Interspecific variation in the relationship between clutch size, laying date and intensity of urbanization in four species of hole-nesting birds

Marie Vaugoyeau [et al.]The increase in size of human populations in urban and agricultural areas has resulted in considerable habitat conversion globally. Such anthropogenic areas have specific environmental characteristics, which influence the physiology, life history, and population dynamics of plants and animals. For example, the date of bud burst is advanced in urban compared to nearby natural areas. In some birds, breeding success is determined by synchrony between timing of breeding and peak food abundance. Pertinently, caterpillars are an important food source for the nestlings of many bird species, and their abundance is influenced by environmental factors such as temperature and date of bud burst. Higher temperatures and advanced date of bud burst in urban areas could advance peak caterpillar abundance and thus affect breeding phenology of birds. In order to test whether laying date advance and clutch sizes decrease with the intensity of urbanization, we analyzed the timing of breeding and clutch size in relation to intensity of urbanization as a measure of human impact in 199 nest box plots across Europe, North Africa, and the Middle East (i.e., the Western Palearctic) for four species of hole-nesters: blue tits (Cyanistes caeruleus), great tits (Parus major), collared flycatchers (Ficedula albicollis), and pied flycatchers (Ficedula hypoleuca). Meanwhile, we estimated the intensity of urbanization as the density of buildings surrounding study plots measured on orthophotographs. For the four study species, the intensity of urbanization was not correlated with laying date. Clutch size in blue and great tits does not seem affected by the intensity of urbanization, while in collared and pied flycatchers it decreased with increasing intensity of urbanization. This is the first large-scale study showing a species-specific major correlation between intensity of urbanization and the ecology of breeding. The underlying mechanisms for the relationships between life history and urbanization remain to be determined. We propose that effects of food abundance or quality, temperature, noise, pollution, or disturbance by humans may on their own or in combination affect laying date and/or clutch size.E. Barba acknowledges funding of project CGL2013-48001-C2-1-P (Spanish Ministry of Science and Innovation).Peer Reviewe

Postural Adaptation of the Spatial Reference Frames to Microgravity: Back to the Egocentric Reference Frame

BACKGROUND: In order to test how gravitational information would affect the choice of stable reference frame used to control posture and voluntary movement, we have analysed the forearm stabilisation during sit to stand movement under microgravity condition obtained during parabolic flights. In this study, we hypothesised that in response to the transient loss of graviceptive information, the postural adaptation might involve the use of several strategies of segmental stabilisation, depending on the subject's perceptual typology (dependence--independence with respect to the visual field). More precisely, we expected a continuum of postural strategies across subjects with 1) at one extreme the maintaining of an egocentric reference frame and 2) at the other the re-activation of childhood strategies consisting in adopting an egocentric reference frame. METHODOLOGY/PRINCIPAL FINDINGS: To check this point, a forearm stabilisation task combined with a sit to stand movement was performed with eyes closed by 11 subjects during parabolic flight campaigns. Kinematic data were collected during 1-g and 0-g periods. The postural adaptation to microgravity's constraint may be described as a continuum of strategies ranging from the use of an exo- to an egocentric reference frame for segmental stabilisation. At one extremity, the subjects used systematically an exocentric frame to control each of their body segments independently, as under normogravity conditions. At the other, the segmental stabilisation strategies consist in systematically adopting an egocentric reference frame to control their forearm's stabilisation. A strong correlation between the mode of segmental stabilisation used and the perceptual typology (dependence--independence with respect to the visual field) of the subjects was reported. CONCLUSION: The results of this study show different subjects' typologies from those that use the forearm orientation in a mainly exocentric reference frame to those that use the forearm orientation in a mainly egocentric reference frame

Comparative analysis of gait and speech in Parkinson's disease: hypokinetic or dysrhythmic disorders?

