1,721,007 research outputs found
Data from: Grasshoppers do not flee from their alarmed predators but from non-alarmed ones
No full text[Methods] Firstly, in a field experiment we sampled the abundance of several grasshopper species in patches after broadcasting repeatedly for several days either little owls’ alarm calls (alarm treatment, simulating scared owls) or non-alarm/contact calls (non-alarm treatment, simulating non-scared owls), or just visiting the patches (control treatment, simulating no owls). In addition, in a mesocosm experiment, we recorded the distribution of migratory locusts (Locusta migratoria) in exposed and sheltered areas before and after broadcasting little owls´ alarm calls (alarm treatment), non-alarm/contact calls (non-alarm treatment) or vocalizations of a woodpigeon (Columba palumbus) as a granivorous, non-predator bird for grasshoppers (control treatment).
The abundance of grasshoppers in the field experiment were sampled in all patches by counting all detected individuals, either inactive or during their flights/jumps, while walking at constant speed (about 2 km per hour) along longitudinal transects 50 m long and with a 5-m band. The number of grasshoppers was used as the response variable to the call treatment because it is a proxy of insect abundance as prey of little owls.
In the mesocosm experiment, locusts behavior was recorded with video cameras and we counted the proportion of individuals in exposed areas at the end of pre-treatment and treatment conditions (day 1st and 2nd of the trials) and calculated the difference as a measure of preference to be exposed versus hidden in response to the call treatments.Alarm calls produced by basal prey have well-known informative value. In multipredator communities, mesopredators, when faced with top predators, may emit alarm calls that could inform basal prey about their lowered predation risk. To test this unexplored possibility, we conducted one field and one mesocosm experiment in which we simulated alarm and non-alarm calls from little owls (Athene noctua) as mesopredators and measured their effects on grasshoppers as prey of little owls but not of top predators. In the field experiment, we found that grasshopper species were significantly more abundant in patches where we simulated either the presence of scared little owls (alarm treatment) or no owls (control treatment) compared to patches where the presence of non-scared little owls (non-alarm treatment) was simulated. In the mesocosm experiment, locusts’ (Locusta migratoria) moved significantly more to exposed areas when we simulated the presence of scared little owls (alarm treatment) or of a granivorous bird (control treatment), while they moved to sheltered areas when we simulated the presence of non-scared owls (non-alarm treatment). These results show that prey could cue on predators’ calls to assess their predation risk and make decisions, revealing unprecedented potential ecological consequences of alarm calls in invertebrate communities.Ministerio de Ciencia, Innovación y Universidades, Award: CGL2014-56769-P. Spanish Ministry of Economy and Competitiveness, Award: CGL2017-83503-P. Government of Extremadura, Award: TA13002. Ministerio de Ciencia, Innovación y Universidades, Award: FJCI-2015-26257, Juan de la Cierva-Formación Fellowship.Peer reviewe
Redness associates with inter-individual differencesin behaviour and hormone profiles in male scops owls (Otus Scops) [dataset]
No full textTodos los años, a partir de la última semana de abril, se visitaron las cajas nido una vez por semana hasta que se detectó la puesta de huevos. Tras de la eclosión de los huevos, se visitaron los nidos semanalmente para registrar los parámetros reproductivos.
La captura de adultos para este estudio se realizó a mano, mientras dormía en el nido en el caso de las hembras y, en el caso de los machos, con trampas para nidos cuando llevan alimento para los pollos. Todos los individuos se marcaron con anillas metálicas y fueron sexados según la placa de incubación (solo presente en hembras). Además, tras la captura, se fotografió a todos los adultos para la asignación de color, se extrajeron muestras de sangre y se recogieron plumas para evaluar el perfil de corticosterona y se midió la tasa de respiraciones por minuto.
Además se midió la territorialidad de los machos como el tiempo que tardaron en responder al canto de otro macho en su territorio, así como la duración de esta respuesta. Para ello se emitieron cantos de machos adultos en el entorno del nido.
En el caso de las hembras, se grabó su comportamiento de respuesta frente al investigador al visitarlas en el nido.
Adicionalmente, se realizaron grabaciones internas en todos los nidos durante el periodo nidícola de los pollos, de las que se extrajeron datos sobre el tiempo de latencia en retornar al nido de ambos progenitores y las tasas de cebas aportadas al nido.This work was founded by Spanish Ministry of Economy and Competitiveness by the projects CGL2008-00718, CGL2011-27561, CGL2014-56769-P and CGL2017-83503-P. ACM was supported by the Spanish Ministry of Economy and Competitiveness (BES-2015-074948). DP was supported by the government of Extremadura (TA13002).Parental care data; Behavioural traits and corticosterone levels dataPeer reviewe
Scops owls' datasets to study the consequences of assortment based on coloration and body size on fledging survival, weight and immunity
No full text[Description of methods used for collection/generation of data] Every year, we visited nest boxes where scops owls breed once a week until egg-laying was detected.
