Food or nesting place? Identifying factors limiting Wryneck populations

In recent decades, farmland bird populations have declined strongly as a consequence of agriculture intensification. Birds may have lost breeding sites, food supply or other crucial resources, with the role of multiple factors often remaining unclear. The ant-eating and cavity-breeding Wryneck (Jynx torquilla) may be limited by the availability of cavities, the number of ants or their accessibility. By comparing occupied and unoccupied breeding territories, we investigated the relative role of these factors in the decline of Wrynecks. We compared the characteristics of known Wryneck breeding territories (availability of breeding cavities, food abundance and ground vegetation structure) with randomly selected, fictitious territories (n=154) in Western Switzerland. We also studied environmental factors that may affect ant nest density. The probability of territory occupancy strongly increased with both nestbox availability and ant abundance. In addition, this probability peaked around 50% of bare ground cover. Habitat types that harbour low ant abundance such as cropland and grassland were avoided. Ant nest density decreased with increasing amounts of bare ground, and it was particularly high in vineyards. Our results showed that breeding cavities, food availability and its accessibility all limit Wryneck distribution. The maintenance and restoration of ant rich grassland, interspersed with patches of bare ground and with hollow trees or dedicated nestboxes in the surroundings, are essential to preserve Wryneck populations. Such a habitat structure could be achieved even in intensively farmed habitats, such as in vineyards or fruit tree plantation

The precipitous decline of the ortolan bunting Emberiza hortulana: time to build on scientific evidence to inform conservation management

In recent decades there has been a marked decline in most ortolan bunting Emberiza hortulana populations in temperate Europe, with many regional populations now extinct or on the brink of extinction. In contrast, Mediterranean and, as far as we know, eastern European popula-tions seem to have remained relatively stable. The causes of decline remain unclear but include: habitat loss and degradation, and related reduction in prey availability; climate change on the breeding grounds; altered population dynamics; illegal captures during migration; and environmental change in wintering areas. We review the current knowledge of the biology of the ortolan bunting and discuss the proposed causes of decline in relation to the different population trends in temperate and Mediterranean Europe. We suggest new avenues of research to identify the factors limiting ortolan bunting populations. The main evidence-based conservation measure that is likely to enhance habitat quality is the creation of patches of bare ground to produce sparsely vegetated foraging grounds in invertebrate-rich grassy habitats close to breeding area

Wide-range dispersal in juvenile Eagle Owls ( Bubo bubo ) across the European Alps calls for transnational conservation programmes

Although juvenile dispersal is an important life history component, it remains one of the less understood ecological processes regulating the dynamics of animal populations. Lack of information about patterns of dispersal hampers the estimation of the actual status and demographic trajectory of populations, and can preclude the development of sound conservation strategies. The Eagle Owl Bubo bubo is an endangered bird species in the European Alps. Many breeding sites have been abandoned in the twentieth century, although some recovery has been reported lately. Moreover, the occupancy of traditional breeding sites across years in well-monitored Alpine populations varies a lot, this despite a relatively high breeding success at the population level. This raises concern about the long-term persistence of Alpine populations. Using conventional and satellite radiotracking, we investigated the spatio-temporal dispersal of 41 juvenile Eagle Owls originating from a population in the southwestern Swiss Alps. Our main goal was to determine dispersal distances, places and times of post-dispersal settlement. Juveniles left their parents between mid-August and mid-November. They covered, on average, 12.7km per night (linear distance between two consecutive day roosts), often crossing high mountain ranges (up to 3,000m altitude). The mean total distance covered by an individual during dispersal was 102km (sum of night movements), with a maximum of 230km. Settlement places were, on average, 46km distant from the birth place. Our study establishes long-distance dispersal in juvenile Eagle Owls, even in a complex topography, suggesting the existence of a wide-scale metapopulation system across the northwestern Alps. This metapopulation dimension should be accounted for in conservation plan

Foraging ecology and reproductive biology of the Stonechat Saxicola torquata: comparison between a revitalized, intensively cultivated and a historical, traditionally cultivated agro-ecosystem

