Effets de la disponibilité potentielle en nids et en nourriture sur l’abondance du Grand Polatouche (Glaucomys sabrinus) en forêt boréale mixte de l’est du Canada

Le Grand Polatouche (Glaucomys sabrinus) est un rongeur arboricole et cavicole associé aux gros arbres et aux vieilles forêts non perturbées. Cette espèce est considérée non seulement comme une espèce clé des forêts de conifères, mais également comme une espèce indicatrice d’aménagement durable en Amérique du Nord. Les résultats d’une étude de 2008 ont cependant montré que la disponibilité en cavités ne semblait pas limiter la présence de l’espèce en forêt boréale québécoise. Nous avons donc réalisé une expérience dans laquelle nous avons ajouté des cavités artificielles (nichoirs) sur la moitié des sites étudiés en 2008 (n=56), afin de déterminer par piégeage, 4 ans plus tard, si la disponibilité de cette ressource influence l’abondance locale de l’espèce ainsi que la dynamique de ses populations. Nous supposons que 1) l’abondance initiale augmente selon la disponibilité potentielle en nourriture (mesurée par la surface terrière de conifères) et en cavités (mesurée par la surface terrière de chicots) ; 2) l’ajout de nichoirs aura une influence positive sur le taux de recrutement et la survie apparente des polatouches et que 3) l’effet de l’ajout de nichoirs dépendra de la disponibilité naturelle en nourriture et en cavités sur chaque site. En prenant en compte l’effet de l’année, des précipitations et de la hauteur des pièges sur la probabilité de détection, nous avons analysé les données selon des modèles N-mélangés (N-mixture model). L’abondance initiale est influencée par la disponibilité en nourriture mais pas par la disponibilité en cavités. De plus, ni l’ajout de nichoirs, ni les caractéristiques des sites n’expliquent l’abondance des populations de polatouches après l’ajout de nichoirs, bien que tous les sites non occupés en 2008 sauf un aient été colonisés en 2012. Nos résultats confirment l’aspect opportuniste de l’espèce et suggèrent que le Grand polatouche n’est peut être pas une bonne espèce indicatrice de vieilles forêts dans nos forêts boréales mixtes

Using dynamicN-mixture models to test cavity limitation on northern flying squirrel demographic parameters using experimental nest box supplementation

Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577–587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our main purpose was to evaluate the impact of an increase in cavity availability on flying squirrel population dynamics in deciduous stands in northwestern Quebec with the dynamic N-mixture model. We compared abundance estimates from this recent approach with those from classic capture–mark–recapture models and generalized linear models. We compared apparent survival estimates with those from Cormack–Jolly–Seber (CJS) models. Average recruitment rate was 6 individuals per site after 4 years. Nevertheless, we found no effect of cavity supplementation on apparent survival and recruitment rates of flying squirrels. Contrary to our expectations, initial abundance was not affected by conifer basal area (food availability) and was negatively affected by snag basal area (cavity availability). Northern flying squirrel population dynamics are not influenced by cavity availability at our deciduous sites. Consequently, we suggest that this species should not be considered an indicator of old forest attributes in our study area, especially in view of apparent wide population fluctuations across years. Abundance estimates from N-mixture models were similar to those from capture–mark–recapture models, although the latter had greater precision. Generalized linear mixed models produced lower abundance estimates, but revealed the same relationship between abundance and snag basal area. Apparent survival estimates from N-mixture models were higher and less precise than those from CJS models. However, N-mixture models can be particularly useful to evaluate management effects on animal populations, especially for species that are difficult to detect in situations where individuals cannot be uniquely identified. They also allow investigating the effects of covariates at the site level, when low recapture rates would require restricting classic CMR analyses to a subset of sites with the most captures

Drivers of amphibian population dynamics and asynchrony at local and regional scales

