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Structure sociale et utilisation de l'espace par la perdrix rochassière (Alectoris graeca saxatilis x Alectoris rufa rufa) : variations saisonnières et individuelles

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Social organization and home ranges of the hybrid partridge (Alectoris graeca saxatilis x Alectoris rufa rufa): seasonal and individual variations. Gibier Faune Sauvage, Vol. 8, mars: 1-30. Seasonal and individual changes in the social organization and home range sizes of natural hybrids between Rock partridge ( Alectoris graeca saxatilis) and Red-legged partridge (Alectoris rufa rufa) were studied in the Southern French Alps by following 40 birds equipped with radio tags for periods varying between two months and two years, between September 1984 and May 1989. The partridges' social behaviour changes throughout the annual cycle. They are predominantly living in groups from late summer, soon after breeding, to early spring when groups will disperse. Between September and March, mean group size is 4.5 individuals. The partridges' tendency to gregariousness is apparently at its highest in winter when 90% of them are living in groups. From September to December, females are more gregarious than males. Groups may be composed of juveniles and adults, and of birds of both sexes. Family groups form fairly stable units contrary to groups made up of nonincubating or unsucessful nesting birds. Partridges have a tendency to separate themselves from their wintering group prior to pairing. Breeding pairs maintain a fairly strict spacing pattern during spring (egg-laying period), but tolerate the presence of lone males within their territory. About 20 % of the birds are unpaired in spring: these are erratic subadult males, widowed males or males which became single after a divorce. In early summer the proportion of solitary birds reaches a peak (53 %) because of clutch incubation. During this period broods appear, but also groups consisting of birds that lost their nests or of nonnesting birds. Seasonal home range areas vary from 2 to 190 ha and home range lengths (determined by the longest movement covered during one season) vary between 0.3 and 25 km according to the individuals. Home range size varies from season to season. Home range area thus decreases between early spring and spring. Then it increases in the late summer period to diminish markedly in winter; home range length also diminishes between early spring and spring then increases again in sum-mer. These seasonal variations are apparently induced both by the breeding cycle and by the food needs in relation to changes in the weather. Further to these general trends, there is a marked difference in home range size between individual birds. It seems that from April to August this variability is neither sex- nor age related, but merely linked to the partridge's " breeding-life history" (whether the bird is paired, even for a short time, or not; bird having experienced nesting success, or not). From September till March, the differences in spatial behaviour between individual birds are seemingly not directly linked to sex, but to ethological factors, and/or to ecological factors like snow depth and duration of snow cover. Thus, some birds leave their breeding site without the occurrence of any apparent change in weather and settle at several kilometres from there to overwinter for 5-6 months. In March they move back to their former breeding range (a migration-like behaviour). Other birds leave their breeding sites only after heavy snow fall to reach areas that will rapidly be snow-free : some birds will stay there until March, but others move back to their breeding sites as soon as the snow has melted. Others still are wintering close to their breeding site. Breeding birds use annual home ranges covering on average an area of 221 ha and measuring 6.7 km in length. Home range annual areas of individual birds vary little (from 194 to 338 ha). In contrast, there is a 1- to 12-fold difference in home range lengths according to the individual. Because of the long distances moved by the birds, all favour-able habitats situated within a radius of at least 6-7 km from the breeding area should be managed, if the goal is to maintain a nucleus of breeders.
... En dehors de la saison de reproduction, l'espèce est grégaire, formant des groupes pouvant atteindre 15 oiseaux en septembre-octobre, même si une proportion non négligeable d'oiseaux peut être observée seule tout au long de l'année. La taille de groupe tend à diminuer en automne et en hiver (Bernard-Laurent, 1991b). Dans les Alpes, la perdrix bartavelle montre un régime alimentaire avec de fortes variations saisonnières : simplement composé de parties végétatives de plantes herbacées de décembre à mai, le régime alimentaire est plus diversifié pendant le reste de l'année et se compose de plantes, de fleurs, de graines, de baies et d'insectes (Didillon, 1993). ...
