Road effects on species abundance and population trend: a case study on tawny owl

  • Shirley van der HorstEmail author
  • Fernando Goytre
  • Ana Marques
  • Sara Santos
  • António Mira
  • Rui Lourenço
Original Article
Part of the following topical collections:
  1. Road Ecology


Urbanization and its inherent road network are one of the major movements that impulse landscape and biodiversity change, and its effects have yet to be fully understood. Few works focus on the effect of this urbanization on abundance and population trend of a certain species, as this study does, using the tawny owl (Strix aluco) as our case study. Although the tawny owl is not threatened at European or global scale, it is often found roadkilled. We studied the effects of different road types on tawny owl abundance in southern Portugal, from 2005 to 2016. In woodlands far from roads, we found high tawny owl abundance, a stable population trend, and low variation in site occupancy. On the contrary, main roads disrupted habitat quality for tawny owls—limiting their abundance and site occupancy and leading to a negative population trend due to disturbance and/or mortality. Secondary roads did not severely disrupt habitat quality, allowing initial occupation and relatively high densities, yet they may act as ecological traps, revealing instability in occupation along the breeding season and a negative population trend. Tawny owl individuals may settle near secondary roads while waiting for a vacant space in woodlands far from roads (the prime high-quality habitats). To avoid the negative effects of roads on tawny owl populations, mitigation efforts should be applied to both main and secondary roads.


Road impacts Population dynamics Strix aluco Main roads Secondary roads 



We would like to thank Clara Silva, Denis Medinas, Edgar Gomes, and Sérgio Godinho for their participation in owl census.

Funding information

This study was partially funded by the project LIFE LINES (Linear Infrastructure Networks with Ecological Solutions, LIFE14 NAT/PT/001081) and by the project Popconnect (PTDC/AAG-MAA/0372/2014).

Supplementary material

10344_2019_1325_MOESM1_ESM.pdf (119 kb)
ESM 1 (PDF 118 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), LabOr - Laboratory of OrnithologyUniversity of ÉvoraÉvoraPortugal
  2. 2.Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), Conservation Biology UnitUniversity of ÉvoraÉvoraPortugal

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