Then, just before the estimated hatching date we visited them to capture and ring the incubating female by hand. After hatching, nests were monitored weekly to record
brood size and the number of fledglings and to make owlet measurements. Males were captured with nest-traps at night during the chick-rearing period while delivering food to the nests.
At capture, we took individual measurements and ringed birds.
In addition, in the first third of the nesting period, parental feeding behavior was filmed at nests after dawn with infrared cameras located inside nest boxes. From these recordings we
calculated parental feeding rate and determined the total richness of prey delivered to the owlets.The persistence of color polymorphism in nature may be driven by disassortative mating based on color. In vertebrates, body size sometimes correlates with coloration, complicating mating patterns, as the selective pressures favoring mixed-color pairs might be counterbalanced by those influencing body size. This complexity is heightened in species with reversed sexual size dimorphism, such as owls, where males are smaller than females, and average dissimilarity in mate size may reflect sexual size dimorphism rather than an active disassortative mating pattern. Here we investigate the fitness consequences of mating by color and body size using a long-term dataset from the color polymorphic Eurasian Scops owl (Otus scops), a bird species with reversed sexual size dimorphism. Results reveal that size-disassortative mating enhances reproductive success, as highly size-dimorphic pairs have higher probability of fledging owlets, which may favor reversed sexual size dimorphism. In addition, larger pairs produce heavier owlets with higher immunocompetence, aligning with the conventional size-based mating hypothesis. Although body size and plumage coloration were correlated within pairs, only differences in body size between pair members, not coloration, were related to higher fitness estimates. While color-based assortative mating had no direct impact on any of the fitness proxies studied, greyer pairs exhibited higher feeding rates to offspring than browner pairs. These results underscore the importance of simultaneously considering traits that may covary with color and shape mating patterns to understand the persistence of color polymorphisms in nature.The study was funded by the Spanish Ministries of Education and Science/FEDER
and of Economy, Industry and Competitiveness, respectively, through the projects CGL2014-56769-P and CGL2017-83503-P.File List: A. Individual data.-- B. Data per nest.-- C. Data per fledging.-- D. Codes for statistical analyses in SAS.Peer reviewe
Typical Males and Unconventional Females: Songs and Singing Behaviors of a Tropical, Duetting Oriole in the Breeding and Non-Breeding Season
No full textRecent research emphasizes that female song is evolutionarily important, yet there are still few species for which we have quantified the similarities and differences between male and female song. Comparing song rates and the structure of female and male song is an important first step to forming hypotheses about functional and evolutionary differences that may exist between females and males, especially in year-round territorial species that may use their songs for breeding and non-breeding activities. We compared female and male singing rates and song structure in a tropical New World oriole, the Venezuelan troupial (Icterus icterus) during both the breeding and non-breeding season and between the dawn and day. Males sang solos at particularly high rates during the breeding season before dawn. Females, however, sang at consistent rates year-round, primarily during the day. Females answered 75% of male day songs, producing duets, whereas males answered only 42% of female songs. Duets were common year-round, but occurred more often during the non-breeding season. Structurally, female songs were higher pitched and shorter than male songs. We detected no sex differences in the number or order of syllables, however, interestingly, answers were shorter than duet initiations and solos, and, during the breeding season, songs that initiated duets were characterized by higher syllable diversity than were answers or solos. The fact that males sing more during the breeding season supports the classical hypothesis that male song is a sexually selected trait. However, our findings that females sing solos and answer the majority of male songs to create duets year-round suggests that female song may have evolved to serve multiple functions not exclusively tied to breeding.https://www.frontiersin.org/articles/10.3389/fevo.2016.00014/ful
Brown and grey morphs differ in their nocturnality in the polymorphic scops owl (Otus scops)
No full textDetectability of morphs in different light environments is one of the mechanisms favoring the persistence of color polymorphism via disruptive selection. This mechanism predicts that different morphs should be more active and successful when light conditions make them more cryptic. In nocturnal birds, no study has analyzed yet whether morphs show a different degree of nocturnality, showing different circadian activity rhythms in relation to night and day light. We analyze activity patterns and hunting efficiency of color morphs in relation to day/night light in the nocturnal polymorphic scops owl (Otus scops). Forty-four percent of owl activity took place in the first hours after sunrise and before sunset. Also, we found that nocturnal activity decreased from grey to brown females and that grey males fed their chicks more than brown ones at night. Visual modeling revealed that grey individuals would be more conspicuous to their prey than brownish ones during the day. These findings suggest that part of the activity of nocturnal scops owls may occur during the day and that grey individuals would be better adapted to forage during night-light than brownish ones. However, brown morphs seemed not to be better adapted to forage at day, suggesting that other mechanisms than visual detection by predators or prey contribute to the persistence of color polymorphism in the species.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The study was funded by the Spanish Ministry of Economy, Industry and Competitiveness through the project CGL2017-83503-P.Peer reviewe
