Article

Past and present small mammals of Isla Mocha (Chile)

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Abstract

We describe archaeozoological and extant small mammals from Isla Mocha, an island located in south-central Chile. Species composition was compared among past and present assemblages. Also composition, as well as individual and population parameters were compared among island habitats. Specimens from archaeological sites included Oligoryzomys longicaudatus, Abrothrix sp., and Octodon pacificus, whereas Abrothrix longipilis, A. olivaceus, Oligoryzomys longicaudatus, and Geoxus valdivianus were captured. Higher richness was observed in intermediate-disturbed habitat. Body size and tail length, as well as body mass did not vary among island habitats for A. longipilis or A. olivaceus. Higher abundance was associated to less perturbed habitat.

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... ranging from 0.6% to 2.7%. O. pacificus was captured in 1959 and described as a new species based on morphological data (Hutterer, 1994) but no further records have been documented ever since (Pefaur and Yañez, 1980;Saavedra et al., 2003). The high genetic distance of O. pacificus relative to the remaining congenerics (2.3%) indicate its distinctiveness. ...
... The high genetic distance of O. pacificus relative to the remaining congenerics (2.3%) indicate its distinctiveness. Hence, the phylogenetic relationships, species delimitation analyses, and pairwise distances support the distinctive taxonomic status of O. pacificus, in spite of its morphological similarity with O. bridgesi (Saavedra et al., 2003). ...
... La presencia de Octodon pacificus (NISP=1, NMI=1), es análogo a nuestros datos previos. Octodon es fácilmente distinguible, al ser claramente más grande que las otras especies presentes (Saavedra et Al. 2003), en este caso se trata de una hemimandíbula derecha, que posee a lo menos la línea de molares completa. La especie fue descrita en 1994, sobre la base de ejemplares colectados por una expedición alemana a isla Mocha en 1971. Aunque algunos especialistas dudan sobre la real validez de esta población como una especie diferente (Iriarte 20 ...
... Una interesante vía de inferencias se puede refundar si se considera incluso la presencia de una especie vicariante o un subgénero de una especie continental, a modo de la discusión de Octodón (Saavedra et Al. 2003). ...
Technical Report
El conjunto óseo analizado da cuenta de un espectro de especies que refleja una amplia variedad de recursos a disposición, tanto terrestres como marítimos. De estos últimos, destacamos la presencia de Pudú así como la identificación de roedores y aves, algunos estos últimos novedosos para el registro zooarqueológico de la isla.
... La presencia de Octodon pacificus (NISP=1, NMI=1), es análogo a nuestros datos previos. Octodon es fácilmente distinguible, al ser claramente más grande que las otras especies presentes (Saavedra et Al. 2003), en este caso se trata de una hemimandíbula derecha, que posee a lo menos la línea de molares completa. La especie fue descrita en 1994, sobre la base de ejemplares colectados por una expedición alemana a isla Mocha en 1971. Aunque algunos especialistas dudan sobre la real validez de esta población como una especie diferente (Iriarte 20 ...
... Una interesante vía de inferencias se puede refundar si se considera incluso la presencia de una especie vicariante o un subgénero de una especie continental, a modo de la discusión de Octodón (Saavedra et Al. 2003). ...
Research
El conjunto óseo analizado da cuenta de un espectro de especies que refleja una amplia variedad de recursos a disposición, tanto terrestres como marítimos. De estos últimos, destacamos la presencia de Pudú así como la identificación de roedores y aves, algunos estos últimos novedosos para el registro zooarqueológico de la isla.
... Aconaemys fuscus, currently confined to the southern Andes, ca. 1,000 years ago inhabited areas close to Santiago, more than 100 km north of its current distribution (Simonetti & Saavedra 1994 (Saavedra et al. 1991, 2003, Simonetti 1994, Simonetti & Saavedra 1994. All sites were excavated using regular archaeological methods, and rodent analysis was made based on usual identification keys (e.g., Reise 1973, Pearson 1995, as well as comparison with voucher specimens deposited in museums and collections. ...
... Four sites were excavated: "P5-1", "P22-1", "P25-1", and "P31-1". Octodon pacificus was the only Octodontid found in these remains (Quiroz & Sánchez 1993, Saavedra et al. 2003. ...
