Sylvia Melanocephala Research Articles

Effects of wind turbine noise on songbird behavior during nonbreeding season.

Anthropogenic noise is one of the fastest growing, globally widespread pollutants, affecting countless species worldwide. Despite accumulating evidence of the negative impacts of wind turbines on wildlife, little is known about how the noise they generate affects ecological systems. Songbirds may be susceptible to noise pollution due to their reliance on vocal communication and thus, in this field study, we examined how songbirds are affected by wind turbine noise. We broadcasted noise produced by one wind turbine in a migratory stopover site during the nonbreeding season. Throughout the study, we repeatedly monitored the acoustic environment and songbird community before, during, and after the noise treatments with passive acoustic monitoring and mist netting. We employed generalized linear mixed effects models to assess the impact of experimental noise treatment on birds behavior and likelihood ratio tests to compare models with variables of interest with null models. The daily number of birds in the presence of wind turbine noise decreased by approximately 30% compared with the before and after phases. This reduction had a significant spatial pattern; the largest decrease was closer to the speaker and on its downwind side, fitting measured sound propagation. Although we found no impact on species diversity, two out of three most common species showed clear avoidance behavior: 45% and 36% decrease in abundance for the lesser whitethroat (Sylvia curruca) and Sardinian warbler (Sylvia melanocephala momus), respectively. In the after phase, there were lingering effects on the lesser whitethroat. The age structure of the lesser whitethroat population was affected because only juvenile birds showed avoidance behavior. No difference in avoidance extent was found between migratory and nonmigratory species, but the impacts of displacement on migrants during stopover are especially troubling from a conservation perspective. Our results stress the need to address the impacts of noise pollution on wildlife when planning noise-generating infrastructures, such as wind turbines, to allow for sustainable development without threatening already declining songbird populations.

DNA metabarcoding, diversity partitioning and null models reveal mechanisms of seasonal trophic specialization in a Mediterranean warbler.

Optimal Foraging Theory (OFT) predicts that a population's trophic niche expansion should occur in periods of food scarcity as individuals begin to opportunistically exploit sub-optimal food items. However, the Niche Variation Hypothesis (NVH) posits that niche widening may result from increased among-individual differentiation due to food partitioning to avoid competition. We tested these hypotheses through a DNA metabarcoding study of the Sardinian Warbler (Curruca melanocephala) diet over a year. We used null models and the decomposition of beta diversity on among-individual dietary differentiation to infer the mechanisms driving the population's niche variation. Warblers fed frequently on berries, with a peak in late summer and, to a lesser extent, in autumn. Their diet also included a wide range of arthropods, with their prevalence varying among seasons. Consistent with OFT, the population's niche width was narrower in spring/summer when the population was strongly specialized in berries. In winter, the population's niche expanded, possibly reflecting seasonal declines in food abundance. As predicted by NVH, among-individual differentiation tended to be higher in winter, but this was mainly due to increased differences in dietary richness rather than to the partitioning of resources. Overall, our results suggest that within-individual niche does not increase in lean periods, and instead, individuals adopt either a more opportunistic or more specialized foraging strategy. Increased competition in periods of scarcity may help explain such patterns, but instead of showing increased food partitioning as expected from NVH, it may reflect OFT mechanisms on individuals with differential competitive ability to access better food resources.

Breeding habitat selection of three sympatric species of Mediterranean warblers in eastern Spain

