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Le présent traite de la recherche d'invariants pour qualifier les systèmes insulaires de l'Océanie. Cette approche se différencie de la plupart des études insulaires qui conduisent à multiplier les monographies d'îles sans qu'aucune loi générale ne puisse être identifiée. La coutume et la gestion coutumière du risque constituent les deux invariants de toute société traditionnelle en Océanie dont elles assurent la résistance face aux perturbations d'origine exogène. Mais la globalisation très rapide que connaît la région actuellement tend à émousser leur opérationnalité face aux deux défis majeurs qui s'affirment : le défi alimentaire et le défi migratoire.

Le présent article traite de la recherche d’invariants pour qualifier les systèmes insulaires de l’Océanie. Cette approche se différencie de la plupart des études insulaires qui conduisent à multiplier les monographies d’îles sans qu’aucune loi générale ne puisse être identifiée. La coutume et la gestion coutumière du risque constituent les deux invariants de toute société traditionnelle en Océanie dont elles assurent la résistance face aux perturbations d’origine exogène. Mais la globalisation très rapide que connaît la région actuellement tend à émousser leur opérationnalité face aux deux défis majeurs qui s’affirment : le défi alimentaire et le défi migratoire.

To forecast the potential impact of plant community and dry-stone wall restoration on an insular population of the lesser white-toothed shrewCrocidura suaveolens Pallas, 1811, shrew and house mouseMus musculus Linnaeus, 1758 abundances were assessed in 3 anthropogenic habitats on Beniguet Island, Brittany, France, by a standardised annual trapping system checked yearly for 9 years and in 6 “natural” habitats by trap-lines. The standardised trapping system showed that abundances of both species fluctuated synchronously for nine years, suggesting that interactions between the species had little impact if any on abundances. Mice were trapped in all habitats, but shrews only in “stone” habitats except for rare occurrences in one damp depression. Ruderal habitat was rarely used by either species. Data suggest that on Beniguet Island: (1)M. musculus is associated with anthropogenic habitats but is not as strictly tied to them as at nearby continental sites; (2)C. suaveolens is synanthropic, as has been reported in continental northern France; (3) shingle beaches and seashore food resources are particularly important forC. suaveolens; (4) the relationship betweenC. suaveolens andM. musculus could not be determined by the experiments and, if it exists at all, appears to be more competitive than predatory. Grassland restoration is unlikely to affect shrew populations. Dry-stone wall restoration may temporarily affect shrews but should ultimately benefit them.

International audience; Shifting cultivation is considered to be the most widespread cultivation system in the tropics. However, it remains poorly understood in some countries. The measurement of agrobiodiversity in these systems, which could be used to better understand its sustainability in the face of social, economic and environmental change, has been the focus of little research. This study aimed to measure the agrobiodiversity on small, family-farmed, shifting cultivation fields in Vanuatu and to test the effect of different demographic pressures, locations and cropping systems. A total of 297 fields in 6 villages were measured and a spatial approach was used for comparisons at the field, farmer and village scales. Shifting cultivation in Vanuatu includes three main cropping systems, based on yams, rain-fed taro or irrigated taro, and other subsidiary systems. The configuration of each farm's cropping system depends on each farmer's choices and opportunities. Agrobiodiversity in fields was high with a mean species richness of 10.2 (±4.8 SD) and an intraspecific richness of 8.6 (±7.3 SD). In a crop sequence, agrobiodiversity decreased for yam and rain-fed taro fields but this decrease was faster in yam fields. Cluster analyses showed that the main factor influencing agrobiodiversity at the field and farmer scale was the cropping system. At the village scale, however, the cropping system only appeared to influence intraspecific richness as no difference in species richness was found between villages. Moreover, ANOVA showed no village effect on agrobiodi-versity, which raises the question of whether there is an effect of scale affecting biodiversity assessments in landscapes. No correlation was found between agrobiodiversity and demographic pressures or fallow length at any spatial scale. This study showed that the agrobiodiversity is variable at the field and farmer scale but is stable across villages and islands and is influenced only by the dominant cropping system. It suggests that this system is still resilient in the face of recent economic, social and environmental changes, but requires further multiple scale studies for a deeper understanding.

The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystems' structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents) and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in δ 15N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers. © 2012 Caut et al.

