The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercailli... more The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercaillie, is endemic to the Cantabrian Mountains of northwest Spain. The range is separated from its nearest neighbouring capercaillie population by a distance of more than 300 km. High genetic differentiation compared to capercaillie elsewhere qualifies the subspecies as an Evolutionarily Significant Unit. An assessment according to the IUCN Red List categories and criteria showed that the subspecies qualifies as Endangered due to rapid population declines, small population size, and severely fragmented range. The implementation of a range-wide recovery plan is vital for the survival of this subspecies.
Counting rare and elusive animals and evaluating their demographic status, are fundamental yet ch... more Counting rare and elusive animals and evaluating their demographic status, are fundamental yet challenging aspects of population ecology and conservation biology. We set out to estimate population size (N c ), genetic effective population size (N e gen ), sex ratio, and movements based on genetic tagging for the threatened Cantabrian capercaillie. We used 9 microsatellite loci to genotype 134 droppings collected at 34 display areas during the breeding season. Using genetic capture-mark-recapture, we estimated 93 individuals (N c , 95% CI: 70-116) in an area of about 500 km 2 , with sex ratio biased towards males (1:1.6). Estimated N e gen (35.5) was 38% of N c , notably higher than the published average in wild populations. This capercaillie population is small and well within concern in terms of population viability. By genetic tagging, we detected mostly short movements; just a few males were recaptured between contiguous display areas. Non-invasive surveys of endangered populations have a great potential, yet adequate sample size and location are key to obtain reliable information on conservation status.
Predators are increasingly recognized as key elements in food webs because of their ability to li... more Predators are increasingly recognized as key elements in food webs because of their ability to link the fluxes of nutrients and energy between spatially separated food chains. However, in the context of food web connectivity, predator populations have been mainly treated as homogeneous units, despite compelling evidence of individual specialization in resource use. It is conceivable that individuals of a predatory species use different resources associated with spatially separated food chains, thereby decoupling cross-habitat linkages. We tested whether intrapopulation differences in habitat use in the generalist freshwater predator Eurasian perch (Perca fluviatilis) led to long-term niche partitioning and affected the degree of ecological habitat coupling. We evaluated trophic niche variability at successively larger timescales by analyzing gut contents and stable isotopes (d 13 C and d 15 N) in liver and muscle, tissues that provide successively longer integration of trophic activity. We found that the use of distinct habitats in perch led to intrapopulation niche partitioning between pelagic and littoral subpopulations, consistent through the various timescales. Pelagic fish showed a narrower niche, lower individual specialization, and more stable trophic behavior than littoral fish, as could be expected from inhabiting a relatively less diverse environment. This result indicated that substantial niche reduction could occur in a generalist predator at the subpopulation level, consistent with the use of a habitat that provides fewer chances of individual specialization. We showed that intrapopulation niche partitioning limits the ability of individual predators to link spatially separated food chains. In addition, we suggest a quantitative, standardized approach based on stable isotopes to measure the degree of habitat coupling mediated by a top predator.
The turnover and distribution of energy and nutrients in food webs is influenced by consumer stoi... more The turnover and distribution of energy and nutrients in food webs is influenced by consumer stoichiometry. Although the stoichiometry of heterotrophs is generally considered to vary only little, there may be intraspecific variation due to factors such as habitat, resources, ontogeny and size. We examined intraspecific variation in Eurasian perch Perca fluviatilis stoichiometry, a common species that exhibits habitat and resource specialization, ontogenetic niche shifts and a large size range. This study investigated the elemental stoichiometry of a wide size range of perch from littoral and pelagic habitats. The mean C:N:P stoichiometry of whole perch was 37:9:1 (molar ratios). However, %C, %P, C:N, C:P and N:P varied with size, morphology, habitat and diet category. These factors together explained 24-40% of the variation in C:N:P stoichiometry. In contrast, perch stoichiometry was not related to diet stoichiometry, suggesting that the former is homeostatically regulated. The results suggest that the high P content of perch may result in stoichiometric constraints on the growth of non-piscivorous perch, and that piscivory is an efficient strategy for acquiring P. Resource polymorphism, individual diet specialization and intraspecific size variation are widespread among animals. Thus changes in stoichiometry with size, habitat, morphology and resource use, and therefore also stoichiometric demands, are probably common.
