Leukocyte profile variation in Dupont’s Lark (Chersophilus duponti) in Spain and Morocco

Stress in birds has been widely studied through the measurement of heterophil-to-lymphocyte ratio (H/L ratio). In this study we aimed to assess for the first time the potential variation of stress, measured as H/L ratio, associated to geography (between-country variation) and seasonality (between seasons and within the breeding season), as well as the leukocyte profiles, in the threatened Dupont’s Lark (Chersophilus duponti), using samples from Spain and Morocco. Furthermore, we tested whether variation in H/L ratio was associated with variables such as population density, presence of blood parasites and individual body condition. We found that H/L ratio did not vary between countries, but individuals captured during the breeding season showed higher values of H/L compared to non-breeding ones. Neither male density, nor date within the breeding season had an effect on the H/L ratio. In Spain, individuals with higher body condition showed lower H/L ratio regardless of whether they were malaria-infected. In Morocco, malaria-infected individuals showed higher values of H/L ratio than the non-infected birds. Moreover, we found that our average values of H/L ratio in Morocco were within the ranges of other passerines, but not in Spain. Individuals with higher H/L ratios may be more stressed or present higher capability to face stressful situations. Although H/L ratio is a useful and relatively easy way to obtain measure of stress, the impact that the environment might have on stress and the way it is explained by H/L ratio must be addressed carefully. This study provides new insight for this species’ biology and provides useful reference information to test the status and survival of other populations.

Population viability analysis of the endangered Dupont’s Lark Chersophilus duponti in Spain

Steppe lands in Europe are critically affected by habitat loss and fragmentation, and hold over 50% of IUCN Red List bird species in Europe. Dupont’s Lark is a threatened steppe-specialist passerine whose European geographic range is restricted to Spain, with less than 2000 pairs and an annual population decline of − 3.9%. Its strongly fragmented habitat leads to a metapopulation structure in the Iberian Peninsula that includes 24 populations and 100 subpopulations. We present an updated Population Viability Analysis based on the latest scientific knowledge regarding distribution, population trends, breeding biology and connectivity. Our results predict metapopulation extinction in 2–3 decades, through a centripetal contraction process from the periphery to the core. The probability of extinction in 20 years was 84.2%, which supports its relisting to Endangered in Spain following IUCN criteria. We carried out a sensitivity analysis showing that some parameters, especially productivity and survival of adults and juveniles, help to increase metapopulation viability. Simulation of management scenarios showed that habitat restoration in a subset of key subpopulations had a positive effect on the overall metapopulation persistence. Translocations of a limited number of individuals from source to recipient locations may help to rescue the most endangered subpopulations without reducing the global time to extinction of the metapopulation. In addition, we identified the most critical areas for action, where local populations of the species are prone to extinction. This work suggests that the viability of the Dupont’s Lark metapopulation could be improved and its risk of extinction reduced if urgent and localized conservation measures are applied. In the short-term, habitat loss and fragmentation due to ploughing, reforestation and infrastructures implementation in Dupont’s Lark habitat must be avoided. Habitat restoration and translocations could help to avoid imminent extinction of critical subpopulations. Restoration of extensive grazing is recommended as the most effective way to achieve the long-term conservation of Dupont’s Lark in Spain.

Connectivity in Spanish metapopulation of Dupont’s lark may be maintained by dispersal over medium-distance range and stepping stones

Background Dupont’s Lark is an endangered bird, whose fragmented distribution in Europe is entirely restricted to Spain. This lark, suffering pronounced population decline and range contraction, inhabits steppes that have long been used for grazing sheep and are now threatened by rural abandonment and land use changes. Thus, for conservation of the lark, increasing knowledge about the connectivity of the Spanish metapopulation and identifying the most important connectivity nodes are crucial. Methods The study was carried out in Spain, using over 16,000 Dupont’s Lark georeferenced observations. We used distance buffers to define populations and subpopulations, based on the available scientific information. We identified potential stepping stones using a MaxEnt probability of presence model. Connectivity was assessed using Conefor software, using the centroid of each subpopulation and stepping stone as nodes. Each node was assigned a quantitative attribute based on total habitat area, within-node habitat quality and internal fragmentation. We evaluated different connectivity scenarios by potential movement thresholds (5–20–100 km) and presence or absence of stepping stones in the network. Results Dupont’s Lark Iberian metapopulation comprises 24 populations and 100 subpopulations, plus 294 potential stepping stones. Movement thresholds and stepping stones had a strong influence in the potential network connectivity. The most important nodes are located in the core of the metapopulation, which shows connectivity among subpopulations in the different indices and scenarios evaluated. Peripheral populations are more isolated and require stepping stones or medium (20 km) or long (100 km) potential movement thresholds to join the network. Discussion Metapopulation connectivity may be greater than expected, thanks to stepping stones and potential medium-distance movements. Connectivity is crucial for conservation and can be increased by preserving or improving adequate habitat in the most important nodes. Given the current species decline, steppe habitat should be urgently protected from land use changes and agriculture intensification, at least in the critical subpopulations and stepping stones. Long-term conservation of steppe lands and Dupont’s Lark in Spain requires the recovery of traditional grazing and more research on juvenile dispersion. Meanwhile, the conservation of potentially critical stepping stones should be incorporated to management plans.

