Au Mont Ventoux, le régime de la Vipère d’Orsini est, pour plus de 99 % constitué d’Orthoptères, insectes très abondants dans le milieu, tandis que les Vertébrés tétrapodes, également présents ne sont pratiquement pas consommés. La sélection des proies ne dépend que de leur taille : les Orthoptères ne sont consommés qu’à partir de 16-17 mm de longueur totale. Cette taille minimale est la même quel que soit l’âge des vipères.
La période d’alimentation, très courte, s’étend de la fin-juin à la fin-septembre pour toutes les vipères, quel que soit leur âge ou leur état sexuel. Les immatures n’entrent en activité qu’au début de la période d’alimentation : leur période annuelle d’activité s’étend sur environ 3,5 mois, contre environ 5 et 6 mois respectivement chez les femelles et les mâles adultes.
Les prises alimentaires sont fréquentes et les contenus stomacaux petits. Les femelles gestantes se nourrissent pendant la gestation.
Un foyer de grégarisation de Dociostaurus maroccanus (Thunb.) a été étudié au cours de cinq missions annuelles (1988-1993). Le site d’étude est un pâturage d’altitude dans l’Anti-Atlas (2 300 m) où les troupeaux estivent. Sur les 2 850 ha de pâturages à Poa bulbosa le nombre de moutons et de chèvres a été estimé à 7 200 têtes (une tête pour 0,4 ha).
Les Acridiens (18 espèces) et leurs prédateurs (14 espèces d’insectes et oiseaux) sont cantonnés autour d’une prairie de fauche et des cultures irriguées (55 ha). Le site de ponte du Criquet marocain est sur un parc à moutons de 2 hectares. La densité moyenne d’oothèques est de 77/m2, dont 37 % sont détruites par des larves de Coléoptères (Méloïdes) et des larves de Diptères. Falco naumanni Fleicher et Pyrrhocorax pyrrhocorax docilis Gm. sont des prédateurs de criquets, importants sur le site. Les Craves à bec rouge ont été observés déterrant les oothèques pour les manger.
Il est connu que les moutons créent les conditions favorables à la grégarisation du Criquet marocain. Nous montrons que le strict calendrier des activités pastorales influence aussi la dynamique des populations acridiennes : les éclosions ont lieu en mai dans un milieu non perturbé par les moutons et à l’abri des prédateurs jusqu’à la fenaison. La transhumance le 28 juillet, en pleine saison de ponte, modifie l’espace et les ressources trophiques disponibles.
Eperua falcata Aubl. is the most common of the large tree species in the lowland rain-forest of Piste Saint Elie (French Guiana). One of these tall trees was felled for scientific purposes and found to have a bole hollowed throughout its entire length. This hollow trunk was filled with organic soil in which a complete adventitious root system had developped. This internal root system originated at the first fork (16 m above ground level) and penetrated the hollow trunk down to soil level through numerous fine roots. In this case the life span of the tree was probably increased, as its stability and its nutrition were improved by the extra roots. Such a situation is quite likely to be exceptional and due to accidental circumstances where both termites (or ants) and microorganisms played an important role.
Further examples of the use of tools (mostly sticks) to scratch various body parts are reported among four species of captive cercopithecines.
The alternative use of hand and stick to scratch the same body part suggests that the two grooming techniques are percieved differently by the animal. Instrumental scratching seems to be pleasurable and to lead to a decrease of «emotional tension» ; when prolonged, it can even lead to sleep. This suggests an analogy with the self-stimulation of brain’s «pleasure centers» by rats.
Agroforestry is a new approach which aims to reconciliate agricultural and forestry sciences. However, agroforestry is an old practice. In the humid areas of the tropical world, peasant agrosystems often associate annual crops and tree crops, agriculture and management of natural forests.
The great diversity of forest environment and of agricultural systems in Indonesia gave rise to a variety of agroforestry practices, which range from fairly simple modifications of the forest ecosystem, or tree-crop enrichment fallows in shifting cultivation, to complex agroforests and sophisticated home-gardens.
Facing the ever increasing problems due to deforestation and genetic erosion, village gardens in Java or complex agroforests in forest areas of Sumatra can contribute to the conservation of natural forests and of their resources.
The traditional knowledge concerning utilization and management of trees, forest stuctures and sylvigenetic mechanisms, which peasants developped over centuries, is of great value. It could inspire programs involving both conservation and economic use of forests in the tropics.
