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De Marchi G.,University of Pavia | Chiozzi G.,Museo Civico di Storia Naturale | Dell'Omo G.,Ornis italica | Fasola M.,University of Pavia
Ibis | Year: 2015

We used GPS data-loggers, video-recordings and dummy eggs to assess whether foraging needs may force the low incubation attentiveness (<55%) of the Crab Plover Dromas ardeola, a crab-eating wader of the Indian Ocean that nests colonially in burrows. The tidal cycle was the major determinant of the time budget and some foraging trips were more distant from the colony than previously known (up to 26km away and lasting up to 45h). The longest trips were mostly made by off-duty parents, but on-duty parents also frequently left the nest unattended while foraging for 1-7h. However, the time spent at the colony area (47%) and the time spent roosting on the foraging grounds (16%) would have allowed almost continuous incubation, as in other species with shared incubation. Therefore, the low incubation attentiveness is not explained by the need for long foraging trips but is largely dependent on a high intermittent rhythm of incubation with many short recesses (5.8±2.6recesses/h) that were not spent foraging but just outside the burrow or thermoregulating at the seashore. As a result, the eggs were warmed on average only 1.7°C above burrow temperature, slightly more during high tide periods and when burrow temperature was lower between 20:00 and 10:00h, only partly counteracting the temperature fluctuations of the incubation chamber. These results suggest that low incubation attentiveness is due to the favourable thermal conditions provided by safe nesting burrows and by the hot tropical breeding season, a combination that allows simultaneous foraging by parents and the exploitation of distant foraging grounds. Why Crab Plovers engage in many short recesses from incubation still remains to be clarified but the need to thermoregulate at the seashore and to watch for predators may play a role. © 2014 British Ornithologists' Union.


Casagrande S.,University of Groningen | Casagrande S.,University of Parma | Costantini D.,University of Glasgow | Dell'Omo G.,Ornis italica | And 2 more authors.
Behavioral Ecology and Sociobiology | Year: 2012

Despite extensive research, the potential costs that keep secondary sexual traits honest and evolutionary stable remain somewhat elusive. Many carotenoid-based signals are regulated by testosterone (T), which has been suggested to impose a cost to the signaller by suppression of the immune system or an increase in oxidative stress. Results are, however, inconsistent, which may be due to the fact that T can be metabolised to both 5α-dihydrotestosterone (DHT, a potent androgen) and oestradiol (E2, a potent oestrogen). To evaluate for the first time the independent effect of these testosterone metabolites on oxidative status, circulating carotenoids and a carotenoid-dependent sexual signal, we administered DHT and E2 to captive non-breeding adult kestrels Falco tinnunculus of both sexes. E2 increased oxidative damage and downregulated the antioxidant barrier without affecting colouration or circulating carotenoids. In contrast, DHT did not affect oxidative status, but increased skin redness, again without affecting circulating carotenoids. No sex-specific effects were found. These results suggest that the pro-oxidant activity of T could be induced indirectly by its metabolite, E2, whereas the other metabolite, DHT, stimulates signal expression. Finally, the study shows that changes in oxidative damage or antioxidant status of plasma were not correlated with either skin redness or circulating carotenoids. © 2012 Springer-Verlag.


Casagrande S.,University of Groningen | Casagrande S.,University of Parma | Dell'Omo G.,Ornis italica | Costantini D.,University of Glasgow | And 2 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2011