The stoichiometry of trophic interactions has mainly been studied in simple consumer–prey systems... more The stoichiometry of trophic interactions has mainly been studied in simple consumer–prey systems, whereas natural systems often harbour complex food webs with abundant indirect effects. We manipulated the complexity of trophic interactions by using simple laboratory food webs and complex field food webs in enclosures in Lake Erken. In the simple food web, one producer assemblage (periphyton) and its consumers (benthic snails) were amended by perch, which was externally fed by fish food. In the complex food web, two producer assemblages (periphyton and phytoplankton), their consumers (benthic invertebrates and zooplankton) and perch feeding on zooplankton were included. In the simple food web perch affected the stoichiometry of periphyton and increased periphyton biomass and the concentration of dissolved inorganic nitrogen. Grazers reduced periphyton biomass but increased its nutrient content. In the complex food web, in contrast to the simple food web, perch affected periphyton biomass negatively but increased phytoplankton abundance. Perch had no influence on benthic invertebrate density, zooplankton biomass or periphyton stoichiometry. Benthic grazers reduced periphyton biomass and nutrient content. The difference between the simple and the complex food web was presumably due to the increase of pelagic cyanobacteria (Gloeotrichia sp.) with fish presence in the complex food web, thus fish had indirect negative effects on periphyton biomass through nutrient competition and shading by cyanobacteria. We conclude that the higher food web complexity through the presence of pelagic primary producers (in this case Gloeotrichia sp.) influences the direction and strength of trophic and stoichiometric interactions.
J.R. 2006: Habitat selection by Cantabrian capercaillie Tetrao urogallus cantabricus at the edge ... more J.R. 2006: Habitat selection by Cantabrian capercaillie Tetrao urogallus cantabricus at the edge of the species' distribution. -Wildl. Biol. 12: 267-276.
The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) lives at the southern edge ... more The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) lives at the southern edge of tetraonids’ distribution range, in entirely deciduous forests. Its conservation planning has been always lek-centred. There is very little information about the specific habitat requirements of hens and broods, even though reproductive success appears to be a limiting factor. We analysed summer surveys from 1997 to 2004, carried out to estimate the reproductive success of the population. We compared the habitat characteristics at different spatial scales of hens with broods, broodless hens, and cocks in summer, with the better known spring habitat in display areas. Summer habitat showed higher proportion of open areas and was associated with more rugged zones at moderate spatial scales (78 ha) than spring habitat at display areas. Cocks and hens showed summer habitat partitioning; hens were associated with higher proportions of open and shrubby habitats. Furthermore, broodless hens preferred areas with higher slope variability than the display and summer areas preferred by cocks. These differences may reflect the sexual dimorphism of the species in reproductive role, energetic demands and conspicuousness. At larger spatial scales a previously developed habitat suitability model performed well to predict good brood-rearing areas. Hens with broods were located in the best-preserved areas in the range, mainly characterized by higher proportion of forest cover at a large (50 km2) scale. We suggest that these characteristics indicate refuge habitats where Cantabrian capercaillie can still breed successfully.
Conservation policies of the European Nature 2,000 network reflect an overarching concern about a... more Conservation policies of the European Nature 2,000 network reflect an overarching concern about alleged negative effects of abandonment of traditional uses. In particular, the abandonment of livestock herding is widely assumed to be responsible of biodiversity decreases through habitat homogenization. However, those negative effects of land abandonment on biodiversity are neither straightforward nor the repeatedly assumed land abandonment has been always supported by hard data. We analyzed the evolution of cattle densities in the Cantabrian Mountains (NW Spain) in the past 20 years, and its relation with the decline in the occupancy of capercaillie leks. Instead of the widely-assumed decrease of livestock numbers, which has been already incorporated into landscape and wildlife management, we found an actual increase in cattle numbers. Those cattle numbers were negatively related to the presence of an endangered, distinctive population of capercaillie, a bird considered an umbrella species in mountain forest ecosystems. Thus our data do not support the alleged role of free-ranging livestock in the conservation of biodiversity. We consider that typological thinking in the relationship of socio-economic changes and biodiversity conservation should be replaced by hard data and consideration of ecosystem naturalness.
