in the province of Santa Fe during a short control campaign, which were screened for Leptospira spp. by direct immunofluorescence assays and isolation attempts in renal tissue samples. A prevalence of 38%of Leptospira spp. was obtained by direct immunofluorescence. The isolates, genotyped by the MLVA, were identified as L. interrogans Canicola (N=2) and L. interrogans Icterohaemorraghiae (N=1), showing an identical genetic profile to the reference strains Hond Utrech IV (serovar Canicola, serogroup Canicola) and M20 (serovar Copenhageni, serogroup Icterohaemorrhagiae), respectively. Our study shows for the first time that the red-bellied squirrel is a renal carrier of Lepto spira interrogans and might act as a reservoir of leptospirosis both in native range and areas of introduction within several European countries, Japan and Argentina. The close association of this introduced squirrel species with humans and domestic animals may increase the probability of disease transmission, particularly in favourable environments. [ABSTRACT FROM AUTHOR]

The introduction of an exotic species usually modifies parasite-host dynamics by the import of new parasites or the exotic species' acquiral of local parasites. The loss of parasites may determine the outcome of an invasion if the introduced species is liberated from co-evolved parasites in its range of invasion. In addition, an introduced species may pose sanitary risks to humans and other mammals if it serves as a reservoir of pathogens or carries arthropod vectors. The red-bellied squirrel, Callosciurus erythraeus (Pallas) (Rodentia: Sciuridae), was introduced into Argentina in 1970, since when several foci of invasion have been closely associated with humans. Investigation of the parasitological fauna of C. erythraeus in Argentina will generate new information about novel parasite-host dynamics and may provide new insight into the reasons for the successful invasion of this species. The objective of this study was to describe the arthropod parasites of C. erythraeus in Argentina in comparison with previous studies of parasites of this species in its native habitat and in the ranges of its invasion. Occasional host-parasite associations with local arthropod parasites not previously described for C. erythraeus are reported; these include the mites Androlaelaps fahrenholzi (Ewing) (Mesostigmata: Laelapidae) and Ornithonyssus cf. bacoti (Mesostigmata: Macronyssidae), the flea Polygenis (Polygenis) rimatus Jordan (Siphonaptera: Rhopalopsyllidae) and the botfly Cuterebra Clark (Diptera: Oestridae: Cuterebrinae). Cheyletus sp. mites (Trombidiformes: Cheyletidae) were also found. The low prevalence and mean intensity of ectoparasite species may influence invasion dynamics. [ABSTRACT FROM AUTHOR]

In coasts bordering highly productive seas, there can be a flux of resources to the terrestrial ecosystem, and terrestrial carnivores can use marine prey extensively. Two native, endangered species (otter Lontra provocax and culpeo fox Pseudalopex culpaeus lycoides) and two exotic species (mink Neovison vison and grey fox Pseudalopex griseus) inhabit the Beagle coast. The objectives of this paper are: (1) to describe the diet, habitat use and distribution of otters, mink and foxes on the coast of the Beagle channel and (2) to discuss the role of marine resources in the ecological interactions among these species. Diet was determined from the analysis of 245 faeces, and distribution was established from sign surveys. Marine prey occurred in the scats of 98.3, 70.4, 35.5 and 18.2% of otters, mink, culpeo and grey foxes, respectively. Other terrestrial species also use marine resources in Southern Patagonia. All this evidence suggests that the Fueguian coastal channels provide an illuminating example of allochthonous food subsidies from the sea. In the community of four sympatric predators, two native (and endangered) and two exotic, coexistence appears to be facilitated by a renewing marine food subsidy. [ABSTRACT FROM AUTHOR]

Invasion pathways and invasion-related lags are critical to understand the invasion process and to manage invasive species. The challenge of dealing with introduced populations increases when charismatic species are involved, such as the case of invasive squirrels. In this study, we integrate previous information into a comprehensive description of the invasion process of Callosciurus erythraeus in Argentina, and we synthesise a framework of invasion pathways and associated lag times for introduced squirrel species. One of the main invasion pathways for introduced squirrels involves the trade of pets and ornamental wildlife, i.e. deliberate transportation by humans as vectors using routes of pet/ornamental trade. This was the case of the importation of C. erythraeus into Argentina in 1970 that originated an invasion focus, which firstly spread through squirrels dispersing into nearby habitat (unaided spread). Apart from this local spread, we have recorded a total of 31 translocations within the country of squirrels taken 33−933 km from the source site (aided spread). Most of these translocations-releases occurred close to the invasion foci that functioned as a source of squirrels. Therefore, a key pathway for the invasion of C. erythraeus in Argentina is the illegal and intentional transport of individuals within country boundaries. Time lags can be found throughout the invasion process. We have previously described a lag in population growth and range expansion in the main invasion focus, and also a lag in vector activity (i.e. a lag in the onset of translocations). We now report a lag in the time between the detection by residents of C. erythraeus in a new area and when they report its observation. This time lag shows a decreasing trend, i.e. recent releases are reported sooner, that could respond to a changing lag in the perception of the problem due to communication activities. We propose a general conceptual framework for invasive squirrels that integrates two invasion pathways (A: aided spread that determines the number of invasion foci, and B: unaided spread that determines the size of each invasion focus) and three types of time lags (1: lag in population growth and spread, 2: lag in vector activity, and 3: lag in perception of the problem (human dimension)). Communication and education activities can be a powerful tool to change perceptions and gain support and active engagement of the local community to deal with invasive, charismatic species. Long-term communication programmes should be implemented along with strict and coordinated government policies. [ABSTRACT FROM AUTHOR]

Abstract: The only known introduction of a squirrel species into South America is the case of the Asiatic red-bellied tree squirrel Callosciurus erythraeus that was introduced in the Pampas Region of Argentina in 1970. To inform management programmes, we analysed the current distribution, expansion rate, and abundance of the red-bellied squirrel in Argentina, and identified invasion pathways. Apart from the first and main focus of invasion, three other invasion foci have originated as a consequence of intentional releases between 1995 and 2000. The main invasion focus already extends over >1300km2, where estimated density averaged 15indha−1 and numbers of squirrels may reach 100,000 individuals. The area invaded in the other three invasion foci varied between <1 and 34km2 and mean densities were around 3–5indha−1. Squirrel abundance and residents’ attitude towards this introduced species in the main invasion focus make eradication unfeasible, though management actions such as control, containment and mitigation of damages should be undertaken. Eradication of the relatively small invasion foci must be immediately evaluated, with priority given to valuable conservation areas under high invasion risk. [Copyright &y& Elsevier]