Thèse d'exercice : Pharmacie : Université de Nantes : 2005. / Bibliogr. f. 114-118 [51 réf.].

Résumé : Les méthodes de capture-recapture servent à décrire l’état d’une population et les processus qui en sous-tendent la dynamique, lorsque les méthodes d’observation et de détection de cette population sont imparfaites. En surveillance des maladies infectieuses, elles peuvent simplement être utilisées pour estimer la taille totale de la population infectée par un pathogène et estimer quantitativement la sensibilité du système de surveillance de ce pathogène. Bien qu'exploitées très largement dans le domaine de la santé publique pour répondre à cet objectif, l'utilisation des méthodes de capture-recapture (CR) en surveillance des maladies infectieuses animales peut être considérée comme récente. Parce que le contexte de surveillance des maladies animales est nettement différent de celui de la surveillance des maladies humaines, des questions demeurent quant à l'intérêt et aux limites de ces méthodes pour estimer la sensibilité des systèmes de surveillance des maladies animales. Pour tenter de répondre à ces questions, nous avons identifié quatre systèmes de surveillance différents par leur complexité, leur efficacité et leur maladie d'intérêt : nous avons retenu les systèmes de surveillance de la fièvre aphteuse au Cambodge, de l’influenza aviaire hautement pathogène (IAHP) H5N1 en Egypte, de la tremblante ovine en France et de l’IAHP H5N1 en Thaïlande. Pour chacun de ces systèmes de surveillance, nous avons déterminé le modèle de CR le plus adapté compte tenu des données générées (respectivement le modèle de CR à deux sources, le modèle log-linéaire à 4 sources, le modèle de comptage tronqué en zéro et le modèle de comptage enflé en zéro). Pour chaque application, nous avons donc estimé le nombre total d'unités épidémiologiques non détectées par les systèmes de surveillance considérés ce qui nous a permis d’apprécier la sensibilité de chaque système de surveillance considéré. Il est ressorti de ces applications que les méthodes de capture-recapture sont relativement faciles à conduire et qu’elles permettent à faible coût d’estimer l’importance réelle d’une maladie sur un territoire quand celle-ci est surveillée de manière imparfaite. Il semble cependant que les pratiques de surveillance et de contrôle des maladies animales limitent les applications à l’échelle de l’animal, et nécessitent d’élargir l’unité épidémiologique à une échelle supérieure (troupeau, commune, etc…). Cet élargissement introduit de nouvelles contraintes (notamment l’hétérogénéité d’abondance) qu’il est nécessaire de prendre en compte pour ne pas biaiser les estimations finales. Ce travail propose des perspectives d’application en épidémiologie descriptive, ainsi que des perspectives méthodologiques de recherche en statistique et en modélisation. / Abstract: Capture-recapture methods are generally used to describe populations when observation processes are imperfect. In the context of disease surveillance, they can be used simply for estimating the total size of the populations infected by a given pathogen, and hence, estimating quantitatively the sensitivity of the surveillance of this pathogen. Although they are widely used in public health, capture-recapture methods have been barely applied to the surveillance of animal diseases. Because the context of animal health is quite different from the context of public health, some questions remain concerning the benefits and the limitations of such methods for estimating the sensitivity of surveillance systems in animal health. For answering this research question, we identified four animal disease surveillance systems that differ by their complexity, their efficiency and their disease of interest. We selected the surveillance of foot-and-mouth disease in Cambodia, of highly pathogenic avian influenza (H5N1) in Egypt and Thailand, and of classical scrapie in France. For each surveillance system, we identified the most appropriate capture-recapture approach (respectively the two-source approach, the three-source approach, the zero-inflated approach and the zero-truncated approach). For each application, we estimated the total number of infected epidemiological units that remained undetected, and accessed an estimation of the sensitivity of each surveillance system. From these applications, we highlighted that these models are relatively easy to implement, and that they allow with little additional income to get an unbiased representation of the disease burden in a population when it is monitored with imperfect surveillance processes. However, it seems that practices used for the monitoring and controlling animal diseases tend to limit the applicability of these methods at the scale of the monitored unit. As a consequence, it is often necessary to enlarge the epidemiological unit (holding, commune, etc…) so that it comprises several monitored units. This enlargement introduces new constraints (abundance induced heterogeneity), that need to be taken into account in order not to bias final estimates. Finally, this work proposes surveillance perspectives for descriptive epidemiology, and methodological perspectives in statistics and modeling as well.