International audienceGait and speech are automatic motor activities which are frequently impaired in Parkinson's disease (PD). Obvious clinical similarities exist between these disorders but were never investigated. We propose to determine whether there exist any common features in PD between spatiotemporal gait disorders and temporal speech disorders. Gait and speech were analyzed on eleven PP undergoing deep-brain-stimulation of the sub-thalamic-nucleus (STN-DBS) and eleven control subjects (CS) under 3 conditions of velocity (natural, slow and speed). The patients were tested with and without L-Dopa and stimulator ON or OFF. Locomotor parameters were recorded using an optoelectronic system. Speech parameters were recorded with a headphone while subjects were reading a short paragraph. The results confirmed that PP walk and read more slowly than controls. Patient's difficulties in modulating walking and speech velocities seem to be due mainly to an inability to internally control the step length and the interpause-speech duration ISD. STN-DBS and levodopa increased patients' walking velocity by increasing the step length. STN-DBS and levodopa had no effect on speech velocity but restored the patients' ability to modulate the ISD. The walking cadence and speech index of rythmicity (SPIR) tended to be lower in patients and were not significantly improved by STN-DBS or levodopa. Speech and walking velocity as well as ISD and step length were correlated in both groups. Negative correlations between SPIR and walking cadence were observed in both groups Similar fundamental hypokinetic impairment and probably a similar rhythmic factor affected similarly the patients' speech and gait. These results suggest a similar physiopathological process in both walking and speaking dysfunction

Use of anthropogenic material affects bird nest arthropod community structure: influence of urbanisation, and consequences for ectoparasites and fledging success

Nests are a critically important factor in determining the breeding success of many species of birds. Nevertheless, we have surprisingly little understanding of how local environment helps shape materials used in construction, how this differs among related species using similar nest sites, or if materials used directly or indirectly influence the numbers of offspring successfully reared. We also have little understanding of any potential links between nest construction and the assemblage of invertebrates which inhabit the nest and in particular, with ectoparasites. We addressed these questions by monitoring the success rates of nest-box using Blue Tits Cyanistes caeruleus and Great Tits Parus major, from rural, urban greenspace and urban garden settings. We collected used nests, identified arthropods present, and measured the proportions of highly processed anthropogenic materials used in their construction. Some 25% of Great Tit nest materials were of an anthropogenic source and this was consistent across habitats, while Blue Tits used little (1-2%) except in gardens (~16%), suggesting that Great Tits preferentially sought out these materials. In fledged nests, increasing use of anthropogenic material was associated with lower general arthropod diversity and ectoparasite predator abundance (Blue Tits only) but higher levels of Siphonapterans (fleas). Higher arthropod diversity was associated with lower flea numbers, suggesting that increased diversity played a role in limiting flea numbers. No direct link was found between breeding success and either anthropogenic material usage, or arthropod diversity and abundance. However, breeding success declined with increasing urbanisation in both species and increased with nest weight in Blue Tits. The interplay between urbanisation and bird ecology is complex; our work shows that subtle anthropogenic influences may have indirect and unexpected consequences for urban birds

Impact of urbanization on abundance and phenology of caterpillars and consequences for breeding in an insectivorous bird

Urbanization can have marked effects on plant and animal populations’ phenology, population size, predator–prey, interactions and reproductive success. These aspects are rarely studied simultaneously in a single system, and some are rarely investigated, e.g., how insect phenology responds to urban development. Here, we study a tri‐trophic system of trees, phytophagous insects (caterpillars), and insectivorous birds (Great Tits) to assess how urbanization influences (1) the phenology of each component of this system, (2) insect abundance, and (3) avian reproductive success. We use data from two urban and two forest sites in Hungary, central Europe, collected over four consecutive years. Despite a trend of earlier leaf emergence in urban sites, there is no evidence for an earlier peak in caterpillar abundance. Thus, contrary to the frequently stated prediction in the literature, the earlier breeding of urban bird populations is not associated with an earlier peak in caterpillar availability. Despite this the seasonal dynamics of caterpillar biomass exhibited striking differences between habitat types with a single clear peak in forests, and several much smaller peaks in urban sites. Caterpillar biomass was higher in forests than urban areas across the entire sampling period, and between 8.5 and 24 times higher during the first brood's chick‐rearing period. This higher biomass was not associated with taller trees in forest sites, or with tree species identity, and occurred despite most of our focal trees being native to the study area. Urban Great Tits laid smaller clutches, experienced more frequent nestling mortality from starvation, reared fewer offspring to fledging age, and their fledglings had lower body mass. Our study strongly indicates that food limitation is responsible for lower avian reproductive success in cities, which is driven by reduced availability of the preferred nestling diet, i.e., caterpillars, rather than phenological shifts in the timing of peak food availability