Understanding habitat selection patterns in congeneric species has raised special interest due to its importance when designing conservation strategies for the species. We analysed reproductive habitat selection of three coexisting warbler species in the eastern Iberian Peninsula. We detected the individuals by their vocalizations at 40 listening points in two study areas (Carcaixent and Alcoy). We used satellite images to identify different vegetation types and their availability. Reproductive habitat selection was analysed by the Ivlev selectivity index and a compositional analysis. In addition, we determined the effect of different habitat variables (dominant vegetation, vegetation height, cover and site) on the presence of the species fitting a binomial GLM with logistic linking function. We found that the Sardinian Warbler ( Curruca Melanocephala) selected scrub-dominated areas; while the Dartford Warbler ( C. undata) preferred areas with low (<50%) vegetation cover; and the Subalpine Warbler ( C. cantillans) was present in areas with scrubs and low (<50%) vegetation cover, avoiding crops. The compositional analysis showed that the species used different vegetation types, in relation to their availability and that the selection differed between species. The Sardinian Warbler was the only species which showed spatial variation in reproductive habitat selection. Our results evidence that the studied warbler species select and avoid different types of vegetation in relation to their specific requirements and the present habitat structure. This represents valuable information to understand the composition of local communities and the reproductive habitat selection of the studied species.

Spontaneous renaturalization of open ecosystems in the hills of Brescia seen through the bird community

The sun-exposed open areas of the Brescia hills overlooking the Po Valley (Avanalpica region) were created by man starting from the 11th century. After the Second World War, following agro-pastoral abandonment, these areas have significantly shrunk. The evolution underway is towards the deciduous forest although in some areas the strong presence of quarries is blocking the vegetational succession or delaying it. Local birds are now largely associated with woodland coenosis and more scarcely with open areas, shrublands and wood edges. Seven open areas species have become extinct over the past 30 years: Woodchat Shrike, Barred Warbler, Rufous-tailed Rock-Thrush, Eastern Black-eared Wheatear, Tawny Pipit, Corn Bunting and Ortolan Bunting. Others, like Red-backed Shrike, Common Whitethroat, Cirl Bunting and Wood Lark have declined. Only the generalist Sardinian Warbler and Blue Rock-Thrush, typical of rocky areas with grassy spaces, are still relatively widespread although slightly decreasing. The Cirl Bunting, a species linked to traditional vineyards and orchards, is not expanding in the new intensively cultivated lands. The Eastern Subalpine Warbler is on the rise even though, due to its very low presence and lack of specific surveys, it may not have been detected in the past. The factors determining the presence of these species, i.e. traditional crops, flat open areas, soils with low grass and often with outcropping and/or rocky substrate, are in sharp decline. We can state that this bird community is negatively influenced by the percentage of tree cover and positively influenced by the presence of quarries which, however, represent an ephemeral and strongly impacting environment. In the absence of fires and/or natural disasters as well as human interventions, which are not likely to occur due to their poor economic sustainability, the prognosis for these birds is to be considered poor and a reduction in both bird and general biodiversity is to be expected.

The Effect of Cats and Dogs on Bird Distribution

Cats and dogs are very common pets in Greece and especially cats, are commonly allowed to roam freely and even become feral. This was thought to have detrimental effects on wildlife, especially birds. I evaluated whether cats and dogs affect the distribution of birds in the north-eastern provinces of Athens. Different areas were sampled and analyzed to determine if areas with different densities of dogs and cats have different densities of birds. Dogs, showed to not impact any bird species apart from Blackbirds which were surprisingly positively correlated with dogs. On the other hand, cats seem to impact Sardinian warblers and blackbirds negatively. Areas with more cats seemed to have a lower number of these two avian species. These findings support that cats can impact wild bird populations and that owners need to be responsible, while it shows no evidence to support that dogs can do the same. However, in this study there were not enough samples to statistically analyze the impact of these two animals on all bird species, while there were also no samples from different natural habitats other than dry Mediterranean bushland with few trees such as pine trees, olive trees and deciduous trees found in gardens.