The study showed that density estimation of Eurasian lynx corresponds to 1.3 and 1.2 independent individuals per 100 km2 in the Jvorniky study area for the two time periods and 0.8 independent individuals per 100 km2 for Beskydy study area. The study failed to identify other large carnivores such a wolf (Canis lupus) and bear (Ursus arctos) from both Beskydy and Javorniky study areas. The estimated density of Lynx is low and their numbers should increase in future. There is enough prey base to support the existing population in the two study areas. The main factors effecting Lynx distribution are habitat fragmentation, poaching by humans, depleting the prey base by over hunting leading to starvation, vehicle collisions. Strict measures should be implemented to protect the species and long term study programmes must be started to get a comprehensive knowledge about the biology of species. Reintroductions must be carried over where there are suitable habitat for the survival and propagation of Lynx. The reason for not detecting wolf or bear might be due to the fact that the study areas are wide and the few migrating wolf or bear might be present outside my study area. Also there is lot of possibility to reintroduce wolf in my study area and I hope this will be done in future to ensure better biodiversity and to ensure wildlife conservation.

Noninvasive methods for monitoring wildlife species have revolutionized the way population parameters, such as population density and survival and recruitment rates, are estimated while accounting for imperfect detection using capture-recapture models. Reliable estimates of these parameters are vital information required for making sound conservation decisions; however to date, noninvasive sampling methods have been of limited use for a vast number of species which are difficult to identify to the individual level–a general requirement of capture-recapture models. Capture-recapture models that utilize partial identity information have only recently been introduced and have not been extended to most types of noninvasive sampling scenarios in a manner that uses the spatial location where noninvasive samples were collected to further inform complete identity (i.e. spatial partial identity models). Herein, I extend the recently introduced spatial partial identity models to the noninvasive methods of remote cameras for species that are difficult to identify from photographs and DNA from hair or scat samples. The ability of these novel models to improve parameter estimation and extend study design options are investigated and the methods are made accessible to applied ecologists via statistical software. This research has the potential to greatly improve wildlife conservation decisions by improving our knowledge of parameters related to population structure and dynamics that inform those decisions. Unfortunately, many species of conservation concern (e.g., Florida panthers, Andean bears) are managed without having the necessary information on population status or trends, largely a result of the cost and difficulty of studying species in decline and because of the difficulty of applying statistical models to sparse data, which can produce imprecise and biased estimates of population parameters. By leveraging partial identity information in noninvasive samples, the models I developed will improve these parameter estimates and allow noninvasive methods to be used for more species, leading to more informed conservation decisions, and a more efficient allocation of conservation resources across species and populations. / Ph. D.

Abstract I used individual-based capture-mark-recapture data and genetic markers to gain understanding of the demographic and genetic processes operating in small and declining populations of two different species, the willow tit Parus montanus and the Siberian flying squirrel Pteromys volans. Both species have declined in Finland and the flying squirrel has been considered to be vulnerable. The willow tit study was conducted in northern Finland, near city of Oulu. The population size in the studied area has on average been stable during the past decade. Adult survival in the willow tit was high and fairly stable and was positively correlated with recruitment. Adult survival has been the most influential vital rate to the population growth rate. Local recruitment and immigration have high variation, inducing variation in the population growth rate. Female willow tits use extrapair copulations to maximise offspring heterozygosity. Heterozygous individuals are supposedly of higher quality than homozygous ones. I found weak negative association between individual homozygosity and recruitment probability. The flying squirrel populations have declined during the past ten years. Furthermore, adult survival has declined in one of the populations, most likely due to habitat loss and fragmentation that decrease the adult survival and limit dispersal. The flying squirrel populations were studied in western Finland. The flying squirrel densities in the studied areas are the highest in Finland and therefore these areas have been regarded as favourable for the flying squirrel. My results question this view. Microsatellite analyses strengthen the view of populations doing poorly, because the heterozygosities in all the populations and particularly in the most isolated one were rather low. High FST values indicate low dispersal even between adjacent populations. Following work should investigate the spatial variation in individual performance and the dispersal processes in these populations. For the flying squirrel it is vital to determine the size and quality of the patches that can support flying squirrels and the ones that apparently can not. Present estimates of survival and genetic diversity can be used to reconstruct a meaningful PVA and projections for these populations.