Breeding dispersal movements of Dupont’s Lark Chersophilus duponti in fragmented landscape

Summary Understanding patterns of dispersal behaviour of threatened species is important in conservation biology and population ecology, especially in fragmented landscapes. Dupont’s Lark Chersophilusduponti is a threatened passerine whose European population has declined by around 40% in the last decade. To study natal and breeding dispersal of the species, we used a long-term mark-recapture dataset (2011–2019) and analysed the records of 32 males (39 dispersal movements) and five females (five dispersal movements) captured during the breeding season at Rincón de Ademuz (Valencia, eastern Spain). Adult birds had a median breeding dispersal of 154 m (Q25-Q75 = 70.0–300.3). Among these captures, two adult males dispersed to a new patch of habitat separated by more than 5,800 m. Only one out of 26 nestlings ringed was trapped as an adult bird, which occurred at a site different from the natal territory (4,500 m). Our results show a low breeding dispersal for the species and are, in essence, in agreement with previous studies carried out in the Ebro Valley metapopulation, one of the core areas for the species in Europe. Nonetheless, unlike in the Ebro Valley, we detected movements of adult birds between habitat patches. The low recovery rate of young birds suggests that they left their natal sites and moved outside the study area or that their survival rate was very low. Future studies focused on the post-fledging survival rate and natal dispersal movements are essential to determine effective conservation measures for the species. Habitat management actions in occupied and potential sites should be carried out close to the areas inhabited by the species to increase the success rate of the interventions and the effective dispersal and therefore population connectivity.

The conservation research–practice gap: a case study of a threatened bird

Conservation research is less often applied in practice than is desirable for the optimization of conservation outcomes. We evaluated this conservation research–practice gap for a threatened passerine, Dupont's lark Chersophilus duponti. We reviewed the literature and classified the conservation interventions proposed by scientists as regulation and legislation, monitoring and research, or management. We sent a questionnaire to managers responsible for species conservation, to gather information about the reasons for implementing, or not, each conservation intervention. We found 16 conservation interventions proposed in the literature, of which 13 (81.2%) had been applied by managers at least once. We found a disparity between the frequency of scientific recommendations and the actions implemented by managers: some measures with high scientific consensus were rarely adopted, whereas approaches less frequently proposed by scientists were more often implemented by managers. Regulatory and monitoring/research interventions were applied more often than management interventions, probably because of legal obligations. Management interventions were less frequently implemented, mainly because of time and budget limitations. There was a negative correlation between the number of interventions implemented and the population trend of the species in each region, which suggests that conservation interventions were more commonly implemented when the species was facing local extinction. Our results indicate a mismatch between science and practice for the conservation of Dupont's lark, the reasons for which seem to be diverse and include factors such as financial and time limitations, legal obstacles and managers' perception of extinction risk. An iterative dialogue needs to be initiated between scientists and managers to evaluate the efficacy of interventions implemented, and facilitate evidence-based conservation.

Hierarchical habitat-use by an endangered steppe bird in fragmented landscapes is associated with large connected patches and high food availability

Multidimensional approaches must be employed when addressing habitat use patterns. In this study, we aim to elucidate the hierarchical nature of space use by species inhabiting fragmented landscapes, using the threatened Dupont’s lark (Chersophilus duponti). The intensity of space use by Dupont’s lark was estimated using the Kernel Density Function on territory locations in 2015. We measured descriptors of habitat quality at metapopulation (connectivity and patch size), landscape (land-use types and anthropogenic disturbance) and microhabitat-scale (plant structure and composition, herbivore abundance and food availability) at 37 sampling stations. We fitted a Partial Least Squares Regression (PLSR) which yielded two components, accounting for 81% of total variance. Metapopulation-scale factors had the greatest explanatory power (32%), followed by microhabitat (17%) landscape (10%) and spatial predictors (3.6%). Connectivity and patch size were key factors explaining habitat use, and wind farms had a negative effect. At microhabitat-scale, space use was positively associated with Coleoptera, Orthoptera, Araneae and Diptera biomass, but negatively with Formicidae and Blattodea biomass, the cover of Stipa spp, Koeleria vallesiana and moss. This research highlights the hierarchical nature of habitat use in fragmented landscapes. Therefore, conservation measures should ensure connectivity, guarantee a minimum patch size, and improve habitat quality within patches.