Cantabrian capercaillie Tetrao urogallus cantabricus is a peripheral population with distinctive ... more Cantabrian capercaillie Tetrao urogallus cantabricus is a peripheral population with distinctive phenotypic, biogeographic, and genetic characteristics. Hence, the population may also show substantial ecological differentiation associated with its habitat in purely deciduous forests. We assessed seasonal diet selection, small-scale habitat selection, and patterns of trophic niche width in Cantabrian capercaillie over two years. Diet was found to be a driver of small-scale habitat selection, a result consistent with previous studies of stand-scale habitat selection. Diet and habitat selection showed the importance of beech Fagus sylvatica, holly Ilex aquifolium, bilberry Vaccinium myrtillus, and ferns in Cantabrian capercaillie’s resource selection. Conversely, the abundant oaks Quercus petraea, birches Betula pubescens, and heaths Erica sp. were used below their availability. The reliance on bilberry appears as a unifying characteristic between central and peripheral capercaillie populations. Cantabrian capercaillie showed stronger reliance on understory resources than range-central populations. It also showed wider trophic niche and higher specialization of feeding events. Trophic niche patterns and reliance on ground resources indicated a marked ecological differentiation, which stresses the need for local data and specific conservation actions.
Sexual dimorphism is often associated with different feeding strategies between sexes because of ... more Sexual dimorphism is often associated with different feeding strategies between sexes because of distinct nutritional demands or intake rates. Capercaillie (Tetrao urogallus) is the most sexually dimorphic grouse, thus sexual segregation in resource use is likely. This study assessed intrapopulation variation in the diet related to habitat use, focusing on differential feeding behaviors between Capercaillie females and males. We used stable isotopes analyses in feathers of Cantabrian Capercaillie, a population living at the southern edge of the range in purely deciduous forests. We analyzed feathers of females and males, and sorted them according to the dominant tree species in the patch where they were found. Mean isotopic values differed both between sexes and among forest types. The latter explained most of the isotopic variance, suggesting that birds consistently selected certain forest types to molt. Capercaillie females showed wider trophic niche and seemingly more intra-gender diversity in resource use than males. The differences between sexes in the trophic variability support the sexual segregation reported in previous studies which is associated with females using the more micro-habitat diverse treeline areas, while males mainly use the inner areas of the forests. Stable isotope analysis proved very useful to assess intersexual niche partitioning in rare species living in rugged terrains where it is logistically difficult to rely on direct approaches (i.e. direct observation, capture and radio-tracking).
The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercailli... more The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercaillie, is endemic to the Cantabrian Mountains of northwest Spain. The range is separated from its nearest neighbouring capercaillie population by a distance of more than 300 km. High genetic differentiation compared to capercaillie elsewhere qualifies the subspecies as an Evolutionarily Significant Unit. An assessment according to the IUCN Red List categories and criteria showed that the subspecies qualifies as Endangered due to rapid population declines, small population size, and severely fragmented range. The implementation of a range-wide recovery plan is vital for the survival of this subspecies.
We analysed the composition and configuration patterns of the forested landscape in the Cantabria... more We analysed the composition and configuration patterns of the forested landscape in the Cantabrian range (NW Spain) determining how different forest communities are currently affected by long-term fragmentation process. We also evaluated the regional reserve network in relation to forest fragmentation and forest heterogeneity at the landscape level. The current landscape scenario is characterised by low forest habitat cover (22%) and a fragment size distribution strongly skewed towards small values (<10 ha). Forest classes differ strongly in fragment size, internal heterogeneity, shape, dispersion and isolation. Beech forests were less fragmented than other types, being the dominant class in terms of surface and fragment occurrence. Fragmentation was heavier in forests occurring in agriculture-suitable areas (i.e. valley bottoms, southern exposures), such as ash-maple and oak forests, as well as in second-growth forests developed after tree-line deforestation for pastures (i.e. holly and rowan forests). The current reserve network in the Asturias region covers preferentially bigger and less isolated forest fragments. This was a consequence of protection biased towards beech forests, to the detriment of an adequate representativeness of most other forest types, some of them with high ecological value. Future expansion of the reserve network should be based on landscape information, to promote both the protection of well-conserved, less-fragmented forests as well as the inclusion of under-represented target forest types. #
Quevedo, M. 2004. Modelling the distribution of Ilex aquifolium at the north-eastern edge of its ... more Quevedo, M. 2004. Modelling the distribution of Ilex aquifolium at the north-eastern edge of its geographical range. -Nord. J. Bot. 23: 129-142. Copenhagen. ISSN 0107-055X.