Carotenoid-based skin colorations vary seasonally in many bird species and are thought to be honest sexually selected signals. In order to provide more insight in the potential signal function and underlying mechanisms of such colorations we here quantified patterns of variation of leg coloration in adult male and female Eurasian kestrels (Falco tinnunculus tinnunculus) over the breeding season, and evaluated the relationship between coloration and levels of carotenoids, androgens and estrogens, oxidative damage and plasma non-enzymatic antioxidant capacity. We studied both reproducing wild and non-reproducing captive birds to test for the effect of diet and breeding effort. Males were more colored than females only during mating, and independently of diet, suggesting that leg-color is a sexually selected trait. Seasonal variation in leg color was associated with circulating carotenoids, but concentrations of these molecules were not related to antioxidant capacity, body condition or oxidative damage. These results indicate that carotenoid-based colorations may not be an honest signal of health status in this species. Production of carotenoid rich eggs coincided with low levels of circulating carotenoids in females, indicating that carotenoids might be a limited resource for laying female kestrels. Finally, young rearing males had higher levels of oxidative damage than females, and wild birds of both sexes had higher levels of these parameters than captive birds. These results may indicate that parental effort and physical activity are costly, independently from hormonal status. Since androgens did not explain carotenoid variation we suggest that multiple interacting factors can regulate carotenoid levels along the season. © 2011 Elsevier Inc.


Lesku J.A.,Max Planck Institute for Ornithology (Seewiesen) | Meyer L.C.R.,University of Witwatersrand | Fuller A.,University of Witwatersrand | Maloney S.K.,University of Witwatersrand | And 4 more authors.
PLoS ONE | Year: 2011

Mammals and birds engage in two distinct states of sleep, slow wave sleep (SWS) and rapid eye movement (REM) sleep. SWS is characterized by slow, high amplitude brain waves, while REM sleep is characterized by fast, low amplitude waves, known as activation, occurring with rapid eye movements and reduced muscle tone. However, monotremes (platypuses and echidnas), the most basal (or 'ancient') group of living mammals, show only a single sleep state that combines elements of SWS and REM sleep, suggesting that these states became temporally segregated in the common ancestor to marsupial and eutherian mammals. Whether sleep in basal birds resembles that of monotremes or other mammals and birds is unknown. Here, we provide the first description of brain activity during sleep in ostriches (Struthio camelus), a member of the most basal group of living birds. We found that the brain activity of sleeping ostriches is unique. Episodes of REM sleep were delineated by rapid eye movements, reduced muscle tone, and head movements, similar to those observed in other birds and mammals engaged in REM sleep; however, during REM sleep in ostriches, forebrain activity would flip between REM sleep-like activation and SWS-like slow waves, the latter reminiscent of sleep in the platypus. Moreover, the amount of REM sleep in ostriches is greater than in any other bird, just as in platypuses, which have more REM sleep than other mammals. These findings reveal a recurring sequence of steps in the evolution of sleep in which SWS and REM sleep arose from a single heterogeneous state that became temporally segregated into two distinct states. This common trajectory suggests that forebrain activation during REM sleep is an evolutionarily new feature, presumably involved in performing new sleep functions not found in more basal animals. © 2011 Lesku et al.


Muller M.S.,Nagoya University | Massa B.,University of Palermo | Phillips R.A.,Natural Environment Research Council | Dell'omo G.,Ornis italica
Current Zoology | Year: 2014

Recently-developed capabilities for tracking the movements of individual birds over the course of a year or longer has provided increasing evidence for consistent individual differences in migration schedules and destinations. This raises questions about the relative importance of individual consistency versus flexibility in the evolution of migration strategies, and has implications for the ability of populations to respond to climatic change. Using geolocators, we tracked the migrations of Scopoli’s shearwaters Calonectris diomedea breeding in Linosa (Italy) across three years, and analysed timing and spatial aspects of their movements. Birds showed remarkable variation in their main wintering destination along the western coast of Africa. We found significant individual consistency in the total distance traveled, time spent in transit, and time that individuals spent in the wintering areas. We found extensive sex differences in scheduling, duration, distances and destinations of migratory journeys. We also found sex differences in the degree of individual consistency in aspects of migration behaviour. Despite strong evidence for individual consistency, which indicates that migration journeys from the same bird tended to be more similar than those of different birds, there remained substantial intra-individual variation between years. Indeed, we also found clear annual differences in departure dates, return dates, wintering period, the total distance traveled and return routes from wintering grounds back to the colony. These findings show that this population flexibly shifts migration schedules as well as routes between years in response to direct or indirect effects of heterogeneity in the environment, while maintaining consistent individual migration strategies. © 2014 Current Zoology.