Identifying the drivers of population fluctuations in spatially distinct populations remains a significant challenge for ecologists. Whereas regional climatic factors may generate population synchrony (i.e., the Moran effect), local factors including the level of density-dependence may reduce the level of synchrony. Although divergences in the scaling of population synchrony and spatial environmental variation have been observed, the regulatory factors that underlie such mismatches are poorly understood. Few previous studies have investigated how density-dependent processes and population-specific responses to weather variation influence spatial synchrony at both local and regional scales. We addressed this issue in a pond-breeding amphibian, the great crested newt (Triturus cristatus). We used capture-recapture data collected through long-term surveys in five T. cristatus populations in Western Europe. In all populations – and subpopulations within metapopulations – population size, annual survival and recruitment fluctuated over time. Likewise, there was considerable variation in these demographic rates between populations and within metapopulations. These fluctuations and variations appear to be context-dependent and more related to site-specific characteristics than local or regional climatic drivers. We found a low level of demographic synchrony at both local and regional levels. Weather has weak and spatially variable effects on survival, recruitment and population growth rate. In contrast, density-dependence was a common phenomenon (at least for population growth) in almost all populations and subpopulations. Our findings support the idea that the Moran effect is low in species where the population dynamics more closely depends on local factors (e.g. population density and habitat characteristics) than on large-scale environmental fluctuation (e.g. regional climatic variation). Such responses may have far-reaching consequences for the long-term viability of spatially structured populations and their ability to response to large-scale climatic anomalies

Suivi d'une espèce rare en vue de sa conservation: dynamique spatiale et temporelle de populations de Pélobate cultripède (Pelobates cultripes) en Aquitaine

Knowledge of key demographic parameters of a population is an essential preliminary step to the establishment of appropriate management measures for effective protection of the species. That's why a conservation program was founded by the association Cistude Nature between 2009 and 2011 in partnership with the National Office of Forest, to enable the acquisition of information on a rare and little known species of amphibian, the western spadefoot toad (Pelobates cultripes). This work has focused mainly on the issues of the species detection, distribution, population dynamics and habitat use. Its main objective was to highlight the environmental parameters required for the presence and the maintenance of its populations. To this end, several approaches have been implemented at different scales of landscape. First, inventory consisted in using different methods of detection and deal in parallel with aquatic breeding habitat selection; a second approach consisted in a radio-tracking monitoring to address terrestrial habitat selection; and a third one consisted in a Capture-Recapture monitoring to address demography and population dynamics. Results show difference in efficiency between the different detection methods employed, with a higher effectiveness for terrestrial inventories. They also show that the species prefer terrestrial open vegetated sites, closed to sunny aquatic habitats with little slope for reproduction. Individuals, active throughout the year, are more mobile in spring when they attend any type of terrestrial habitats rather bushy or forestry than in winter when they remain more exposed near the breeding site. The study on pilot Gironde coast site hosted a population of three hundred individuals, for 2/3 males, presumably closed to exchange with negligible temporary migration, with a low capture probability (p<0,20), higher in May, June and November, and a relatively low survival rate (S=0,50), higher for males than females. This study emphasizes on the importance of terrestrial habitats in amphibian protection and underlines the importance of long term demography studies to appropriately adjust efficient conservation strategies.La connaissance des paramètres démographiques clefs d'une population constitue une étape préliminaire essentielle à la mise en place d'actions de gestion appropriées pour une protection efficace des espèces. C’est pourquoi un programme d’étude et de conservation, a été initié par l’association Cistude Nature entre 2009 et 2011 en partenariat avec l'Office National des Forêts, pour permettre l'acquisition d'informations sur une espèce d'amphibien rare et méconnue, le Pélobate cultripède (Pelobates cultripes). Ce travail de recherche s'est concentré essentiellement sur les problématiques de détection de l’espèce, de distribution, de dynamique de populations et d’utilisation d’habitat. Son objectif principal était de mettre en évidence les paramètres environnementaux nécessaires à la présence et au maintien de ses populations. Pour ce faire, plusieurs approches ont été mises en place à différentes échelles du paysage. Une première consistait en des inventaires selon différentes méthodes de détection, elle permit de traiter parallèlement la sélection d’habitat en termes de milieu aquatique de reproduction; une seconde consistait en un suivi télémétrique afin de traiter la sélection d'habitat terrestre; et une troisième en un suivi par Capture-Marquage-Recapture afin de traiter de la démographie et la dynamique de population de cette espèce. Les résultats montrent une différence d'efficacité entre les méthodes de détection employées avec une efficacité plus importante des inventaires terrestres qu'aquatiques. Ils montrent également une préférence de l'espèce pour les zones terrestres ouvertes mais végétalisées, proches d'habitats aquatiques ensoleillés, peu pentus et de taille modérée pour la reproduction. Les individus, actifs toute l'année, sont plus mobiles au printemps où ils fréquentent tout type de milieux terrestres, plutôt buissonnants ou forestiers en comparaison à la saison hivernale, où ils restent plus à découvert, proche du site de reproduction. L'étude de population sur le site pilote du littoral girondin, a révélé, une population constituée de trois centaines d'individus, mâles pour les 2/3, à priori plutôt fermée aux échanges, présentant des migrations temporaires négligeables, un faible taux de capture (p<0,20), plus élevé en mai, juin et novembre et un taux de survie relativement faible (S=0,50), plus élevé pour les mâles que les femelles. Cette étude souligne l'importance des milieux terrestres dans la protection des amphibiens et met en évidence la nécessité d'études démographiques à long terme pour orienter de façon appropriée la stratégie de conservation et d'aménagement des territoires