Melanism influences the use of social information in a polymorphic owl. Parental care [dataset]
No full textSocial information use has well-known fitness benefits. However, causes underlying the apparent inter-individual variability in the propensity to use social information are poorly studied. Melanins are pigments responsible for most of intra-specific color variation in vertebrates and their variation is often associated with changes in behaviour. Here, we explored whether melanism is related to individual propensity to use social information in the color polymorphic scops owl Otus scops. We manipulated social information on predation risk at nests by broadcasting calls of the sympatric little owl Athene noctua and found that owlets of brownish females exposed to alarm calls had lower levels of natural antibodies than those of greyish females. In parallel, we found changes in parental behaviour contingent on coloration because when exposed to the risky treatment brownish females returned earlier to nests than greyish females and owlets raised by brownish females were fed with smaller prey than those raised by greyish ones. These results provide support for a previous ignored role of melanins on the propensity to use social information, which may help to explain the maintenance of melanin-based color polymorphisms wherever social environments are variable.The study was funded by the Spanish Ministries of Education and Science/FEDER and of Economy and Competitiveness, respectively, through the projects CGL2011-27561/BOS, CGL2014-56769-P and CGL2017-83503-P and by the Government of Extremadura through the contract TA13002 to D.P.Nest_ID Nest identification Treatment Experimental treatment applied to each nest Year Year of study Laying date Laying date of the first egg within each nest Pre-treatment recording time Recording time before the application of the treatment to calculate provisioning rate During-treatment recording time Recording time during the application of the treatment to calculate provisioning rate Pre-treatment male latency Time elapsed from the onset of filming before treatment until the male returned to its normal activities During-treatment male latency Time elapsed from the onset of filming during treatment until the male returned to its normal activities Change in male latency Difference in male latency between during- and pre-treatment periods Pre-treatment female latency Time elapsed from the onset of filming before treatment until the female returned to its normal activities During-treatment female latency Time elapsed from the onset of filming during treatment until the female returned to its normal activities Change in female latency Difference in female latency between during- and pre-treatment periods Pre-treatment female provisioning rate Female provisioning rate during the pre-treatment period During-treatment female provisioning rate Female provisioning rate during the treatment Change in female provisioning rate Difference in female provisioning rate between during- and pre-treatment periods Pre-treatment male provisioning rate Male provisioning rate during the pre-treatment period During-treatment male provisioning rate Male provisioning rate during the treatment Change in male provisioning rate Difference in male provisioning rate between during- and pre-treatment periods Pre-treatment prey size Size of the provisioned prey (separated by commas) during the pre-treatment period Pre-treatment mean prey size Mean size of all the provisioned prey during the pre-treatment period During-treatment prey size Size of the provisioned prey (separated by commas) during treatment During-treatment mean prey size Mean size of all the provisioned prey during the treatment Change in prey size Difference in mean prey size between during- and pre-treatment periods Female_ID Female identification Female_color Female color as brownish (1) versus greyish (0) Male_ID Male identification Male_color Male color as brownish (1) versus greyish (0)Peer reviewe
Melanism influences the use of social information in a polymorphic owl
No full textSocial information use has well-known fitness benefits. However, causes underlying the apparent inter-individual variability in the propensity to use social information are poorly studied. Melanins are pigments responsible for most of intra-specific color variation in vertebrates and their variation is often associated with changes in behaviour. Here, we explored whether melanism is related to individual propensity to use social information in the color polymorphic scops owl Otus scops. We manipulated social information on predation risk at nests by broadcasting calls of the sympatric little owl Athene noctua and found that owlets of brownish females exposed to alarm calls had lower levels of natural antibodies than those of greyish females. In parallel, we found changes in parental behaviour contingent on coloration because when exposed to the risky treatment brownish females returned earlier to nests than greyish females and owlets raised by brownish females were fed with smaller prey than those raised by greyish ones. These results provide support for a previous ignored role of melanins on the propensity to use social information, which may help to explain the maintenance of melaninbased color polymorphisms wherever social environments are variableThe study was funded by the Spanish Ministries of Education and Science/FEDER and of Economy and Competitiveness, respectively, through the projects CGL2011-27561/BOS, CGL2014-56769-P and CGL2017-83503-P and by the Government of Extremadura through the contract TA13002 to D.P.Peer reviewe
