Effetti del clima sul successo riproduttivo del grillaio Falco naumanni

2013

Food for flight: pre-migratory dynamics of the Lesser Kestrel Falco naumanni.

2014

Capsule The post-reproductive stage of Lesser Kestrel is crucial for migratory fuelling and survival. Aims To describe the summer pre-migratory ecology of the Lesser Kestrel in Sicily and review existing data in Southern Europe. Methods We identified the main summer roosts and then made roost counts every ten days from 2010 to 2012. We used case-sensitive modelling procedures to detect biases in counts (generalized linear mixed models), assess the annual population trends from 2005 to 2012 (TRends and Indices for Monitoring); and to model habitat preferences (generalized linear model). We sampled pellets to describe the birds’ diet during the peak month prior to migration. Results We discov…

Lesser kestrel diet and agricultural intensification in the Mediterranean: An unexpected win-win solution?

2018

Abstract Farmland bird species have suffered dramatic declines in recent decades, especially in Mediterranean areas. The intensification of agricultural practices has led to reduced invertebrate prey, which represent the bulk of the diet of many farmland birds. In this study, we investigated the spatial and temporal variation in the diet of the lesser kestrel (Falco naumanni) during the breeding season, monitored over a five-year period between 2006 and 2013 in the Gela Plain (Sicily). Our aim was to understand whether, and to what extent, farming practices affected the reproductive outputs of this predominantly insectivore bird in order to find a profitable compromise between conservation …

Trends of neighbouring populations of Lesser Kestrel reveal intraspecific differences in response to climate change

2015

Information transfer determined by association of neighbours in European bee-eater (Merops apiaster) colonies

2007

The Information Centre Hypothesis (ICH) and the Two-Strategies Hypothesis (TSH) predict that foraging success is enhanced by information exchanged among individuals within a colony or roost. Nest location within a colony may be critical in this regard, as individuals with abundant, nearby neighbours likely have greater access to information regarding a new food resource than relatively isolated breeders. To determine how the availability of neighbours influences information transfer, we quantified foraging success in a population of European bee-eaters (Merops apiaster) provided with a honey bee (Apis mellifera) hive as a new food resource. To quantify potential information transfer we deve…

Habitat- and density-dependent demography of a colonial raptor in Mediterranean agro-ecosystems

2016

Agricultural intensification is considered the major cause of decline in farmland bird populations, especially in the Mediterranean region. Food shortage increased by the interaction between agricultural intensification and density-dependent mechanisms could influence the population dynamics of colonial birds.Weused demographic data on lesser kestrels (Falco naumanni), a key species of Mediterranean pseudo-steppes, to understand the importance of land-use changes and density-dependent mechanisms in the light of its fluctuating conservation status in the Western Palearctic. Our analysis indicated an important influence of land uses (artichokes, arable and grassland fields) and colony size on…

Nest attendance of conspecifics and heterospecifics as social phenotypes affecting breeding lesser kestrels Falco naumanni

2013

Nest aggregation and reproductive synchrony promote Lesser Kestrel Falco naumanni seasonal fitness

2013

Several factors promote coloniality by enhancing the fitness of colony members. In birds, spatial proximity among nests, breeder abundance and reproductive synchrony have been proposed as primary factors responsible for enhanced colonial defence and foraging success, which, in turn, enhance reproductive success. Whether these factors function synergistically or antagonistically remains, however, an open question due to the absence of an integrated analysis of their effects on fitness. We studied a large population of the Lesser Kestrel, Falco naumanni, a facultative colonial species, breeding in colonies of different sizes in their typical pseudo-steppe habitat. We quantified both the singu…

Rapid change in host use of the common cuckoo Cuculus canorus linked to climate change

2010

Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo, Cuculus canorus , have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and af…

Anti-brood Parasite Defences: The Role of Individual and Social Learning

2017

In this chapter, we consider the ways in which learning is involved in the anti-brood parasitism defences that hosts deploy across the nesting cycle. Brood parasitism varies in space and through time, and hosts have accordingly evolved plastic defences that can be tuned to local conditions. Hosts can achieve their defence plasticity by individual and social learning, as well as by experience-independent mechanisms. While these mechanisms can profoundly affect the coevolutionary dynamics between hosts and their brood parasites, our understanding of how they feature across the host nesting cycle is far from complete. Hosts can actively defend themselves against brood parasitism via a variety …