Data sources and data quality are indispensable in economical, medical, pharmaceutical or other studies and provide the basis for reliable study results in numerous research questions. Depending on the purpose of use, a high quality of data is a prerequisite. However, with increasing registry quality, costs also increase accordingly. Considering these time and cost consuming factors, this work is an attempt to estimate the cost advantages when applying statistical tools to existing registry data. This includes methodological considerations and suggestions regarding the evaluation of data quality including factors such as bias and reliability after dealing properly (or not) with missing data (MD), and possible consequences when ignoring the incompleteness of data. Results for the quality analysis of the gastric cancer patients’ data example showed that millions of Euros in study costs can be saved by reducing the time horizon. On average, €523,126.70 can be saved for every year that the study duration is shortened. Replacing additionally the over 25% of MD in some variables, data quality was immensely improved, but still showed quality difficulties, which – beside MD in variables – could be an indication for completely missing entries of patients in the registry. Capturerecapture methods were therefore discussed to demonstrate how the total completeness in a registry can be estimated. Since it was not possible to illustrate the CARE method with the example of the gastric cancer patients due to the given data structure (no access to required variables), other data sets had to be chosen – the publicly accessible data of the amyotrophic lateral sclerosis (ALS) and data of towed vehicles in the City of Chicago. The consequence of ignoring MD was further analyzed using bankruptcy prediction data sets of agribusiness companies and confirmed the assumption that MD have a negative impact on the data quality, in this case also regarding the misclassifications of predictions of bankrupted companies. Using the decision tree method (known as one of the most suitable methods in predicting financial distress), the percentage of correctly bankruptcy-predicted of bankrupted companies (one year to bankruptcy) with MD imputation was 87.5%, whereas it was only 60% when completely omitting MD. Overall, my findings showed dearly the importance of statistical methods to improve data quality which in turn helps to avoid drawing biased conclusions due to incomplete data.

L’estimation de fréquence des maladies est nécessaire pour générer des hypothèses étiologiques et évaluer leur l’impact médico-économique. Cependant, il est possible que ces estimations ne reflètent pas uniquement les caractéristiques de fréquence intrinsèque d’une maladie mais aussi de variations dues à des choix méthodologiques qui diffèrent entre études. Cette hypothèse d’une variabilité des fréquences liée à des facteurs méthodologiques a été initialement soulevée par notre premier travail qui visait à estimer la prévalence du syndrome de Gougerot-Sjögren (SGS) primitif au sein de la population française de la Seine-Saint-Denis pendant la période 2007. Malgré une bonne exhaustivité d’identification des cas de 90 % calculée par la méthode de capture-recapture, notre estimation de prévalence de 1,02 cas pour 10 000 habitants est la plus faible estimation de fréquence du SGS primitif publiée dans la littérature à ce jour. En particulier, ce travail a souligné le possible impact des méthodologies de type « recensement » ou « échantillonnage » sur les estimations établies par des études de fréquence. Cette étude a montré aussi pour la première fois une prévalence 2 fois supérieure chez les patients non-européens par rapport aux européens avec des possibles phénotypes distincts. Pour explorer plus en détail l’hypothèse d’une variabilité entre les estimations générées par les approches de « recensement » ou de « échantillon », nous avons réalisé un deuxième travail qui consistait en une méta-analyse de la prévalence de la maladie de Behçet (MB) rapportée par 45 études internationales publiées dans la littérature. Des analyses en sous-groupes et par méta-régression ont montré des variations notables de la prévalence de MB entre zones géographiques mais aussi selon le type d’étude (recensement vs échantillonnage) utilisé. En analyse par méta-régression multivariée, seule la variable « type d’étude » était significativement associée aux valeurs de prévalence de la MB. En conclusion, ces travaux soulignent l’impact de la méthodologie utilisée pour conduire les études de fréquence des maladies. Les différences conceptuelles entre les études de recensement et les études échantillonnage soulevant la question sur la comparabilité des estimations obtenues par ces deux approches. / Estimating the frequency of diseases is of major importance for generating etiologic hypotheses and for assessing their global burden. Although such estimates may reflect the intrinsic frequency characteristics of a disease, they may also reflect variations due to methodological differences between studies. In our first study, we raised this assumption that the variability of disease frequency estimates is linked to methodological factors. This population-based survey aimed at estimating the prevalence of primary Sjögren's syndrome (pSS) in Seine-Saint-Denis, France, during 2007. Despite a high completeness of case-finding, 90%, assessed by capture-recapture analysis, the estimated prevalence of pSS of 1.02 cases per 10,000 adults was the lowest prevalence estimate published in the literature. Also, this study was the first to show a two-fold higher prevalence of pSS in people of non-European than European background and possible ethnicity-related differences in disease phenotypes. In addition, this study highlighted the possible effect of "census" or "sampling" designs on frequency estimates reported from population-based surveys. To explore in more detail the assumption that "census" or "sampling" approaches generate variability in frequency estimates of diseases, we performed a second study, involving a meta-analysis of the prevalence of Behçet's disease (BD) in published reports of 45 international studies. Subgroup and meta-regression analyses showed notable variations in BD prevalence estimates geographically but also by study design (census vs sampling). On multivariate meta-regression analysis, only study design significantly predicted BD prevalence estimates. In conclusion, this thesis highlights the importance of study design in population-based estimates of disease frequency. Conceptual differences between census and sample studies raise questions about the extent to which estimates obtained by either of these two approaches are comparable.