Interspecific variation in the relationship between clutch size, laying date and intensity of urbanization in four species of hole-nesting birds

The increase in size of human populations in urban and agricultural areas has resulted in considerable habitat conversion globally. Such anthropogenic areas have specific environmental characteristics, which influence the physiology, life history, and population dynamics of plants and animals. For example, the date of bud burst is advanced in urban compared to nearby natural areas. In some birds, breeding success is determined by synchrony between timing of breeding and peak food abundance. Pertinently, caterpillars are an important food source for the nestlings of many bird species, and their abundance is influenced by environmental factors such as temperature and date of bud burst. Higher temperatures and advanced date of bud burst in urban areas could advance peak caterpillar abundance and thus affect breeding phenology of birds. In order to test whether laying date advance and clutch sizes decrease with the intensity of urbanization, we analyzed the timing of breeding and clutch size in relation to intensity of urbanization as a measure of human impact in 199 nest box plots across Europe, North Africa, and the Middle East (i.e., the Western Palearctic) for four species of hole-nesters: blue tits (Cyanistes caeruleus), great tits (Parus major), collared flycatchers (Ficedula albicollis), and pied flycatchers (Ficedula hypoleuca). Meanwhile, we estimated the intensity of urbanization as the density of buildings surrounding study plots measured on orthophotographs. For the four study species, the intensity of urbanization was not correlated with laying date. Clutch size in blue and great tits does not seem affected by the intensity of urbanization, while in collared and pied flycatchers it decreased with increasing intensity of urbanization. This is the first large-scale study showing a species-specific major correlation between intensity of urbanization and the ecology of breeding. The underlying mechanisms for the relationships between life history and urbanization remain to be determined. We propose that effects of food abundance or quality, temperature, noise, pollution, or disturbance by humans may on their own or in combination affect laying date and/or clutch size

Les effets maternels en tant que médiateurs des changements globaux : mécanismes et conséquences sur les populations d'oiseaux : comparaison de populations à différents niveaux d'urbanisation

In global changes context, the transformation of rural or natural area into urban area is well studied. At once cause and consequence of global changes, urbanization induces high selections pressures on populations and ecosystems. Factors such as habitat destruction, temperature, luminosity and soil permeability increase diminish biodiversity in town. Environmental characteristics influence phenotypes and survival of organisms. Parents can modulate environmental influence on young or future adult phenotype by investing in reproduction. The aim of this thesis was to understand the role of maternal effects on urban bird phenotypes through description and relation between environmental variation, differences in phenology and in phenotypes within and among populations at different levels of urbanization. For this purpose, two species were selected; the blue tit (Cyanistes caeruleus) and the great tit (Parus major), present along an urbanisation gradient. Monitoring of three reproductive seasons were realised in seven sites in urban area, (parks of Paris), on in three sites in suburban areas and five reproductive seasons in two sites in rural area (Fontainebleau forest and private forest of CEREEP). The phenology, reproductive success and phenotype (coloured signals, body and physiological condition) of adults and nestlings were measured. Thesis results showed that for the two species, phenology did not differ between habitats but reproductive success was lower in Paris than in rural areas. Moreover, great tit coloration and nestling body condition varied with habitat. In order to understand how and which factors influenced great tit colouration, a supplementation experiment was realised after moult. Finally to study temperature influence on great tit reproductive success, a heating nest experiment was realised. Thesis results showed that blue and great tits are highly able to adapt to urban environments even if their reproductive success was decreased in urban area which explained presence in all Europeans cities.Dans le contexte des changements globaux, la transformation du milieu rural ou naturel en milieu urbain est particulièrement bien étudiée. A la fois cause et conséquences des changements, l’urbanisation exerce de fortes pressions de sélection sur les populations et les écosystèmes. En effet, les facteurs tels que la perte d’habitat naturel, la hausse de la température, de la luminosité ou de la perméabilité des sols érodent la biodiversité en ville. Les contraintes environnementales influencent les phénotypes et la survie des organismes. Les parents peuvent moduler l’influence de l’environnement sur le phénotype du jeune et du futur adulte en s’investissant dans la reproduction. L’objectif de cette thèse était de comprendre le rôle des effets maternels sur les phénotypes des oiseaux urbains à travers la description et la mise en relation des variations environnementales, phénologiques et phénotypiques entre et au sein de populations aviaires à différents niveaux d’urbanisation. Pour mener à bien ce projet, deux espèces ont été sélectionnées : les mésanges bleues (Cyanistes caeruleus) et les mésanges charbonnières (Parus major) présentes le long du gradient urbain-rural. Le suivi de trois saisons de reproduction a été réalisé sur sept sites en zone urbanisée (parcs et jardins de Paris), une saison sur trois sites en zone semi-urbanisée et cinq saison sur deux sites en zone rurale (forêt de Fontainebleau et bois privés du CEREEP). La phénologie, le succès de reproduction ainsi que le phénotype (condition corporelle, condition physiologique et signaux colorés) des adultes et des jeunes ont été mesurés. Les résultats montrent que l’urbanisation n’influence pas la phénologie mais le succès de reproduction des deux espèces est plus faible sur Paris par rapport à la zone rurale. De plus, la coloration des adultes et la condition corporelle des jeunes varient avec l’habitat. Afin de mieux comprendre ce qui influence la coloration des mésanges charbonnières, une expérience de supplémentation a été mise en place après la mue des adultes. Enfin pour mieux cibler l’effet de la température sur le succès de reproduction des mésanges charbonnières, une expérience de chauffage des nids a été réalisée. Tous les résultats récoltés montrent que les mésanges bleues et charbonnières ont de grandes capacités d’adaptation aux facteurs environnementaux même si leur succès de reproduction est diminué en zone urbaine ce qui explique en partie la pérennité de leurs présences dans les centres urbains à travers l’Europe

