Daniela Campobello

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

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 after 1990, when spring temperatures in many areas had started to increase, we found that relative parasitism of residents and short-distance migrants decreased. This change in host use was positively related to increase in spring temperature, consistent with the prediction that relative change in phenology for different migrant classes drives host-use patterns. These findings are consistent with the hypothesis that climate change affects the relative abundance of different host races of the common cuckoo.

Effects of nautical traffic and noise on foraging patterns of Mediterranean damselfish (Chromis chromis).

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 and school density were analysed. C. chromis specimens were also collected from 2007 to 2008 to evaluate their physiological state using the Body Condition Index as a proxy of feeding efficiency. The MPA was more exploited by nautical tourism during holidays than on weekdays, particularly in the middle of the day. Greater traffic volume corresponded with lower feeding frequencies. The escape reaction was longer in duration (>1 min) when boat passed nearby, while moored boats did not induce an escape response. We found no differences in density between schools in the A- and B-zones and worse body conditions among those individuals inhabiting the B-zone in one area only. Overall, our findings revealed a significant modification of the daily foraging habits of C. chromis due to boat noise, which was slightly buffered by no-take zones established within the MPA.

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

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 predator rather than as a parasite. Higher predation than parasitism frequencies probably explain the more prompt change in defence when cowbirds were encountered as egg predators. Annual fluctuations in frequencies of both parasitism and predation suggest that defence acquired via observing conspecifics may contain outdated information and probably explains the warblers’ reliance on individually learned over socially learned defence.

Effects of nest and colony features on Lesser Kestrel ( Falco naumanni ) reproductive success

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 Kestrel, when controlled for the annual effect, demonstrated a significant effect for some nest and colony features. Most of them, like the height from the ground, nest depth, reused nests and the presence of Jackdaws, are likely to be related to the predation pressure faced by Lesser Kestrel nests. Westward and southward nests had a better egg survival with respect to those on the cold sides and in the interior of buildings. The location of colony on the agricultural plain and human disturbance ranked as the most important variables, with core location of a colony and high disturbance levels negatively affecting the reproductive success of the Lesser Kestrel in the Gela Plain, so urging a more environmentally aware land use management of this Important Bird Area.

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

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, and Reed Warbler. The highest number of parasitized species was in anthropic areas (15 host species), whereas wetlands supported the highest number of parasitized nests (471). Conclusion Cuckoos select a different suite of hosts in Italy from those in continental Europe, but this was not always explained on the basis of different geographical distribution. Results support the ‘host preference’ hypothesis. We suggest further analyses to avoid over‐ or underestimates of parasitism on each host species when parasite preferences are examined.

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

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 developed a neighbour index that incorporated both the number and proximity of neighbours into a single continuous measure. The change in feeding rate of individual birds after introducing the honey bee hive was positively correlated with our neighbour index, suggesting that information transfer among colony members, at least in part, selects for colonial breeding in European bee-eaters.

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

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 reclassified a map with respect to habitat suitability classes according to the resulting distribution model. Methods. Ecological Niche Factor Analysis was used with GIS cartography customised with habitat and anthropogenic variables recorded during field surveys carried out in four study plots (~500ha) and at different spatial scales. Keyresults.Thestonecurlewselectedareaswithlowvegetationcover,suchas fieldsfollowingartichokeharvestingand tillage,closetoruralbuildingsandunpavedroads.Incontrast,thestonecurlewavoidedareaswithhighvegetationcoverand areas highlydisturbed byhuman-induced fires.Theoccurrenceof naturalvegetation wasneitherpreferred noravoided.The mostrobustmodelwasbasedonalarge-scaleanalysis(200mfromthebirdlocationpoints),accordingtowhichtheoptimal area for stone curlew distribution during its breeding season was restricted to 1% of the entire study area. Conclusions.Twouncorrelatedfactors,‘marginality’and‘tolerance’,describedthestonecurlew’snicheinthearea.The first index indicated selection for habitats that were marginal with respect to those available in the area, whereas the second indicatedaspecieswithamedium–wideenvironmentalniche.Inparticular,thestonecurlewoccupiedamuchmorerestricted niche(lowtolerance)inrelationtoindividualvariables.Theuseofcustomiseddatabasesatalargescaleofanalysiswasfound to more effectively reveal ecological requirements of this marginal and specialised species. Implications. Our results allowed us to indicate practical land management actions for the stone curlew, such as preventionofhuman-induced firesandincreaseofpastoralactivities.Ourresultsindicatedapotentiallypositiveroleoflittledisturbedserviceroadsalongruralbuildingsinstonecurlewdistribution,whichwarrantsfurtherresearch.Inaddition,studies are neededtoverify thepresenceof anecological trap inartichoke fields,theirpreferred habitat. As weshowedfor thestone curlew, niche analyses conducted at a large scale using customised databases could greatly improve habitat suitability models of farmland species.

