Citizen science at Sa Dragonera Island! Saturady 24 April.

Do you like wildlife photgraphy? Suscribe for the Red Ring Challenge here and join our long-term research on the Yellow-legged gull at Sa Dragonera Island.

Take a picture of a marked gull and win an original T-Shirt. 

Presence-absence data of marked animals are extremely important as they can be used to estimate annual survival probability and movements of individuals within the breeding colony. 

The project, funded by the Spanish Ministery of Science and Education, will investigate how the management of discards from human activities influences the ecology of gulls. 

To subscribe write your name and telephone number to:

medgulls@gmail.com

 

 

 

New Publication on avian scavangers and anthropized landscapes!

Gangoso, L., Cortés-Avizanda, A., et al. 2021. Avian scavengers living in anthropized landscapes have shorter telomeres and higher levels of glucocorticoid hormones. Science of the Total Environment.146920, https://doi.org/10.1016/j.scitotenv.2021.146920  

Abstract:  Habitat anthropization is a powerful stressor affecting the health and fitness of organisms, ultimately impacting their population dynamics. In vertebrates, stressful living conditions are usually associated with elevated glucocorticoids-based responses (GCs) as well as shorter telomeres, which are in turn associated with decreased overall body condition fitness and life expectancy. However, our understanding of how habitat anthropization per se and population processes synergistically, or independently, may affect GCs and telomere dynamics in natural populations is still very limited. 

Here, we assessed the physiological footprint of habitat anthropization and conspecific density in 65 GPS-tagged Eurasian griffon vultures (Gyps fulvus) from two populations of the Iberian Peninsula. We examined how extrinsic (human footprint values and conspecifics density within individual activity areas) and intrinsic (sex and home range size) factors determine GCs deposited in feathers (CORT_f) and telomere length as proxies of overall individual condition and quality. We found strong differences in both physiological markers between populations, with higher CORT_f levels and shorter telomeres in vultures living in the northern, more anthropized area. We also found sex-specific patterns of CORT_f, with females having higher levels than males. In both sexes, telomere length decreased as the density of conspecifics increased. Previous studies in these populations have shown lower survival rates in individuals who exploit more anthropized areas, and here we show a potential physiological causal link. We highlight the existence of complex effects of chronic stress associated both with living in anthropized environments and with population-related processes likely associated to the spatial distribution of resources.

Cover!

The article by Sergio et al. 2021 on Ecological Application (here) made the cover of the last issue. Nice pic.

Well done Fabrizio!

New Publication: Don't mess with encounter probabilities!

Tavecchia, G., Gimenez, O., Choqut, R., Oro, D., Tenan, S. and Sanz-Aguilar, A. 2021.The trap of hidden processes: Why ‘quick & dirty’ methods to estimate mortality are not always good. A comment to De Pascalis et al. (2020) Biological Conservation, 109057, doi: 10.1016/j.biocon.2021.109057

CMRR models can be difficult to build and many conservation biologists are tempted to shortcut them for simpler, ‘quick & dirty’, methods, trading difficulty with the lack of precision. In some particular cases, it is a winning trade, however, in most cases, it is a very hazardous practice. The proportion of animal seen alive vs those seen dead depends, by definition, on the detection probability, p, that an animal alive is detected and on the probability, λ, that a dead animal is found or retrieved (c) and the tag reported (r), with λ = c*r. Not taking thi into acocunt would lead to biased estimates. Explore scenarios through an R shiny application provided at https://github.com/oliviergimenez/bias_recovery.

Yellow Legged Gull campaign on the starting blocks!

The Yellow-legged gull campaign is on the starting blocks. Last year it has been difficult due to the lockdown in the middle of the breeding season. This year we are ready to catch up with a new fieldwork campaign in Ibiza and some extra help. We are warming up with some press notes and radio interview.

Illustration by Pelopanton

A press note about the project here and a radio interview by Dr. Ana Sanz-Aguilar here 

Ph.D. with the GEDA

Guillermo Gomez Perez will begin his doctorate in Ecology at the Universidad Cumplutense of Madrid on the demography of Griffon vultures in central Spain. 