1] The southern Bay of Biscay (NW Spain) shows a very active hydrography due to the different ori... more 1] The southern Bay of Biscay (NW Spain) shows a very active hydrography due to the different origins of its Central Waters, the local modifications exerted on them by continental effects and the recurrence of mesoscale processes such as slope currents, upwellings and eddies. In order to assess the role of the different sources of variability we conducted a monthly series of CTD sampling in the central Cantabrian Sea along a coastal-oceanic transect, from 1993 to 2003. We analyzed the spatial variability of the hydrographic processes over different timescales. The thermohaline properties of Central Waters varied between those typical of the subpolar mode of the Eastern North Atlantic Central Water (ENACWsp) and a local mode, the Bay of Biscay Central Water (BBCW), though there has been a clear shift toward the BBCW prevalence in the last years. The Iberian Poleward Current (IPC) conveyed subtropical Central Waters (ENACWst) into the region almost every winter. This slope current may display a double-core structure during some extreme events. The upper layers of the ocean showed a long-term trend toward increasing temperature and decreasing salinity, and accordingly density was on the decrease. These patterns suggest an enhancement of the water column stratification. Coastal upwellings are an important source of inshore variability and counteract these long-term changes on the coast. However, their intensity seems to be decreasing and their seasonal pattern changing toward a general advancement of the upwelling-favorable season.
Deep-sea Research Part Ii-topical Studies in Oceanography, 2002
Mesozooplankton distribution and community structure in the Bellinghausen-Bransfield sector of th... more Mesozooplankton distribution and community structure in the Bellinghausen-Bransfield sector of the Antarctic Ocean were investigated during the FRUELA cruises (December 1995-February 1996. Total mesozooplankton biomass ranged between 0.015 and 1.43 g C m À2 . Biomass was higher in the Southern boundary of the Antarctic Circumpolar Current (SbyACC) area and in coastal waters of the Antarctic Peninsula. Total mesozooplankton abundance ranged from 0.4 Â 10 3 to 1.3 Â 10 5 individuals m À2 , of which 41.6-99.5% corresponded to copepods, mainly families Oithonidae, Oncaeidae, Pseudocalanidae, Calanidae and Metrididae. There was no evidence of coupling between mesoscale physical features and biomass or community structure. While coastal stations mainly at the Gerlache Strait remained in a highly productive state through the spring-summer, oceanic stations experienced a marked shift from a productive condition during FRUELA 95 to a low biomass, pteropod-dominated situation during FRUELA 96, possibly due to changing weather conditions. The median ingestion rates of herbivorous crustaceans during the FRUELA cruises were 0.7 mg Chl a m À2 day À1 . Measured ingestion rates represented only 0.1% of the chlorophyll standing stock or 10% of the daily primary production. Thus, crustacean mesozooplankton had little control on the development of phytoplankton blooms in the area. r (J.A. Cabal). 0967-0645/01/$ -see front matter r 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 7 -0 6 4 5 ( 0 1 ) 0 0 1 2 8 -X
A large proliferation of Noctiluca scintillans (Dinophyceae: Noctilucidea) was observed in neriti... more A large proliferation of Noctiluca scintillans (Dinophyceae: Noctilucidea) was observed in neritic waters off the central Cantabrian coast during late April 1995. Eggs of Acartia clausi (Crustacea: Copepoda) were the most conspicuous prey within vacuoles of Noctiluca. Noctiluca ingested 73 % of the total stock of A. clausi eggs. This intense predation on copepod eggs could potentially affect the recruitment of nauplii. The potential impact on the stock of Acartia clausi eggs and on the daily egg production of the population is discussed. There is a negative correlation between the average number of ingested eggs by a single Noctiluca cell and the abundance of Noctiluca. This fact, coupled with the lack of significant correlation between the former variable and the abundance of Acartia clausi eggs, suggests that interference processes play a major role in regulating the predator-prey interaction between Noctiluca and Acartia eggs. 0 Elsevier, Paris / Ifremer / Cnrs / Ird Noctiluca I Acartia / copepod eggs I predation I Bay of Biscay
The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercailli... more The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercaillie, is endemic to the Cantabrian Mountains of northwest Spain. The range is separated from its nearest neighbouring capercaillie population by a distance of more than 300 km. High genetic differentiation compared to capercaillie elsewhere qualifies the subspecies as an Evolutionarily Significant Unit. An assessment according to the IUCN Red List categories and criteria showed that the subspecies qualifies as Endangered due to rapid population declines, small population size, and severely fragmented range. The implementation of a range-wide recovery plan is vital for the survival of this subspecies.