Cedar tree is a mountain forest species that occurs naturally in the Maghreb region. This study describes the consequences of a strong attack of Thaumetopoea pityocampa Schiff. on century-old cedars in Chréa National Park, 50 km southwest of Algiers. Period of damage was assessed by nest census. After two consecutive defoliation events, maximum reduction in growth rate was recorded one year after the first defoliation. Up to 50 % of growth lost were calculated for a complete defoliation. A reduction in growth rate in subsequent years was lower due to trees undergoing recovery growth. These results could contribute to improved management of insect infestations and the protection of cedar plantations, and raise questions about the potential increase of insect attacks with climate change.
The Mastomys erythroleucus population of a sahelo-sudanian woodland has been studied from August 1976 to October 1979 on two quadrats : a control quadrat (QC) 2.5 ha in size, and a provisioned quadrat (QA) 4 ha in size, where food pellets were regurlarly provided twice a week since September 1976 (yearly food supplement : 120 kg/ha/yr).
The following changes were observed on the provisioned quadrat : (1) an increased population density, (2) an increased production of young, and (3) an improvement of their survival rate. Two further changes were also noticed : (4) while the number of immigrants was not significantly different on the two quadrats during the experiment, the duration of their stay was greater on the provisioned area than on the control area, and (5) the size of the resident females home ranges was decreased.
Whereas the experimental increase in food availability and predictibility triggered in this case an increase in Mastomys erythroleucus population density through a better recruitment, it was not influential in preventing the population decline which took place at a similar rate on both quadrats in 1977.
This paper presents preliminary data on the feeding strategy of the Black colobus, Colobus satanas, in central Gabon. The study was conducted in the Réserve de la Lopé, using frequency method and systematic monthly samples to quantify the diet on one focal group of monkeys.
The Black colobus feeds predominantly on immature seeds, unlike most of its folivorous relatives, while the consumption of young leaves is second in importance. Despite considerable variation in resource availability, seeds always dominate in the monthly diet. An increase in young leaf consumption was associated with an abundance of flush leaves, but also a reduction in seed availability ; a subsequent seasonal peak of flush leaves showed rm increase in their contribution to the diet, as seeds were also commonly available. Mature leaves were rarely eaten, and their occurence in the diet could explain some aspects of concomitant geophagy.
Seasonal variation in diet and resources is compared with that of other primates of North-East Gabon : availability of foliage also partly influences consumption, but the dependence largely on fruit pulp and lack of seeds in the diet contrasts sharply with Black colobus. A similar biomass of Cercopithecidae is found in North-East Gabon where colobus are absent, and Lopé where one might have expected a larger biomass if the Black colobus had been a true folivore.
Folivorous and frugivorous dietary strategies are contrasted on the basis of energetically economical vs expensive feeding. The Colobinae tend towards economical feeding strategies with their specialized digestive apparatus, but C. satanas represents a contrast, favoring an expensive seed-eating strategy. A hypothetical mechanism for the behavioural regulation of these strategies is discussed, based on conditioning principles. With such behavioural flexibility, we suggest that seed-eating by Black colobus may be a positive choice rather than a result of selective pressures against folivory.
Un aliment artificiel à base de céréales fut distribué pendant les neuf mois de la saison sèche 1976-1977 sur 2,25 ha d’une savane sahélienne du Nord-Sénégal, qui supporte une population du Gerbillidé Taterillus pygargus.
Les résultats d’une série de piégeages avec marquages et recaptures multiples sur la surface approvisionnée et sur une surface témoin montrent que les conséquences du supplément nutritionnel furent d’une part une prolongation de la saison de reproduction, d’autre part une concentration d’individus pendant la première partie de la saison sèche, de novembre à janvier ; mais, le très fort déclin qui affecta la population de Taterillus dès le mois de décembre 1976 ne fut pas modifié par la présence du supplément alimentaire : l’origine de la mortalité ne pouvait donc être une raréfaction de la nourriture disponible.
Une analyse des contenus stomacaux de Leporinus friderici, Myleus rhomboidalis et M. ternetzi a été réalisée à partir d’échantillons provenant de deux peuplements distincts de Guyane Française, prélevés aux différentes saisons caractéristiques de cette région néotropicale : la grande saison des pluies, la grande saison sèche et la petite saison des pluies, l’étude du régime alimentaire en petite saison sèche ayant été volontairement omise.