Introduction : Selon la publication conjointe par l’Organisation Mondiale de la Santé (OMS) et la Banque Mondiale du rapport mondial sur la prévention des traumatismes chaque année les accidents de la route sont responsables de plus de 1,2 million de morts dans le monde. 90% de ces décès surviennent dans les pays à revenu faible ou intermédiaire. Les accidents de la route concernent toutes les tranches d’âge, mais touchent plus particulièrement les jeunes actifs. La lutte contre ce fléau se heurte à la qualité des données sur les accidents de la route recueillies et rapportées, par le défaut de performance ou d’efficacité des outils de collecte des données existants et la non-représentativité des populations d’étude. Face à l’augmentation grandissante des accidents de la circulation dans les pays en développement et particulièrement dans notre pays, le Mali, et l’absence notoire d’un système de collecte de données fiable et extrapolable à la population générale, nous avons mis en en place un projet de recherche. Objectif : Etait de caractériser les accidents corporels de la route enregistrés dans les structures de santé et dans tous les commissariats de police du District de Bamako afin de proposer un système d’information efficace et durable permettant de doter le Mali d’un système de surveillance opérationnel et pertinent, à même d’aider à la prise de décision et aux actions opérationnelles de prévention et de prise en charge des accidents de la route favorisant ainsi la création d’un observatoire national de la sécurité routière basé sur la remontée et le codage des procès-verbaux. Méthode : A partir d’un appariement des données accidentelles corporelles de la route des structures de santé et de la police. Nous avons procédé à une estimation du nombre d’accidents par la méthode de capture-recapture sur une période de quatre mois (de Janvier à Avril) et assuré une surveillance épidémiologique sur 12 mois (de janvier à Décembre 2012) ne portant que sur les données collectées à la police. Résultats : L’estimation globale des accidentés a été nettement supérieur au dénombrement des 2 sources soit 8518 (8047-8990) victimes, contre 1432 pour la police et 3586 pour la santé. Nous pouvons conclure que la capture-recapture est une méthode sensible d’estimation de l’exhaustivité du nombre d’accidents de la route applicable dans les pays à revenu faible. Par contre avec la mortalité, cette sous-estimation diminue soit 99 versus 57 pour la police et 54 pour la santé. L’étude de la surveillance des AVP de Janvier à décembre 2012 a enregistré 2512 accidents avec 3905 victimes dont 407 blessés graves et 142 tués, impliquant 4434 véhicules. L’analyse des facteurs prédictifs de la gravité a révélé une vulnérabilité des moins de 15 ans OR=1,10(1,05-1,15) et des 60 ans et plus OR=1,15(1,06-1,25). Parmi les causes des accidents, l’imprudence du piéton a été le facteur le plus associé à la gravité des AVP OR=1,22 (1,06-1,40). Le défaut de lumière a été significativement associé à la gravité des accidents de la route à Bamako OR=1,05 (1,02-1,09). L’analyse des facteurs prédictifs de la létalité a élucidé un risque de mourir plus élevé chez les 60 ans et plus OR=1,06 (1,01-1,12). Les ménagères auraient un risque plus faible de décès que les autres couches socio professionnelles OR=0,97 (0,96-0,99). Parmi les causes des accidents de la route, l’imprudence du piéton a été le facteur le plus associé au risque de décès 1,11 (1,02-1,23) Les conditions climatiques surtout la saison des pluies et la saison froide ont été les périodes assez mortelles des accidentés de la route OR=1,08 (1,03-1,13). Conclusion : nous pouvons dire que cette étude a permis d'élucider les facteurs humains significativement associés à la gravité et la létalité des accidents de la route, mais aussi mis en évidence la nette sous-estimation du nombre des victimes de la route par la méthode de capture-recapture ayant comparé deux sources de données (police et hôpital). / Introduction: According to the joint publication by the World Health Organization (WHO) and the World Bankof the world report on the prevention of the traumas every year the road accidents are responsible for more than1.2 million deaths. 