Now showing 1 - 5 of 339
- ItemOpen AccessEffect of implementation of irrigation on raptor and corvid populations in a Mediterranean agrosystem(Museu de Ciències Naturals de Barcelona, 2023) Villanúa, D.; Cabodevilla, X.; Ardaiz, J.; Lizarraga, A.; Zufiaurre, A.We analyzed changes in the composition of the community of birds of prey and corvids in a rainfed agrosystem after the transformation of 37.2 % of the sampled area into irrigated land between 2005 and 2020. We sampled 57 transects (372 km per year) and fitted generalized linear mixed models (GLMM) to study changes in species occurrence. Our results showed that specific richness and the Shannon index did not vary significantly between rainfed and irrigated transects, but there was a certain positive trend when comparing the years 2005 and 2020. Regarding the differences detected for each species, the occurrence of Montagu’s harrier Circus pygargus, hen harrier Circus cyaneus, Eurasian short-toed eagle Circaetus gallicus, griffon vulture Gyps fulvus and carrion crow Corvus corone was significantly lower in irrigated land than in rainfed land, while magpie Pica pica, Western marsh harrier Circus aeruginosus, common kestrel Falco tinnunculus and black kite Milvus migrans showed a significantly higher occurrence in the irrigated transects. In addition, our findings confirm a significant decrease in occurrence between 2005 and 2020 both in rainfed and irrigated areas for Montagu’s harrier, hen harrier and magpie, while Western marsh harrier, golden eagle Aquila chrysaetos, common buzzard Buteo buteo, red kite Milvus milvus, griffon vulture Gyps fulvus, red-billed chough Pyrrhocorax pyrrhocorax and Western jackdaw Coloeus monedula were detected significantly more frequently in 2020 than in 2005. These results suggest that assessment of the impact of a new irrigation system should focus on the most characteristic species of rainfed agrosystems because the apparently positive effect on other species, equally protected but more generalist, may mask the real effect on conservation.
- ItemOpen AccessReappraising the use of forearm rings for bat species(Elsevier, 2023) Lobato-Bailón, Lourdes; López-Baucells, Adrià; Guixé, David; Flaquer, Carles; Camprodon, Jordi; Florensa-Rius, Xavier; Mas, Maria; Torrent, Laura; Ordeix, Laura; Tallo-Parra, Oriol; Ribas, Maria P.; Marco, Ignasi; Carvajal, Annaïs; López-Bejar, M.; Napp Avelli, Sebastián; Pailler-García, Lola; Espunyes, Johan; Cabezón Ponsoda, ÓscarLong-term mark-recapture studies are essential for bat conservation. Over the last decades, millions of bats across Europe and America have been marked with forearm rings for this purpose. Although it is considered a cost-effective method compared to Passive Integrated Transponders (PIT) tags, direct injuries from using forearm rings have been reported since their very first use. Yet, their impact on bats' welfare has not been systematically evaluated and remains a highly controversial issue among the scientific community and policymakers. Here we assess the impact of forearm rings and PIT tags on the health of different bat species. We reviewed 12 years of the existing recapture data of free-ranging bats from NE Spain and evaluated the impact of both marking tools in a captive colony of Carollia perspicillata, by assessing the development of skin lesions and levels of cortisol metabolites in guano (CG) after marking. We report that 55.1 % (435/790) of the recaptured free-ranging bats with forearm rings presented skin lesions. All banded C. perspicillata (n = 22, 100 %) developed skin lesions, whereas none of the PIT-tagged (n = 21) presented lesions. Levels of CG were significantly higher after marking with forearm rings only for one group. Banded C. perspicillata exhibited discomfort-associated behaviours due to forearm rings. Under the “precautionary principle”, we recommend the ban of forearm rings for all bat species until species-specific studies under controlled conditions are performed and approved by a legally constituted ethics committee. Consideration of other long-term marking tools is mandatory to align with global bat conservation strategies.