An effective strategy to reintegrate biodiversity within otherwise intensively cultivated agroecosystems is to create set-aside and wildflower areas. It remains largely unknown, however, whether the ecological performance of an agroecosystem revitalized in this manner is comparable—from a species' population biology perspective—to traditionally exploited farmland. To address this question we compared, during two successive years, the trophic ecology and breeding performance of an insectivorous, indicator passerine (the Stonechat Saxicola torquata) in a revitalized intensively cultivated farmland (RIC) and a traditional, extensively cultivated farmland (TEC) in southern Switzerland. The chicks' diet and prey abundance did not differ between the RIC and TEC, with orthopterans, caterpillars (Lepidoptera) and coleopterans predominating (approx. 80% of diet biomass). Although Stonechat pairs initiated more broods in TEC than in the RIC, reproductive success (number of fledglings/territory×year) did not differ significantly between the TEC and RIC. The chicks' condition (body mass) was slightly better in TEC than in RIC, while no such effect could be shown for chick constitution (tarsus length) in either year. The inter-site (RIC vs. TEC) variation fell well within the inter-annual variation of breeding parameters, indicating that environmental stochasticity could be a greater determinant of reproductive output and young quality than agroecosystem type. Although in need of replication, these results suggest that incentives for setting aside farmland and creating wildflower areas within agroecosystems may not only enhance plant and invertebrate diversity, as has been demonstrated earlier, but can also support functioning populations of vertebrates situated at higher trophic levels along the food chai

Impact of weather variation on feeding behaviour, nestling growth and brood survival in Wrynecks Jynx torquilla

While habitat destruction is thought to be the most important reason for the decline of the Wryneck Jynx torquilla throughout Europe, it has been hypothesised that weather factors may also play a crucial role. We studied the impact of variations in ambient temperature and rainfall on feeding behaviour, nestling growth and daily brood survival probabilities in a population from the Swiss Alps. We recorded the frequency of food provisioning and measured nestlings' growth on 6days at 17 nests, and monitored the success of 181 broods from 2002 to 2006. The mean feeding frequency was 7.9 feedings per hour, and increased with temperature and with nestling age. Changes of body mass, tarsus length and of the 8th primary feather were not strongly influenced by temperature and rainfall. Body growth was negatively influenced by the initial size of the different body measures towards the end of the growing phase of the corresponding body measure, pointing towards compensatory growth. Daily brood survival probabilities declined in the course of the season and with increasing rainfall, and they increased with increasing temperature and with increasing nestling age. Our findings highlight that the effects of adverse weather on feeding behaviour, nestling growth and nest survival in Wrynecks are complex, as they alter with the age of the nestlings and possibly with the duration of the adverse weather event

The Aversive Effect of Electromagnetic Radiation on Foraging Bats—A Possible Means of Discouraging Bats from Approaching Wind Turbines

Large numbers of bats are killed by collisions with wind turbines and there is at present no accepted method of reducing or preventing this mortality. Following our demonstration that bat activity is reduced in the vicinity of large air traffic control and weather radars, we tested the hypothesis that an electromagnetic signal from a small portable radar can act as a deterrent to foraging bats. From June to September 2007 bat activity was compared at 20 foraging sites in northeast Scotland during experimental trials (radar switched on) and control trials (no radar signal). Starting 45 minutes after sunset, bat activity was recorded for a period of 30 minutes during each trial and the order of trials were alternated between nights. From July to September 2008 aerial insects at 16 of these sites were sampled using two miniature light-suction traps. At each site one of the traps was exposed to a radar signal and the other functioned as a control. Bat activity and foraging effort per unit time were significantly reduced during experimental trials when the radar antenna was fixed to produce a unidirectional signal therefore maximising exposure of foraging bats to the radar beam. However, although bat activity was significantly reduced during such trials, the radar had no significant effect on the abundance of insects captured by the traps

Seasonal and daily movement patterns of an alpine passerine suggest high flexibility in relation to environmental conditions

Mountains naturally offer variable habitat conditions, but their biodiversity is currently facing the extra challenge of adapting to rapid environmental shifts that are much more pronounced than in the lowlands. Among adaptive responses, intra- and inter-seasonal movements represent potentially important coping strategies for wildlife that remain largely unexplored. We investigated the seasonal and daily movements of the ring ouzel Turdus torquatus, a European mountain bird species that is declining in many parts of its distribution. We tracked individuals breeding in the Swiss Alps using light-level geolocators and multi-sensor loggers. Of the birds traced to their nonbreeding grounds, two-thirds reached the Atlas Mountains while one-third stayed in Spain, a region potentially more significant for overwintering than previously thought. The birds remained mostly above 1000 m throughout the annual cycle, highlighting a strict association of ring ouzels with mountain habitats. We also evidenced flexible daily elevational movements, especially upon spring arrival on the breeding grounds in relation to date and snowfall occurrence, suggesting adaptive potential in response to environmental variation. This study shows how modern technology can deliver deeper and valuable insights into movements, behavioural patterns and life-history strategies for relatively little-studied animal species. By doing so, it paves the way for refined assessments of species’ vulnerability to ongoing global change while providing basic conservation guidance