Structure et dynamique de populations de l'Emyde lépreuse Mauremys leprosa (Schweigger, 1812) dans des milieux aquatiques pollués contrastés

International audiencePollution contributes to the degraded state of continental aquatic ecosystems and biodiversity. Some species appear to be tolerant to aquatic pollution, yet little is known about the effects of such pollution on population structure and dynamics. Here, we investigated how wastewater treatment plant (WWTP) effluents of the Cabestany City, in southern France, contribute to the pollution levels of the Fosseille River, and we tested how they could affect population structure and medium-term dynamics of the native freshwater turtle, the Mediterranean Pond Turtle Mauremys leprosa (Schweigger, 1812). Amongst the 68 pesticides surveyed from water samples collected along the river in 2018 and 2021, a total of 16 pesticides were detected, among which eight were found in the upstream section of the river, 15 in the river section located downstream of the WWTP, and 14 in the outfall of the WWTP, exhibiting the contribution of effluents to the river pollution. From 2013 to 2018 and in 2021, capture-mark-recapture protocols were carried out on the freshwater turtle population living in the river. Using robust design and multi-state models, we showed a stable population throughout the study period, with high year-dependent seniority, and a bidirectional transition occurring primarily from the upstream to the downstream river sections of the WWTP. The freshwater turtle population consisted mostly of adults, with a male biased sex ratio detected downstream of the WWTP neither related to sex-dependent survival, recruitment, nor transition, suggesting a male bias in the hatchlings or primary sex ratio. Also, the largest immatures and females were captured downstream of the WWTP, with females having the highest body condition, whereas no such differences were observed in males. This study highlights that population functioning of M. leprosa is driven primarily by effluents induced resources, at least over the medium-term

Six Years of Monitoring: Investigating The Impacts of Wastewater Treatment Plant Effluents on Mediterranean Pond Turtle

Anthropogenic changes can significantly impact the suitability of aquatic habitats for freshwater species. In this study, we examined the population structure and phenotype of the Mediterranean Pond Turtle (Mauremys leprosa) in relation to physico-chemical water parameters investigated in three rivers in southwestern France. While all rivers were impacted by agricultural activities, two of them also received effluents of wastewater treatment plant (WWTP). Our results revealed the presence of caffeine and pesticides in all rivers, and pharmaceuticals only in the downstream river sections of the WWTPs. Overall, both the diversity and concentration of pollutants were the highest in the WWTP downstream sections. Based on pollutant and organic matter concentrations, conductivity, and temperature, a principal component analysis and a hierarchical clustering defined three levels of habitat integrity. In the least altered habitats, characterized by cold waters and scarce trophic resources, although immatures were well represented, turtle growth and body size were the lowest. Conversely, in the highly degraded habitats characterized by warm waters and abundant trophic resources, although immature turtles were poorly represented, turtle growth and body size were the highest. Our results thus highlight the dichotomy between the profits derived from effluents induced organic pollution and the drawbacks related to the effects of pollutants on turtle physiology and reproduction. To better understand the adaptive capacities of M. leprosa to environmental degradation, future studies should focus on the bioaccumulation of organic pollutants in turtle follicles, and their effects on morphology and long-term survival

