Long-term persistence of conservation-reliant species: challenges and opportunities

“Conservation-reliant species” – those fully dependent on continued management actions – are booming and, with limited conservation budgets, securing funds to sustain their long-term viability is becoming overwhelming. This study assesses the degree of dependence on conservation actions of two obligatory cavity-nesters, the Lesser Kestrel Falco naumanni and the European Roller Coracias garrulus, whose populations in Europe were recently recovered through artificial nest-site provisioning. Using long-term monitoring data and population surveys conducted in their main Portuguese stronghold, we examined temporal changes in the availability and use of semi-natural (cavities in rural abandoned buildings) and artificial nest-sites. We further assessed the financial costs of nest-site provisioning and evaluated the potential use of tourism revenues as a conservation funding source. Following the implementation of conservation projects, the Lesser Kestrel and Roller populations have been increasing but more than 65% of all breeding pairs currently nest in artificial nest-sites. Semi-natural nest-sites remain suitable for approximately 30 years and are expected to disappear by the end of this century. Lesser Kestrels and Rollers will thus become fully dependent on artificial nest-sites and sustaining their current population sizes is estimated to cost 4500€ per year. This represents less than 1% of the region’s lodging income, largely supported by nature-based tourism. Our findings suggest that reactive conservation measures can be very effective at recovering endangered populations but can make them fully reliant on the perpetuation of those measures. This demands long-term funding, which can be alleviated by tourism revenues in areas with high nature capital values

Inter- and intra-specific differences in butterfly behaviour at boundaries

To plan effective conservation measures and to predict which species will be able to change distribution in response to climate change, there is an increasing need for understanding species dispersal abilities and how species move in complex landscapes. Responses to habitat boundaries affect emigration rates from habitat and are therefore important determinants of species dispersal. There are, however, few studies linking dispersal parameters to likelihood of crossing barriers across several species. In this study, dispersal and likelihood of crossing boundaries, which are presented here as tall and dense tree plantation, were investigated for seven butterfly species. Effects of adult age and sex on the dispersal and behaviour at boundaries were also analysed. Our results demonstrate differences in movements and response to habitat boundaries between species belonging to different butterfly families. Pieridae species were the most likely to cross boundaries and most mobile, whilst with the Lycaenidae species only a small fraction of individuals crossed the tall dense boundary. Individuals and species that moved with longer move bouts (i.e. steps) were more likely to cross boundaries. Therefore, we propose using step length, which is relatively easy to measure, as a proxy for butterfly dispersal at the landscape level. Female butterflies moved less than males within habitat but crossed boundaries more often than males, indicating that dispersal data needs to be collected for the two sexes separately to provide more accurate estimates of species ability to colonise new areas

Effectiveness of the European Natura 2000 network at protecting Western Europe's agro-steppes

Assessing progress towards achieving conservation targets is required for all countries committed to the Convention on Biological Diversity. The Natura 2000 network is the largest protected area network in the world and was created to protect Europe's threatened species and habitats, often requiring active management. This study assesses the effectiveness of areas classified under the EU Birds Directive at protecting Western Europe's agro-steppes, the last remnants of suitable habitat for several endangered bird species. We quantify agro-steppe habitat change in the last 10 years using high-resolution aerial images of 21 Special Protection Areas and surrounding areas. The selected SPAs hold one third of the global population of great bustards Otis tarda, a flagship conservation species. Agro-steppe area losses occurred across all sites surveyed but were 45% lower inside Natura 2000 compared to non-protected areas. Natura 2000 sites still lost over 35,000 ha of agro-steppe habitat in 10 years, an area that could hold more than 500 great bustards. These low yield farmlands are being converted predominately to permanent and irrigated crops. At the current rate of habitat conversion, agro-steppes could be reduced to 50% of the present area during the next century. Moreover, the greater conversions outside protected sites may transform the remaining agro-steppes into isolated “islands” with low population connectivity. Our study on agro-steppes illustrates the relevant contribution of Natura 2000 at protecting Europe's key habitats, but also highlights crucial insufficiencies that still need to be addressed to achieve the CBD conservation targets and halt biodiversity loss.info:eu-repo/semantics/publishedVersio

Temperature and microclimate refugia use influence migratory timings of a threatened grassland bird