Genomic data reveal contrasting patterns of divergence among island and mainland birds of the Eastern Mediterranean

Islands have been characterized as natural laboratories because of their distinct and often identifiable role in promoting genetic variation and population differentiation, but they have also been considered evolutionary sinks of biodiversity. Here, we extend classical studies of island biogeography based in the Eastern Mediterranean to compare genetic divergences and population structure among birds in insular and continental populations. We focused on populations of six passerine species (Short‐toed Treecreeper, Great Tit, Eurasian Wren, Eurasian Blackbird, Common Chaffinch and Sardinian Warbler) with breeding populations on the islands of Cyprus and Crete and compared those with a continental population from mainland Greece. We sampled 172 individuals from six species and used double‐digest RAD sequencing to examine population‐level genetic divergence and structure. Population structure analyses using single nucleotide polymorphisms revealed structure between the islands and mainland for all six species, and this was most pronounced in Short‐toed Treecreeper, Great Tit and Eurasian Wren. For all species with the exception of the Sardinian Warbler, the populations from the two islands were more differentiated from each other than either was from mainland Greece, reflecting variation in island colonization dynamics. Patterns ranged from pronounced population differentiation among populations, e.g. in Short‐toed Treecreeper, where taxonomic revisions are potentially warranted, to others with weak structure among insular and continental populations, such as in Common Chaffinch and Sardinian Warbler. Although some patterns are consistent with increased rates of genetic drift in smaller populations explaining greater differences among the island populations than either insular population has from continental source populations, in others, including in Eurasian Blackbird and Common Chaffinch, higher nucleotide diversity in Cyprus may reflect a demographic pattern of post‐glacial north‐westward expansion.

Breeding birds of ‘Nomentum’ nature reserve (central Italy): a forest remnant landscape surrounded by an agro-urbanized matrix

We carried out a standardized breeding bird atlas of “Nomentum” nature reserve (central Italy), located in a fragmented hilly forest near a large urbanized area (Rome). In order to obtain data about local composition, occurrence, distribution and richness, we correlated data with environmental heterogeneity and vegetation structure variables. We recorded 58 species in 48 500x500 m-wide atlas units, with Parus major, Corvus cornix, Turdus merula, Sylvia atricapilla, Sylvia melanocephala, as the most occurring in frequency (> 80%). Although synanthropic species represent only slightly more than 20% in number and urban environments are relatively reduced in size, these species show a higher mean occurrence when compared to mosaic species, despite the fact that these last are higher in species number and mosaic habitats are widely diffused. Local urbanization may disrupt communities, facilitating opportunistic species linked to these environments (i.e. synantropic) and inducing a decline in mosaic species. Moreover, the homogenization induced by anthropization could, at least partially, explain the lack of correlation between habitat diversity and species richness, at local scale. Finally, tree density and diameter do not affect total bird richness at this spatial grain/scale. In this regard, further analyses could test for possible correlations between habitat variables and single ecological guilds.

Fruit abundance and trait matching determine diet type and body condition across frugivorous bird populations

Research on seed‐dispersal mutualisms has been highly unbalanced towards the plants, largely overlooking the fitness effects of fruit resources on frugivorous animals. Moreover, despite morphological mismatches like gape limitation may reduce the abundance of fruits that are actually accessible to a frugivore species, there is very little evidence on the trait‐matching implications from a frugivore's perspective. Here, we refine recent resource‐provisioning models to comprehensively test the joint effects of fruit abundance and trait matching on diet type and body condition (a surrogate of fitness) across frugivorous bird populations: Sardinian warblers Curruca melanocephala inhabiting ten Mediterranean forests differing in the abundance and composition of fleshy fruits. We hypothesised the abundance of fruit resources to have positive effects on the degree of frugivory and body condition of warblers, and such effects to be more pronounced when accounting for both trait matching (accessible fruits) and resource provisioning (energy in accessible fruits). We found a sharp threshold over which warblers shifted from a diet with very little or even no fruits to a predominantly frugivorous diet with increasing the local abundance of accessible fruits. We also found a strong positive relationship between the abundance of accessible fruits and the body condition of warblers (body mass and residual body mass), an effect that was more pronounced in females than in males. Although diet type and body condition were much better predicted when accounting for trait matching, accounting for resource provisioning did not improve the explanatory power of fruit resources. The fact that we detected strong and sex‐dependent effects of fruit resources on body condition just a few weeks before the breeding season suggests that fruit resources likely affect the timing and success of reproduction, a question that deserves further research. Our findings provide new insight into the fitness consequences of seed‐dispersal mutualisms for frugivorous animals.