At least five marine turtles and 49 terrestrial or freshwater amphibians and reptiles have been listed from the French West Indies since the beginning of human settlement. Among terrestrial or freshwater species, two groups may be distinguished. The first group comprises 35 native species, of which seven are currently extinct or vanished. These species are often endemic to a bank and make up the initial herpetofauna of the French West Indies. Disregarding two species impossible to rule on due to lack of data, the second group includes twelve species that were introduced. Except for marine turtles and some terrestrial species for which the decline was due to human predation, the extinctions primarily involved ground living reptiles of average size and round section body shape. Habitat degradation and mammalian predator introductions have probably contributed to the extinction of these species, in addition to a possible direct impact of man. To better understand the threats to species, we suggest studying the interactions between native herpetofauna and introduced competitors or predators, taking into account the habitat structure. This would help to give the necessary information for successful management measures for conservation or restoration. As an example, the conservation of the Petite Terre (Guadeloupe) Iguana delicatissima population requires identifying both the mechanisms that regulate its population and their relationships to catastrophic climatic events. Key words: Amphibians; biological invasions; conservation; French West Indies; Guadeloupe; Iguana delicatissima; Petite Terre; Reptiles; threats.

Focus on introduced amphibians and reptiles

Focus on synanthropic mammals

Overview: Introduced species, the "good", the "worrisome" and the "bad"

Original french edition published in February 2010 under the title "Les invasions biologiques, une question de natures et de sociétés". Editions Quae 2010 (ISBN: 978-2-7592-0372-7); Lessons from biological evolution: good and bad

Version anglaise publiée en 2011 sous le titre "Biological invasions, a question of nature and society". Editions Quae, Versailles (FR) (ISBN: 978-2-7592-0872-2); Les leçons de l'évolution biologique : entre bien et mal

In the Mediterranean, the survival of endemic long-lived seabirds despite the long-standing introduction of one of the most damaging alien predator, the ship rat (Rattus rattus), on most islands constitutes an amazing conservation paradox. A database gathering information on approximately 300 Western Mediterranean islands was analyzed through generalized linear models to identify the factors likely to influence ship rat presence and to account for how ship rat presence and island characteristics may have driven the presence and abundance of seabirds. Our review showed that few Mediterranean islands remain rat-free. At the regional scale, rat presence was only a limiting factor in the abundance of the smallest seabird, the storm petrel (Hydrobates pelagicus), while the distribution and abundance of the three shearwaters were more influenced by island characteristics. We hypothesized that the long-term persistence of these seabirds may have been facilitated by the various biogeographical contexts of Mediterranean islands, likely to provide intra-island refuges. © 2009 Springer Science+Business Media B.V.

In the south-west Indian Ocean tourist activity is omnipresent. Whatever the degree of human development of states and territories tourism weighs heavily on the employment level of labor and economic growth. In these conditions, it appears that tourism contributes to fight against poverty for the least developed countries and it supports the economies of countries already in development. However, for the richiest as well as the poorest, the foundation of tourism development are everywhere fragile and durability is still uncertain. This durability is intrinsically linked to structural conditions of development of tourism and to the risks (natural or anthropogenic, exogenous or endogenous). The example of a health risk, such as chikungunya, sheds light on the economic vulnerability of tourism regardless of the vulnerability of societies face to the same risk., Dans le sud-ouest de l'océan Indien l'activité touristique est omniprésente. Quel que soit le degré de développement humain des Etats et territoires concernés le tourisme pèse fortement sur le niveau d'emploi de la main d'oeuvre et sur la croissance économique. Dans ces conditions, il apparaît que le tourisme contribue à la lutte contre la pauvreté pour les pays les moins développés et qu'il soutient l'économie des pays déjà engagés dans la voie du développement. Néanmoins, pour les plus riches comme pour les plus pauvres, les fondements du développement touristique sont partout fragiles et la durabilité, quoiqu'à nuancer, est toujours incertaine. Cette durabilité est intrinsèquement liée aux conditions structurelles de mise en tourisme des territoires ainsi qu'aux risques qu'ils soient naturels ou anthropiques, exogènes ou endogènes. A ce titre, l'exemple d'un risque sanitaire, comme le chikungunya, nous éclaire sur la vulnérabilité économique du tourisme indépendamment de la vulnérabilité des sociétés face à ce même risque suivant les pays considérés.