BiodiverCity: a first investigation on bird communities in two urban green areas of Palermo, Sicily

2019

Since the 1980s, there has been a growing worldwide interest on urban bird diversity. The avifauna of Mediterranean cities has been however poorly investigated with standardized methods. Accordingly, our investigation aimed to record breeding and migrating species in two XVIII-century green areas of Palermo town: Villa Trabia (8 ha) and the Botanical Garden (10 ha). Starting from spring 2019, we carried 15 census sessions by point-counts, during the morning hours (10 points at Villa Trabia and 11 at the Botanical Garden, set with a minimum distance of 50 m) by recording, in each point, all the birds seen or heard within 10 min. Our preliminary results show that the study sites are mainly vi…

Asymmetrical interspecific communication of predatory threat in mixed-species colonies of lesser kestrels (Falco naumanni) and jackdaws (Corvus moned…

2019

Sympatric species derive benefits by attending to information conveyed by heterospecifics. Our previous finding of reduced vigilance among jackdaws and lesser kestrels residing in mixed-species colonies suggested a reliance on interspecific communication of information regarding predatory threats. To test for interspecific communication of threat, we first determined whether jackdaw and lesser kestrel call structure varied with perceived threat. In this call production phase of our study, free-living birds in mixed-species colonies were presented with models representing a potential nest predator (European magpie) or with non-threatening stimuli (wood pigeon or wooden dowel) in proximity to…

Status e biologia del Capovaccaio Neophron percnopterus in Sicilia

2003

From macro- to micro-climate? 3D Analysis of lesser kestrel Falco naumanni nest attendance

2013

Nest attendance, extended phenotype and social selection in multispecies colonies

2017

Colonial species interact not only with conspecifics but often with other species nesting in the same site. The effect of conspecific traits have been measured recently with a multilevel selection analysis, but the effect of social traits of heterospecifics on individual fitness remain unquantified. We recorded nest attendance effort of two species, lesser kestrels (Falco naumanni) and jackdaws (Corvus monedula), nesting on the Gela Plain (Sicily, Italy). Both species are secondary-cavity nesters breeding in abandoned rural buildings where they form single-species or mixed-species colonies. By correlating reproductive success as a measure of fitness to conspecific and heterospecific nest at…

Aquila di Bonelli (Hieraaetus fasciatus), Status e biologia riproduttiva in Sicilia

2000

Avian brood parasitism in a Mediterranean region. hosts and habitat preferences of Common Cuckoos Cuculus canorus

2009

Capsule Cuckoos in Italy support the ‘host preference’ hypothesis. Aims To identify the species parasitized in a Mediterranean area, in Italy; to quantify the frequency of parasitism on each host species; and to determine whether some species and/or habitat types are parasitized more than expected from a homogeneous distribution. Methods Nest records dating from 1865 were compiled from literature, nest card programmes, and personal communication with ornithologists working in the region. Comparisons of parasitism frequencies were made among and within habitats for all cuckoo hosts. Results The most frequently parasitized hosts were Great Reed Warbler, European Robin, Marsh Warbler, Redstart…

Social phenotype extended to communities: Expanded multilevel social selection analysis reveals fitness consequences of interspecific interactions

2015

In social species, fitness consequences are associated with both individual and social phenotypes. Social selection analysis has quantified the contribution of conspecific social traits to individual fitness. There has been no attempt, however, to apply a social selection approach to quantify the fitness implications of heterospecific social phenotypes. Here, we propose a novel social selection based approach integrating the role of all social interactions at the community level. We extended multilevel selection analysis by including a term accounting for the group phenotype of heterospecifics. We analyzed nest activity as a model social trait common to two species, the lesser kestrel (Falc…

Effetti del traffico nautico sul comportamento di Chromis chromis

2011

Nuovi dati sulla biologia alimentare dell’Aquila di Bonelli, Hieraaetus fasciatus, durante il periodo riproduttivo

2001

Vigilance and antipredator responses of lesser kestrels (Falco naumanni) and jackdaws (Corvus monedula) nesting in single- versus mixed-species colon…

