Research Station Petite Camargue Alsacienne

Sainte-Foy-lès-Lyon, France

Research Station Petite Camargue Alsacienne

Sainte-Foy-lès-Lyon, France
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Saggese K.,University of Basel | Saggese K.,University of Oslo | Korner-Nievergelt F.,Swiss Ornithological Institute | Korner-Nievergelt F.,Oikostat GmbH | And 3 more authors.
Animal Behaviour | Year: 2011

Supplementary feeding of wild birds during winter is one of the most popular wildlife management activities, and is likely to have profound influence on the behavioural ecology of a species. At garden bird feeders, birds are now often fed well into the breeding season. Providing food within an established songbird territory, however, is likely to influence the territorial behaviour of the resident male. We used song performance during the dawn chorus in early spring to study behavioural changes in food-supplemented great tits, Parus major. After 2 weeks of continuous food supply within their territory, supplemented males started dawn singing later than control males, and thus postponed their regular dawn chorus before sunrise. This effect was maintained 2 weeks after food supplementation had ended. However, we did not find an effect of long-term feeding on song output. Our results were largely unexpected because formal models and field studies on short-term food supplementation suggested an earlier start of dawn singing or a higher dawn song output. Because we did not observe great tits visiting the feeders before sunrise or food supplementation increasing the numbers of conspecific intruders, the reasons for the delay in the start of dawn singing remain unclear; possible explanations include the presence of predators at feeding stations and the quality of the supplementary food itself. Delaying dawn singing could potentially affect the reproductive success of supplemented males, for example if females base extrapair mating decisions on dawn song performance of their mates. © 2010 The Association for the Study of Animal Behaviour.

Sprau P.,Netherlands Institute of Ecology | Sprau P.,Research Station Petite Camargue Alsacienne | Roth T.,Research Station Petite Camargue Alsacienne | Roth T.,University of Basel | And 4 more authors.
Behavioral Ecology | Year: 2010

In communication, vocal signals are often used for long-range signaling. Yet, little experimental evidence is available on the role of territorial signals across territory boundaries and their effectiveness at different propagation distances. In many songbird species, song overlapping and rapid broadband trills are used and perceived as agonistic signals, yet they differ in their propagation distance. Trills degrade quickly over distance, suggesting that their agonistic function may decrease faster over distance than that of song overlapping. Here, we tested whether different signaling distances of a rival affect singing responses of a territorial male and whether such distance effects differ when a rival uses rapid broadband trills or song overlapping. We exposed male nightingales (Luscinia megarhynchos) to songs of simulated rivals broadcast from 2 distances outside their territories. Each subject was exposed either to a moderate alternating playback without trills or to an agonistic playback, that is, to an alternating playback with trills or to an overlapping playback without trills. Irrespective of the treatment, males sang more songs containing trills in response to near than to far playback. As expected, males responded more strongly to the 2 agonistic treatments than to the moderate treatment. However, males did not clearly decrease responsiveness to playback containing trills broadcast from afar. This indicates that trills maintain their agonistic function even at distances at which information encoded in frequency bandwidth is degraded. Taken together, our results show that information encoded in signals used for resource maintenance is important also in communication across territory boundaries. © 2010 The Author.

Sprau P.,Netherlands Institute of Ecology | Roth T.,Research Station Petite Camargue Alsacienne | Roth T.,University of Basel | Amrhein V.,Research Station Petite Camargue Alsacienne | And 3 more authors.
Animal Behaviour | Year: 2012

In communication networks, territorial neighbours often regulate social relations using long-range signals. However, such relations may be affected when unfamiliar third parties threaten the territorial integrity of the neighbourhood. We investigated responses of vocally interacting nightingales, . Luscinia megarhynchos, that were successively challenged by simulated rivals prospecting the neighbourhood. Using playback experiments, we tested whether territorial behaviour of males is affected differently dependent on whether their neighbours were challenged with aggressively or moderately singing rivals and whether information from the observed interaction is being used in subsequent encounters with the simulated prospector. Males sang more moderately the closer they were to a neighbour that was threatened by an aggressively singing rival. When challenged themselves, these males then discriminated between rivals depending on how they had previously interacted with their neighbour. Thus, males condition their vocal behaviour on their neighbour's situation and use information from neighbour-stranger interactions in future decision making. These findings reveal that in social networks, rivals' behaviour and distance to neighbours matter, emphasizing the importance of considering multiple individuals and their spatial relations when assessing the functions of territorial signalling. © 2012 The Association for the Study of Animal Behaviour.