M. ternetzy est un herbivore strict, qui consomme quasi-exclusivement des feuilles prélevées sur les arbres pendant les inondations de la saison des pluies, et des feuilles flottant à la dérive en saison sèche.
M. rhomboidalis se nourrit surtout de graines Euterpe oleracea en saison sèche. Cette espèce diversifie son régime alimentaire en saison des pluies en consommant plusieurs espèces de graines et des arthropodes.
Le régime de L. friderici présente un caractère omnivore marqué. Ce poisson se nourrit essentiellement en saison des pluies et consomme alors des graines et des arthropodes tombés des feuillages.
Ces résultats sont interprétés comme exprimant les préférences alimentaires de ces espèces en saison des pluies, alors qu’en saison sèche se développent des stratégies de survie.
Vingt et une espèces de palmiers réparties en 9 genres ont été recensées sur 10,56 ha dans les forêts de l'est amazonien, vallée du Tocantins, Etat du Parà. La densité moyenne de palmiers (ou d'axes pour les espèces multicaules) de hauteur égale ou supérieure à 1 m est de 602 par hectare. Une comparaison avec deux autres inventaires situés dans le centre et l'ouest de l'Amazonie révèle la pauvreté en espèces et genres de palmiers et leur faible densité dans ces forêts de la région orientale. (Résumé d'auteur)
Les stratégies de développement de deux Graminées pérennes Andropogon ascinodis et Schizachyrium sanguineum ont été comparées au cours du cycle annuel dans deux savanes soudaniennes peu anthropisées du nord de la Côte-d’Ivoire (Ouango-Fitini) et au Burkina Faso (Nazinga).
La morphologie, le mode de croissance et le mode de reproduction sont très semblables : la stratégie globale de vie des deux plantes est conforme au type «compétiteur » défini par Grime (1979). On peut donc s’interroger sur ce qui peut expliquer leur coexistence fréquente dans les mêmes milieux. Une étude détaillée du rythme saisonnier de croissance (effectifs des tiges et des feuilles, natalité, mortalité et durée de vie des feuilles), et de certains aspects de la morphologie (nombre et longueur des entre-nœuds) met en évidence des différences dans leur architecture qui correspondent à de légères variations de la stratégie de croissance.
L’hypothèse est proposée que ces quelques différences, ainsi que l’hétérogénéité temporelle du milieu, peuvent expliquer la coexistence de ces deux espèces. La possibilité d’une appétence différente pour les grands herbivores est également examinée.
The relationships between a community of nine nocturnal frugivorous mammal species and the plants on which they feed were studied during 14 consecutive months in a secondary forest near Cayenne, French Guiana.
Two major trophic groups can be defined :
1.-The seed eaters, which open unripe fruits to eat their seeds. All are rodents : Coendou prehensilis (average adult weight 4 000 g), Echimys armatus (400 g) and Oryzomys concolor (35 g).
2.-The pulp eaters, which specialize in ripe fruits. They eat the pulp and swallow most of the seeds which are disseminated with their feces. Five of them are marsupials : Didelphis marsupialis (1 000 g), Philander opossum (400 g), Caluromys philander (300 g), Marmosa cinerea (80 g) and Marmosa murina (45 g). The sixth species is a Procyonid Carnivore : Potos flavus (3 000 g) .
These differing types of feeding strategies are discussed in relation to the morphology of the teeth and digestive tract of the species.
Species with a similar diet and comparable body size generally live in different forest layers.
The population density and biomass of these nocturnal frugivorous mammals were estimated on the basis of direct counts along forest trails at night, trapping results and radio-tracking.
Out of the 127 plant species listed, 26 play a major role as a food source for the mammals studied. The trunk diameter (DBH) of the 13 most common species was measured, and the distribution of these trees mapped in the 8.5 ha study area. These 13 tree species account for approximately half of the total basal area, which is considered here as an index of standing crop biomass. The same 13 species account for 25 % of the total number of individual trees.
Fruit production was measured during 13 months by weighing all fallen fruits along 1 200 m of trails. Fruit production and consumption of the same species were also estimated by the use of fruit collectors located under fruiting trees.
Special attention was given to the phenological cycles of trees. Three types of fruiting cycles could thus be related to three different foraging strategies of the sympatric frugivorous mammals : 1.-Species with a low fruit production spread over an extended time period. Only a few fruit ripen at the same time, but fruiting takes place almost all year long. Such trees are early- or late-pionneer species ; their fruits have tiny seeds which are mainly eaten by small vertebrates which scatter them more or less homogeneously.