The original description of <em>Sylvia melanocephala</em> (Aves: Sylviidae), with notes on David Piesch’s birds of Sardinia (1784)

The name of the Sardinian Warbler Sylvia melanocephala is usually attributed to Gmelin (1789), but it dates from Piesch (1784). The correct name of the Sardinian Warbler is thus Sylvia melanocephala (Piesch, 1784). Comments are added on other bird species described by Piesch (1784) from Sardinia.

Behavioural repeatability in Sardinian warblers (Sylvia melanocephala): larger individuals are more aggressive

Birds can behave aggressively towards conspecifics to defend a territory and to compete for access to food and mates. The effects of phenotypes, such as sex and age, in aggressive behaviour have not yet been fully understood. Moreover, differences in aggression levels can reflect alternative behavioural strategies (i.e. proactive–reactive axis). We aimed to understand the relation between aggressive behaviour and different phenotypes (i.e. age, sex, body size) and between behaviours present in the proactive–reactive axis (i.e. aggression, exploration and fear). We studied the behaviour of a highly territorial species that shows sexual dimorphism, the Sardinian warbler (Sylvia melanocephala), using four behavioural tests: mirror, exploration, predation and tonic immobility. The tests measured respectively aggression, exploration and fear (the last two). Our results showed that the studied behaviours were not related to each other, suggesting an absence of the proactive–reactive axis. Only body size was found to predict aggressive behaviour, which might signal fighting ability in this species. Males and females did not differ in their aggression levels, suggesting that both sexes might play a role in territory defence. These results may reflect the importance of territorial defence in both sexes for species evolution.

The effect of vegetation structure on seasonal density of Sylvia warblers in the eastern Iberian Peninsula

ABSTRACT Capsule Vegetation characteristics determine seasonal habitat selection by Eurasian Blackcaps Sylvia atricapilla, Dartford Warblers Sylvia undata, and Sardinian Warblers Sylvia melanocephala, and changes in these characteristics affect the structure of bird communities. Aims To evaluate the effect of vegetation structure on the seasonal density of Sylvia warblers in the eastern Iberian Peninsula. Methods During spring 2015 and winter 2015/16, we carried out linear transects in natural and agricultural habitats to quantify the presence of three warbler species: Eurasian Blackcap, Dartford Warbler, and Sardinian Warbler. In addition, we recorded the height, cover, and richness of the vegetation in each transect. We analysed the data using canonical correspondence analysis and general linear models. Results The densities of Eurasian Blackcaps and Dartford Warblers varied seasonally. Agricultural land had a significant effect on bird density: positive for the Eurasian Blackcap and negative for the Dartford Warbler. Furthermore, vegetation variables influenced the distribution of the warbler species in different ways. Conclusion Our results suggest that the segregation of the different warbler species across microhabitats can explain their coexistence. Additionally, in contrast to the Dartford Warbler, the Sardinian Warbler showed flexible habitat selection and varied its habitat according to the available niche.

Grazing pressure and the interaction dynamics of the endemic Cyprus Warbler Sylvia melanothorax and its recently colonising congener the Sardinian Warbler S. melanocephala