Amrhein V.,Research Station Petite Camargue Alsacienne | Amrhein V.,University of Basel | Scaar B.,Research Station Petite Camargue Alsacienne | Baumann M.,Research Station Petite Camargue Alsacienne | And 4 more authors.
Methods in Ecology and Evolution | Year: 2012

1. It is increasingly acknowledged that skewed adult sex ratios (ASRs) may play an important role in ecology, evolution and conservation of animals. 2. In birds, published estimates on ASRsmostly rely onmist netting data. However, previous studies suggested that mist nets or other trap types provide biased estimates on sex ratios, with males being more susceptible to capture than females. 3. We used data from a Constant Effort Site ringing scheme to show how sex ratios that are corrected for sex- and year-specific capture probabilities can be directly estimated by applying capture-recapture analysis, for example, in a Bayesian framework. 4. When capture data were pooled from the 19 years of study, we found that in the blackbird (Turdus merula) and the blackcap (Sylvia atricapilla), the observed proportions of males were 57% and 55%, respectively. However, when the observed annual proportions of males were corrected for the sex-specific capture probabilities, the proportions of males did not clearly differ from50%in most study years, and thus, the apparent male-bias in the ASRs almost completely disappeared. 5. We propose that published estimates on ASRs in birds should be re-evaluated if based solely on observed sex ratios frommist netting studies. 6. We further propose that data from national bird ringing schemes and in particular from Constant Effort Site ringing programs can provide valuable information on ASRs, if analysed using capture-recapture models. We discuss important assumptions of those models; for example, movements that may differ between sexes should be taken into account, as well as the occurrence of transient individuals that do not hold breeding territories within a study site. © 2012 The Authors. Methods in Ecology and Evolution, © 2012 British Ecological Society.

Hahn S.,Swiss Ornithological Institute | Amrhein V.,University of Basel | Amrhein V.,Research Station Petite Camargue Alsacienne | Zehtindijev P.,Bulgarian Academy of Science | Liechti F.,Swiss Ornithological Institute
Oecologia | Year: 2013

Whether migratory animals use similar resources during continental-scale movements that characterize their annual cycles is highly relevant to both individual performances and population dynamics. Direct knowledge of the locations and resources used by migrants during non-breeding is generally scarce. Our goal was to estimate migratory connectivity of a small Palaearctic long-distance migrant, the common nightingale Luscinia megarhynchos, and to compare resources used in non-breeding areas with resources used at the breeding grounds. We tracked individuals of three geographically separated populations and characterised their stable isotope niches during breeding and non-breeding over 2 years. Individuals spent the non-breeding period in population-specific clusters from west to central Africa, indicating strong migratory connectivity at the population level. Irrespective of origin, their isotopic niches were surprisingly similar within a particular period, although sites of residence were distant. However, niche characteristics differed markedly between breeding and non-breeding periods, indicating a consistent seasonal isotopic niche shift in the sampled populations. Although nightingales of distinct breeding populations migrated to different non-breeding areas, they chose similar foraging conditions within specific periods. However, nightingales clearly changed resource use between breeding and non-breeding periods, indicating adaptations to changes in food availability. © 2013 Springer-Verlag Berlin Heidelberg.

Roth T.,University of Basel | Roth T.,Research Station Petite Camargue Alsacienne | Buhler C.,Hintermann and Weber | Amrhein V.,University of Basel | Amrhein V.,Research Station Petite Camargue Alsacienne
American Naturalist | Year: 2016

Global change causes community composition to change considerably through time, with ever-new combinations of interacting species. To study the consequences of newly established species interactions, one available source of data could be observational surveys from biodiversity monitoring. However, approaches using observational data would need to account for niche differences between species and for imperfect detection of individuals. To estimate population sizes of interacting species, we extended N-mixture models that were developed to estimate true population sizes in single species. Simulations revealed that our model is able to disentangle direct effects of dominant on subordinate species from indirect effects of dominant species on detection probability of subordinate species. For illustration, we applied our model to data from a Swiss amphibian mon­itoring program and showed that sizes of expanding water frog populations were negatively related to population sizes of endangered yellow-bellied toads and common midwife toads and partly of natterjack toads. Unlike other studies that analyzed presence and absence ofspecies, our model suggests that the spread of water frogs in Central Europe is one of the reasons for the decline of endangered toad species. Thus, studying population impacts of dominant species on population sizes of endangered species using data from biodiversity monitoring programs should help to inform conservation policy and to decide whether competing species should be subject to population management. © 2016 by The University of Chicago.