- ItemOpen AccessFunctional habitat suitability and urban encroachment explain temporal and spatial variations in abundance of a declining farmland bird, the Little Bustard Tetrax tetrax(Resilience Alliance, 2022) Arroyo, Beatriz; Estrada, Alba; Casas, Fabian; Cardador Bergua, Laura; De Cáceres, Miquel; Bota, Gerard; Giralt, David; Brotons, Lluís; Mougeot, FrançoisSpecies response to land use can be examined under a functional perspective, where habitats are described according to species´ resource dependencies. Distribution or abundance models based on resource availability rather than land use types can be more informative about the ultimate processes behind observed population or distribution trends. Habitat use may depend on resources available, as well as disturbances that affect accessibility to such resources. Increasing human presence and urban encroachment may thus alter the relationships between habitat suitability and species abundance. Using 10 years of field data, we investigated whether variability in Little Bustard (Tetrax tetrax) abundance was explained by functional habitat suitability (assessed through resource-based models) and urban encroachment. We found that spatial and temporal variations in Little Bustard abundance were explained by functional habitat suitability and avoidance of urban areas, but that the significance of each variable varied with spatial scale. Little Bustard abundance at each observation point significantly increased with local nesting but not foraging habitat suitability, and decreased with increasing proportion of urban areas. At larger spatial scales, temporal changes in Little Bustard abundance were highly significantly related to changes in foraging habitat suitability. Moreover, the positive relationship between foraging habitat suitability and Little Bustard abundance weakened as the proportion of urban areas increased, and almost disappeared when the proportion of urban areas was more than 5%. Our results underline the benefits of using resource-based models to better understand processes that relate animal abundance and habitat suitability, while simultaneously considering avoided elements of the landscape.
- ItemOpen AccessA trait-based approach to both forestry and timber building can synchronize forest harvest and resilience(Oxford University Press, 2023) Osborne, Peter; Aquilué, Núria; Mina, Marco; Moe, Kiel; Jemtrud, Michael; Messier, ChristianAlong with forest managers, builders are key change agents of forest ecosystems’ structure and composition through the specification and use of wood products. New forest management approaches are being advocated to increase the resilience and adaptability of forests to climate change and other natural disturbances. Such approaches call for a diversification of our forests based on species’ functional traits that will dramatically change the harvested species composition, volume, and output of our forested landscapes. This calls for the wood-building industry to adapt its ways of operating. Accordingly, we expand the evaluation of the ecological resilience of forest ecosystems based on functional diversification to include a trait-based approach to building with wood. This trait-based plant-building framework can illustrate how forecasted forest changes in the coming decades may impact and guide decisions about wood-building practices, policies, and specifications. We apply this approach using a fragmented rural landscape in temperate southeastern Canada. We link seven functional groups based on the ecological traits of tree species in the region to a similar functional grouping of building traits to characterize the push and pull of managing forests and wood buildings together. We relied on a process-based forest landscape model to simulate long-term forest dynamics and timber harvesting to evaluate how various novel management approaches will interact with the changing global environment to affect the forest-building relationships. Our results suggest that adopting a whole system, plant-building approach to forests and wood buildings, is key to enhancing forest ecological and timber construction industry resilience.
- ItemOpen AccessImplementing Deep Learning algorithms for urban tree detection and geolocation with high-resolution aerial, satellite, and ground-level images(Elsevier, 2023) Velasquez-Camacho, Luisa; Etxegarai, Maddi; Miguel Magaña, Sergio deUrban forests are becoming increasingly important for human well-being as they provide ecosystem services that contribute to improving well-being of city dwellers and to addressing climate change. However, despite their importance, there is an information gap in most of the world's urban forests due to the high cost and complexity of conducting standard forest inventories in urban environments. New technologies based on artificial intelligence can represent a smart and efficient alternative to costly traditional inventories. In this paper, we present an approach based on deep learning algorithms for the detection, counting, and geopositioning of trees using a combination of ground-level and aerial/satellite imagery. We tested several convolutional networks, exploring different combinations of hyperparameters and adjusting the query distance between ground-level images, detection radius, and various resolutions of satellite and aerial images. Our methodology is able to detect and accurately locate 79% of the urban street tree with a positional accuracy of 60 cm to the center of the canopy. Additionally, this approach allows us to determine the availability of photographs of urban trees, indicating from which Google Street View image each tree is visible. Our research provides a scalable and replicable solution to the scarcity of urban tree data and information worldwide, demonstrating the potential of artificial intelligence to revolutionize the way in which we inventory and monitor urban forests.