He will be supervised by Dr Ana Sanz-Aguilar (GEDA- IMEDEA, CSIC/UIB), Dr. Martina Carrete (Pablo Olavide University) and Dr Guillermo Blanco (Natural History Museum, CSIC). Welcome Guillermo!

New publication on seabirds and stable isotopes !

Ramírez F, Vicente-Sastre D, Afán I, Igual JM, Oro D, Forero MG (2021) Stable isotopes in seabirds reflect changes in marine productivity patterns. Mar Ecol Prog Ser 662:169-180. https://doi.org/10.3354/meps13615

 ABSTRACT: Seabirds have been proposed as suitable candidates for tracking and monitoring changes in marine systems (bioindicators). However, their suitability depends on our ability to link the large degree of environmental variability inherent to marine systems with a few, relevant, and accessible signals (biomarkers) informing on changes in their feeding behavior or reproductive performance. We combined satellite remote-sensing records with stable isotope data (δ¹⁵N and δ¹³C) and breeding parameters (fledging success) spanning several years (2001-2014) to investigate the ecological responses to environmental variability by 2 sympatric seabirds inhabiting the western Mediterranean: Scopoli’s shearwater Calonectris diomedea and Cory’s shearwater C. borealis. 

Both species showed similar annual variations in their stable isotopic composition, likely as a response to the trophic consequences of changes in the magnitude and timing of the annual peak in marine productivity (as proxied by satellite imagery of chlorophyll a concentrations). In contrast, no relevant responses were observed in their breeding performance, suggesting that their life-history strategy has evolved to constancy in breeding success, which diminishes its value as a biomarker of changes in marine productivity patterns. Despite this limitation, combining remote sensing and stable isotopes in seabirds is a reliable and powerful tool for the early detection of fine-scale, climate-driven changes in marine productivity patterns and its cascading effects across communities and trophic levels, especially under the current scenario of ocean warming. 

New publication on eradication of introduced fish !

Tiberti, R, Buchaca, T, Boiano, D, Knapp, R. A., Rovira, Q. P, Tavecchia, G, Ventura, M, Tenan, S., 2021. Alien fish eradication from high mountain lakes by multiple removal methods: Estimating residual abundance and eradication probability in open populations. J Appl Ecol. 2021; 00: 1– 14. https://doi.org/10.1111/1365‐2664.13857

1. Invasive alien species are among the most important threats to biodiversity. Plans for their eradication have been implemented worldwide but estimating residual population size and eradication probability to assess removal success is complicated by the imperfect detection of residual individuals.
2. Most methods to assess residual abundance and eradication probability rely on the often unrealistic assumption that a population is closed to mortality and recruitment processes during the implementation of removal actions. We extended existing removal models and developed a novel analytical approach to estimate residual population size and derive eradication probability in open populations while accounting for multiple removal methods.
3. We apply this approach to 20 eradication projects in Europe and the United States that used mechanical methods to return high mountain lakes to their original fishless condition.
4. The new removal model incorporates (a) a mechanistic description of the ecological process underlying survival and recruitment probabilities during the eradication period and (b) the use of multiple, concomitant removal methods (i.e. electrofishing, gillnetting, fyke‐netting) at multiple sites simultaneously.
   
5. We used a subset of ‘control’ lakes where eradication success was confirmed by more than 5 years of post‐removal surveys to validate the model. For these lakes, eradication success, evaluated by whether the 95% Bayesian credible interval for estimated residual population size encompassed values of <2 individuals, was confirmed in 13 out of 15 lake‐by‐species case studies. In addition, the model correctly assigned an eradication probabilities equal to 0 for the eradications that are still in progress.
6. Synthesis and applications. Our study provides insights into the dynamics of fish populations subject to eradication in high mountain lakes of different countries. In addition, the analytical approach proposed accounts for demographic processes and multiple removal methods in multiple sites and seasons. It can represent an informative tool to estimate residual population size and eradication probability of alien species to optimize eradication efforts and efficacy of conservation actions. The extension to open populations makes the approach useful to evaluate long‐term eradication plans.