... Outside the breeding season, the species is gregarious, forming groups of up to 15 individuals in September-October, even if a proportion of birds can be observed alone along the year. The group size tends to decrease along autumn and winter (Bernard-Laurent, 1991b). In the Alps, Rock Partridge diet shows high seasonal variations: merely composed by green parts of herbaceous plants from December to May, the diet is more diversified during the rest of the year: Partridges feed on plants, flowers, seeds, berries and insects (Didillon, 1993). ...
Chapter
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The chapter of this book (available in English and French languages) document the conservation status and management of Rock partridge populations, that are listed in the Annex II/A of the Birds Directive, in the various countries of its European distribution.
... Per comprendere appieno tali movimenti, la tecnica più appropriata è quella della radiotelemetria. A tale riguardo, però, a parte gli studi svolti sulle Alpi Marittime francesi su una popolazione di ibridi naturali tra Alectoris rufa e A. graeca (Bernard-Laurent, 1988, 1991b, l'unica indagine condotta su individui di Coturnice dotati di trasmettitori è quella effettuata da Pandolfi et al. (2001) sui Monti Sibillini nelle Marche. Tra l'autunno 2000 e l'inverno 2001, radiocollari del peso di 12 g sono stati applicati a sei animali (5 giovani e una femmina adulta) catturati mediante prodine a scatto manuale. ...
... Ciò conferma la tendenza della specie a non compiere ampi spostamenti quando le disponibilità trofiche si mantengono sufficienti nei territori in quota. Le dimensioni degli home-range dei tre animali studiati (minimo 7,56 ha -massimo 186,33 ha; metodo del Minimo Poligono Convesso) sono simili a quelle riscontrate da Bernard-Laurent (1988, 1991b per gli individui appartenenti alla popolazione di ibridi naturali tra Alectoris rufa e A. greca. ...
... Per comprendere appieno tali movimenti, la tecnica più appropriata è quella della radiotelemetria. A tale riguardo, però, a parte gli studi svolti sulle Alpi Marittime francesi su una popolazione di ibridi naturali tra Alectoris rufa e A. graeca (Bernard-Laurent, 1988, 1991b, l'unica indagine condotta su individui di Coturnice dotati di trasmettitori è quella effettuata da Pandolfi et al. (2001) sui Monti Sibillini nelle Marche. Tra l'autunno 2000 e l'inverno 2001, radiocollari del peso di 12 g sono stati applicati a sei animali (5 giovani e una femmina adulta) catturati mediante prodine a scatto manuale. ...
... Ciò conferma la tendenza della specie a non compiere ampi spostamenti quando le disponibilità trofiche si mantengono sufficienti nei territori in quota. Le dimensioni degli home-range dei tre animali studiati (minimo 7,56 ha -massimo 186,33 ha; metodo del Minimo Poligono Convesso) sono simili a quelle riscontrate da Bernard-Laurent (1988, 1991b per gli individui appartenenti alla popolazione di ibridi naturali tra Alectoris rufa e A. greca. ...
Book
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The Rock Partridge Alectoris graeca (all the recognized subspecies) is included in the Annex I of “Bird” Directive 2009/147/EC and show an unfavorable status in Italy. The National Action Plan for the species detects the threats and the limiting factors to the conservation of its populations. The main treaths are the abandonment of agricultural and pastoral activities in mountain areas and the failure of management strategy. The Plain defines an organic framework of measures to ensure long-term survival of the populations and promotes cooperation of competent Authorities and Stakeholders. These actions are aimed at the conservation and improvement of breeding habitats, control of the actual limiting factors (isolation of populations, poaching and genetic pollution), and to promote the correct management strategies. The Plan highlights, also, some actions to monitor the demographic parameters of the species, to investigate its sanitary and genetic status, and to improve the knowledge on the species ecology.