Muller M.S.,Nagoya University | Massa B.,University of Palermo | Phillips R.A.,Natural Environment Research Council | Dell'Omo G.,Ornis italica
Animal Behaviour | Year: 2015

Long-term pair bonds occur in diverse animal taxa, but they are most common in birds, and can last from a few years to a lifetime. In many of these species, after the reproductive season, birds migrate to distant nonbreeding grounds where they remain for several months, and until recently, little was known about whether partners maintain contact during migration. This gap in knowledge was primarily due to past methodological difficulties in tracking long-term, large-scale movements of individuals. However, the development of new animal-borne geolocation devices has enabled researchers to track movements of individuals for a year or more. We tracked the annual migrations of both members of breeding pairs of Scopoli's shearwaters, Calonectris diomedea, breeding on Linosa Island (Italy) and found that although they did not migrate together, they did spend a similar number of days travelling to and from similar terminal nonbreeding areas. Although migration destinations were alike, they were not identical. That partners did not appear to travel or spend time together in the nonbreeding season suggests that similarities were not due to behavioural coordination. We performed additional analyses to uncover alternative, potential proximate mechanisms. First, we found that body mass of breeding adults during the chick-rearing period correlated positively with the decision to migrate further south, so conceivably pair members may migrate to similar areas because of shared reproductive costs; however, partners were not of similar body mass. Distances between nonbreeding areas for individuals that nested closer together were smaller than for individuals that nested far apart. As neighbours tend to be more closely related due to high natal philopatry, this suggests that similarities within pairs in migration behaviour may reflect the influence of shared genes on migration strategy. © 2015 The Association for the Study of Animal Behaviour.


Zavalaga C.B.,University of North Carolina at Wilmington | Zavalaga C.B.,Nagoya University | Halls J.N.,University of North Carolina at Wilmington | Mori G.P.,Calle Eduardo del Castillo 2543 Lima | And 2 more authors.
Marine Ecology Progress Series | Year: 2010

GPS loggers and time-depth recorders were used to characterize the foraging behavior of the sexually dimorphic Peruvian booby Sula variegata on 2 islands in northern Peru. We evaluated whether (1) its foraging behavior differed from tropical boobies and temperate gannets (the Peruvian boobies feed in areas of enhanced productivity and high fish density), and (2) females and males exploited different foraging habitats as a consequence of size dimorphism. Birds foraged only during daylight hours, 1 to 3 times a day, in trips of short duration (median = 1.8 h). Overall, 92% of the total foraging time was spent flying. They fed exclusively on anchovetas Engraulis ringens, which were captured in shallow dives (median = 2.5 m, max = 8.8 m) with a dive median rate of 11 dives h- (max = 37 dives h-1). The median foraging range was 25 km (max = 68 km), whereas the median total distance traveled was 69 km (max = 179 km). Foraging site fidelity was high, and the orientation of foraging flights in any given day was similar among birds that departed at the same time. There were no sex-specific differences in 13 of 15 foraging variables; however, females dived slightly deeper and spent a larger proportion of time sitting on the water. We speculate that (1) the foraging behavior of Peruvian boobies contrasts with that of their tropical and temperate relatives as a result of the proximity and predictability of food sources, elevated energetic demands of the brood (up to 4 chicks) and high prey encounter rate in the Peruvian upwelling system, and (2) the lack of spatial segregation between sexes may be related to the attraction of birds to feeding aggregations that are formed in the vicinity of the colonies. Once the foraging patches are localized, females dive deeper because of passive mechanisms associated with a heavier mass. © Inter-Research 2010.