SummaryThe recent classification of the endemic Cyprus Warbler to a Species of European Conservation Concern by BirdLife International has renewed interest in its interaction with the Sardinian Warbler, a widespread Sylvia that was first confirmed as breeding in Cyprus in the 1990s and has since expanded in numbers and range. In areas where the Sardinian Warbler has become established, there has been a reduction in the abundance of the Cyprus Warbler, leading some researchers to suggest the recently arrived species is outcompeting its endemic congener. However, clear evidence of competition between the two species has not been found, and more recent research has suggested the closely related warbler species show preferences for subtly different scrub habitats, which might be influenced by the extent of grazing. We carried out line transect surveys during the breeding season at 48 scrub and open woodland sites across Cyprus in 2012, 2014 and 2016, recording Cyprus Warblers and Sardinian Warblers in order to estimate their densities. In addition, we recorded vegetation characteristics and estimated grazing pressure at these 48 sites. Our analysis showed that the Sardinian Warbler continues to increase in abundance over time and its higher abundances were associated with lower Cyprus Warbler abundances. Sardinian Warbler however was negatively associated with all but very low grazing pressure, whereas the Cyprus Warbler was more tolerant of grazing. Our findings suggest continued grazing of scrub sites is important for the maintenance of suitable habitat for the endemic warbler, which will help improve its conservation status.

Increased songbird nest depredation due to Aleppo pine (Pinus halepensis) encroachment in Mediterranean shrubland

BackgroundIn recent decades, a decrease of passerine densities was documented in Mediterranean shrublands. At the same time, a widespread encroachment of Aleppo pines (Pinus halepensis) to Mediterranean shrubland occurred. Such changes in vegetation structure may affect passerine predator assemblage and densities, and in turn impact passerine densities. Depredation during the nesting season is an important factor to influence passerine population size. Understanding the effects of changes in vegetation structure (pine encroachment) on passerine nesting success is the main objective of this study. We do so by assessing the effects of Aleppo pine encroachment on Sardinian warbler (Sylvia melanocephala) nest depredation in Mediterranean shrublands. We examined direct and indirect predation pressures through a gradients of pine density, using four methods: (1) placing dummy nests; (2) acoustic monitoring of mobbing events; (3) direct observations on nest predation using cameras; and (4) observation of Eurasian jay (Garrulus glandarius) behaviour as indirect evidence of predation risk.ResultsWe found that Aleppo pine encroachment to Mediterranean shrublands increased nest predation by Eurasian jays. Nest predation was highest in mixed shrubland and pines. These areas are suitable for warblers but had high occurrence rate of Eurasian jays.ConclusionsEncroaching pines directly increase activity of Eurasian jays in shrubland habitats, which reduced the nesting success of Sardinian warblers. These findings are supported by multiple methodologies, illustrating different predation pressures along a gradient of pine densities in natural shrublands. Management of Aleppo pine seedlings and removal of unwanted trees in natural shrubland might mitigate arrival and expansion of predators and decrease the predation pressure on passerine nests.

The Effect of Pine Forest Structure on Bird-Mobbing Behavior: From Individual Response to Community Composition

Pine-forest bird communities are affected by the forest structure and the density and composition of its understory vegetation. In this study, we focused on the combined effects of vegetation structure and caller identity on the mobbing behavior of birds in breeding and non-breeding seasons. We examined the effect of the understory structure and the density of three types of conifer forest habitats on bird behavior by broadcasting three different types of mobbing calls: Those of two all-year resident species in the state Israel (Sardinian warbler Sylvia melanocephala Gmelin and great tit Parus major L.) and one European species (coal tit Periparus ater L.), which is absent from these habitats. The mobbing call attracted 689 birds of 17 species, which represented 31% to 95% of the forest bird species that we detected in point counts at the same study plots. Bird reactions to mobbing calls were affected by the status and season, depending on forest type. Our results show that responses were stronger in forests with developed understory in comparison to forests with no understory, especially in winter. The highest number of responders and highest species richness of responders were observed in winter. P. major calls generated more interspecific than intraspecific responses, whereas S. melanocephala calls generated equal levels of inter- and intraspecific reactions. Both species generated different response patterns across the three forest habitat types. The response level of responders is higher when the mobbing calls are issued by local species rather than the P. ater. In winter, the response of non-resident species was higher than of resident species. Based on these results, we encourage the managers to maintain well-established understory vegetation, with special attention to the shrubs layer, to promote species diversity and rich behavioral responses of birds in the conifer forests in the eastern Mediterranean region.