2.-Species with synchronous, but irregular cycles of fruit production. Such trees have rather large seeds which are very attractive to seed-eating rodents. These animals even destroy part of the fruit crop before ripening. The massive, irregular, and unpredictable fruiting cycles of these species may reduce seed predation by rodents. The few trees belonging to this category which do not bear fruit synchronously with their conspecifics may have their crop totally destroyed by rodents.
3.-Species with synchronous and regular cycles of fruit production. Such trees have rather large seeds, which are ingested by large frugivorous vertebrates and spread through their feces. Chemical or physical deterrents are generally present in such fruits before ripening. The tree species belonging to this category have successive and partly overlapping periods of fruit production. In this way, food is made available for pulp-eaters during most of the year. This pattern of fructification is presumably the end-result of a long lasting mutual interaction between plants and seed-scattering vertebrates.
Frugivorous mammals apparently need two different kinds of fruit in their diet, some rich in sugar and others rich in fat. Trees producing these two categories of fruit produce their crop successively, so that the necessary nutrients are made available throughout the year.
A definite decrease in fruit production takes place in our study area just before the beginning of the dry season. The marsupial pulp-eaters have adapted to this temporary food shortage by storing fat during the season of plenty. However, their production of young is strongly affected by this seasonal food shortage, as shown by an increased mortality rate of pouch youngs.
One hectare of sahelian savanna has been sampled for birds’ droppings during a whole annual cycle. Calculation shows that birds have recycled 12,8 kg of nitrogen and 0,9 kg of phosphorus, so birdlife has a non negligeable impact on soil fertility.
Birds’ contribution reaches 80 % of the amount of nitrogen that will be recycled by above ground vegetal litter, and 64 % of phosphorus. These percentages would be lower if the underground vegetal parts were included. This deposit is much more important below tree cover since birds use to perch in trees rather than outside.
Two wells being close to the study area, birds may have concentrated there, particularly during the dry season. Therefore it is not advisable to extrapolate results to the whole Ferlo region.
Processes leading to forest regeneration in a mature rain forest of French Guiana were studied on six plots representing initial stages of regeneration, from 2 to 10 years following clear-cutting.
The first woody species to appear in plots after tree felling are light demanding species growing from seeds remaining dormant in the rain forest soil. Such a «seed bank» is very heterogeneous, its composition being strongly influenced by the proximity of forest gaps and tree falls. Burning and increased soil compaction can prevent dormant seeds from germinating. Other seeds are disseminated by frugivorous bats and birds, yet other by wind. A few other regenerating plants are sucker shoots from cut stumps of shade tolerant species of the undergrowth, which grow easily beneath the canopy of pioneers.
The pioneer vegetation (Table I) is characterized by a low species richness : no more than 15 species (out of a grand total of 113 found 3.5 years after clear cutting), contribute to 85 % of the woody community. The seeds of these pioneer species are dispersed by bats and birds. Twenty species of frugivorous bats were observed in the study area, out of which only 4 (Table II) were abundant in the regenerating forest. Forty species of birds (Table III) also contribute to seed dispersal, out of which 16 species are restricted to second-growth. Some of these birds have a limited flight range and tend to disperse seeds more or less evenly around feeding trees. Other birds, particularly «lek» forming species (Pipridae), tend to defecate mainly around their traditional display grounds and generate a more aggregative dispersal of seeds. Some generalist species with a mixed insectivorous and frugivorous diet (Turdus albicollis and Ramphocelus carbo) are the first birds to colonize newly formed gaps in the forest.
The «seed rain» generated by bats during the night and by birds during the day, was measured (Table IV) both in the open and under the trees, using plastic collecting sheets. Only bats defecate in the open in a 50 metre wide belt bordering the forest edge. Seed rain generated by birds was observed only under isolated trees used as perches in the open, and to a lesser extent in the undergrowth of the mature forest.
