New Thesis defense with the GEDA!

Guillermo Gómez López had just obtained his Ph.D. at the University Complutense of Madrid with a thesis titled "Unravelling offspring sex ratios and survival in Old World vultures: insights from long-term monitoring" supervised by A. Sanz-Aguilar, G. Blanco y M. Carrete.  The thesis obtained the maximum note with laude. Congratulations Guillermo!!! Well done!!

New publication on immigrationa and population turnover!

Natsukawa, H., Tavecchia, G., Frías, Ó., Sergio, F., Hiraldo, F., Blanco, G. 2025 Immigration hides the decline caused by an anthropogenic trap and drives the spectacular increase of a mobile predator. Oecologia 207, 15 (2025). https://doi.org/10.1007/s00442-024-05656-2

In a shell:This study shows how massive immigration into a contaminated population of black kites, driven by an increased food supply and flock attraction, transformed a declining trend into a population increase, while highlighting the potential risks of anthropogenic subsidies as evolutionary traps

Abstract:  Accurate identification of decreasing trends is a prerequisite for successful conservation, but can be challenging when immigration compensates local declines in abundance. Here, we show that a potential declining trend driven by low vital rates was overridden and converted into a spectacular increase by massive immigration into the population of a semi-social raptor, the black kite Milvus migrans, breeding in a highly contaminated area near a major landfill. Immigration was promoted by a growing food-base of live prey, coupled with the attraction exerted by the progressive gathering of a large flock of non-breeders at the area, resulting in an “attraction spiral” that lured large numbers of breeders to settle into a contaminated population incapable of self-sustenance. Immigration was so prevalent that, in little more than a decade, over 95% of the original population was substituted by immigrants, which showed the enormous potential of immigration as a rescue mechanism. At the same time, immigration may hide cryptic threats, as shown here, and expose some species, especially group-living mobile ones, to rapid attraction to anthropogenic subsidies, whose potential role as evolutionary traps is well known. The dynamics exposed here may become increasingly common, affecting many other species in our growingly anthropogenic world. Our results remark the often overlooked importance of immigration in ecology, evolution, and conservation as a key player for population dynamics and their more realistic forecast.

 

 

New publication: IPM and tortoise populations!

Segura A., Rotger, A. and Rodriguez-Caro, R., 2025. Hidden Threats to Persistence: Changes in Population Structure Can Affect Well-Preserved Spur-Thighed Tortoise Populations. Herpetologica. https://doi.org/10.1655/Herpetologica-D-23-00066

In a shell: This study on Spur-thighed Tortoises highlights a shift towards a female-biased population, with high juvenile mortality from raven predation, and emphasizes the importance of female survival and sex-ratio especially in the context of climate change.

Abstract:  Population structure and survival are key components of wildlife management. Long-term monitoring of long-lived species, particularly those with indeterminate growth, is crucial when studying demographic processes. Here, we examined a population of Spur-thighed Tortoises, Testudo graeca, over a 7-yr period (17% of its life span), including changes in population structure, causes of mortality, and growth patterns. We found a change in population structure, as evidenced by lower young adult density (both males and females) and a more female-biased population compared to the start of the study. Juvenile mortality was high, and the main cause was predation by common ravens. 

Photo from iNaturalist

For adults, mortality was relatively low and was mostly observed in winter or due to anthropogenic reasons (forestry or road mortality). We also modeled adult size-dependent survival and juvenile threshold survival (minimum number of juveniles needed to reach the adult stage to maintain population viability) using a Bayesian framework and matrix projection models, respectively. Adult survival was high (0.97), but with variation between the sexes. Female survival was not size dependent, but male survival decreased when size exceeded 150 mm carapace length. In this population, longer female life spans and climate change effects seemed to be the most likely reasons for our female-biased population. This study particularly pinpoints the importance of high survival in older females, which contributes to species credit, and stresses the negative potential of low juvenile and male densities in the population. Indeed, the annual juvenile threshold survival range was estimated between 0.32 and 0.49, not accounting for the predation exerted by common ravens in subadults. Therefore, if predation reduces juvenile survival rates below this threshold, population viability can be affected in the future. The study contributes to this species’ conservation by anticipating time-lagged demographic responses based on current climate trends (less annual rainfall and more days over 40°C) and predation.

GEDA at 11F

GEDA joined the activities of the International Women and Girls on Science.

Dr. A. Sanz-Aguilar explained her research and spoke about her experience to children at school. 

 

Upcoming activities at IMEDEA can be found here

GEDA at the 26th Spanish Ornithological Congress! (I)

GEDA is participating to the Spanish Ornithological Congress held in Valencia (12-16 of February program here). The contributions, from seabirds to ticks to demographic trends of Balearic vertebrates, illustrate the work of GEDA members.

 

New Publication on Shearwaters!

Genovart, M., Ramos, R., Igual, J.M., Sanz-Aguilar, A., Tavecchia, G., Rotger, A., Militão, T., Vicente-Sastre, D., Garcia-Urdangarin, B., Pradel, R., González-Solís, J. and Oro, D. (2024), Individual Choices of Wintering Areas Drive Adult Survival Heterogeneity in a Long-Lived Seabird. Ecol Evol, 14: e70675. https://doi.org/10.1002/ece3.70675

In a shell:Wintering area preferences and environmental variability drive survival heterogeneity in long-distance migratory seabirds.