Maternal effects as mediators for climate change : mechanisms and consequences on birds populations

Dans le contexte des changements globaux, la transformation du milieu rural ou naturel en milieu urbain est particulièrement bien étudiée. A la fois cause et conséquences des changements, l’urbanisation exerce de fortes pressions de sélection sur les populations et les écosystèmes. En effet, les facteurs tels que la perte d’habitat naturel, la hausse de la température, de la luminosité ou de la perméabilité des sols érodent la biodiversité en ville. Les contraintes environnementales influencent les phénotypes et la survie des organismes. Les parents peuvent moduler l’influence de l’environnement sur le phénotype du jeune et du futur adulte en s’investissant dans la reproduction. L’objectif de cette thèse était de comprendre le rôle des effets maternels sur les phénotypes des oiseaux urbains à travers la description et la mise en relation des variations environnementales, phénologiques et phénotypiques entre et au sein de populations aviaires à différents niveaux d’urbanisation. Pour mener à bien ce projet, deux espèces ont été sélectionnées : les mésanges bleues (Cyanistes caeruleus) et les mésanges charbonnières (Parus major) présentes le long du gradient urbain-rural. Le suivi de trois saisons de reproduction a été réalisé sur sept sites en zone urbanisée (parcs et jardins de Paris), une saison sur trois sites en zone semi-urbanisée et cinq saison sur deux sites en zone rurale (forêt de Fontainebleau et bois privés du CEREEP). La phénologie, le succès de reproduction ainsi que le phénotype (condition corporelle, condition physiologique et signaux colorés) des adultes et des jeunes ont été mesurés. Les résultats montrent que l’urbanisation n’influence pas la phénologie mais le succès de reproduction des deux espèces est plus faible sur Paris par rapport à la zone rurale. De plus, la coloration des adultes et la condition corporelle des jeunes varient avec l’habitat. Afin de mieux comprendre ce qui influence la coloration des mésanges charbonnières, une expérience de supplémentation a été mise en place après la mue des adultes. Enfin pour mieux cibler l’effet de la température sur le succès de reproduction des mésanges charbonnières, une expérience de chauffage des nids a été réalisée. Tous les résultats récoltés montrent que les mésanges bleues et charbonnières ont de grandes capacités d’adaptation aux facteurs environnementaux même si leur succès de reproduction est diminué en zone urbaine ce qui explique en partie la pérennité de leurs présences dans les centres urbains à travers l’Europe.In global changes context, the transformation of rural or natural area into urban area is well studied. At once cause and consequence of global changes, urbanization induces high selections pressures on populations and ecosystems. Factors such as habitat destruction, temperature, luminosity and soil permeability increase diminish biodiversity in town. Environmental characteristics influence phenotypes and survival of organisms. Parents can modulate environmental influence on young or future adult phenotype by investing in reproduction. The aim of this thesis was to understand the role of maternal effects on urban bird phenotypes through description and relation between environmental variation, differences in phenology and in phenotypes within and among populations at different levels of urbanization. For this purpose, two species were selected; the blue tit (Cyanistes caeruleus) and the great tit (Parus major), present along an urbanisation gradient. Monitoring of three reproductive seasons were realised in seven sites in urban area, (parks of Paris), on in three sites in suburban areas and five reproductive seasons in two sites in rural area (Fontainebleau forest and private forest of CEREEP). The phenology, reproductive success and phenotype (coloured signals, body and physiological condition) of adults and nestlings were measured. Thesis results showed that for the two species, phenology did not differ between habitats but reproductive success was lower in Paris than in rural areas. Moreover, great tit coloration and nestling body condition varied with habitat. In order to understand how and which factors influenced great tit colouration, a supplementation experiment was realised after moult. Finally to study temperature influence on great tit reproductive success, a heating nest experiment was realised. Thesis results showed that blue and great tits are highly able to adapt to urban environments even if their reproductive success was decreased in urban area which explained presence in all Europeans cities

