Dark nests and egg colour in birds: a possible functional role of ultraviolet reflectance in egg detectability

Due to the conspicuousness of ultraviolet colour in dark environments, natural selection might have selected for ultraviolet egg coloration because it would enhance egg detectability by parents in murky nests. Here we tested this hypothesis by using comparative and experimental approaches. First we studied variation in egg coloration of 98 species of European passerines measured using UV-visible reflectance spectrometry (300-700 nm) in relation to nesting habits. Analyses based on raw data and controlling for phylogenetic distances both at the species and the family level revealed that hole-nester species showed eggs with higher ultraviolet reflectance than those nesting in open habitats. The experimental approach consisted on the manipulation of ultraviolet reflectance of experimental eggs introduced outside the nestcup of the hole-nester spotless starling Sturnus unicolor and the study of retrieval of these eggs. Ultraviolet-reflecting eggs (“controls”) were more frequently retrieved to the nest cup than non-reflecting (“-UV”) eggs. These results were not due to “-UV” eggs being recognized by starlings as parasitic because when a parasitic egg is detected, starling removed it from the nest-box. Therefore, these results are consistent with the hypothesis that ultraviolet egg colours are designed to provide highly detectable targets for parent birds in dark nest environments

Multiparasitism and repeated parasitism by the great spotted cuckoo Clamator glandarius on its main host, the magpie Pica pica: effects on reproductive success, nest desertion and nest predation

This work was supported by the research project PID2020-1159506BI00 financed by MCIN/AEI/10.13039/501100011033. Permits - The research was conducted according to relevant Spanish national (Real Decreto 1201/2005, de 10 de Octubre) and regional guidelines. All necessary permits were obtained from the Consejeria de Medio Ambiente y Ordenacion del Territorio de la Junta de Andalucia (Spanish Regional Government). Field work was licensed by the Andalusian authority for wildlife protection (DGGMN; ref.: SGYB/FOA/AFR/CFS 15/03/2012).Brood parasites are expected to lay only one egg per parasitized nest, as the existence of several parasitic nestlings in a brood increases competition and can lead the starvation of some of them. However, multiparasitism (laying of two or more eggs by one or more parasitic females in a single host nest) is surprisingly frequent. Here, we study multiparasitism by different females or by the same female (repeated parasitism) in the great spotted cuckoo Clamator glandarius, a non-evictor brood parasite that mainly parasitizes the magpie Pica pica, and whose chicks may be raised together with host nestlings in the same nest. We used a total of 262 magpie nests found during four breeding seasons. Multiparasitism and repeated parasitism are very frequent because this brood parasite is less virulent than other cuckoo species and magpie hosts can successfully raise more than one parasitic nestling per nest. The total number of cuckoo chicks fledged was higher in multiparasitized nests than in single- or double-parasitized magpie nests. Magpie breeding success (i.e. the proportion of eggs that produce young that leave the nest) did not differ between single-, double-, and multiparasitized magpie nests. These results suggest that multiparasitism is an adaptation in the great spotted cuckoo. The intensity of parasitism (number of cuckoo eggs per nest), after controlling for the potential effect of year, did not affect nest desertion or nest predation rate, neither during the incubation nor the nestling periods. This implies that nest concealment does not affect the susceptibility of one nest being parasitized and predated, as nest predation rate was similar regardless of the intensity of parasitism. Predation rate during the nestling phase did not vary according to intensity of parasitism, which does not support either the 'mutualism' hypothesis or the 'predation cost of begging' hypothesis.MCIN/AEI/10.13039/501100011033 PID2020-1159506BI00Spanish national 1201/200

Territoriality and variation in home range size through the entire annual range of migratory great spotted cuckoos (Clamator glandarius)

Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-019-41943-2.We would like to thank Juan José Castro for his help capturing cuckoos in Spain. Marco van der Velde provided excellent support for the lab analyses regarding sex determination of cuckoos. Two anonymous reviewers provided useful comments that helped to improve our manuscript.Variation in home range size throughout the year and its causes are not well understood yet. Migratory brood parasites offer a unique opportunity to incorporate this spatio-temporal dimension into the study of the factors regulating home range dynamics. Using satellite transmitters, we tracked sixteen migratory great spotted cuckoos (Clamator glandarius) of both sexes for up to three years. We constructed home ranges in all major staging areas, from the Spanish breeding areas to the African wintering grounds, analyzed their temporal and geographical variation and investigated their main potential determinants (e.g. food and host availability). We found that home ranges were significantly larger in the breeding area compared to non-breeding areas. Using NDVI as a proxy for food availability, we showed that breeding area home ranges have significantly lower food availability per km2 than home ranges elsewhere which could explain why cuckoos use alternative areas with higher food availability before initiating migration. We also found some evidence for sex differences. Additionally, we found no indications of territoriality in this species, providing novel information into the current debate on brood parasite territoriality. Overall, food availability seems to be an important factor regulating home range dynamics and influencing migratory patterns throughout the year in great spotted cuckoos.This study was partially funded by the Spanish Ministerio de Economía y Competitividad/FEDER (research projects CGL2011-25634/BOS and CGL2017- 89338-P)

Migration behavior and performance of the great spotted cuckoo (Clamator glandarius)