Article
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We describe the Holocene distribution of the Octodontids Aconaemys fuscus, Octodon bridgesi, O. degus, O. lunatus, O. pacificus and Spalacopus cyanus from Central Chile. We compared ancient and present day ranges. The Holocene pattern was inferred from zooarchaeological records. Octodon degus, O. lunatus, O. bridgesi, and Aconaemys fuscus showed a reduction in their geographic range. Although specific mechanisms remain to be tested, human disturbance seems to be the distal factor that explains the reduction of ranges for some taxa. Describimos la distribución holocénica de los roedores octodóntidos Aconaemys fuscus, Octodon bridgesi, O. degus, O. lunatus, O. pacificus y Spalacopus cyanus en Chile central, y la comparamos con su distribución actual. El patrón de distribución holocénico se infirió de registros zooarqueológicos. Octodon degus, O. lunatus, O. bridgesi y Aconaemys fuscus muestran una reducción en su rango geográfico. A pesar de que los mecanismos específicos que explican este patrón permanecen sin ser resueltos, la perturbación humana parece ser el factor distal que explicaría la reducción en el rango de distribución para algunas de estas especies.
... In the past, humid forests occupied a large part of the lowland and lower slopes of the island, which were optimal habitats for Eupsophus insularis and other highly threatened species whose current presence on the island is uncertain (e.g., R. darwinii and the emblematic Mocha's degu; Saavedra et al., 2003). The increasing demand for territory by the human population and resources extracted from the forest (mainly firewood) constitute serious threats for E. insularis. ...
Article
Eupsophus insularis inhabits a small island in the southeast Pacific, and its natural history is unknown. The species is listed as Critically Endangered based on its restricted distribution, i.e., an island under ongoing habitat deterioration. We assessed the distribution, habitat requirements, density, diet, and threats of the species with the aim of proposing strategies for its conservation. The species is restricted to a terrestrial strip 24205 m above sea level associated with pristine temperate humid forests located in areas of low slope. A capturerecapture study indicated that its density was 1566 individuals/ha of optimal habitat. Its diet is composed mainly of invertebrates of the humid forest floor. The high prevalence of chytrid fungus and habitat loss are important threats to the species. Herein, we present data to help with the management of the species on the island and that might help in designing more robust strategies to mitigate present and future threats.
... Sin embargo, este dato debe ser tomado con cautela ya que el ejemplar en cuestión proviene de superficie. Resulta interesante destacar la presencia de Octodon, catalogado anteriormente como Octodon bridgesi en Sanchez y colaboradores (1994), sugerido como un error de identificación (Saavedra et al. 2003), dado que Hutterer (1994) describe posteriormente para la isla la especie Octodon pacificus. Resulta problemático que ambas especies que tienen una amplia similitud mandibular, así como que hay especialistas que dudan sobre la validez de esta especie (Iriarte 2008). ...
Technical Report
Resumen En el conjunto analizado-procedente de prospecciones superficiales-, hay una alta abundancia de fragmentos óseos que fueron asignables solo a nivel de clase Mammalia, sin embargo, dentro de los elementos identificados se da cuenta de un amplio espectro de especies, mezcladas con fauna doméstica reciente, pero presentes en el registro arqueológico tanto a nivel local como a provincial, de este registro destacan los especímenes pertenecientes a la Familia Camelidae.
... Sin embargo, este dato debe ser tomado con cautela ya que el ejemplar en cuestión proviene de superficie. Resulta interesante destacar la presencia de Octodon, catalogado anteriormente como Octodon bridgesi en Sanchez y colaboradores (1994), sugerido como un error de identificación (Saavedra et al. 2003), dado que Hutterer (1994) describe posteriormente para la isla la especie Octodon pacificus. Resulta problemático que ambas especies que tienen una amplia similitud mandibular, así como que hay especialistas que dudan sobre la validez de esta especie (Iriarte 2008). ...
Technical Report
El conjunto óseo analizado da cuenta de un espectro de especies que refleja una amplia variedad de recursos a disposición, tanto terrestres como marinos. De estos últimos, destacamos una gran variedad de recursos ictiológicos, novedosos para el registro de la isla Mocha.