Six Years of Monitoring: Investigating The Impacts of Wastewater Treatment Plant Effluents on Mediterranean Pond Turtle

International audienceAnthropogenic changes can significantly impact the suitability of aquatic habitats for freshwater species. In this study, we examined the population structure and phenotype of the Mediterranean Pond Turtle (Mauremys leprosa) in relation to physico-chemical water parameters investigated in three rivers in southwestern France. While all rivers were impacted by agricultural activities, two of them also received effluents of wastewater treatment plant (WWTP). Our results revealed the presence of caffeine and pesticides in all rivers, and pharmaceuticals only in the downstream river sections of the WWTPs. Overall, both the diversity and concentration of pollutants were the highest in the WWTP downstream sections. Based on pollutant and organic matter concentrations, conductivity, and temperature, a principal component analysis and a hierarchical clustering defined three levels of habitat integrity. In the least altered habitats, characterized by cold waters and scarce trophic resources, although immatures were well represented, turtle growth and body size were the lowest. Conversely, in the highly degraded habitats characterized by warm waters and abundant trophic resources, although immature turtles were poorly represented, turtle growth and body size were the highest. Our results thus highlight the dichotomy between the profits derived from effluents induced organic pollution and the drawbacks related to the effects of pollutants on turtle physiology and reproduction. To better understand the adaptive capacities of M. leprosa to environmental degradation, future studies should focus on the bioaccumulation of organic pollutants in turtle follicles, and their effects on morphology and long-term survival

Data from: Using dynamic N-mixture models to test cavity limitation on northern flying squirrel demographic parameters using experimental nest box supplementation.

1. Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. 2. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577-587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our main purpose was to evaluate the impact of an increase in cavity availability on flying squirrel population dynamics in deciduous stands in northwestern Québec with the dynamic N-mixture model. We compared abundance estimates from this recent approach with those from classic capture-mark-recapture models and generalized linear models. We compared apparent survival estimates with those from Cormack-Jolly-Seber (CJS) models. 3. Average recruitment rate was 6 individuals per site after 4 years. Nevertheless, we found no effect of cavity supplementation on apparent survival and recruitment rates of flying squirrels. Contrary to our expectations, initial abundance was not affected by conifer basal area (food availability) and was negatively affected by snag basal area (cavity availability). 4. Northern flying squirrel population dynamics are not influenced by cavity availability at our deciduous sites. Consequently, we suggest that this species should not be considered an indicator of old forest attributes in our study area, especially in view of apparent wide population fluctuations across years. 5. Abundance estimates from N-mixture models were similar to those from capture-mark-recapture models, although the latter had greater precision. Generalized linear mixed models produced lower abundance estimates, but revealed the same relationship between abundance and snag basal area. Apparent survival estimates from N-mixture models were higher and less precise than those from CJS models. However, N-mixture models can be particularly useful to evaluate management effects on animal populations, especially for species that are difficult to detect in situations where individuals cannot be uniquely identified. They also allow investigating the effects of covariates at the site level, when low recapture rates would require restricting classic CMR analyses to a subset of sites with the most captures

Influence of inulin on bread: Kinetics and physico-chemical indicators of the formation of volatile compounds during baking

CDD Gaëlle ARVISENET entre septembre 2012 et août 2016 au CSGAThe influence of inulin on the formation and release of white bread volatiles was studied during baking, using an innovative on-line baking extraction device. Kinetic studies were performed to follow the development of crust physical properties and the formation of volatiles responsible for the flavour of breads having different amounts of inulin. It was demonstrated that inulin accelerated the formation of the bread crust and the Maillard reaction. It led to breads with an overall quality similar to that of non-enriched breads, but baked for a shorter time. Correlations between some crust properties and the amount of Maillard volatiles were determined. They showed that crust water activity, moisture and clearness could be good indicators of the Maillard reaction during the baking of bread