90 % of these deaths arise in low-income countries or intermediary. The fight against thisplague is impeded by the quality of the data which were collected and reported concerning road accidents, by thelack of performance and efficiency of the existing tools of data collection and the non-representativeness of thepopulations of study. In the face of the growing increase of the traffic accidents in developing countries andparticularly in our country, Mali, and the serious lack of a reliable and extrapolable data collection system in thegeneral population, we put in position a research project.Objective: It is to characterize the personal accidents of the road recorded in the structures of health and in allthe police stations of the District of Bamako in order to propose an effective and sustainable information systemallowing to endow Mali of an operational and relevant monitoring system which is able to help in the decisionmakingand in the operational actions of prevention and coverage of the road accidents thus, favoring thecreation of a national monitoring observatory of the road safety based on the rise and the coding of reports.Methods: we proceeded to an estimation of the number of accidents by the method of capture - recapture over aperiod of four months (from January to April, 2012) from a matching of the physical accidental data of the roadof the structures of health and the police. We also led an epidemiological surveillance over 12 months (fromJanuary to April 2012) concerning only the data collected in the police services.Results: The global estimation of the accident victims was absolutely upper to the enumeration of 2 sources thatis 8518 (8047-8990) victims, against 1432 for the police and 3586 for the health services. We can conclude thatthe capture - recapture is a sensitive method of estimation of the exhaustiveness of the applicable number of roadaccidents in low-income countries. On the other hand with the mortality, this underestimate decreases 99 versus57 for the police and 54 for the health services. The study of the surveillance of the RTA from January toDecember, 2012 recorded 2512 accidents with 3905 victims, among whom 407 badly wounded persons and 142persons killed, involving 4434 vehicles.The analysis of the predictive factors of the gravity revealed a vulnerability of individuals who were under 15OR=1.10 (1.05-1.15) and those who were 60 years old or above OR=1.15 (1.06-1.25).Among the causes of the accidents, the carelessness of the pedestrian was the factor the most associated with thegravity of the RTA OR=1.22 (1.06-1.40). The defect of light was associated significantly with the gravity of theroad accidents in Bamako OR=1.05 (1.02-1.09).The analysis of the predictive factors of the lethality showed arisk of dying higher with those were 60 years old and above OR=1.06 (1.01-1.12). The housewives had a lowerrisk of death more important than the other socio-professional classes OR=0.97 (0.96-0.99). Among the causesof the road accidents, the carelessness of the pedestrian was the factor the most associated with the risk of death1.11 (1.02-1.23). Weather conditions especially the rainy season and the cold season were the most lethal periodsof the road accident victims OR=1.08 (1.03-1.13).Conclusion: we can say that this study allowed to clarify human factors significantly associated to the gravityand the lethality of the road accidents, but it has also highlighted the important under estimation of the number ofthe victims of the road by the capture-recapture method which has compared two springs of data (police andhospital)

The population of bottlenose dolphins off the east coast of Scotland has been studied since the late 1980s, initially focused on the inner Moray Firth, where a Special Area of Conservation (SAC) was designated under the EU Habitats Directive. The population has since expanded its distributional range and currently ranges from the Moray Firth to the Firth of Forth. The main aims of this thesis were: (1) to estimate population parameters for this population using a 25 year individual recognition dataset, and (2) to increase knowledge of the distribution and abundance of dolphins in areas outside the SAC, especially to investigate areas of high use in St Andrews Bay. Apparent survival rate for adults and sub–adult dolphins was estimated at 0.946 (SE=0.005) accounting for temporary emigration caused by the population's range expansion. Sex-specific survival was estimated for males (0.951, SE=0.013) and females (0.956, SE=0.011) using multistate models to minimize bias caused by individuals of unknown sex. Using a newly developed approach, fecundity rate was estimated at 0.222 (95% CI=0.218-0.253) from an expected mean inter-birth interval of 4.49 yrs (95% CI=3.94-4.93). Total population size was estimated as ~200 individuals, after accounting for temporary emigration and for heterogeneity in capture probabilities. In St Andrews Bay, an area used regularly in summer by approximately half the estimated population, habitat use modelling identified the entrance to the Firth of Tay and waters around Montrose as high use areas for dolphins, whose presence was influenced by tidal current speed and direction. The results suggest that the conservation and management plan for this small and isolated population of bottlenose dolphins should be reviewed to adapt it to current knowledge, especially regarding the uncertainty around the potential impacts of offshore renewable energy developments off the east coast of Scotland.