... Especies primitivas de Octodontia habrían aparecido y diversificado repentinamente en Sur América en el Oligoceno temprano, unos 31 millones de años atrás, posiblemente siguiendo las migraciones trasatlánticas desde África. El Degú de la Mocha probablemente representa la taxa hermana del Degu de Briges (Octodon bridgesi), uno de las especies de Octodon más frecuentes de Chile y Argentina (Honeycutt et al. 2003, Saavedra et al. 2003. ...
Technical Report
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Isla Mocha es una de las pocas islas continentales presentes en Chile central y que a pesar de su tamaño, constituye un área relevante por su importancia científica, escénica, ecológica y tectónica (Lequesne et al. 1999). Se localiza en el sector I, exactamente, en la VIII Región del Bio-Bio, Chile, a 35 km de la costa pacífica y frente a la Caleta de Tirúa, Provincia de Arauco (Figura 1). Se caracteriza por presentar básicamente dos áreas, una central montañosa cubierta de bosques y que constituye la actual Reserva Nacional Isla Mocha, y una exterior plana conformada por praderas, matorrales y playas, dentro de la cual vive el total de la población humana (Quiroz y Zumaeta 1997). Durante el terremoto del 27 de febrero de 2010, Isla Mocha fue severamente impactada por el tsunami generado. Este impacto se evidenció principalmente en la destrucción de casas, zonas ganaderas, infraestructura portuaria y embarcaciones de los pescadores locales. Por esta razón y como una manera de enfrentar un proceso de reconstrucción de manera sustentable que constituya un modelo basado en un óptimo uso de los recursos naturales y su conservación, se elabora este Plan de Ordenamiento Territorial y Conservación para la Isla Mocha, en el marco de lo dispuesto en la propuesta “Isla Mocha-Tirúa, modelo de reconstrucción sustentable para el desarrollo del ecoturismo”, presentada por WWF al programa Innova Reconstrucción. Este Plan, será un insumo sustantivo para el diseño e implementación de actividades vinculadas al turismo en función de la minimización de riesgos específicos y el establecimiento de mecanismos de protección en dichas áreas, considerando la identificación de las potencialidades, limitaciones y riesgos del territorio, así como aspectos básicos de distribución de fauna costera de interés para el ecoturismo.
... Today, introduced and crop species dominate and there are only small, dispersed and fragmented relicts of forest. At the edge of the forest, due to tree logging and subsequent erosion a shrubby ecotone dominates, separating the old-growth forests from disturbed grassland (Saavedra et al., 2003). The lifestyle of the island inhabitants is strongly influenced by the isolation from the continent. ...
Chapter
The importance of ocean pollution, including pollution from plastics, has been recognized for a long time. However, the current generation and disposal of plastic worldwide has no precedent. Plastic litter accounts for 50-80% of waste items stranded on beaches, floating on the ocean surface and lodged in the seabed. Floating plastic debris is usually ingested by marine animals by mistake, or because it resembles their natural food. This plastic intake by animals such as seabirds can produce entanglement, intoxication, internal wounds, digestive tract blockage and ulcers among other conditions. While these damages are important, further concerns have arisen about plastics sorbing potentially hazardous hydrophobic chemicals. These compounds found in the waters where plastics are, can be plastic additives from other degrading plastics such polychlorinated biphenyls (PCBs) or chemicals from other sources like persistant organic pesticides (POPs), both with the capacity of being sorbed by plastics. However, the importance of the ingestion of plastic-derived chemicals present in the natural prey of seabirds through biomagnification, compared with the amount of these chemicals intake via plastic debris is still being studied. The finding of PCBs and POPs in the ingested plastic pellets and plastic fragments, have led to additional research aimed at assessing the relative potential of plastic as a vector of pollutants transport. The results of these studies are until now contradictory, largely because the role of the dilution and cleaning mechanisms of the studied chemicals are under debate. The impact of plastic debris on individuals is well known although it is not entirely clear how plastic ingestion at the individual level could impact the whole population and how this will impact entire ecosystems. For example, one strategy to mitigate damage caused by ingested plastics is to regurgitate them, so the transference of these plastics to chicks is not uncommon while being fed. As most chicks are unable to regurgitate plastic fragments, these accumulate in their stomachs eventually causing death. At present, the implications of chemicals sorbing on the population size of seabirds is unknown. The effectiveness of using seabirds as monitors has increased considerably in recent years. Sampling the stomach contents of beached birds, birds killed accidentally by fishing activities or by examining regurgitated pellets of predators that feed on seabirds can be useful as well. Nonetheless, there are still questions to answer before we can confidently assess the impact of plastic waste on the environment through seabirds. For example: Is there a linear relationship between pollutants sorbed and the surrounding plastic debris? Or do birds reach a point where they become saturated by these chemicals independently of their plastic ingestion? Throughout this chapter we will evaluate the progress made to answer the open questions about the impact of plastic debris on seabirds and discuss the future of seabirds as a group and their use as monitors of plastic pollution to evaluate the health of ecosystems.
