Temporal patterns of bird mortality due to road traffic collisions in a Mediterranean region

Abstract

Capsule: There was significant variation on the incidence of road traffic mortality across bird species, due to seasonal and weather effects but also due to differences between years. Aims: To assess patterns of mortality due to traffic collision for six common bird species over a period of nine years in relation to seasonality and weather. Methods: Road mortality surveys were performed on four road sections from 2005 to 2013 in southern Portugal. The analysis controlled for survey frequency, and carcass persistence and detectability. Results: Overall, bird mortality decreased over time and was generally higher during spring and summer months. The lack of strong relationships between the weather variables and the observed mortality patterns suggests the existence of additional factors important in explaining the observed trends. Conclusions: Our study provides evidence that bird mortality due to collision with vehicles may change between years and was highest during the breeding season. This could have population consequences, and highlights the need to further address large temporal scales in roadkill research.

Roadkill mortality decreases after road inauguration

“…Road mortality is usually linked to species' seasonal abundance (Erritzoe et al 2003;Garrah et al 2015;Seo et al 2015;Pinto et al 2020). In our study, mammal victims showed little seasonal variation, maybe related to climate stability on our study area that does not produce great oscillation in species abundance through the year.…”

“…Local climatic conditions influence survival and reproduction in animals (Salewski et al 2013;Bensouilah and Barrientos 2021), and then modulating both the offspring abundance and the probability of roadkills (Mazerolle 2004;Pinto et al 2020). In our study, important differences in autumn rains were detected among the two annual cycles, being the first annual cycle wetter than the second (Fig.…”