2011

Dazzled and confused? Habituation and sensitization in free-living Yellow Warblers

2004

Predation of Egretta garzetta on Aphanius fasciatus in a natural reserve of Western Sicily

2006

Social transmission in avian brood parasitism systems

Obligate brood parasites lay all of their eggs in nests of other species, leaving the burden of parental care entirely to the hosts. As a consequence of being parasitized, hosts’ reproductive success is often reduced. This strategy has triggered a coevolutionary dynamic involving behavioural, physiological and morphological adaptations and counter-adaptations from the two players, whose conflicting functions are to successfully parasitize a nest, and prevent or reduce the negative effects of parasitism. In parasite systems studied in the New and Old worlds, warbler hosts exhibited different degrees of learning antiparasite defences from conspecifics. By quantifying strength and direction of…

Effects of Nest and Colony Features on Lesser Kestrel (Falco naumanni) Reproductive Success

2012

The Lesser Kestrel is a facultative colonial raptor mostly breeding in man-made structures. During 2009-2011 we checked the fate of 545 nests found in 18 colonies located in south-eastern Sicily. We determined the reproductive success of breeding pairs by analysing the survival time of each egg to hatching ( n = 2,495) and each nestling to fledging ( n = 1,849) with the linear hazard model of survival times. We determined whether egg and nestling survival differed between years with a Gehan–Wilcoxon test. By Cox regressions, we related the survival times with nest and colony features. Egg and nestling survival times showed a strong annual effect. The two reproductive stages of the Lesser K…

Great tit (Parus major) breeding in fire-prone oak woods: differential effects of post-fire conditions on reproductive stages

2011

Wildfires negatively affect the overall reproductive success of several woodland avian species, but there is scarce information about which stages of the nesting cycle are specifically affected. We conducted a 3-year study to identify the effects of fire on the reproductive parameters of the great tit (Parus major) and the survival of its nests at different stages of the nesting cycle. We recorded the occupancy rate, clutch and brood size, hatching, fledging and nesting success in nest boxes placed on study plots with different post-fire age. By examining the post-fire succession, we analysed the survival of eggs and nestlings under predation risks. As the forest matured after a wildfire, …

Effects of Nautical Traffic and Noise on Foraging Patterns of Mediterranean Damselfish (Chromis chromes)

2012

Chromis chromis is a key species in the Mediterranean marine coastal ecosystems where, in summer, recreational boating and its associated noise overlap. Anthropogenic noise could induce behavioural modifications in marine organisms, thereby affecting population dynamics. In the case of an important species for the ecosystem like C. chromis, this could rebound on the community structure. Here, we measured nautical traffic during the summer of 2007 in a Southern Mediterranean Marine Protected Area (MPA) and simultaneously the feeding behaviour of C. chromis was video-recorded, within both the no-take A-zone and the B-zone where recreational use is allowed. Feeding frequencies, escape reaction…

Ospiti e preferenze del Cuculo Comune Cuculus canorus in Italia

2009

Avian brood parasitism in the new and old worlds

Interactive effects of micro- and macro-habitat features on reproductive success of lesser kestrels (Falco naumanni)

2015

Parassitismo di cova: Implicazioni coevolutive e limitazioni ecologiche di una strategia alternativa, la difesa al nido

2015

Evolutionary consequences of social transmission in avian brood parasitism systems

Obligate brood parasites lay all of their eggs in nests of other species, leaving the burden of parental care entirely to the hosts. As a consequence of being parasitized, hosts’ reproductive success is often reduced. This strategy has triggered a coevolutionary dynamic involving behavioural, physiological and morphological adaptations and counter-adaptations from the two players, whose conflicting functions are to successfully parasitize a nest, and prevent or reduce the negative effects of parasitism. In parasite systems studied in the New and Old worlds, warbler hosts exhibited different degrees of learning antiparasite defences from conspecifics. By quantifying strength and direction of…

Individual learning in the refinement of nest defence responses of the Yellow Warbler (Dendroica petechia)

2006

Diurnal habitat suitability for a Mediterranean steppeland bird, identified by Ecological Niche Factor Analysis