... Today, introduced and crop species dominate and there are only small, dispersed and fragmented relicts of forest. At the edge of the forest, due to tree logging and subsequent erosion a shrubby ecotone dominates, separating the old-growth forests from disturbed grassland (Saavedra et al., 2003). The lifestyle of the island inhabitants is strongly influenced by the isolation from the continent. ...
Chapter
Full-text available
Seabirds can serve as fundamentally important components of biodiversity of insular ecosystems, playing an important role as vectors of marine-derived nutrients, increasing primary production which in turn is transferred through the food web, and influencing the numbers and types of primary and secondary consumers. The status and trends of seabirds can be an excellent indicator of the impacts of human activities on their populations and communities. These impacts include loss of breeding sites through trampling and grazing by introduced domesticated animals; mortality by introduced mammalian predators such as rats, dogs and cats; egg and chick harvest; and interactions with local and regional fisheries. These impacts have occurred on most human-inhabited islands, ranging from the tropics to the sub-polar regions. Until the 1990s, the general state of knowledge about seabirds of oceanic islands in Chile was poor, since virtually no basic ecological information such as population size, breeding biology or the extent of conservation problems had been compiled for many species. Human communities of oceanic and coastal insular systems in Chile currently possess only a small percentage of people who retain local traditional ecological knowledge, as a result of the recent influx of immigrants during the second half of the 20th century and the progressive decline of the ancestral native population. The relationship of recently arrived human communities with the biodiversity of the insular systems has been restricted to the use and exploitation of resources to satisfy basic needs for the human population (e.g. heating, food). Many of these activities have a negative impact on the biodiversity of the island, including seabirds. As a resource, seabirds were usually ignored by island communities because they did not provide any immediate benefit. In the 1990s, initiatives of national and foreign researchers began in different islands of Chile to elucidate basic aspects of the ecology and conservation status of several seabird species. The information generated was shared with the island communities associated with these seabird species in order to increase awareness and build support for conservation actions. This community engagement was undertaken based on the understanding that island communities, especially isolated ones, have particular characteristics that distinguish them from the inhabitants of the continent. These include a strong sense of belonging to the place, a heightened sense of community among residents, a detachment from the nearby continental areas, and a sense of not belonging to the central government that manages the island. Here we document community engagement experiences and results on five significant Chilean seabird islands distributed in a wide latitudinal range: (1) Robinson Crusoe, Santa Clara and Alejandro Selkirk islands (the Juan Fernandez Archipelago) (34° S), inhabited by six species of procellarids (Pink-footed Shearwater Puffinus creatopus, Kermadec Petrel Pterodroma neglecta, De Filippi's Petrel Pterodroma defilippiana, White-bellied Storm-Petrel Fregetta grallaria, Juan Fernandez Petrel Pterodroma externa and Stejneger's Petrel Pterodroma longirostris); (2)Mocha Island (38° S) where the Pink-footed Shearwater Puffinus creatopus breeds; (3) Punihuil Island, Chiloe (42° S) with a mixed-colony of Humboldt (Spheniscus humboldtii) and Magellanic (Spheniscus magellanicus) penguins; (4) Guafo Island, Quellen town (44°S) with the largest colony of Sooty Shearwater Puffinus griseus in the world; and (5) Navarino Island (55°S), Cape Horn Biosphere Reserve, that is inhabited by rich ensembles of seabirds and shorebirds, including cormorants, plovers, sandpipers, steamer-ducks and geese. On all of these islands, islanders have participated in initiatives that support the conservation of resident seabird species, including the cessation of chick and egg harvests, development of special interest tourism around birds, removal of introduced animals and responsible pet ownership, and as a general rule, inclusion of birds as co-inhabitants of the community.
