Global climate change is driving rapid distribution shifts in marine ecosystems; these are well established for lower trophic levels, but are harder to quantify for migratory top predators. By analysing a 25-year sightings-based dataset, we found evidence for rapid northwards range expansion of the critically endangered Balearic shearwater Puffinus mauretanicus in northeast Atlantic waters. A 0.6 degrees C sea surface temperature increase in the mid-1990s is interpreted as an underlying controlling factor, while simultaneous northward shifts of plankton and prey fish species suggests a strong bottom-up control. Our results have important conservation implications and provide new evidence for climate-driven regime shift in Atlantic ecosystems.
In order to examine the dynamics and potential impact of the recently introduced sacred ibis Threskiornis aethiopicus, we review the published and unpublished data and report new information on its distribution in West European countries and particularly in France. This species, which escaped from zoos during the 1990s, is well established and has spread on the Atlantic coast and in Mediterranean region of France, with a mid-winter population reaching ca. 3200 individuals in winter 2004À2005 and ca. 1100 breeding pairs in spring 2005. The species has also escaped from zoological parks in Belgium, Germany, Spain, Italy and Portugal, and feral populations are established in Piedmont (Italy) and in the Canary Islands (Spain). The species dispersing ability has led to observations over hundreds of kilometres from the established colonies. We identify that in temperate habitats the sacred ibis shows a behavioural flexibility similar to that known in its tropical native range, including a large diet spectrum (insects, molluscs, refuse, bird eggs, etc.) and an ability to use various habitats (meadows, rubbish dumps, marshes, reedbeds, seashore, ploughed fields, etc.). This plasticity, the fact that predation by ibises is observed on nests of threatened bird species, and the number of potential sources of ibis in Europe (zoos) are causes of concern suggesting that precautionary measures should be taken to prevent the spread of this new alien species.
SUMMARY: Surveys carried out in the 1980s showed that 8,000-10,000 Balearic shearwaters regularly gathered in inshore waters of central and northern Biscay, particularly off the coast of Vendée and in the Mor-Braz area, western France. This distribution, apparently linked to particular oceanographical conditions (thermal front), was strikingly overlapping with that of clupeid fish, particularly anchovies. Recent surveys (1999)(2000) have shown that the species has become far less numerous in these "traditional" haunts. Conversely, its abundance has increased in the western Channel, some hundreds of kilometres to the North, during the 1990s. Reasons for this northward shift (e.g. changes in prey distribution due to fishing activities or water warming in Biscay) remain hypothetical and further study is needed.Key words: Atlantic Ocean, Balearic shearwater, clupeid fisheries, distribution, English Channel, long-term changes, Puffinus mauretanicus, thermal front. RESUMEN: NUEVOS CAMBIOS EN LA DISTRIBUCIÓN ESTIVAL DE LA PARDELA BALEAR PUFFINUS MAURETANICUS FRENTE A LA COSTA OCCIDENTAL DE FRANCIA. -Inspecciones realizadas en los años 1980 mostraron que unas 8.000-10.000 pardelas baleares se congregaban regularmente en aguas interiores del centro y norte de la Bahía de Vizcaya, particularmente frente a Vendeé y la zona de Mor-Braz, en el oeste de Francia. Esta distribución, aparentemente ligada a condiciones oceanográfi-cas particulares (un frente térmico), se solapa notablemente con la de peces clupeidos, en particular anchoas. Seguimientos recientes (1999)(2000) han mostrado que la especie se ha vuelto bastante menos numerosa en estos lugares. Por el contrario, su abundancia se ha incrementado en el canal de la Mancha, varios cientos de kilómetros al norte, durante los años 1990. Las razones de este traslado hacia el norte (por ejemplo cambios en la distribución de las presas debidos a las actividades pesqueras o al calentamiento del agua en la Bahía de Vizcaya) son hipotéticas y es necesario un mayor estudio.Palabras clave: cambios a largo plazo, canal de la Mancha, distribución, frente térmico, océano Atlántico, pardela balear, pesquerías de clupeidos, Puffinus mauretanicus.
Four to 10 years after the successful eradication of the Norway rat ( Rattus norvegicus ) from three islands of the Sept-Îles Archipelago and one in the Molène Archipelago (Brittany, France), the abundance index of the lesser white-toothed shrew ( Crocidura suaveolens ) increased by factors of 7-25, depending on the island and the year. Moreover, in the same region, the abundance index of the greater white-toothed shrew ( Crocidura russula ) on Tomé Island increased by factors of 9 and 17, one and two years after the Norway rat eradication, respectively.The maximum variation of the abundance index for the lesser white-toothed shrew during seven years on the rat-free island of Béniguet in the same region was a factor of only 2.5. Moreover, the distribution of the lesser white-toothed shrew on Bono island, restricted before the eradication to two steep areas with few rats, increased and encompassed virtually the entire island four years after rats disappeared.These results suggest strong detrimental interactions between the introduced Norway rat and the two Crocidura shrew species on temperate oceanic islands. However, our data do not indicate the ecological mechanisms at work in these interactions.The main reason this shrew recovery was detected after rat eradication was the inclusion in the eradication protocol of the evaluation of impacts on the local biota of eliminating alien species. The rigor of the sampling procedure was also crucial to this discovery. This example demonstrates that an eradication operation can be extremely useful for both scientists and managers if it is planned as a research project.
We investigated spatio-temporal distribution patterns of the Critically Endangered Balearic shearwater Puffinus mauretanicus in the northern part of its migratory range, using a combination of effort-corrected land-and boat-based survey data (2007−2010). The species was recorded regularly along the western English Channel (Western Channel) coasts of northwest France and the southwest UK, with peak counts occurring during the summer and autumn months. Foraging aggregations comprising hundreds to thousands of birds (~1 to 20% of the global population) were recorded in the large shallow embayments of northern Brittany in all survey years. Elsewhere, most birds were recorded on passage, with maximum birds-per-hour (BPH) of 169 off northwest France and 36 off the southwest UK. Few birds were recorded offshore, beyond sight of land. A distance-from-shore analysis revealed that the species passed closer to shore than other pelagic seabirds such as sooty shearwater Puffinus griseus. A constant-effort seasonal survey from the southwest tip of the UK mainland recorded the species on 93% of survey days, with BPH rates peaking in the morning between 08:00 and 11:00 h. These results have important monitoring and conservation implications for this Critically Endangered species. In particular, the records of large aggregations in spatially restricted areas of the Western Channel during the inter-breeding period suggests the species could be vulnerable to impacts such as oil spills, or disturbance from offshore construction projects. We also provide evidence that some birds remain in the survey area during the breeding season, suggesting it may be an important site for non-breeding birds.
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