Counting rare and elusive animals and evaluating their demographic status, are fundamental yet ch... more Counting rare and elusive animals and evaluating their demographic status, are fundamental yet challenging aspects of population ecology and conservation biology. We set out to estimate population size (N c ), genetic effective population size (N e gen ), sex ratio, and movements based on genetic tagging for the threatened Cantabrian capercaillie. We used 9 microsatellite loci to genotype 134 droppings collected at 34 display areas during the breeding season. Using genetic capture-mark-recapture, we estimated 93 individuals (N c , 95% CI: 70-116) in an area of about 500 km 2 , with sex ratio biased towards males (1:1.6). Estimated N e gen (35.5) was 38% of N c , notably higher than the published average in wild populations. This capercaillie population is small and well within concern in terms of population viability. By genetic tagging, we detected mostly short movements; just a few males were recaptured between contiguous display areas. Non-invasive surveys of endangered populations have a great potential, yet adequate sample size and location are key to obtain reliable information on conservation status.
Predators are increasingly recognized as key elements in food webs because of their ability to li... more Predators are increasingly recognized as key elements in food webs because of their ability to link the fluxes of nutrients and energy between spatially separated food chains. However, in the context of food web connectivity, predator populations have been mainly treated as homogeneous units, despite compelling evidence of individual specialization in resource use. It is conceivable that individuals of a predatory species use different resources associated with spatially separated food chains, thereby decoupling cross-habitat linkages. We tested whether intrapopulation differences in habitat use in the generalist freshwater predator Eurasian perch (Perca fluviatilis) led to long-term niche partitioning and affected the degree of ecological habitat coupling. We evaluated trophic niche variability at successively larger timescales by analyzing gut contents and stable isotopes (d 13 C and d 15 N) in liver and muscle, tissues that provide successively longer integration of trophic activity. We found that the use of distinct habitats in perch led to intrapopulation niche partitioning between pelagic and littoral subpopulations, consistent through the various timescales. Pelagic fish showed a narrower niche, lower individual specialization, and more stable trophic behavior than littoral fish, as could be expected from inhabiting a relatively less diverse environment. This result indicated that substantial niche reduction could occur in a generalist predator at the subpopulation level, consistent with the use of a habitat that provides fewer chances of individual specialization. We showed that intrapopulation niche partitioning limits the ability of individual predators to link spatially separated food chains. In addition, we suggest a quantitative, standardized approach based on stable isotopes to measure the degree of habitat coupling mediated by a top predator.
The turnover and distribution of energy and nutrients in food webs is influenced by consumer stoi... more The turnover and distribution of energy and nutrients in food webs is influenced by consumer stoichiometry. Although the stoichiometry of heterotrophs is generally considered to vary only little, there may be intraspecific variation due to factors such as habitat, resources, ontogeny and size. We examined intraspecific variation in Eurasian perch Perca fluviatilis stoichiometry, a common species that exhibits habitat and resource specialization, ontogenetic niche shifts and a large size range. This study investigated the elemental stoichiometry of a wide size range of perch from littoral and pelagic habitats. The mean C:N:P stoichiometry of whole perch was 37:9:1 (molar ratios). However, %C, %P, C:N, C:P and N:P varied with size, morphology, habitat and diet category. These factors together explained 24-40% of the variation in C:N:P stoichiometry. In contrast, perch stoichiometry was not related to diet stoichiometry, suggesting that the former is homeostatically regulated. The results suggest that the high P content of perch may result in stoichiometric constraints on the growth of non-piscivorous perch, and that piscivory is an efficient strategy for acquiring P. Resource polymorphism, individual diet specialization and intraspecific size variation are widespread among animals. Thus changes in stoichiometry with size, habitat, morphology and resource use, and therefore also stoichiometric demands, are probably common.