Dans les îles, éradiquer pour protéger ?

International audience; Breeding success of 5 Cory's shearwater Calonectris diomedea sub-colonies of Lavezzu Island (Lavezzi Archipelago, Corsica) was checked annually for 25 consecutive years from 1979 to 2004. Between 1989 and 1994, 4 ship rat Rattus rattus controls were performed in several subcolonies. In November 2000, rats were eradicated from Lavezzu Island and its 16 peripheral islets (85 ha) using traps then toxic baits. We compare cost (number of person-hours required in the field) and benefit (Cory's shearwater breeding success) of control and eradication. The average breeding success doubled when rats were controlled or eradicated (0.82) compared to the situation without rat management (0.45). Moreover, the average breeding success after eradication (0.86) was significantly (11%) higher than after rat controls (0.75). Furthermore, the great variation in breeding success recorded among sub-colonies both with and without rat control declined dramatically after eradication, suggesting that rats had a major impact on breeding success. The estimated effort needed to perform eradication and checking of the permanent bait-station system during the year following eradication was 1360 person-hours. In contrast, rat control was estimated to require 240 or 1440 person-hours per year when implemented by trained and untrained staff, respectively. Within 6 yr, eradication cost is lower than control cost performed by untrained staff and confers several ecological advantages on more ecosystem components than Cory's shearwater alone. Improved eradication tools such as hand or aerial broadcasting of toxic baits instead of the fairly labour-intensive eradication strategy we used would dramatically increase the economic advantage of eradication vs. control. Therefore, when feasible, we recommend eradication rather than control of non-native rat populations. Nevertheless, control remains a useful management tool when eradication is not practicable

Figure également dans le rapport d'activités 2008 "Réserve de Béniguet", pour le ministère chargé de l'Environnement (MEEDDAT) et Office National de la Chasse et de la Faune Sauvage (ONCF) (p.28-32); Echantillonnage standardisé des micromammifères de l'île de Béniguet. Transfert de méthode et résultats de l'année 2008

La prise de conscience récente du rôle majeur que jouent les invasions biologiques dans l'érosion de la biodiversité a motivé la mise en place d'un module qui leur a été spécifiquement consacré au sein de l'expédition " Santo 2006 ". Ce module a concentré son attention sur un nombre restreint de groupes zoologiques et botaniques et a tenté, au-delà d'un inventaire des espèces allochtones de l'île, de réaliser une approche écologique en comparant quatre sites présentant un gradient d'anthropisation. L'analyse comparative des sites n'est pas achevée, mais un panorama global des espèces allochtones rencontrées est proposé. En dépit de son apparent isolement des importantes routes commerciales depuis la fin de la Deuxième Guerre mondiale, les écosystèmes de l'île d'Esperitu Santo hébergent au moins quatorze espèces mentionnées au nombre des cent espèces identifiées par l'IUCN comme les plus dangereuses pour le maintien de la biodiversité des écosystèmes envahis. À noter cependant qu'une de ces espèces, le porc, a été introduite par les premiers occupants de l'île et joue actuellement un rôle culturel, nutritionnel et économique majeur pour les populations locales.

Migrations, Urbanization and Health in the South Pacific. The archipelagoes of the South Pacific are experiencing rather important population movements. These consist of international migrations towards destinations outside of the South Pacific, descent of mountain inhabitants towards the coasts, depopulation of the small islands to the benefit of the larger ones, and circular migrations of rather low volume. But the island populations continue to increase and live in a climate of growing food dépendance, while nutritional imbalances are appearing or becoming more serious in the transitional economic system that has come into existence., Les archipels du Pacifique sud voient se développer dans leur ensemble d'importants déplacements de population : développement des migrations internationales vers des destinations extérieures au Pacifique sud, descente des populations montagnardes vers les côtes, dépeuplement des petites îles au profit des plus grandes, migrations circulaires de faible amplitude. Mais la population insulaire continue à augmenter et vit dans une dépendance alimentaire croissante tandis que des déséquilibres nutritionnels apparaissent ou se renforcent dans une économie de transition qui se met en place., Connell John. Migrations, urbanisation et santé dans le Pacifique Sud. In: Cahiers d'outre-mer. N° 168 - 42e année, Octobre-décembre 1989. pp. 395-423.