2011

Context The negative effects of agricultural intensification and policies, use of pesticides, fertilisers and mechanised harvesting on several populations of pseudo-steppe birds have increasingly required more detailed and effective habitat suitability models. Distribution models of farmland species are prone to incur recordings of false absence data. Ecological Niche Factor Analysis (ENFA) allows identification of environmental predictors of species distribution by using presence data only. Aims We quantified the diurnal habitat preferences and niche width of one steppe species, the stone curlew (Burhinus oedicnemus), with unfavourable conservations status in a Mediterranean area and recl…

Under my wing: lesser kestrels and jackdaws derive reciprocal benefits in mixed-species colonies

2011

In mixed-species assemblages, antipredator benefits for a timid species nesting close to a more pugnacious one are often reported. Advantages for the protected species are usually manifested in terms of higher reproductive success than conspecifics nesting remote to the protector species. Whether the protector species also accrues any benefit remains untested, and the species-specific behavioral traits underlying enhanced reproductive output in mixed-species associations remain poorly documented. We studied associations between lesser kestrels (Falco naumanni) and jackdaws (Corvus monedula) nesting in rural buildings in the Gela Plain (Italy). We tested for interspecific interactions of jac…

An integrated analysis of micro- and macro-habitat features as a tool to detect weather-driven constraints: A case study with cavity nesters.

2017

The effects of climate change on animal populations may be shaped by habitat characteristics at both micro- and macro-habitat level, however, empirical studies integrating these two scales of observation are lacking. As analyses of the effects of climate change commonly rely on data from a much larger scale than the microhabitat level organisms are affected at, this mismatch risks hampering progress in developing understanding of the details of the ecological and evolutionary responses of organisms and, ultimately, effective actions to preserve their populations. Cavity nesters, often with a conservation status of concern, are an ideal model because the cavity is a microenvironment potentia…

Mechanisms of refinement of avian nest defence behaviour

2003

Neighbour dearest: Colonial lesser kestrels (Falco naumanni) benefit from nest attendance of neighbouring jackdaws (Corvus monedula)

2013

Connecting the data landscape of long-term ecological studies: the SPI-Birds data hub

2021

The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and eco-logical processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change).

Humoral responses during wound healing in Holothuria tubulosa (Gmelin, 1788)

2021

Abstract Wounds in living organisms trigger tissue-repair mechanisms. The sea cucumber (Holoturia tubulosa) is an excellent model species for achieving a better understanding of the humoral and cellular aspects involved in such healing processes. Consequently, this study assesses data on its morphometric, physiological and humoral responses 1, 2, 6, 24 and 48h after wound induction. In particular, morphometric data on the weight, width, length and coelomic-fluid volume of the species were estimated at different times during our experiments. In addition, the humoral aspects related to the enzymatic activity of esterase, alkaline phosphatase and peroxidase, as well as the cytotoxic activity o…

Do not disturb the family: roles of colony size and human disturbance in the genetic structure of lesser kestrel

2015

Dispersal and philopatry are fundamental processes influencing the genetic structure and persistence of populations, and might be affected by isolation and habitat perturbation. Habitat degradation induced by human activities could have detrimental consequences on the genetic structure of populations. Therefore, it is crucial to understand the role of human impact in promoting or disrupting the genetic structure. Here, we conducted a genetic analysis using 12 polymorphic microsatellite markers of 70 lesser kestrels Falco naumanni from 10 breeding colonies of two subpopulations in Sicily (southern Italy). Genetic differentiation between the two subpopulations was negligible, and linear dista…

Use of social over personal information enhances nest defense against avian brood parasitism

2011

Interactions with conspecifics influence the behavioral repertoire of an organism, as they apply to foraging techniques, song acquisition, habitat selection, and mate choice. Few workers have studied the role of social interactions in molding defense responses, especially the defense of the nest. We tested the effect of social interaction on nest defense of the reed warbler (Acrocephalus scirpaceus), one of the main hosts of the brood-parasitic common cuckoo (Cuculus canorus) in Europe. This parasite reduces its host’s breeding success; therefore, any response that prevents successful parasitism should be selected. Because of their high nesting density and consistent cuckoo-specific respons…

Old versus new world: adaptive significance of nest defence in two brood parasitism systems