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

AbstractSeveral 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 singular and interactive effects of nest distance, breeder abundance and reproductive synchrony on kestrel fitness measured as the time to survival of eggs to hatching and nestlings to fledging. Egg survival increased as reproductive stages became more synchronous with the timing of colony breeding, whereas nestling survival benefited from a higher synchrony with most nests in the entire population. Nestling survival was also positively affected by the interaction between nest distance and breeder abundance. Our results suggest that the presence of additional breeders in the colony is not sufficient per se, to trigger colonial advantages, but instead, that synchronised reproduction among multiple breeding pairs nesting in close spatial proximity is necessary to realise those benefits. Our findings provide a novel perspective for future investigations that explore the mechanisms underlying fitness variation among Lesser Kestrel colonies and group-living species in general.ZusammenfassungNesterhäufung und reproduktive Synchronie begünstigen die saisonale Fitness beim RötelfalkenFalco naumanni Verschiedene Faktoren begünstigen die Koloniebildung durch die Optimierung der Fitness der einzelnen Koloniemitglieder. Es wurde angenommen, dass für die Koloniebildung bei Vögeln die räumliche Trennung der Nester, die Anzahl der Brüter, als auch die Synchronisierung der Reprodution primäre Faktoren darstellen für eine verbesserte Koloniebehauptung und Nahrungssuche und somit auch den Erfolg der Fortpflanzung begünstigen. Ob diese Faktoren synergistisch oder antisynergistisch wirken bleibt soweit offen, da bisher noch keine integrative Analyse auf deren Effekte auf die Fitness durchgeführt wurde. In dieser Studie wurde eine groβe Population des Rötelfalken, Falco naumanni, untersucht, eine fakultativ koloniebildende Art, die in verschiedenen Koloniegröβen in einem steppenartigen Habitat lebt. Quantifiziert wurden sowohl singuläre als auch interaktive Effekte der Nestdistanz, Brüter Häufigkeit und der reproduktiven Synchronie auf die Fitness der Rötelfalken, gemessen an der Überlebensrate der Eier, der Zeit vom Schlüpfen bis zum Nestling und zum Flüggewerden. Weiterhin konnte gezeigt werden, dass die Überlebensrate der Eier mit der Synchronisierung des Nistens in der Kolonie steigt, wohingegen das Überleben der Nestlinge ansteigt mit der Synchronisierung des Nistens der gesamten Population. Das Überleben der Nestlinge war auβerdem positive beeinflusst von der Interaktion zwischen dem Abstand der Nester und der Abundanz der Brüter. Unsere Ergebnisse lassen vermuten, dass die Anwesenheit zusätzlicher Brüter in der Kolonie allein nicht ausreicht, den Erfolg der Kolonie positiv zu beeinflussen, sondern dass stattdessen die synchronisierte Reproduktion vieler Brutpaare die in enger Nachbarschaft nisten, dafür von Nöten ist. Unsere Ergebnisse weisen neue Perspektiven für zukünftige Forschungsansätze auf, die sich mit den Mechanismen der Fitnessvariationen in Kolonien des Rötelfalken und anderen in Gruppen lebenden Arten befassen.

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

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 (Falco naumanni) and jackdaw (Corvus monedula), nesting in either single‐ or mixed‐species colonies. By recording reproductive outcome as a measure of relative fitness, our results reveal an asymmetric system wherein only jackdaw breeding performance was affected by the activity phenotypes of both conspecific and heterospecific neighbors. Our model incorporating heterospecific social phenotypes is applicable to animal communities where interacting species share a common social trait, thus allowing an assessment of the selection pressure imposed by interspecific interactions in nature. Finally, we discuss the potential role of ecological limitations accounting for random or preferential assortments among interspecific social phenotypes, and the implications of such processes to community evolution.

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

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 discovered five roosts in Sicily with numbers of Lesser Kestrels varying annually (mean ± sd: 2112 ± 387; min–max: 1797–2544). Counts at the main roost were not biased by meteorological conditions and showed an August peak followed by persistent decline through October. Less urbanized and heterogeneous agricultural areas with large cereal fields were the most significant habitats preferred during summer. Within this landscape, Lesser Kestrels prey on seasonally high concentrations of the small cricket Grylloderes brunneri. Conclusion Arable land not fragmented by agricultural intensification supports habitat rich with Orthopterans and attracts a large number of Lesser Kestrels fuelling before migration. Conservation of such pre-migratory habitats is as vital as conservation of breeding areas.