Old counts suggest the collapse of two Red-backed Shrike Lanius collurio populations

Doi: http://dx.doi.org/10.13157/arla.65.2.2018.sc1

Authors: José Luis TELLERÍA

E-mail: telleria@ucm.es

Published: Volume 65.2, July 2018. Pages 283-290.

Language: English

Keywords: bird monitoring, conservation, landscape change and temporal baseline.

Summary:

This note evaluates the numerical change in the Red-backed Shrike populations inhabiting two contrasting areas (coastal farmlands and inland pasturelands) in the Basque Country in 1974-1975 and 2014-2016. It attempts to show whether a decrease in these populations occurred before the onset of the Spanish bird monitoring programme (Sacre, 1998), which has detected declines of 58% (year 2014) and 75% (year 2016) from 1998. Results indicate the collapse of the two populations, with a loss of 95% of breeding pairs over the last forty years. The trends cannot be only explained by tree and urban encroachment in the study areas. However, because of environmental differences between the two study areas, it may be inferred that the decline could be related to processes acting on the species at larger scales. The results highlight our incomplete temporal scope for assessing the actual trends of this declining species and suggest a need to review its conservation status.