La base de données sur l'écologie des coléoptères saproxyliques (FRISBEE): un outil taxinomique et écologiques pour l'évaluation de l'état de conservation des forêts. La base de données sur l'écologie des Coléoptères saproxyliques français (FRench Information system on Saproxylic BEetle Ecology, FRISBEE) a pour objectif la compilation organisée de l'information écologique disponible pour toutes les espèces de Coléoptères associées au bois mort ou dépérissant, ou aux micro-habitats connexes. Cette base de données relationnelles est composée de 4 tables: (i) une table bibliographique, (ii) une table taxinomique, dotée d'une référentiel taxinomique des espèces avec leur valeur patrimoniale, (iii) une table écologique, incluant 11 descripteurs du bois ou traits écologiques caractérisant l'association des insectes aux attributs ligneux, (iv) et une table photographique. La base FRISBEE constitue un outil pragmatique pour l'évaluation de l'état de conservation des forêts ou pour l'analyse fonctionnelle des assemblages d'espèces. / The FRench Information system on Saproxylic BEetle Ecology (FRISBEE) is aimed at organizing species-specific ecological information for all wood-associated beetle species in France. Four tables are linked in a relational database structure: (i) the reference table, (ii) the taxonomical table, containing information with standardized nomenclature and species patrimonial value, (iii) the ecological table, including 11 wood parameters or ecological traits that categorize the association of a species to different wood attributes, (iv) and the photographic table. The FRISBEE database is meant to serve as a pragmatic tool for assessing the conservation status of forests and for carrying out functional analyses of saproxylic beetle assemblages.
The structure of the woody vegetation of 65 sample plots of sudanian savannas in northern Togo is analyzed using correspondance analysis (reciprocal averaging).
Five groupings of species were identified, each with some characteristic species, and a number of environmental factors responsible for the presence or absence of the latter were singled out. The role of anthropic and edaphic factors is emphasized. Man drastically alters the floristic structure of the vegetation, either directly by selecting useful species, or indirectly by creating conditions (fallow fields) that favour ruderal species with quickly sprouting new shoots. The nature of the soil is equally important : in areas with similar rainfall, differences in soil type explains the presence of either sahelian or guinean species.
Our results are compared with those of previous vegetation surveys. Four of our species groupings correspond to vegetation categories already described. However, our fifth grouping, characteristic of eroded areas, had never been identified previously.
The two sites of the northwest of Madagascar, where Ramanantsoa (1976) observed “sacred lemurs”, have been revisited in order to assessing the present status of Eulemur macaco and the possible impact of human beliefs and practices on conservation. All the sacred relationships towards lemurs described in 1976 are still in practice, and very similar descriptions about the benefic (or malefic in case of non-respect) effect of the “sacred lemurs” have been quoted by our informants. A direct impact on lemur conservation, and utilisation of study sites for scientists, as suggested by G.-A. Ramanantsoa, do not appear as realistic options, considering the remote location of both sites. In contrast, a further study of religious practices concerning lemurs should be an important contribution for shaping sustainable development programmes involving local populations.
The national nature reserve of Saint-Brieuc Bay, located in the north of Brittany, is a site of international importance for the wintering of the Black-bellied Brent goose Branta bernicla bernicla although its preferred food, eelgrass, is completely absent. Local monitoring points out that the green seaweeds Ulva armocicana represents 90% of the food eaten by the Brent geese. These algae are responsible for the spectacular green tides which greatly impact this bay each summer. The 400 odd tons consumed each winter by the Brent geese are insufficient to curb this phenomenon. However, the resorption policy of the nitrogenized surpluses arriving in the bay in order to fight against the aestival green tides could, in the long term, reduce this food resource and force geese to find a Substitution food which, locally, could be a grass growing on salt-marshes (Puccinellia maritima) or winter cereals growing in arable lands bordering the bay. To avoid possible crop, the national nature reserve could have to increase the surface of Puccinellia maritima meadows by mowing or by converting to pasture on the climacic areas with Halimione portulacoides as is the practice on the Atlantic coast, in Aiguillon Bay. This will have to be done with caution, the areas with sea-purslanes being important feeding grounds for young fish during the high tides. It is quite singular to see that, in this bay, a wintering area of international interest for a water bird developed thanks to serious environmental perturbation and that this ornithological interest could be disrupted by current curative policies of water quality restoration, should no compensatory measures come to balance for the hoped reduction of the green tide.