The study of brood parasitism has traditionally been focused on the breeding period, but recent evidence suggests that it urgently needs a new spatio-temporal perspective to explore novel avenues on brood parasite-host co-evolutionary interactions. Many brood parasites are migrants, but their ecology outside their short breeding season is poorly known. The great spotted cuckoo (Clamator glandarius) is one of the classical models in the study of brood parasitism, however, there is very little information on its migratory strategy, route and wintering grounds. Furthermore, there is no previous information on the geographical distribution of mortality and its causes in this species; information that is critical to understand the fluctuations in cuckoo populations and detect potential conservation risks. Using satellite tracking technology, we provide novel insight into the migratory behavior and performance of the great spotted cuckoo. We found individuals from southern Spain to be long-distance nocturnal migrants that use the East Atlantic Flyway for both post and pre-breeding migration, and that winter in the western Sahel. We found evidence of individual variation in their migration route, particularly regarding their post-breeding behavior in Spain. Our study also suggests that the south of Morocco is the most dangerous area due to a large number of deaths during the post-breeding migratory period. Furthermore, we found that natural predation seems to be the main cause of death, probably due to raptors, although human activities (i.e. hunting) could also played a role in the southern Mediterranean shore. Our study offers novel findings and challenges traditional ideas on the ecology of this species providing a good example of how the new spatio-temporal perspective can expand our knowledge on brood parasites.This study was partially funded by the Spanish Ministerio de Economía y Competitividad/ FEDER (research projects CGL2011-25634/BOS and CGL2017-89338-P to M.S.)

Energy performance improvement and cultural enhancement of the Andalusian rural heritage: case study – “El Cortijo del Fraile”

The renovation of old cortijos, haciendas or lagares is a topical subject within the context of enhancing the Andalusian agrarian architecture. The abandonment of these unique farmhouses structures due to the industrialisation of the harvesting process has already drawn the administration’s attention to the importance of encouraging its maintenance. The Public Works and Housing Office and the Culture Office of the Andalusian Government, as well as local administrative bodies, have promoted its identification, examination and analysis to manage rehabilitation policies that facilitate the adaptation of these spaces of architectural heritage to new uses. This research paper gathers the methodology for the energy renovation of these constructions, enhancing their characteristic infrastructures and most significant assets. Various strategies support the traditional existing facilities of the “cortijos” inserting new technologies to supply the needs of the new programmes, optimizing the existing resources. Increasing rainwater collection surfaces and storage; improving the filtering and recycling methods to recycle rainwater, grey water and sewage; and increasing the effectiveness of solar and wind energy collection with new technologies that complement the old passive knowledge with updated designs or active systems. The main goal of this paper is to find strategies to extrapolate its application in similar cases among the Mediterranean European context. The application of this methodology in a case study shows the energy performance improvements proposed for the “Cortijo del Fraile”, located on the southeast of Nijar (Almería), inside the Natural Park of “Cabo de Gata-Nijar”

Sexually Selected Egg Coloration in Spotless Starlings

It has been recently proposed that the blue-green coloration in eggs of many avian species may constitute a sexually selected female signal. Blue-green color intensity would reflect the physiological condition of females, and hence it might also affect the allocation of male parental care. In this study, we use three different experimental approaches to explore the importance of sexual selection on blue-green egg coloration of spotless starling (Sturnus unicolor) eggs. First, experimental deterioration of female body condition (by means of wing feather removal) negatively affected the intensity of blue-green egg coloration. Second, blue-green color intensity of artificial model eggs had a significant positive influence on paternal feeding effort. Finally, we found a negative relationship between the effect of experimental food supply on nestling immunocompetence and the intensity of blue-green coloration of eggs, suggesting that egg color predicts nutritional conditions that nestlings will experience during development. All these results taken together strongly support a role of sexual selection in the blue-green coloration of spotless starling eggs.This research was funded by the Spanish Ministry of Education and Science and the Fondo Europeo de Desarrollo Regional (FEDER; CGL2004-01777/BOS).Peer reviewe

Great spotted cuckoo nestlings have no antipredatory effect on magpie or carrion crow host nests in southern Spain

Host defences against cuckoo parasitism and cuckoo trickeries to overcome them are a classic example of antagonistic coevolution. Recently it has been reported that this relationship may turn to be mutualistic in the case of the carrion crow (Corvus corone) and its brood parasite, the great spotted cuckoo (Clamator glandarius), given that experimentally and naturally parasitized nests were depredated at a lower rate than non-parasitized nests. This result was interpreted as a consequence of the antipredatory properties of a fetid cloacal secretion produced by cuckoo nestlings, which presumably deters predators from parasitized host nests. This potential defensive mechanism would therefore explain the detected higher fledgling success of parasitized nests during breeding seasons with high predation risk. Here, in a different study population, we explored the expected benefits in terms of reduced nest predation in naturally and experimentally parasitized nests of two different host species, carrion crows and magpies (Pica pica). During the incubation phase non-parasitized nests were depredated more frequently than parasitized nests. However, during the nestling phase, parasitized nests were not depredated at a lower rate than non-parasitized nests, neither in magpie nor in carrion crow nests, and experimental translocation of great spotted cuckoo hatchlings did not reveal causal effects between parasitism state and predation rate of host nests. Therefore, our results do not fit expectations and, thus, do not support the fascinating possibility that great spotted cuckoo nestlings could have an antipredatory effect for host nestlings, at least in our study area. We also discuss different possibilities that may conciliate these with previous results, but also several alternative explanations, including the lack of generalizability of the previously documented mutualistic association.This work was partially supported by the Junta de Andalucía (research project CVI-6653) and the Spanish Ministerio de Economía y Competitividad/FEDER (research project CGL2011-25634/BOS to MS). There was no additional funding received for this study

Análisis de la actividad científica de la Comunidad Autónoma de la Región de Murcia. Biomedicina 1999-2005.

An analysis of scientific activity in Biomedicine in Murcia between 1999-2005 is presented