Grassland intensification dramatically impacts grasshoppers: Experimental evidence for direct and indirect effects of fertilisation and irrigation

European mountain hay meadows are hosting an exceptionally rich biodiversity. They are currently threatened by both land abandonment and farming intensification via aerial irrigation and slurry application. The consequences of mountain grassland intensification on arthropods are still poorly documented, which is a serious handicap to proposing ecologically-friendly management guidance. Six experimental treatments mimicking a gradient of management intensity (including irrigation, fertilisation and various combinations thereof) were initiated in 2010 at twelve montane and subalpine Swiss meadow sites. In 2013, we sampled orthopterans to assess the influence of management practice on that taxonomic group. In parallel, the changes in vegetation height and ambient temperature (at 10 cm above ground level) induced by the intensification process were quantified in order to better appraise the underlying mechanisms. Intensification had a negative impact on Caelifera (grasshoppers), with decreases in densities and species richness reaching as much as 70% and 50%, respectively, in the most intensively managed treatment plots. Intensification furthermore led to a marked increase in mean vegetation height and a cooling of ambient temperature by up to 4.2 ◦C. Such microhabitat and microclimate alterations are likely to affect Caelifera development, in particular thermophilous species. In contrast, Ensifera (bushcrickets) densities and species richness showed no significant response to our experimental manipulations. Finally, the application of irrigation by sprinklers alone had limited impact on both orthopterans and meadow microclimate. We conclude that orthopterans, in particular Caelifera, are fairly sensitive to grassland management intensification: fertilisation should be avoided in focal areas for biodiversity conservation

Impact of weather and climate variation on Hoopoe reproductive ecology and population growth

Preserving peripheral populations is a key conservation issue because of the adaptive potential to environmental change they provide for the species as a whole. Yet, peripheral populations are often small and isolated, i.e. more vulnerable to stochastic events and prone to extinction. We studied a peripheral population of Hoopoe (Upupa epops), a rare insectivorous farmland bird, in the Swiss Alps. We first investigated the effect of weather variation on food provisioning to chicks by Hoopoe parents. Second, while accounting for density-dependence, we tested the extent to which breeding success is governed by weather circumstances and assessed the possible consequences of climate variation on population growth. Provisioning rate and provisioned prey biomass were negatively affected by adverse weather (cool, rainy days), were higher in males and also increased with brood size. Much smaller proportions of molecrickets (Gryllotalpa gryllotalpa; the most profitable prey locally, constituting 93% of chicks' food biomass) were provisioned on days with adverse weather, irrespective of brood size. Rainfall prior to hatching and during the first days of chick life had a negative impact on their survival, and there was a positive effect of temperature on chick survival just before fledging. Reproductive output was negatively affected by precipitation during the hatching period, but was enhanced by warm temperature just before hatching and in the last days before fledging. Our model showed that the variable reproductive output has a strong impact on the population growth: a succession of adverse, rainy springs would cause a rapid decline of the population. This case study confirms that conservation efforts may be obliterated if risks linked to increasing climate variability are not properly accounted for in the management of small peripheral population

Landscape woody features, local management and vegetation composition shape moth communities in extensively managed grasslands

1. Agricultural intensification has led to a dramatic impoverishment of biodiversity. Moths are not an exception: rapid declines of common and widespread species have been reported and it is still not clear which conservation measures should be applied to restore their populations. 2. We investigated how much of the variation in moth assemblages inhabiting extensively managed meadows in a region of high-intensity agriculture is explained by surrounding woody landscape features, meadow management and vegetation composition, and which specific variables are the most influential. 3. Results show that the percentage of forest and the length of hedgerows within a 250 m radius were especially important for forest macromoths, explaining 42% of variation in abundance and 23% of species richness, whereas meadow management played a relatively marginal role. The abundance of grassland macromoths was also positively influenced by the length of hedgerows in the landscape (combined with elevation it explained 10% of the variance), while it responded negatively to uncut refuge and to delayed mowing (7%). Regarding grassland macromoth species richness, the annual harvesting frequency was the main predictor (4%). In contrast, micromoth abundance was more influenced by meadow management, notably the date of the first cut (4%) and vegetation composition (8%, though not conclusive due to a single outlier), whereas landscape features explained nothing. 4. Altogether, these results demonstrate the importance of both woody features within farmed landscapes and biodiversity-friendly meadow management for the maintenance of integral moth communities