Costantini D.,University of Antwerp | Costantini D.,University of Glasgow | Dell'Omo G.,Ornis italica
Conservation Physiology | Year: 2015

A major challenge in conservation physiology is to find out biomarkers that reliably reflect individual variation in wear and tear. Recent work has suggested that biomarkers of oxidative stress may provide an additional tool to assess the health state of individuals and to predict fitness perspectives. In this study, we assessed whether three biomarkers of plasma oxidative status predicted the following factors: (i) the resight probability as breeder in the next seasons; and (ii) the cumulative reproductive output over multiple years in Scopoli's shearwaters (Calonectris diomedea) using a 7 year individual-based data set. Our results show that shearwaters having higher levels of a marker of oxidative damage (reactive oxygen metabolites) in 2008 had a lower resight probability in the next years and a lower number of chicks raised from 2008 to 2014. In contrast, two biomarkers of antioxidant defences (non-enzymatic antioxidant capacity of plasma and thiols) did not have any predictive value. Increased concentrations of plasma reactive oxygen metabolites, together with the significant individual repeatability over time in this metric of oxidative stress found in numerous studies, suggest that this metric might serve as a blood-derived biomarker for health and fitness perspectives in birds and, possibly, also in other taxa. © The Author 2015.


Franco A.,Instituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana | Hendriksen R.S.,Technical University of Denmark | Lorenzetti S.,Instituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana | Onorati R.,Instituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana | And 4 more authors.
PLoS ONE | Year: 2011

The aim of the study was to elucidate the association between the zoonotic pathogen Salmonella and a population of land iguana, Colonophus subcristatus, endemic to Galápagos Islands in Ecuador. We assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population. Additionally, we investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) on XbaI-digested DNA and determined the antimicrobial susceptibility to a panel of antimicrobials. The study was carried out by sampling cloacal swabs from animals (n = 63) in their natural environment on in the island of Santa Cruz. A high prevalence (62/63, 98.4%) was observed with heterogeneity of Salmonella subspecies and serovars, all known to be associated with reptiles and with reptile-associated salomonellosis in humans. Serotyping revealed 14 different serovars among four Salmonella enterica subspecies: S. enterica subsp. enterica (n = 48), S. enterica subsp. salamae (n = 2), S. enterica subsp. diarizonae (n = 1), and S. enterica subsp. houtenae (n = 7). Four serovars were predominant: S. Poona (n = 18), S. Pomona (n = 10), S. Abaetetuba (n = 8), and S.Newport (n = 5). The S. Poona isolates revealed nine unique XbaI PFGE patterns, with 15 isolates showing a similarity of 70%. Nine S. Pomona isolates had a similarity of 84%. One main cluster with seven (88%) indistinguishable isolates of S. Abaetetuba was observed. All the Salmonella isolates were pan-susceptible to antimicrobials representative of the most relevant therapeutic classes. The high prevalence and absence of clinical signs suggest a natural interaction of the different Salmonella serovars with the host species. The interaction may have been established before any possible exposure of the iguanas and the biocenosis to direct or indirect environmental factors influenced by the use of antimicrobials in agriculture, in human medicine or in veterinary medicine. © 2011 Franco et al.


Costantini D.,University of Glasgow | Carello L.,Ornis italica | Dell'Omo G.,Ornis italica
Journal of Zoology | Year: 2010

Changes in local weather conditions may affect reproduction in birds. In this study, we evaluated how changes in both local weather and winter North Atlantic Oscillation (the NAO, an index of non-local climatic conditions) could explain variation in selected reproductive traits (laying date, clutch size, hatching and fledging success) in Mediterranean kestrels Falco tinnunculus over 10 years. Kestrels (1) delayed the laying date in rainier springs; (2) laid smaller clutches after warmer and rainier winters, independently from the laying date; (3) had higher hatching success after warmer and dry winters and in warmer and rainier springs; (4) had higher fledging success in warmer and rainier springs. Thus, changes in the weather and the winter NAO index affected reproductive decisions and reproductive success. Predicting the long-term effects of global warming on the viability of Mediterranean populations of kestrels and other birds of prey is difficult. Whether the reproduction of birds of prey will be positively or negatively affected by global warming will depend on the relative importance of changes in temperature and rainfall. © 2009 The Authors. Journal compilation. © 2009 The Zoological Society of London.

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