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Sara Marques et al. 2010. Impact of roads on ungulate species: a preliminary approach in Portugal
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Roe deer’s collisions correspond to a 9% of amount cases, which support the reduced number of
animals killed by cars. Population estimates show that current populations of roe deer in
Portugal include between 3000 and 5000 animals (Vingada et al. 2010), with the highest
densities concentrated in the northern region of the country where the roe deer collisions were
higher (districts of Braga, Viana do Castelo and Bragança).
The red deer vehicle-collisions correspond to a 5% of the cases which proof the reduced and
scattered distribution of this animal at Portugal (Vingada et al. 2010). The data of red deer
collisions were mostly in the districts of Coimbra, Viseu, Bragança, Viana do Castelo and
Castelo Branco which is according to dispersed Portuguese northern and central populations
(Tejo Internationa, Lousã and Montesinho).
According to the analysis of road type the majority of ungulate vehicle-collisions occurred at
National Roads (EN), with overwhelming percentage of 70,4%, probably due to the high traffic
volume and bad road conditions. The lower number of accidents with ungulate in main roads
(IP), complementary roads (IC) and high speed road (A) could be explained by the existence of
lateral road protections (fences) in both sides of the road which avoid the invasion of wild
animals. Only two cases of wildlife vehicle-collisions were recorded in forestry ways (CF)
because this type of road has not regularly traffic, although of the bad conditions.
The majority of ungulate vehicle-collisions occurred in winter, particularly in November,
December and January. This can be explained by the fact that the big game hunting period is
mainly from October to February and it’s precisely in this time of the year that the animals are
more restless (Fonseca and Correia 2008). The August ungulate-vehicle collisions’ peak can be
derived from the holiday’s traffic growth in Portugal.
As expected the overwhelming percentage of accidents occurred at night (70,9%) because it’s
precisely the time of the day that the ungulates are more active (Apollonio et al. 2010). During
the dawn, day and evening the number of accidents involving ungulates are smaller.
This study indicates that there are some variables that can contribute to the ungulate vehiclecollisions
increase such as the road type, time of the day and month of the year. The first
variable can be amended by man in the sense of prevent and mitigate the accidents with wildlife,
particularly involving large animals, such as ungulates, but the second concerns to the biology
and behaviour of animals.
Gradually there is a growing concern in the road planning and implementation, according to the
measures to prevent and mitigate the impacts on wildlife. The design of infrastructures in the
landscape has an enormous relevance to wildlife because it causes mainly the fragmentation of
available ungulate habitat and resulting in a diminished habitat connectivity and permeability.
Mitigations measures that include wildlife crossing structures not only substantially reduce road
mortality, but also allow movements of animals across the road (Huijser et al. 2009). Properly
designed wildlife crossing structures may help to reduce the barrier effect of roads while
decrease ungulate vehicle-collisions (Gagnon et al. 2007). This connectivity is essential to
survival probability of the fragmented populations of some species, in determinate regions. As
referred by Seiler (2004) if these measures will be combined with traffic adjustments, such as
reduced speed limits, rerouting of traffic flow or improvement of features roads, traffic safety
may further be improved and the collisions with wildlife will reduce.
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.