The stoichiometry of trophic interactions has mainly been studied in simple consumer–prey systems... more The stoichiometry of trophic interactions has mainly been studied in simple consumer–prey systems, whereas natural systems often harbour complex food webs with abundant indirect effects. We manipulated the complexity of trophic interactions by using simple laboratory food webs and complex field food webs in enclosures in Lake Erken. In the simple food web, one producer assemblage (periphyton) and its consumers (benthic snails) were amended by perch, which was externally fed by fish food. In the complex food web, two producer assemblages (periphyton and phytoplankton), their consumers (benthic invertebrates and zooplankton) and perch feeding on zooplankton were included. In the simple food web perch affected the stoichiometry of periphyton and increased periphyton biomass and the concentration of dissolved inorganic nitrogen. Grazers reduced periphyton biomass but increased its nutrient content. In the complex food web, in contrast to the simple food web, perch affected periphyton biomass negatively but increased phytoplankton abundance. Perch had no influence on benthic invertebrate density, zooplankton biomass or periphyton stoichiometry. Benthic grazers reduced periphyton biomass and nutrient content. The difference between the simple and the complex food web was presumably due to the increase of pelagic cyanobacteria (Gloeotrichia sp.) with fish presence in the complex food web, thus fish had indirect negative effects on periphyton biomass through nutrient competition and shading by cyanobacteria. We conclude that the higher food web complexity through the presence of pelagic primary producers (in this case Gloeotrichia sp.) influences the direction and strength of trophic and stoichiometric interactions.
J.R. 2006: Habitat selection by Cantabrian capercaillie Tetrao urogallus cantabricus at the edge ... more J.R. 2006: Habitat selection by Cantabrian capercaillie Tetrao urogallus cantabricus at the edge of the species' distribution. -Wildl. Biol. 12: 267-276.
The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) lives at the southern edge ... more The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) lives at the southern edge of tetraonids’ distribution range, in entirely deciduous forests. Its conservation planning has been always lek-centred. There is very little information about the specific habitat requirements of hens and broods, even though reproductive success appears to be a limiting factor. We analysed summer surveys from 1997 to 2004, carried out to estimate the reproductive success of the population. We compared the habitat characteristics at different spatial scales of hens with broods, broodless hens, and cocks in summer, with the better known spring habitat in display areas. Summer habitat showed higher proportion of open areas and was associated with more rugged zones at moderate spatial scales (78 ha) than spring habitat at display areas. Cocks and hens showed summer habitat partitioning; hens were associated with higher proportions of open and shrubby habitats. Furthermore, broodless hens preferred areas with higher slope variability than the display and summer areas preferred by cocks. These differences may reflect the sexual dimorphism of the species in reproductive role, energetic demands and conspicuousness. At larger spatial scales a previously developed habitat suitability model performed well to predict good brood-rearing areas. Hens with broods were located in the best-preserved areas in the range, mainly characterized by higher proportion of forest cover at a large (50 km2) scale. We suggest that these characteristics indicate refuge habitats where Cantabrian capercaillie can still breed successfully.
Conservation policies of the European Nature 2,000 network reflect an overarching concern about a... more Conservation policies of the European Nature 2,000 network reflect an overarching concern about alleged negative effects of abandonment of traditional uses. In particular, the abandonment of livestock herding is widely assumed to be responsible of biodiversity decreases through habitat homogenization. However, those negative effects of land abandonment on biodiversity are neither straightforward nor the repeatedly assumed land abandonment has been always supported by hard data. We analyzed the evolution of cattle densities in the Cantabrian Mountains (NW Spain) in the past 20 years, and its relation with the decline in the occupancy of capercaillie leks. Instead of the widely-assumed decrease of livestock numbers, which has been already incorporated into landscape and wildlife management, we found an actual increase in cattle numbers. Those cattle numbers were negatively related to the presence of an endangered, distinctive population of capercaillie, a bird considered an umbrella species in mountain forest ecosystems. Thus our data do not support the alleged role of free-ranging livestock in the conservation of biodiversity. We consider that typological thinking in the relationship of socio-economic changes and biodiversity conservation should be replaced by hard data and consideration of ecosystem naturalness.