2011

Social versus individual learning: fitness consequences of two different strategies for defence

2014

Nest defence against avian brood parasites is promoted by egg-removal events in a cowbird–host system

2011

Recent studies of birds have found that the antiparasite behaviour of host species is modified by social learning. We tested whether individual or social learning modifies the nest defence of yellow warblers, Setophaga petechia, against the parasitic brown-headed cowbird, Molothrus ater. Using field experiments, we exposed warblers to simulated events of nest parasitism and predation, or allowed them to observe conspecifics mobbing a cowbird. Intensity of nest defence by yellow warblers was greater after simulated threats at their nest than after they had observed mobbing of cowbirds by conspecifics. Warblers defended their nests more aggressively when they perceived a cowbird as an egg pre…

Un modello di distribuzione e idoneità ambientale di una specie steppica in pericolo: l’Occhione Burhinus oedicnemus

2009

Un modello di distribuzione e idoneità ambientale di una specie steppica in pericolo: dell’occhione Burhinus oedicnemus

2009

Zealous fathers and lazy mothers? Role of coloniality in biparental care of Lesser Kestrel (Falco naumanni)

2012

Social phenotype extended to communities: expanded multilevel social selection analysis reveals fitness consequences of interspecific interactions.

2014

In social species, fitness consequences are associated with both individual and social phenotypes. Social selection analysis has quantified the contribution of conspecific social traits to individual fitness. There has been no attempt, however, to apply a social selection approach to quantify the fitness implications of heterospecific social phenotypes. Here, we propose a novel social selection based approach integrating the role of all social interactions at the community level. We extended multilevel selection analysis by including a term accounting for the group phenotype of heterospecifics. We analyzed nest activity as a model social trait common to two species, the lesser kestrel (Falc…

Analysis of Prey Composition in Eurasian Reed Warblers' Acrocephalus scirpaceus Droppings at Four Breeding Sites in Italy

2022

Our aim was to investigate the among-populations diversity of prey composition in Eurasian Reed Warblers’ diets via their droppings, both to assess the ecological validity of this sampling method and to test whether the prey species most abundant in fecal samples were also the most present in the Italian study site. We collected fecal samples at four sites throughout Italy, for a total of 144 samples. Within reedbeds, the breeding habitat of the Eurasian Reed Warbler, we also collected arthropods by carrying out entomological sweepings at one of the study sites. Within the fecal samples, we identified dozens of prey species, belonging mainly to Araneae, Coleoptera, Diptera, Hymenoptera and …

Evolutionary consequencesof social information use in birds

2017

Social interactions, at intra- and inter-specific levels, have been lately the focus of new perspectives in examining the role of information use within communities. Acquiring information can change individual and social phenotypes, with important implications on community structure and its evolution. At the same time, social behaviour, and the patterns of connections among individuals arising from social interactions, can be shaped by individual phenotypes, and ultimately influence the spread of information through communities. Thus, the fingerprint of the evolutionary consequences of information use can be detected in both the mechanisms that determine responses to information at the indi…

Effects of microclimate on nest site selection and breeding success of lesser kestrel Falco naumanni in the Gela Plain (Sicily)

2013

Changes in behavioural response of Mediterranean Seabass (Dicenthratus labrax L.) under different feeding distributions

2009

Captive-induced behavioural deviations may involve many aspects of fish behaviour such as swimming activity and enhancement of individual aggressiveness. We studied seabass (Dicentrarchus labrax) behaviour as a function of manual and automatic feeding distribution modes. Under manual mode, the food is distributed over an extended area for a longer period, and its precise location is not always predictable, while with pneumatic automatic feeders, fish receive the same amount of resource, which is concentrated in the same surface area over a shorter period. We compared seabass behaviour under automatic and manual conditions collecting video image recordings before, during, and after feeding d…

Reed Warbler Hosts Do Not Fine-Tune Mobbing Defenses During the Breeding Season, Even When Cuckoos Are Rare