Would a bird by any other name sing as sweet?

Ample material for a lexicological and terminological study is provided by over ten thousand species of birds, many with multiple local names. Some of them follow the scientific name, while more creative ones put forward different characteristics of a bird, e.g. Sylvia melanocephala ‘black-headed wood-dweller’ vs fauvette mélanocéphale ‘black-headed warbler’ vs pěnice bělohrdlá ‘white-throated warbler’ vs occhiocotto ‘cooked eye’ vs Sardinian warbler, etc. This onomasiological diversity makes one wonder how bird names are created in different languages, what morphological structures are resorted to, and what semantic features are included in different names of the same bird. Such questions have already been discussed in terminology as far as concepts or artefacts are concerned. This paper compares the names for Sylvia atricapilla and Sylvia melanocephala in some thirty languages, using a combination of intra- and cross-linguistic methods and assembling the two “arch-concepts”. The study points out the specificity of bird names, between linguistic signs, scientific terms and proper nouns or nicknames. The underlying denomination principle consists in selecting a limited number of salient but distinctive semantic features, i.e. characteristics of the bird, and attributing them the corresponding lexical items: nouns, adjectives, suffixes or combining forms.

Seed dispersal by dispersing juvenile animals: a source of functional connectivity in fragmented landscapes.

Juvenile animals generally disperse from their birthplace to their future breeding territories. In fragmented landscapes, habitat-specialist species must disperse through the anthropogenic matrix where remnant habitats are embedded. Here, we test the hypothesis that dispersing juvenile frugivores leave a footprint in the form of seed deposition through the matrix of fragmented landscapes. We focused on the Sardinian warbler ( Sylvia melanocephala), a resident frugivorous passerine. We used data from field sampling of bird-dispersed seeds in the forest and matrix of a fragmented landscape, subsequent disperser identification through DNA-barcoding analysis, and data from a national bird-ringing programme. Seed dispersal by Sardinian warblers was confined to the forest most of the year, but warblers contributed a peak of seed-dispersal events in the matrix between July and October, mainly attributable to dispersing juveniles. Our study uniquely connects animal and plant dispersal, demonstrating that juveniles of habitat-specialist frugivores can provide mobile-link functions transiently, but in a seasonally predictable way.

Impact of alien rats and honeybees on the reproductive success of an ornithophilous endemic plant in Canarian thermosclerophyllous woodland relicts

Islands harbor a considerable portion of global biodiversity and endemic biota, and also are the recipients of the largest proportional numbers of alien invaders. Such invaders may jeopardize the performance of native species, through either their direct or indirect effects. In this study, we investigated the reproductive ecology of the endemic scrambling perennial herb Canarina canariensis in remnants of the former thermosclerophyllous woodland of Tenerife (Canary Islands), assessing how two widespread alien invasive species, the honeybee (Apis mellifera) and the black rat (Rattus rattus), affect its reproductive success. Apis mellifera visits its flowers whereas the black rat consumes both its flowers and fruits. Here, we compared the pollination effectiveness of different animal guilds (vertebrates vs insects) by means of selective exclosures and determined the level of floral herbivory. Three bird species (Phylloscopus canariensis, Cyanistes teneriffae and Sylvia melanocephala), a lizard (Gallotia galloti) and two insects (A. mellifera and the butterfly Gonepteryx cleobule) were the main flower visitors. Phylloscopus canariensis was the most frequent visitor in the early flowering season whereas A. mellifera predominated in the flowers during mid and late flowering periods. Birds increased fruit set, whilst lizards and insects had a negligible effect. Rats consumed about 10% of the flowers and reduced fruit set to one third. Besides contributing little to plant reproduction, A. mellifera might interfere with bird pollination by depleting flowers of nectar. We conclude that both alien species can threaten C. canariensis reproduction and hence population sustainability in the thermosclerophyllous vegetation. Apis mellifera, in particular, may become especially detrimental if apiculture keeps expanding, or if this bee becomes active earlier in the season due to global warming.

