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  • 1
    In: Biodiversity Data Journal, Pensoft Publishers, Vol. 11 ( 2023-04-20)
    Abstract: In the past decades, agricultural land abandonment and declining land-use intensity became common, especially in the Mediterranean countries of southern Europe. In some areas, this development opened up possibilities for rewilding and the recolonisation or expansion of large mammal populations. Yet, in some instances, co-occurrence of wild mammals and free-ranging domestic herbivores might lead to potential conflicts. It is, therefore, necessary to study the ecological interactions between wild and domestic mammal species to understand the effects of land abandonment and rewilding on biodiversity and ecosystem services. Camera traps are an effective tool for studying species interactions and occupancy dynamics as they allow for long-term monitoring with minimal interference. We conducted a long-term monitoring programme with camera traps in the Peneda-Gerês National Park in northern Portugal. The area has undergone substantial land-use changes following the abandonment of agricultural areas in the past 60 years. While agro-pastoral activities, especially the breeding of free-ranging horses and cattle, are still common in the area, the intensity of these activities has decreased significantly, promoting natural succession and an increase or return of several large mammal species in recent years. Overall, our project aims at: (1) assessing the population trends of the medium and large sized mammals in the area over time; (2) analysing the effects of passive rewilding on occurrence, abundance and behaviour; and (3) understanding potential interactions or conflicts between wild and domestic herbivores. In this publication, we present results of a primary occupancy analysis between 2015 and 2020, as well as a comparison between occupancy and density estimates for 2019. Our publication provides a dataset from long-term camera-trap monitoring in the Peneda-Gerês National Park between 2015 and 2021. We established a 16 km² grid of 64 cameras deployed yearly during the summer months. Together with this publication, we publish the data and images collected between 2015 and 2021, using both the Camtrap DP standard and the GBIF Darwin Event Core. We obtained a total of 934,810 pictures on 41,234 trap nights. The pictures were automatically grouped into sequences with each sequence representing a distinct occurrence event, resulting in 80,191 occurrences. Out of those, 14,442 contained observations of a species, while the remaining were either blank or the species was not identifiable. We only obtained the information whether a species was present or absent on a picture, disregarding the number of individuals. Most observations were of domestic cattle ( Bos taurus ) and horses ( Equus caballus ), followed by European roe deer ( Capreolus capreolus ) and wild boar (Sus scrofa ). Further observations include red fox ( Vulpes vulpes ), gray wolf ( Canis lupus ), Eurasian badger ( Meles meles ), stone marten ( Martes foina ), common genet ( Genetta genetta ), Iberian ibex ( Capra pyrenaica ) and red deer ( Cervus elaphus ). We estimated occupancy and densities for the most common species. The project is on-going and additional data will be included in the future. The dataset is freely available for ecological analysis, but also for training machine-learning systems in automated image classification as all pictures have been manually classified.
    Type of Medium: Online Resource
    ISSN: 1314-2828 , 1314-2836
    Language: Unknown
    Publisher: Pensoft Publishers
    Publication Date: 2023
    detail.hit.zdb_id: 2736709-5
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  African Journal of Ecology Vol. 60, No. 3 ( 2022-09), p. 423-432
    In: African Journal of Ecology, Wiley, Vol. 60, No. 3 ( 2022-09), p. 423-432
    Abstract: Le distance sampling par piège photographique (Camera trap distance sampling ou CTDS en anglais) est une technique de recensement développée récemment qui permet d’estimer l’effectif de populations animales non marquées avec des pièges photographiques. Cette technique requiert l’estimation de la distance entre le piège photographique et l’animal observé, ce qui était précédemment obtenu en comparant la position de l’animal à des points de référence placés à des intervalles prédéfinis. Ici nous testons une approche de photogrammétrie pour estimer les distances entre les pièges photographiques et les animaux observés. Nous avons appliqué les deux approches, points de référence et photogrammétries, à cinq espèces d’ongulés de tailles différentes ( Giraffa camelopardalis, Equus grevyi, Oryx dammah, Kobus megaceros et Eudorcas thomsonii ) ainsi qu’une espèce d’oiseau ( Numida meleagris ) vivant dans un espace clôturé et avons estimé leur densités de populations avec le CTDS. Les deux méthodes ont fourni des distances d’observations fortement corrélées (ρ = 0.99, p 〈 0.001). Un t‐test jumelé a révélé une moyenne légèrement plus élevée et significative pour la technique de photogrammétrie (MD = 0.28 m, p 〈 0.001). Celle‐ci est néanmoins négligeable dans la mesure où, pour les analyses, les distances étaient groupées dans des intervalles allant de 2 à 5 mètres. En règle générale, les estimations d’abondances étaient proche du nombre réel d’individus dans l’enclos, et ce pour les deux techniques, avec l’exception des zèbres pour lesquels les densités étaient sous‐estimées. La technique de photogrammétrie offre une alternative pour dériver les distances entre les pièges photographiques et les animaux observés et pourrait être particulièrement utile dans des habitats ouverts où les animaux sont peu cachés.
    Type of Medium: Online Resource
    ISSN: 0141-6707 , 1365-2028
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2019879-6
    SSG: 12
    SSG: 14
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