The evolution of iris colour in relation to nocturnality in owls
No full textBirds, due to their multiple colourful displays, constitute a classic paradigm for the study of colour evolution. Although avian eyes are remarkably coloured, the functional basis behind inter-specific variability in iris colouration remains poorly understood. Owls are an ideal system to shed light on the role of ecology in promoting iris colour evolution as they show inter-specific variation in iris colour and in niche specialization with some species being strictly nocturnal and others active during the day. Owls perching for hunting at night might be unnoticed by both predators and their prey if they had dark irises, which would predict that dark irises were more likely to evolve in strictly nocturnal species than in diurnal ones. Using phylogenetic comparative models, we tested the camouflage hypothesis for eye colour. The proportion of dark-eyed owl species is higher among strictly nocturnal owls than among diurnal ones. Ancestral state reconstruction revealed that the owl ancestor of the family Strigidae was more likely bright-irided whereas the ancestor of the family Tytonidae was more likely dark-irided. Our results show robust support for the coevolution of iris coloration and nocturnality in the owls, and suggest that shifting to a nocturnal niche would be a prerequisite leading to the evolution of dark eyes in owls. The specific evolutionary pathway by which iris coloration and activity rhythm coevolve, however, remains to be investigated further as we have found only partial support for the idea that dark irises in birds might be an adaptive feature evolved due to the selective advantage of concealment from undesired visual receptors.Peer reviewe
Data from: The evolution of iris colour in relation to nocturnality in owls
No full textdata for dryads
Raw data used for comparative analyses on eye colour in owlsBirds, due to their multiple colourful displays, constitute a classic paradigm for the study of colour evolution. Although avian eyes are remarkably coloured, the functional basis behind inter‐specific variability in iris colouration remains poorly understood. Owls are an ideal system to shed light on the role of ecology in promoting iris colour evolution as they show inter‐specific variation in iris colour and in niche specialization with some species being strictly nocturnal and others active during the day. Owls perching for hunting at night might be unnoticed by both predators and their prey if they had dark irises, which would predict that dark irises were more likely to evolve in strictly nocturnal species than in diurnal ones. Using phylogenetic comparative models, we tested the camouflage hypothesis for eye colour. Ancestral state reconstruction revealed that the owl ancestor of the family Strigidae was more likely bright‐irided whereas the ancestor of the family Tytonidae was more likely dark‐irided. We found that iris colour and activity rhythm have more likely evolved in concert than independently, and a non‐significant trend of dark eyes to evolve more easily in owl species presenting strictly nocturnal habits than in diurnal species. The transition from diurnality to nocturnality was a previous requisite for the evolution of dark irises in owls. Taken together our results are only partly consistent with the camouflage hypothesis suggesting that dark irises in owls have primarily evolved to enhance concealment in nocturnal conditions.Peer reviewe
Informational Mismatches: A Neglected Threat of Climate Change to Interspecific Interactions
No full textInterspecific interactions are deeply affected by the current scenario of climate change. This is because interactions are sensitive to many traits of interacting species as phenology, distribution, behavior, and relative abundances which may be differently influenced by climate change in each species. In this scenario, positive interactions, which require temporal coordination of events of life history of interacting species, could be particularly altered due to differential effects of climate change on phenology, apart from by the effects on abundance and distribution. Hitherto, studies focusing on the effects of climate change on positive biotic interactions are scarce and mainly focused on plant-pollinator interactions. Here I propose that, by inducing informational mismatches, climate change may lead to individuals from competing species relying on heterospecific social information to making mis- or un-informed decisions. The idea is that competing species are valuable sources of social information to each other provided overlap of their activities occurs. However, whenever coordination of events fails, competing species will co-occur at the wrong moment, co-occur only in small numbers or even not co-occur at all and thus they will not be able to access useful or any social information from heterospecifics. In that scenario, interacting species would be mis- or un- informed, and, consequently, decision taking will be impaired, leading to disequilibrium in the community. Throughout the manuscript, I will develop the idea of mismatches of information and illustrate it with some case studies.The research of the author was supported by the Spanish Ministry of Education and Science/FEDER through the projects CGL2011-27561/BOS and CGL2014-56769-P. The contract of the author was supported by the Government of Extremadura by the TA13002 while writing.Peer reviewedPeer Reviewe
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