Os efeitos da perda de hábitat e da fragmentação já estão bem estabelecidos na literatura, porém pouco se sabe sobre como o uso do habitat pode ser modificado em função de alterações na quantidade e na qualidade da mata. Este trabalho tem como objetivo compreender melhor como a perda e modificação do hábitat afeta o uso do espaço pelas aves de subosque na escala da comunidade e população. Para isso, utilizamos um banco de dados de aves, que inclui informação sobre captura e recaptura de 2.121 indivíduos, coletados em um gradiente de cobertura florestal, com fragmentos de 2,85 ha a 10.000 ha, localizados em Mata Atlântica no estado de São Paulo. As análises foram feitas por espécie, por grupos de espécies de acordo com guilda trófica e grau de sensibilidade a alterações antrópicas, e para a comunidade de forma geral. Para testar se a qualidade da vegetação influencia a abundância e frequência de uso do espaço, utilizamos dados de três áreas de florestas contínuas, com diferentes níveis de alteração (floresta secundária, mata com corte seletivo e mata madura). Observamos que, apesar de haver uma queda na abundância total da comunidade em fragmentos pequenos, há um aumento na frequência de uso do ambiente, evidenciado pelo aumento na taxa de recaptura com a perda de habitat. O mesmo padrão foi encontrado para aves com média sensibilidade, frugívoras e insetívoras. Aves com baixa sensibilidade, no entanto, mostraram maiores abundancia e taxa de recaptura em fragmentos menores e áreas mais desmatadas. Verificamos também que a frequência de uso do espaço foi maior em floresta secundária, bem como a abundância de aves. Nossos resultados sugerem que além de conduzir a uma perda de espécies e de indivíduos, a perda de hábitat também leva ao aumento na intensidade do uso do habitat. Este aumento se dá em particular para espécies de média sensibilidade, uma vez que espécies com alta sensibilidade estão ausentes de fragmentos pequenos. Observamos que, além da matriz como barreira à dispersão, a própria qualidade da mata se apresenta como um fator que modifica o uso do habitat. Esta variação no uso do habitat pode impedir que as mesmas desenvolvam seu papel de dispersores de sementes entre os fragmentos. Por fim, estudos sobre uso do espaço hoje praticamente não abordam a intensidade com que o hábitat é utilizado pelos indivíduos, sendo uma informação importante que pode ser facilmente estudada através de dados de captura e recaptura, geralmente subutilizados / The effects of habitat loss and fragmentation area well established in the literature, however not much is known about how habitat use can be modified due to alterations in habitat quantity and quality. This work aims to understand how habitat loss and changes to habitat quality affects the habitat use by understory birds at the community and population level. We analysed a database, which includes capture and recapture data from 2.121 individuals, of birds sampled along a gradient of Atlantic Forest cover and fragment size varying from 2,85 ha to 10.000 ha in the São Paulo State. We analysed data by species, by groups of species according to their trophic guilds and sensitivity to habitat change, and at the community level. To test if the quality of vegetation affects species abundance and the intensity of habitat use, we used data from three continuous forests, with different levels of habitat modification (secondary forest, forest selective logged and mature forest). Our results show that, although the total species abundance decreased in small fragments, the intensity of habitat use increases, as shown by the increase in recapture rates with habitat loss. This pattern was observed for birds with high and medium sensitivity, frugivorous and insectivorous. Species with low sensitivity, however, showed higher species abundance and recapture rate in small fragments. We also show that the frequency of habitat use was higher in secondary forest, as was the abundance of individuals. Our results suggest that habitat loss not only leads to smaller populations, but it also modifies the intensity of habitat use. This pattern was mostly observed for species with medium levels of sensitivity, as highly sensitive species were no longer present in small patches. Our results indicate that the matrix may act as a barrier for dispersal, but habitat quality may also further influence habitat use. This variation in habitat use can affect birds ability to disperse seeds between the fragments. Finally, studies of habitat use almost never focuses on the intensity of habitat use, even though this information can be easily evaluated using capture and recapture data, with the latter being usually underused