Roth T.,University of Basel | Roth T.,Hintermann and Weber AG | Roth T.,Research Station Petite Camargue Alsacienne | Strebel N.,University of Basel | And 3 more authors.
Ecology | Year: 2014

As a response to climate warming, many animals and plants have been found to shift phenologies, such as appearance in spring or timing of reproduction. However, traditional measures for shifts in phenology that are based on observational data likely are biased due to a large influence of population size, observational effort, starting date of a survey, or other causes that may affect the probability of detecting a species. Understanding phenological responses of species to climate change, however, requires a robust measure that could be compared among studies and study years. Here, we developed a new method for estimating arrival and departure dates based on site-occupancy models. Using simulated data, we show that our method provided virtually unbiased estimates of phenological events even if detection probability or the number of sites occupied by the species is changing over time. To illustrate the flexibility of our method, we analyzed spring arrival of two long-distance migrant songbirds and the length of the flight period of two butterfly species, using data from a longterm biodiversity monitoring program in Switzerland. In contrast to many birds that migrate short distances, the two long-distance migrant songbirds tended to postpone average spring arrival by ∼0.5 days per year between 1995 and 2012. Furthermore, the flight period of the short-distance-flying butterfly species apparently became even shorter over the study period, while the flight period of the longer-distance-flying butterfly species remained relatively stable. Our method could be applied to temporally and spatially extensive data from a wide range of monitoring programs and citizen science projects, to help unravel how species and communities respond to global warming. © 2014 by the Ecological Society of America.

Roth T.,Hintermann and Weber AG | Roth T.,University of Basel | Roth T.,Research Station Petite Camargue Alsacienne | Plattner M.,Hintermann and Weber AG | And 2 more authors.
PLoS ONE | Year: 2014

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world. © 2014 Roth et al.

Roth T.,Research Station Petite Camargue Alsacienne | Roth T.,University of Basel | Amrhein V.,Research Station Petite Camargue Alsacienne | Amrhein V.,University of Basel
Journal of Applied Ecology | Year: 2010

Survival estimation forms the basis of much ecological research, and usually requires data on marked animals. In population studies of territorial animals, however, data are often collected on animal territory occupancy without identification of individuals. Previously, these data could not be used to estimate demographic parameters such as survival. We developed a hierarchical site-occupancy model for estimating survival from territory occupancy data without individual identification. We defined survival as the probability that an individual occupying a territory survives until the next reproductive period and settles in the same territory again. To evaluate our model, we used simulated data as well as real data from a long-term study on nightingales Luscinia megarhynchos, from which mark-recapture data and territory occupancy data were available. When applied to simulated data sets on territory occupancy, with parameter settings that are typical for different monitoring programmes (i.e. 10 years duration, three or eight visits per season, and 55 or 200 territories surveyed), our model yielded unbiased estimates of survival if the probability of detecting an occupied territory during a single visit was p = 0·5 or p = 0·7. When applied to the data on nightingale territory occupancy, estimates of survival from our model were very similar to the estimates obtained from a traditional mark-recapture model (Cormack-Jolly-Seber model) applied to the ringing data from the same nightingale population. Synthesis and applications. Data collection for mark-recapture analysis is usually invasive and labour intensive, and suitable data are rarely available from large-scale monitoring programmes covering entire regions or countries. Applying our model to territory occupancy data from such monitoring programmes could make large amounts of data available for research on animal demography. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.

Amrhein V.,Research Station Petite Camargue Alsacienne | Amrhein V.,University of Basel | Lerch S.,Research Station Petite Camargue Alsacienne | Lerch S.,University of Basel
Journal of Animal Ecology | Year: 2010

1. In territorial contests, not only acoustic or other signals, but also the movements of a territorial intruder are likely to influence the response of a resident. 2. We tested this movement hypothesis by simulating moving vs. stationary intruders into the territories of winter wrens Troglodytes troglodytes, using the same non-interactive song playbacks in both treatments. 3. Male winter wrens showed a different long-term singing reaction in response to a moving than to a stationary intruder. 4. One day after experiencing an intruder that was switching between three locations, residents started to sing earlier before sunrise, and they sang more and longer songs at dawn than before the intrusion. 5. Residents receiving the same playback from one location only reacted by starting to sing later relative to sunrise, and by singing fewer and shorter songs than before the intrusion. 6. We could not discriminate between the treatments when examining the short-term singing reactions during and immediately after the playbacks. However, our results clearly demonstrate an effect of the spatial behaviour of territorial intruders on the long-term territory defence of residents at dawn, about 24 h after an intrusion. 7. We argue that spatial behaviour of territorial intruders should be an integral part of the study of animal territory defence behaviour. Investigating long-term changes in territory defence at dawn is a sensitive tool for discriminating between different types of intruders. © 2009 British Ecological Society.

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