First successful eradication of invasive Norway rats Rattus norvegicus from a small Mediterranean island (Isola delle Femmine, Italy)

Invasive alien species, once introduced, may affect local biodiversity, both directly (e.g. by predation) and indirectly (e.g. by reducing the vegetation cover). Among those, rats (Rodentia, Muridae) are listed among the most invasive species, exerting strong impacts particularly when introduced to island ecosystems. Accordingly, black rats Rattus rattus have been eradicated from a number of islands in the Mediterranean basin to protect breeding seabirds. Where the larger Norway rat Rattus norvegicus is present, extent of damage may be even higher. In our work, we present the results of the first eradication program dealing with Norway rats in a small Mediterranean island (Isola delle Femmine, Sicily, Southern Italy). The eradication took place in 2007-2008 and, since then, no rat has been observed on the island, thus proving the success of the management action. Vegetal cover increased on the island after rat eradication. Furthermore, the Sardinian warbler and the blackbird started to breed on the island.

First evidence for the joint dispersal of mycorrhizal fungi and plant diaspores by birds.

Seed dispersal allows plants to colonise new sites and escape from pathogens and intraspecific competition, maintaining plant genetic diversity and regulating plant distribution. Conversely, most plant species form mutualistic associations with arbuscular mycorrhizal (AM) fungi in a symbiosis established immediately after seed germination. Because AM fungi are obligate symbionts, using the same dispersal vector as their host should be highly advantageous for their survival, but the co-dispersal of seeds and AM fungal spores has never been confirmed. We aim to clarify the potential role of European birds, essential dispersers for many plant species, as co-dispersers of seeds and AM fungal spores. In total, 63 bird droppings with intact seeds were placed in sterilised soil and maintained for 4months in a protected environment to avoid contamination. Additionally, 173 bird droppings and 729 gauze swabs used to clean birds' feet were inspected for AM fungal spores. Although no spores were detected by direct observation of these samples, seven Rubus ulmifolius seedlings obtained from four independent droppings of Erithacus rubecula and Sylvia melanocephala were colonised by AM fungi. Our results show that birds can effectively co-disperse viable seeds and AM fungal spores, potentially over long distances, providing a pivotal mechanism to understand the cosmopolitan distribution of AM fungi.

Reproductive success of the Canarian Echium simplex (Boraginaceae) mediated by vertebrates and insects.

Oceanic island ecosystems favour the appearance of novel interactions as a consequence of their depauperate and disharmonic flora and fauna. We investigated Echium simplex, endemic to the Anaga Biosphere Reserve in NE Tenerife, Canary Islands, belongs to the Canarian bird-flower element. Along two flowering seasons, we studied the breeding system of E.simplex, identified the floral visitors and compared the pollination effectiveness of different animal guilds (insects versus vertebrates) by means of selective exclosures. E.simplex is self-compatible but selfing significantly reduced fruit set. The flowers were visited by five bird species (mostly Phylloscopus canariensis and Serinus canarius, but also Cyanistes teneriffae, Sylvia atricapilla and Sylvia melanocephala), a lizard species (Gallotia galloti) and over a hundred insect species (mainly hymenopterans and coleopterans). Flying insects increased fruit set whereas small flower dwellers (mostly beetles) decreased both fruit and seed set. Vertebrates had a negligible effect on reproductive success. We conclude that although the floral resources provided by E.simplex may be important to some vertebrate species, these do not appear to contribute to increase fitness of the plant, which was more dependent upon flying insects for fruit and seed set. We additionally found that plant reproductive structures are heavily damaged by feral goats, which threaten the maintenance of this Canarian endemic species.