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Octodon (Octodontidae) is an endemic genus of rodents that is typical of southwestern South America and represented by 4 species. Octodon pacificus, commonly referred to as the Mocha Island degu, was initially described from specimens collected in 1959 at Mocha Island, a small coastal island located along the central coast of Chile. Fifty-seven years after its original collection, we report the discovery of a female O. pacificus carcass, identified by its morphological characteristics and its specific locality. In addition, based on the cytochrome b (Cytb) gene of the mitochondrial DNA obtained from O. pacificus and other congeneric species, we assessed phylogenetic relationships within the Octodontidae. Bayesian phylogenetic reconstruction indicated that O. degus represented the basal Octodon sp., followed by O. lunatus; O. bridgesii and O. pacificus were identified as sister taxa. Remarkably, the genetic divergence between O. bridgesii and O. pacificus is low, which suggests that 1 of 2 scenarios may be at play: the occurrence of a recent peripatric speciation process in O. pacificus, or the presence of O. bridgesii on Mocha Island. Documented collections of archeozoological material obtained from Mocha Island only include specimens of O. pacificus, a finding that supports our 1st proposed scenario. While the core of Mocha Island is a national reserve, strong anthropogenic landscape modifications have affected the coastal plains—the only known habitat of O. pacificus. Rodent control using killing traps and poison is a common practice on the island; therefore, population surveys and conservation initiatives are needed to conserve this endangered species. El género Octodon (Octodontidae) se compone por cuatro especies de roedores endémicos del suroeste de América del Sur. Ocotodon pacificus fue descrito a partir de especímenes colectados en 1959 en Isla Mocha, una pequeña isla ubicada en la costa de Chile Central. Cincuenta y siete años después de su único registro, mediante un estudio morfológico, reportamos la identificación de una carcasa de una hembra de O. pacificus colectada en la localidad tipo para la especie. Adicionalmente, utilizando secuencias parciales del gen mitocondrial Cytb de esta y las otras tres especies del género, mediante un análisis Bayesiano se reconstruyeron las relaciones filogenéticas dentro de la familia Octodontidae. Con un elevado soporte de valores de probabilidad posterior, Octodon degu figura en un clado basal separado de un grupo hermano compuesto por Octodon lunatus, Octodon bridgesii y O. pacificus. La alta similitud genética observada entre O. bridgesii y O. pacificus es sugestivo de dos posibles escenarios: la ocurrencia de un evento de especiación peripátrica, o que O. brigdesii posee una población en la Isla Mocha. Análisis de osamentas de roedores en restos arqueológicos colectados en la isla, solo incluyen el diagnóstico de
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We describe the current state of the ruil (Nothofagus alessandrii) forest, a rare and endemic temperate forest in central Chile. Because of a long history of land-use, the ruil forest has suffered intense deforestation and fragmentation. By 1991, there remained 352.2 ha of forest in 183 fragments, most of them small and regular and a few large and irregular. From 1981 to 1991 the forest disappeared at a rate of 8.15% per year, to our knowledge, the highest value reported in forest fragmentation. Fragments are surrounded by a matrix of Pinus radiata plantations. Only 42 ha of forest (12% of the total area) are protected in a public reserve. An analysis of the composition of the forest shows that 13.8% of the total species are introduced. Pinus radiata is the only tree that has invaded this forest successfully. The 45.4% of native tree species are shade-tolerant and dependent on biotic pollinators and dispersers. These species should be the targets for future conservation efforts as they are particularly sensitive to fragmentation. We conclude that the current situation of the ruil forest is critical, and it will disappear in the next decade unless we conduct an active strategy of conservation, including integrated efforts both inside and outside protected areas and between landowners and public agencies.
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