Abstract

GODINHO, Sérgio  and  ONOFRE, Nuno. Terrestrial vertebrates mortality in irrigation canals of Vale da Ribeira de Seda (Cabeção - Alto Alentejo - Portugal). Silva Lus. [online]. 2013, vol.21, n.1, pp.21-42. ISSN 0870-6352.

The present study intends to illustrate the impact caused by irrigation canals in terrestrial vertebrates, namely those that live in the neighbourhood of this type of infrastructure. Our aim was to evaluate seasonal and spatial patterns in the different mortality rates registered in the canals surveyed. During 10 months of monitoring process 4.29 Km of canals were regularly inspected in order to assess all individuals, dead or alive, caught inside of it. A total of 401 individuals of 34 different species were registered, being 59.8%, 28.4% and 11.8% mammals, reptiles and amphibians, respectively. 73.8% of the total individuals were found already dead. According with the results, we found that the canals can negatively influence the surrounding ophidian and anuran populations, since the largest mortality peaks were registered during reproduction and juvenile dispersion times. In terms of spatial patterns in mortality, the results also show that the wider the canals’ sectors are, with more landscape heterogeneities and with a more rugged terrain, the largest are the mortality scores, both in individuals and species numbers. As a conclusion, we point the need of more detailed studies on these impacts, as well as the adoption of mitigating measures such as the ones we suggest here and which are already tested by others.

Keywords : irrigation canals; linear infrastructures; mortality; terrestrial vertebrates.

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