Abstract Background Seasonal changes in resource availability are known to influence the migratory behaviour of animals, including both timing and distance. While the influence of environmental cues on migratory behaviour has been widely studied at the population level, it has rarely been examined at the spatial scale at which individuals experience their environment. Here, we test the hypothesis that individuals exposed to similar large-scale environmental cues may vary in migratory behaviour in response to the different microclimate conditions they experience at fine scales. Methods We combine high-spatial and temporal resolution microclimate and habitat information with GPS tracking data for a partially migratory threatened grassland bird. Data from 47 little bustards (Tetrax tetrax; 67 breeding events) tracked between 2009 and 2019 was used to (i) evaluate individual consistency in migratory behaviour (timing and distance) and (ii) assess whether the local environmental characteristics experienced by individuals – and in particular their use of microclimate refugia - influence distance and timing of migration, from and to the breeding sites. Results Migratory distance was consistent for birds tracked over multiple years, while the timing of migration showed high variability among individuals. Departures from breeding areas spanned from May to August, with a few birds remaining in their breeding areas. Vegetation greenness (a proxy for food availability) was positively associated with the time birds spent in the breeding area. The best model also included a positive effect of microclimate refugia availability on breeding season length, although an interaction with temperature suggested that this effect did not occur at the highest relative temperatures. The return date to breeding grounds, although spanning from September to April, was not influenced by the environmental conditions or food availability. Conclusions Food availability, measured by a vegetation greenness proxy, was associated with later migration at the end of the breeding season. Availability of cooler microclimate refugia may also allow for later departures from the breeding sites in all but the hottest conditions. Management measures that increase microclimate refugia availability and provide foraging resources can thus potentially increase the length of the breeding season for this species

Antipredator benefits of heterospecific colonial breeding for a predominantly solitary bird

Predation risk profoundly shapes how animals behave and is one of the main forces driving the formation or maintenance of groups. For some species, group living may be facultative, and individuals may live solitarily or aggregate with conspecifics or heterospecifics, but the advantages of each strategy are still poorly known. Here, we investigated whether a predominantly solitary breeding species, the European roller, Coracias garrulus, acquires antipredator benefits from nesting in mixed-species colonies dominated by lesser kestrels, Falco naumanni. We compared the risk-taking behaviour of solitary rollers and rollers breeding in colonies by conducting two experiments. First, we investigated rollers’ latency to resume incubation when presented with a novel object, and second assessed their latency to resume chick provisioning and their investment in mobbing behaviour towards a predator model. We additionally compared the breeding performance and nest predation rate of rollers in each social context (solitary versus colonial) using data from 300 breeding attempts across 6 years. We found that rollers breeding in colonies returned to their nests sooner during the presentation of both the novel object and the predator model and attacked the predator model less frequently than solitary rollers, suggesting they can use heterospecifics as cues in deciding whether it is safe to return to their nests. In addition, rollers in colonies suffered less nest predation than solitary ones, but this did not translate into a higher productivity. Future studies should investigate whether breeding in colonies provides other advantages to rollers, such as increased adult survival or fitness.info:eu-repo/semantics/acceptedVersio

Using Smart Sensors to Track Woody Debris in Flume Experiments

When triggered by floods, large wood travels downstream accumulating around river structures that may cause structural damage and eventually collapse. The use of sensors embedded within the woody debris has been recently employed in the study of debris transport in river catchments. However, their application for woody debris has not been fully explored yet and their validation is at an early stage. In this framework, laboratory experiments are designed to track the movement of a woody dowel along a tilting flume by using a smart sensor. The woody dowel is 200 mm long and has a diameter of 35 mm. It has a cylindrical borehole with a diameter of 25 mm along its whole length. A sensor tag is placed within the borehole to detect the movements of the woody dowel. The experiments consist of releasing the woody dowel into the flume tank and tracking its movements for different flow conditions. Experiments are recorded by two cameras capturing woody dowel movements from the top. By coupling the sensor outputs and the video recordings, it is possible to compute positions, velocity, acceleration and angular velocity of the woody dowel. Results show that the sensor embedded in the woody dowel can detect minor changes in the flow field. A smoothed particle hydrodynamics (SPH) model has been used to simulate the experiments. The comparison of laboratory and numerical data has allowed the refinement of numerical modelling of woody debris transport which ultimately contributes to better assessment of the hazard it poses

Experience modulates both aromatase activity and the sensitivity of agonistic behaviour to testosterone in black-headed gulls

In young black-headed gulls (Larus ridibundus), exposure to testosterone increases the sensitivity of agonistic behaviour to a subsequent exposure to this hormone. The aim of this paper is twofold: to analyze whether social experience, gained during testosterone exposure, mediates this increase in hormonal sensitivity (priming), and whether this in turn is mediated by an increase in central aromatase activity. To this end, we performed three experiments. In the first juvenile gulls were exposed to two consecutive treatments with testosterone (T1 and T2), with more than a week interval in between. During T1, half of the birds were housed in social isolation (Iso) and the other half in groups (Soc). All birds were re-housed in a new social situation during the second treatment. The increase in social behaviour during T2 was significantly more rapid in Soc than Iso birds. In experiment 2 we show that 17ß-estradiol treatment facilitates the behaviour measured in experiment 1. In experiment 3 we used a set-up comparable with that of experiment 1, but birds were sacrificed early in the T2 period. Aromatase activity in the preoptic area and the hypothalamus was measured using the tritiated water releasing method. In some parts of the preoptic area and hypothalamus aromatase activity was higher in Soc birds relative to Iso birds. The results indicate that social experience can modulate the increase of social behaviour to testosterone via modulation of aromatase activity and independently of actual hormone levels

Hotspots in the grid: Avian sensitivity and vulnerability to collision risk from energy infrastructure interactions in Europe and North Africa

Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape-scale planning and mitigation. The identification of high-vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy. We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 × 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines. Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey. Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird-EI conflicts