Cantabrian capercaillie Tetrao urogallus cantabricus is a peripheral population with distinctive ... more Cantabrian capercaillie Tetrao urogallus cantabricus is a peripheral population with distinctive phenotypic, biogeographic, and genetic characteristics. Hence, the population may also show substantial ecological differentiation associated with its habitat in purely deciduous forests. We assessed seasonal diet selection, small-scale habitat selection, and patterns of trophic niche width in Cantabrian capercaillie over two years. Diet was found to be a driver of small-scale habitat selection, a result consistent with previous studies of stand-scale habitat selection. Diet and habitat selection showed the importance of beech Fagus sylvatica, holly Ilex aquifolium, bilberry Vaccinium myrtillus, and ferns in Cantabrian capercaillie’s resource selection. Conversely, the abundant oaks Quercus petraea, birches Betula pubescens, and heaths Erica sp. were used below their availability. The reliance on bilberry appears as a unifying characteristic between central and peripheral capercaillie populations. Cantabrian capercaillie showed stronger reliance on understory resources than range-central populations. It also showed wider trophic niche and higher specialization of feeding events. Trophic niche patterns and reliance on ground resources indicated a marked ecological differentiation, which stresses the need for local data and specific conservation actions.
Sexual dimorphism is often associated with different feeding strategies between sexes because of ... more Sexual dimorphism is often associated with different feeding strategies between sexes because of distinct nutritional demands or intake rates. Capercaillie (Tetrao urogallus) is the most sexually dimorphic grouse, thus sexual segregation in resource use is likely. This study assessed intrapopulation variation in the diet related to habitat use, focusing on differential feeding behaviors between Capercaillie females and males. We used stable isotopes analyses in feathers of Cantabrian Capercaillie, a population living at the southern edge of the range in purely deciduous forests. We analyzed feathers of females and males, and sorted them according to the dominant tree species in the patch where they were found. Mean isotopic values differed both between sexes and among forest types. The latter explained most of the isotopic variance, suggesting that birds consistently selected certain forest types to molt. Capercaillie females showed wider trophic niche and seemingly more intra-gender diversity in resource use than males. The differences between sexes in the trophic variability support the sexual segregation reported in previous studies which is associated with females using the more micro-habitat diverse treeline areas, while males mainly use the inner areas of the forests. Stable isotope analysis proved very useful to assess intersexual niche partitioning in rare species living in rugged terrains where it is logistically difficult to rely on direct approaches (i.e. direct observation, capture and radio-tracking).
The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercailli... more The Cantabrian capercaillie Tetrao urogallus cantabricus, a subspecies of the western capercaillie, is endemic to the Cantabrian Mountains of northwest Spain. The range is separated from its nearest neighbouring capercaillie population by a distance of more than 300 km. High genetic differentiation compared to capercaillie elsewhere qualifies the subspecies as an Evolutionarily Significant Unit. An assessment according to the IUCN Red List categories and criteria showed that the subspecies qualifies as Endangered due to rapid population declines, small population size, and severely fragmented range. The implementation of a range-wide recovery plan is vital for the survival of this subspecies.
We analysed the composition and configuration patterns of the forested landscape in the Cantabria... more We analysed the composition and configuration patterns of the forested landscape in the Cantabrian range (NW Spain) determining how different forest communities are currently affected by long-term fragmentation process. We also evaluated the regional reserve network in relation to forest fragmentation and forest heterogeneity at the landscape level. The current landscape scenario is characterised by low forest habitat cover (22%) and a fragment size distribution strongly skewed towards small values (<10 ha). Forest classes differ strongly in fragment size, internal heterogeneity, shape, dispersion and isolation. Beech forests were less fragmented than other types, being the dominant class in terms of surface and fragment occurrence. Fragmentation was heavier in forests occurring in agriculture-suitable areas (i.e. valley bottoms, southern exposures), such as ash-maple and oak forests, as well as in second-growth forests developed after tree-line deforestation for pastures (i.e. holly and rowan forests). The current reserve network in the Asturias region covers preferentially bigger and less isolated forest fragments. This was a consequence of protection biased towards beech forests, to the detriment of an adequate representativeness of most other forest types, some of them with high ecological value. Future expansion of the reserve network should be based on landscape information, to promote both the protection of well-conserved, less-fragmented forests as well as the inclusion of under-represented target forest types. #
Quevedo, M. 2004. Modelling the distribution of Ilex aquifolium at the north-eastern edge of its ... more Quevedo, M. 2004. Modelling the distribution of Ilex aquifolium at the north-eastern edge of its geographical range. -Nord. J. Bot. 23: 129-142. Copenhagen. ISSN 0107-055X.
