Data from remote sensing are often used as proxies to quantify biological processes, especially at 13 large geographical scales. The Normalized Difference Vegetation Index (NDVI) is the most 14 frequently used proxy for primary productivity. Assuming a direct, positive interrelation between 15 primary and secondary production in terrestrial habitats, NDVI is often used to predict food 16 availability for higher trophic levels. However, the relationship between NDVI and arthropod 17 biomass has rarely been tested. In this study, we analyzed extensive datasets of arthropod 18 communities from semi-natural grasslands in central Europe to test the relationship between 19 arthropod biomass of consumer trophic levels ('herbivores', 'mixed' and 'carnivores') in 20 grassland communities and NDVI during the spring season. We found that arthropod biomass 21 generally increased with NDVI. The same positive relationship between biomass and NDVI was 22 observed for each individual trophic level. Cross-correlation analyses did not show statistically 23 2 significant lags between the NDVI and biomass of herbivores and carnivores. All in all, our study 24 provides correlational evidence for the positive relation of primary and secondary productivity in 25 temperate terrestrial habitats during spring. Moreover, it supports the applicability of NDVI data 26 as a suitable habitat-specific proxy for the food availability of insectivores during spring.
Población reproductora en 2019 y método de censo 54El trabajo de cientos de personas que aportan información y de las comunidades autónomas que mantienen activo su sistema de seguimiento de avifauna hacen posible la actualización de la situación de la población de muchas especies de aves.¡Muchas gracias a todos! Coordinación de la colección Juan Carlos del Moral (SEO/BirdLife) Fotografía de portada Dos machos de ganga ortega y una hembra de ganga ibérica visitan un bebedero.
Moult is a vital and endogenously controlled process in the avian life. However, birds may modulate their feather renovation properties, such as the extent of moult, based on exogenous factors. Despite the large body of knowledge about moult patterns, numerous questions remain unclear. In this study, we aimed to improve our knowledge about the factors that affect variation in the extent of the post-juvenile moult in passerines by performing inter-and intra-specific comparative analyses. We assessed the effect of internal and external factors on passerines' moult by comparing post-juvenile moult extent among 16 wheatear species (genus Oenanthe) from the Palearctic Ecozone. The tested factors included migration distance used as a proxy of time available for moulting and habitat type. We also explored the relationship between the extent of the moult, migration distance, and sex in the Northern Wheatear Oenanthe oenanthe across a latitudinal gradient in Western Europe. The results indicate that post-juvenile moult extent in wheatears was negatively related to migration distance, such that species with shorter migration distances moult extensively compared to long-distance migratory species. In contrast, the extent of post-juvenile moult in the Oenanthe genus was not related to preferred habitat type (arid or non-arid) of the species. Migration distance was also related to post-juvenile moult extent in the Northern Wheatear, with fewer renewed feathers in northern populations. However, the extent of the post-juvenile moult did not differ between sexes. Thus, our results support that time constraints affect moult extent in long-distance migratory species and populations.
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