2021

Hosts of brood parasitic cuckoos often employ mobbing attacks to defend their nests and, when mobbing is costly, hosts are predicted to adjust their mobbing to match parasitism risk. While evidence exists for fine-tuned plasticity, it remains unclear why mobbing does not track larger seasonal changes in parasitism risk. Here we test a possible explanation from parental investment theory: parents should defend their current brood more intensively as the opportunity to replace it declines (re-nesting potential), and therefore “counteract” any apparent seasonal decline to match parasitism risk. We take advantage of mobbing experiments conducted at two sites where reed warblers (Acrocephalus sc…

Planning conservation actions by investigating nest preferences and biotic and abiotic factors within lesser kestrel (Falco naumanni) colonies

The lesser kestrel (Falco naumanni) was until recently classified as a Vulnerable species. It is a cavity nester species finding proper nest sites in natural cliff holes or, as more frequently today, cavities found within rural buildings. These are often abandoned and therefore, with no maintenance, the main structures of kestrel colonies have been collapsing across years. To counterbalance the reduced availability of nesting sites for kestrels, and because of their unfavorable conservation status, artificial nest boxes have been placed in several areas of their breeding range. On our study site, the Gela Plain in Sicily, as on other Mediterranean breeding areas, high temperatures may reach…

Intra- and inter-specific social selection of vigilance and defense phenotypes in breeding colonies of lesser kestrels and jackdaws

2012

Parassitismo di cova. Significato adattativo della difesa al nido e delle interazioni interspecifiche.

Enemy recognition of Reed Warblers (Acrocephalus scirpaceus): threats and reproductive value act independently in nest defence modulation

2010

Organisms should respond more aggressively towards species perceived as a danger to their offspring, but intensity of defence may be gauged by the value of current offspring weighed against the value of future reproductive opportunities. We tested whether defensive responses of nesting reed warblers (Acrocephalus scirpaceus) are the result of an interaction effect between the type of stimulus confronted and the value of the warbler’s nesting attempt. We quantified the ability of reed warblers to discriminate among brood parasites, nestling predators and non-threatening species at different stages of the breeding cycle. We also determined whether variables that influence the value of offspri…

Evolutionary significance of antiparasite, antipredator and learning phenotypes of avian nest defence.

2018

AbstractAvian nest defence, which is expected to serve both antiparasite and antipredator functions, may benefit or be detrimental to birds, although selective forces that potentially operate on nest defence have not been quantified as a whole. Together with fitness values, we analysed two traits of nest defence, intensity and plasticity, in two distantly related passerine species, yellow warbler (Setophaga petechia) in North America and reed warbler (Acrocephalus scirpaceus) in Europe, both favourite host species for brood parasites. Breeders that escaped parasitism were the most vocal among reed warblers, whereas there was no specific defence phenotype that predicted prevention of parasit…

Predazione di Egretta garzetta su Aphanius fasciatus nella riserva naturale orientata “Saline di Trapani e Paceco

2006

The Egiptyan Vulture's food habits in Sicily

2002

Asymmetrical interspecific communication in avian mixed species colonies

Sympatric species derive benefits by attending to information conveyed by heterospecifics. We previously reported reduced vigilance among jackdaws (Corvus monedula) and lesser kestrels (Falco numanni) residing in mixed species colonies and conducted the present study to test for interspecific communication of threat associated with European magpies (Pica pica) as nest predators. After quantifying structural differences in jackdaw and lesser kestrel calls relative to European magpie versus non-predator models, we played back calls of jackdaws and lesser kestrels representative of the different model types to test whether receivers perceive threat-related variation in either conspecific or he…

Warblers from the New vs Old World: Quantifying selection by examining behaviours in two brood parasitism systems

Modello di distribuzione e di idoneità ambientale dell'occhione, Burhinus oedicnemus

2009

Decoupled Acoustic and Visual Components in the Multimodal Signals of the Common Cuckoo (Cuculus canorus)

2021

Because of its parasitic habits, reproduction costs of the common cuckoo (Cuculus canorus) are mostly spent in pre-laying activities. Female costs are limited to searching host nests and laying eggs, whereas, males spend time in performing intense vocal displays, possibly with territorial purpose. This last aspect, together with a sexual plumage dimorphism, points to both intra- and inter-sexual selections operating within this species. One element triggering sexual selection is a differential fitness accrued by different phenotypes. Before analyzing possible sexual selection mechanisms operating in cuckoos, it is therefore necessary to verify whether there is a variability among male secon…