1] The southern Bay of Biscay (NW Spain) shows a very active hydrography due to the different ori... more 1] The southern Bay of Biscay (NW Spain) shows a very active hydrography due to the different origins of its Central Waters, the local modifications exerted on them by continental effects and the recurrence of mesoscale processes such as slope currents, upwellings and eddies. In order to assess the role of the different sources of variability we conducted a monthly series of CTD sampling in the central Cantabrian Sea along a coastal-oceanic transect, from 1993 to 2003. We analyzed the spatial variability of the hydrographic processes over different timescales. The thermohaline properties of Central Waters varied between those typical of the subpolar mode of the Eastern North Atlantic Central Water (ENACWsp) and a local mode, the Bay of Biscay Central Water (BBCW), though there has been a clear shift toward the BBCW prevalence in the last years. The Iberian Poleward Current (IPC) conveyed subtropical Central Waters (ENACWst) into the region almost every winter. This slope current may display a double-core structure during some extreme events. The upper layers of the ocean showed a long-term trend toward increasing temperature and decreasing salinity, and accordingly density was on the decrease. These patterns suggest an enhancement of the water column stratification. Coastal upwellings are an important source of inshore variability and counteract these long-term changes on the coast. However, their intensity seems to be decreasing and their seasonal pattern changing toward a general advancement of the upwelling-favorable season.
Deep-sea Research Part Ii-topical Studies in Oceanography, 2002
Mesozooplankton distribution and community structure in the Bellinghausen-Bransfield sector of th... more Mesozooplankton distribution and community structure in the Bellinghausen-Bransfield sector of the Antarctic Ocean were investigated during the FRUELA cruises (December 1995-February 1996. Total mesozooplankton biomass ranged between 0.015 and 1.43 g C m À2 . Biomass was higher in the Southern boundary of the Antarctic Circumpolar Current (SbyACC) area and in coastal waters of the Antarctic Peninsula. Total mesozooplankton abundance ranged from 0.4 Â 10 3 to 1.3 Â 10 5 individuals m À2 , of which 41.6-99.5% corresponded to copepods, mainly families Oithonidae, Oncaeidae, Pseudocalanidae, Calanidae and Metrididae. There was no evidence of coupling between mesoscale physical features and biomass or community structure. While coastal stations mainly at the Gerlache Strait remained in a highly productive state through the spring-summer, oceanic stations experienced a marked shift from a productive condition during FRUELA 95 to a low biomass, pteropod-dominated situation during FRUELA 96, possibly due to changing weather conditions. The median ingestion rates of herbivorous crustaceans during the FRUELA cruises were 0.7 mg Chl a m À2 day À1 . Measured ingestion rates represented only 0.1% of the chlorophyll standing stock or 10% of the daily primary production. Thus, crustacean mesozooplankton had little control on the development of phytoplankton blooms in the area. r (J.A. Cabal). 0967-0645/01/$ -see front matter r 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 7 -0 6 4 5 ( 0 1 ) 0 0 1 2 8 -X
A large proliferation of Noctiluca scintillans (Dinophyceae: Noctilucidea) was observed in neriti... more A large proliferation of Noctiluca scintillans (Dinophyceae: Noctilucidea) was observed in neritic waters off the central Cantabrian coast during late April 1995. Eggs of Acartia clausi (Crustacea: Copepoda) were the most conspicuous prey within vacuoles of Noctiluca. Noctiluca ingested 73 % of the total stock of A. clausi eggs. This intense predation on copepod eggs could potentially affect the recruitment of nauplii. The potential impact on the stock of Acartia clausi eggs and on the daily egg production of the population is discussed. There is a negative correlation between the average number of ingested eggs by a single Noctiluca cell and the abundance of Noctiluca. This fact, coupled with the lack of significant correlation between the former variable and the abundance of Acartia clausi eggs, suggests that interference processes play a major role in regulating the predator-prey interaction between Noctiluca and Acartia eggs. 0 Elsevier, Paris / Ifremer / Cnrs / Ird Noctiluca I Acartia / copepod eggs I predation I Bay of Biscay
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