Proprioceptive contribution of postural control as assessed from very slow oscillations of the support in healthy humans

International audienceMaintaining erect human posture depends on graviceptive information. This can come from at least of three origins: vestibular, visual and somaesthetic. We hypothesize here that subject's use proprioception rather than visual or vestibular cues for their control of upright body posture and this even when subjects stand on a tilting body support surface. In order to find experimental evidence for this hypothesis, we exclude in our experiments visual cues (eyes close) and by keeping frequency and amplitude of the tilt stimulus so low that it would be below the detection threshold for vestibular semi-circular canal stimuli. The orientations of body segments were analysed during various phases of the perturbation cycle. Segmental stabilisations were defined in terms of both the global anchoring index calculated during the whole perturbation cycle and an appropriate sequential anchoring index calculated during various phases in the perturbation cycle. We show that subjects tend to align their bodies with the space vertical and do so better for their heads than for their upper bodies and lower bodies. A further finding is that stabilisation is related to the tilt stimulus in the form that it is minimal at the turning points of the tilt, where peak tilt velocity is minimal with the sinusoidal stimulus used. These finding suggest first that proprioceptive cues are predominant in the control of body orientation in quasi-static condition and second that the head and trunk stabilisation strategies used as the basis of postural control depend on the properties of the moving support

Impaired vertical postural control and proprioceptive integration deficits in Parkinson’s disease

International audienceThe aim of the present study was to investigate how the orientation and stabilization components of postural control may be affected as the result of the impaired proprioceptive integration possibly occurring in Parkinson's disease. To determine the proprioceptive contribution to postural control, parkinsonian patients and control subjects were asked to maintain vertical stance while very slow sinusoidal oscillations were being applied in the lateral and antero-posterior planes to the platform on which they were standing. The amplitude and frequency of their movements were kept below the semicircular canal perception threshold. Data were collected with the ELITE automatic motion analyzer and the two postural components (orientation and segmental stabilization) were analyzed at head and trunk levels while the subjects were performing the task with their eyes open and closed. The results show that 1) the parkinsonian groups' performances were affected in terms of both the postural orientation and stabilization components in comparison with the control group, 2) the use of vision improved the parkinsonian patients' postural performances, and 3) both parkinsonian patients and control subjects achieved better postural performances when antero-posterior perturbations rather than lateral perturbations were applied to the foot support. These results suggest that Parkinson's disease is associated with proprioceptive impairment, which may be an important factor contributing to these patients' postural deficits. On the basis of these results, the visual dependence observed in parkinsonian patients is re-defined as an adaptive strategy partly compensating for the impaired proprioception