PhD-Dissertation Reviews in Ornithology (2019-2020 Academic Year)

This section includes the abstracts of some of the PhD-Dissertations submitted in Spain during the 2019-2020 academic year as well as some others not published in earlier volumes of Ardeola . They are in alphabetical order by University where they were presented and, then, by year and alphabetical order of the author’s surname. This section also includes a link to access the full version of the reviewed thesis when available. Abstract:To build infrastructures, we rely on the construction sector, which produces aggre-gates and cement through mining activity. The reconciliation of the extractive activity and conservation of natural values is a crucial issue. Currently, our capacity to return ecosystems affected by mining activities to their original situation is limited. An alternative to restoration is the creation of ecosystems for fauna of conservation concern. Cliff-nesting birds (birds that rely primarily on rocky or sandy walls to breed) colonize human-created environments such as mining sites (quarries and aggregate pits from the cement and aggregate sector). However, mining restoration often fails to consider the cliff-nesting fauna that may have colonized these areas. Further-more, previous work has failed to address how important these man-made habitats are for the conservation of cliff-nesting birds, and how to manage their presence during the active phases of the mining sites. The aim of this thesis is to study the cliff-nesting bird community at mining sites, and to give management recommendations to enhance biodiversity by improving breeding habitats for cliff-nesting bird species in Mediterranean areas of Spain. We expect mining sites to have the potential of accommodating a varied community of cliff-nesting birds. We studied three aspects to manage these communities: (i) the potential risk of generating by excess of predation; (ii) the process of and preferences of cliff-nesting at different scales; and (iii) the ecological services of cliff-nesting colonized by secondary cavity-user birds, the Rock Sparrow Petronia petronia being the most abundant species. With this work, we aimed to explore alternatives to conventional restoration actions, to improve vulnerable biodiversity and to reconcile fauna with mining activity. Our study supports incorporating actions to promote cliffs, together with managing the mining sites to form a heterogeneous mosaic of habitats that satisfy the requirements of the cliff-nesting species (roosting, feeding, etc.). Finally, the study of these complementary habitats inside and outside the mining sites should be pursued in future lines of research, to improve the management and conservation of cliff-nesting species in mining sites. Early bird development modulators: the role of steroids and oxidative stress on ageing. Abstract:Life history traits are a set of morpho-logical, physiological or behavioural features or changes that occur through the organism’s life and ultimately determine its fitness. The expression of these life history traits is often subject to trade-offs whose resolution pro-motes the existence of different life history strategies. These trade-offs often involve physiological mechanisms that must be addressed in order to fully understand their origin and evolutionary significance. These mechanisms may include, for instance, the direct effects (and associated costs) of certain hormones or the increased production of reactive oxygen species as a result of some physiological processes, which may consti-tute a significant cost that constraints the expression of some life history traits. These processes can exert profound effects during early development, when on immunocompetence or oxidative status. We also found that increased exposure to oxidative stress during early development impairs nestling growth and exerts contrasted effects on different branches of the immune system, stimulating humoral innate immunity and tending to suppress cell-mediated immune responses. The latter effect may suggest an adaptive allocation of resources among components of the immune system that are subject to a trade-off. Finally, we found no support for the widely accepted notion that oxidative stress is the main mechanism ex-plaining individual variability in telomere length. Other processes, like cell prolifera-tion rate, could be relatively more important at least during the characteristic telomere attrition process associated to early development. The last contribution of this thesis is a call for caution when trying to infer oxidative status of individuals by using one or few biomarkers of oxidative stress: despite the magnitude of our experimental induction of oxidative stress via Diquat injections –as revealed by clear effects on individual growth–, this was not captured by two widely used markers of oxidative stress (malondialdehyde concentration and trolox equivalent antioxi-dant capacity of plasma). This warns against simplistic approaches to oxidative stress responses, and claims for the use of multiple markers of oxidative damage and/or tracking their variations in different tissues. Abstract: Oceans are suffering from rapid environmental change, tential of SIA as a good geographic marker to study migratory movements of marine predators. Bulwer’s Petrels migrated to two main non-breeding areas, the Central and the South Atlantic, which implied different phenological and migratory strategies. This species showed to be resilient to environment changes during the non-breeding season, but more sensitive to them during the season, resulting in a lower survival in years with higher sea surface temperature. Indeed, we inferred the increasing temperature of the will sharply decrease Bulwer’s Petrel survival, compromising their populations viability, and making them an excellent sentinel of the changes occurring in oceanic food webs. Multi-colony approaches to study migratory and foraging strategies in pelagic seabirds. temporal variability in the inference of spatial use at a colony or population level, and to calculate the degree in which the movements of a single population can be representative of those of the entire species. These tools are applicable to individual movement data regardless of the species or tracking device. We also used these tools to demonstrate the spatial and ecological segregation between the non-breeding distributions of three taxa of Calonectris Shearwaters studied, as well as detecting a stronger degree of migratory connectivity at a population than at a colony level. The later result indicates that individuals of different colonies within a population mix in the non-breeding areas, but birds from different populations do not, which has important implications for their population dynamics and for their conservation and management. Lastly, we demonstrated segregation among the foraging distributions of three neighbouring colonies of Cory’s Shearwaters, both in the waters surrounding the colony and in distant, foraging grounds. We found evidence of both environmental and behavioural drivers behind this segregation, and suggest a mechanism through which transfer of information between individuals can be shaping the distributions of foraging seabirds. This thesis provides relevant tools for the field of movement ecology, as they can be used for analysing movements of mobile species, regardless of species, tracking device or spatiotemporal scale. In addition, they are relevant for the field of seabird ecology as they provide insights into the causes of space and habitat use in long-ranging pelagic seabirds. Abstract: Movement is a fundamental component of behaviour and thus both are inextricably linked, so variation in migratory is a complex and than freshwater species. We tested this hypothesis by comparing the pro-inflammatory response to PHA and its associated energy costs in Dunlins Calidris alpina , a long migratory shorebird breeding in sub-arctic latitudes and wintering mostly, but not exclusively, in marine habitats. We found that the pro-inflam-matory response of dunlins overwintering in marine habitats was significantly lower than that of dunlins overwintering in freshwater areas. Associated to this lower pro-inflam-matory response, marine dunlins did not vary their BMR and reduced significantly their body mass. Conversely, dunlins from freshwater habitats significantly increased their BMR and did not vary their body mass. These findings support the hypothesis according to which the selection pressures exerted by parasites have a role in the evolution of migration strategies of shorebirds. Academic Signalling and evolutionary responses to bacterial environments in birds. The case of the Spotless Starling Sturnus Abstract:Birds are continuously making decisions; the food to eat, the partner to mate, or the host to parasitize. Decision-making has enormous fitness consequences and, at least partially, is modulated by the information received from the environment, that from clues and signals emitted by other organisms. Abstract:Bacteria are common symbionts of macro-organisms frequently establishing mutualistic associations, in which both the symbiont and the host get benefits. One of these benefits is protection of the host against pathogens, by means of defensive substances that the bacteria synthesize. The microbial community associated with the host may be different among individuals of the same species and, consequently, be a property that causes differences in the abilities of those individuals. These differences could be of interest to potential partners and, thus, the production of signals associated with this quality could be under selection. Thus, the quality of an in-dividual’s microbiome could be the information transmitted by some existing sexual signals in hosts of beneficial bacteria. The evolution and maintenance of the signals depends on the reliability of the information transmitted. In this scenario, it would be the female