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Honeybee colonies have increased exponentially in the Mediterranean Basin

Evidence for pollinator declines largely originates from mid-latitude regions in North America and Europe. Geographical heterogeneity in pollinator trends combined with geographical biases in pollinator studies can produce distorted extrapolations and limit understanding of pollinator responses to environmental changes. In contrast with the declines experienced in some well-investigated European and North American regions, honeybees seem to have increased recently in some areas of the Mediterranean Basin. The Mediterranean Basin is home to approximately 3300 wild bee species, or approximately 87% of those occurring in the whole western Palaearctic region. Because honeybees can have negative impacts on wild bees, it was hypothesized that a biome-wide alteration in bee pollinator assemblages may be underway in the Mediterranean Basin involving a reduction in the relative number of wild bees. This hypothesis was tested using published quantitative data on bee pollinators of wild and cultivated plants from studies conducted between 1963 and 2017 in 13 countries from the European, African and Asian shores of the Mediterranean Sea. The density of honeybee colonies increased exponentially and wild bees were gradually replaced by honeybees in flowers of wild and cultivated plants. The proportion of wild bees at flowers was four times greater than that of honeybees at the beginning of the period, the proportions of both groups becoming roughly similar 50 years later. The Mediterranean Basin is a world biodiversity hotspot for wild bees and wild bee-pollinated plants, and the ubiquitous rise of honeybees to dominance as pollinators could in the long run undermine the diversity of plants and wild bees in the region. informacion[at] Herrera (2020) Gradual replacement of wild bees by honeybees in flowers of the Mediterranean Basin over the last 50 years. Proc Royal Society B 287(1921). Doi 10.1098/rspb.2019.2657
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General versus specific surveys: estimating the suitability of different road-crossing structures for small mammals

General versus specific surveys: estimating the suitability of different road-crossing structures for small mammals

The use of wildlife road-crossing structures (WCS hereafter) is less monitored for small mammals than for more emblematic species. Furthermore, because of the undeniable difficulty of small mammal track identification, most biologists usually carry out general surveys without species recognition. Here it is hypothesized that general surveys traditionally used for monitoring WCS by small mammals may be biased because the degraded habitats along roads are mainly used by generalist and not specialist species. For this reason, authors compared the results of a general small-mammal survey with those from a species-specific one, focusing on 3 study species: 1 habitat generalist (North American deer mouse), 1 forest specialist (southern red-backed vole), and 1 prairie specialist (meadow vole). We sampled along 4 types of WCS (overpasses, open-span underpasses, and both elliptical and box culverts) in Banff National Park (Canada), by placing footprint track tubes along the WCS, and as a reference in front of their entrances (mainly located in roadside grasslands) and in the surrounding woodlands. Using the traditional general survey, significant differences in small-mammal presence among WCS and reference sites were not detected. In contrast, species-specific surveys showed that only the deer mouse (a generalist species) consistently used the WCS. The deer mice did not show preferences for any WCS type, whereas the specialist species (voles) used only overpasses. Therefore, general surveys used without species identification can overestimate the value of WCS for specialist small mammals, with relevant conservation implications. As a consequence, species-specific surveys of WCS suitability for small mammals is recommended. Authors also suggest improving the habitat (or at least the cover availability) in the WCS and along the space between them and the surrounding environments to increase WCS suitability for specialist species. informacion[at] D'Amico et al (2015) General versus specific surveys: estimating the suitability of different road-crossing structures for small mammals. J Wildl Manage 79(5) 854–860 DOI: 10.1002/jwmg.900