 Abstract:Seasonal migration has evolved as an adaptation for exploiting peaks of resource abundance and avoiding unfavourable climatic conditions. Differential migratory strategies and choices of wintering areas by long-distance migratory species may impose varying selective pressures and mortality risks with fitness consequences. Recently developed tracking technologies allow wintering movements of migratory species to be studied. However, these technologies typically involve a limited number of tracked individuals, which gives low statistical power for any robust estimate of survival probabilities. Additionally, when utilising geolocators, data become accessible only upon individual recapture, presenting a potential source of bias. We used multievent modelling to include information of 147 identified wintering tracks in the analysis of 1104 long-term individual capture histories (2000–2022) of migratory seabird Calonectris diomedea and then test if individual preferences for wintering areas may drive heterogeneity in adult survival. 

Photo: P. Arcos

We also examined individual fidelity to wintering areas and tested if climatic and oceanographic conditions, as represented by the wNAO and SOI climatic indices, influenced survival and fidelity. The probability of fidelity to a wintering area was ca. 0.79. Annual changes between areas were influenced by environmental variability driven by the wNAO. Survival probability was influenced by the SOI and differed between wintering areas; these differences coupled with high wintering site fidelity, generated individual heterogeneity in adult survival. Our study reveals that, over the last two decades, some individuals wintered in less suitable areas, with nonnegligible consequences on adult survival, the parameter to which the population growth rate is most sensitive in long-lived species. Winter oceanographic conditions such as stormy weather or the proximity to upwellings probably play a relevant role in driving survival heterogeneity. Further research is needed to enhance our understanding of how the interlinked effects of climate, local selective pressures and individual condition shape population dynamics in migratory species.

 

New publication on European Storm Petrel foraging areas!

 Bolumar Roda, S., Rotger, A., santangeli A., Tavecchia, G., Sola, A., [...] and Sanz-Aguilar, A., 2024. Coping with ocean dynamics: Foraging strategy and implications for conservation of a small petrel. Biological Conservation, 302: 110913 https://doi.org/10.1016/j.biocon.2024.110913  

 In a shell: The study used GPS tracking and oceanographic data to model foraging habitats of European Storm-petrels in the Western Mediterranean, identifying key regions influenced by dynamic oceanographic features that largely fall outside Marine Protected Areas, highlighting the need for conservation measures.

Abstract: Seabirds' distribution is generally influenced by the ecological dynamics of marine environments. Understanding how oceanographic features shape seabird foraging behaviour remains a challenge. We combined GPS tracking locations (n = 2883) of 39 European Storm-petrels (Hydrobates pelagicus) breeding in four West Mediterranean colonies during incubation over multiple years (2019–2021) with near-real-time remotely sensed oceanographic drivers. We model habitat selection using GPS tracking data from one colony, Benidorm Island, and use data from other three colonies for validation.

Photo: V. Paris

We show that suitable foraging areas are strongly characterized by low sea surface temperature, high chlorophyll concentration and eddy kinetic energy. Based on this model, we predict habitat suitability maps for 2018–2022. Cross-validation using data from the other three colonies highlights that the identified suitable areas are universally applicable across other Storm-petrel colonies in the Western Mediterranean. We identified the Alboran Sea, the North African coast, the Gulf of Lion and the Ebro River Delta as the most suitable regions. These areas are characterized by high mesoscale variability, suggesting the importance of dynamic oceanographic features in determining foraging habitat. Identified main foraging areas are largely outside of Marine Protected Areas (MPAs), thus vulnerable to anthropogenic threats such as overfishing and energy infrastructure development. The critical foraging areas identified for this species underscore the need to expand the MPA network and/or adopt sustainable resource extraction in unprotected marine areas.

New Publication on vultures !

Santangeli A, Fozzi I, De Rosa D, et al. Quantifying the regulation and cultural ecosystem services associated with Griffon Vultures Gyps fulvus in Sardinia, Italy. Bird Conservation International. 2024;34:e35. doi:10.1017/S0959270924000327 

 In a shell: The study shows the roles in carcass disposal, greenhouse gas mitigation, cultural identity, and ecotourism of Griffon Vultures in Sardinia, while emphasizing the need for their conservation to ensure sustainable human-wildlife coexistence.

Abstract: In the Anthropocene, recognising nature’s role in human well-being is pivotal for biodiversity conservation. Despite their significance, knowledge gaps persist regarding ecosystem services, even for well-studied species like vultures. Our study focuses on the Griffon Vulture Gyps fulvus in Sardinia, Italy, exploring their cultural and regulating services, including carcass disposal and resulting greenhouse gas (GHG) mitigation. Through surveys of natural reserve visitors and data on carcass provision and GHG emissions, we assess public perception, economic value, and environmental impacts associated with vultures. The public perception of Griffon Vultures is predominantly positive, with a strong acknowledgment of their role in disease prevention and carcass disposal, highlighting their contribution to regulation services. 

Furthermore, vultures are widely recognised as a key element characterising the agropastoral landscapes of Sardinia, underscoring their cultural importance. The economic evaluation, through willingness to pay for vulture-watching and photography opportunities, indicates a significant appreciation of these birds, with almost three-quarters of respondents willing to pay an entrance fee at vulture observation sites. We also show that supplanting the disposal role of vultures at studied feeding sites (during 2017–2022) would result in the emission of 96 tons of CO2 equivalent, which highlights the critical role of vultures in climate mitigation. This study not only sheds light on the ecological and cultural significance of Griffon Vultures in Sardinia but also underscores the economic and environmental benefits of their conservation. It emphasises the need for continued efforts in vulture conservation, integrating ecological, cultural, and economic perspectives to foster a sustainable coexistence between humans and wildlife.