... L'impact de la fermeture des habitats sur les populations de perdrix bartavelle est moins bien connu. Cette perdrix, qui ne présente pas d'adaptations spécifiques au froid, évite les enneigements trop importants et peut effectuer des mouvements migratoires en hiver dans les milieux ouverts des altitudes moyennes ou basses (Bernard-Laurent 1991, Lüps 2004). La raréfaction de ces habitats est de fait une des pistes évoquées pour expliquer le déclin des populations dans les années 1970 et 1980 (Bernard-Laurent and De Franceschi 1994). ...
Thesis
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Mountains are reservoirs of biodiversity whose strong altitudinal gradients over short distances are associated with strong spatial heterogeneity of local environmental conditions. While biodiversity has so far been rather well preserved in mountains due to poor accessibility, predictions of ongoing climate change suggest even more rapid and marked effects in mountains than in plains. My main objective is to understand how global change are impacting the population dynamics of mountain galliformes. My work has shown (1) a strong heterogeneity of demographic strategies between populations of rock ptarmigan (Lagopus muta) (2) that black grouse populations (Tetrao tetrix) show spatially very heterogeneous trends, influenced by local conditions (3) that for such species that are difficult to count and show strong spatial and interannual variability it is necessary to rely on long-term monitoring to reach a satifactory statistical power to detect a decline.
... It is found in mainland Greece (except of Thrace), and in the Ionian islands and in Kithira. Up to the present, the only information we have conceming the rock partridge in Greece is drawn from WnrsoN (1962), P.qpeev,ccEl-ou (1979, VAvA'Leres et al ' (1993) and HoEr-zrNcER (1988, 1991. However, no data are available in Greece about home range of the species. ...
Article
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Summary Natural marking is suggested as the suitable method for the determination of the home range of rock partridge (Alectoris graeca graeca). This marking is due to the fact that some individuals bear black markings on their chest, which have a characteristic shape and arrangement. The constancy of the shape and arrangement of these were checked on 207 captive individuals, and we found that 14 (6,7%) of them bear black markings on their breasts. The geographical distribution, where this particular characteristic is observed, was determined after examining 93 hunted individuals, 11 of which (12%) bore black markings.
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Changes in abundance and the risk of extinction of the rock partridge Alectoris graeca saxatilis in the Dolomitic Alps were investigated using a density-dependent model that incorporated dispersal and environmental stochasticity. The study was based on spring and summer counts collected from sample areas in geographically distinct mountain groups. Extinction probability was investigated by simulating a discrete population and a metapopulation consisting of local populations connected by dispersal. Persistence was not guaranteed when the species was examined as a discrete population. When we used a metapopulation approach, the persistence was assured but local extinctions with subsequent recolonizations of a number of empty areas were observed. The analysis was repeated using hunting statistics, when there were no restrictions on hunting policies, and a similar high extinction pattern was found. Our simulations suggested that long-term persistence of rock partridge could be guaranteed only when immigration was included into the demographic model. However, if the increased population's fragmentation recorded since the 1950s persists the extinction of some of the subpopulations appears inevitable.
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1. Time series data on five species of gamebird from the Dolomitic Alps were used to examine the relative importance of dispersal and common stochastic events in causing synchrony between spatially structured populations. 2. Cross‐correlation analysis of detrended time series was used to describe the spatial pattern of fluctuations in abundance, while standardized time series were used to describe both fluctuations and the trend in abundance. There were large variations in synchrony both within and between species and only weak negative relationships with distance. 3. Species in neighbouring habitats were more likely to be in synchrony than species separated by several habitats. Species with similar density‐dependent structure were more likely to be in synchrony. 4. In order to estimate the relative importance of dispersal and environmental stochasticity, we modelled the spatial dynamics of each species using two different approaches. First, we used estimating functions and bootstrapping of time series data to calculate the relative importance of dispersal and stochastic effects for each species. Second, we estimated the intensity of environmental stochasticity from climatic records during the breeding season and then modelled the dispersal rate and dispersal distance for each species. The two models exhibited similar results for rock ptarmigan, black grouse, hazel grouse and rock partridge, while contrasting patterns were observed for capercaillie. 5. The results suggest that environmental stochasticity plays the dominant role in synchronizing the fluctuations of these galliform species, although there will also be some dispersal between populations.
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