Saproxylic beetles are species-rich, mostly small and cryptic, and difficult to sample. Different methods are traditionally used to collect saproxylic beetles. These are (i) direct active collection techniques, (ii) rearing techniques and (iii) mass trapping methods. Window-flight trapping is currently the most frequently used technique for catching flying active saproxylic beetles. Thanks to the combination of different trap principles, window-flight trap devices may differ by a large number of intrinsic parameters. This paper offers further insight into the influence of 3 trap factors on the catches of dead wood associated beetles, by comparing (i) cross-vanes or single-plane WFT (shape effect), (ii) black or transparent CWFT (silhouette effect), (iii) low or high CWFT (height effect). Six ecological data sets from French upland or lowland, deciduous or coniferous forests, with paired freely hanging window traps on each plot, were compiled in this study and analysed with a methodological point of view to compare the efficiency of sampling methods. Trap shape had a significant and strong effect on the abundance and species richness of saproxylic beetles. The single-plane traps caught a higher number of individuals and species. Nevertheless, given time/cost constraints, cross-vanes traps are recommended. Our study shows that black and transparent cross-vanes traps yielded similar saproxylic samples in terms of abundance, richness and overall composition. Our results confirm the vertical differentiation of saproxylic beetle assemblage. They suggest that low cross-vanes window traps yield more species-rich and individual-rich samples than canopy traps. Except Melyrids, no abundant species showed a strong association with top traps. Further optimisation analyses based on larger datasets are required to make sampling methods more reliable.
The Yam beetle Heteroligus meles is found in tropical Africa both North and South of the equator, and in savannas (in humid areas along watercourses) as well as in rain-forests.
This species is monovoltine in West Africa. Its life-cycle is characterized by two migrating flights : one (the feeding migration) takes place at the beginning of the rains away from the areas where the larvae have developped ; it is effected by imagos of low body weight. The second migration flight (the breeding migration) occurs at the outset of the dry season in a reverse direction and is effected by heavier imagos.
At Makokou (Gabon), which is located South of the climatic equator, but North (0.4°N) of the geographic equator, preliminary observations suggest the coexistence of two sympatric populations of yam beetles, one with a boreal life-cycle and the other with an austral life-cycle — as it is the case for the bat Hipposideros caffer.
An attempt is made to assess the relationships between soil conditions and the spatial distribution of two sympa trie species of rain forest trees belonging to genus Eperua (Caesalpiniaceae). The study was carried out at the Paracou study site, French Guiana, on the domed hills of precambrian basement rock, locally schistose or migmatic.
The relationships between the distribution of individuals of both species and soil variables (126 samples) were studied using factor analysis and hierarchical classification.
Eperua falcata is mostly found on hydromorphic or shallow vertically drained soils, often with a high exchangeable aluminium content. This tree appears to be well adapted to unfavourable soil conditions, but it can also be found in other situations.
Eperua grandiflora is also adapted to shallow soils, but it does not withstand hydromorphic conditions as well as E. falcata ; it is also very sensitive to the high aluminium content of the soil.
The two Eperua species are therefore complementary to one another, except on shallow soils, thus allowing genus Eperua to fill different edaphic niches.
The tracks of wolves crossing the frontiers make it possible to study the exchange of population. An increase in the crossings is recorded which is due to an increase in the number of wolves in Soviet Karelia. The culling of populations resulted in a slight decrease of the number of wolves in the Soviet Union.
The seasonality of fruit-production in an Ivory Coast lowland rain-forest has been studied over a whole year cycle along a 15 km transect in the Taï National Park.
A definite seasonality has been found, most trees bearing fruits in December-January, in the middle of the dry season. This is particularly the case for animal-dispersed species, by far the most numerous. The peak production of fruits by wind-dispersed species occurs a little later, at the end of the dry season, whereas mechanically dispersed (autochorous) species bear fruit at the end of the rains.
The breeding biology and demography of Blue tit (Parus caeruleus) and Coal tit (Parus ater) populations of southern France and Corsica were compared from 1976 to 1980. The following differences between the mainland and the island populations were found :
1. — The onset of the breeding season is delayed in Corsica, egg-laying beginning three to four weeks later than on the mainland.
2. — The clutch-size is smaller on the island, the clutch averaging three more eggs on the mainland. 3. — The mortality of the nestlings is also much higher in Corsica than in southern France, due to heavy parasitism by Trypocalliphora sp. and food shortage which cause heavy mortality.
4. — However, the survival rate of adult tits is higher in Corsica than on the mainland.
5. — Contrary to what is the rule in southern France, Corsican tits do not apparently breed at the time of maximum food abundance.
The demographic strategies of the Corsican populations of Blue and Coal tits are apparently K-selected.