Trends in the abundance of Cantabrian Capercaillie Tetrao urogallus cantabricus at leks on the southern slope of the Cantabrian Mountains, north-west Spain

Abstract

We analysed the trend of the number of singing males of Cantabrian Capercaillie Tetrao urogallus cantabricus in 207 leks on the southern slope of the Cantabrian mountains, north-west Spain, in the period 1981 to 2003. The area of occupancy in 1981–1982 covered up to approximately 2,070 km2, but in 2000–2003 it was 693 km2, a 66% area reduction in 22 years. The 1981–1982 census estimated a minimum number of 274 singing male Capercaillie on the southern slope, but in 2000–2003 only an estimated 81 males were recorded, a reduction of 70%. A linear regression was used to detect and describe the changes in the size of the total population of the southern slope as well as individual subpopulations. The overall trend for the total subpopulations was a significant decrease in the number of males (y = 39.94−0.018x; R2 = 0.944, P < 0.001). The negative regression slopes indicated that the number of males had fallen in all the subpopulations considered. In the western core area the greatest annual mean rate of decline was detected in the Sierra de Picos de Ancares subpopulation (−6.22%) and in the eastern core in the Sierra de Riaño subpopulation (−3.43%). The principal local limiting factors (habitat fragmentation, human disturbance, small population size and competition) that have caused the population decline are discussed, together with the demographic, genetic and evolutionary consequences for the surviving subpopulations.

Population genetics of the endangered Cantabrian capercaillie in northern Spain

“…Field studies have confirmed previously the existence of discontinuities in the distribution of the Cantabrian capercaillie at the centre of the range (Obeso & Ba˜nuelos, 2003;Pollo et al, 2005). However, none of the previously proposed fragmentation scenarios, on which predefined regions were based, were able to explain a larger proportion of the genetic variation than the inferred genetic clusters (Table 2).…”

“…Second, subdivision between the northern and southern populations was observed, likely as a result of the mountain ridge that seems to act as a natural barrier to gene flow. Sylvicultural practices have caused changes in the forest structure of the Cantabrian Mountains that have been negatively associated to the distribution and dynamics of the Cantabrian capercaillie, particularly in the eastern populations (Pollo et al, 2003(Pollo et al, , 2005, and this has been reflected in the differential migration rates and genetic variability along the distribution range. Also, even though the Cantabrian capercaillie habitat mainly consists of deciduous forests (Obeso & Ba˜nuelos, 2003), other forests types are also occupied.…”

Demographic Status and Genetic Tagging of Endangered Capercaillie in NW Spain

“…Its range has declined steeply since the early 1980s [5], [6], and it has been isolated long enough from other capercaillie populations to be considered an Evolutionary Significant Unit [7]. The subspecies has additional biogeographical interest due to its location at the rear edge of the species range [8].…”

The Changes in Rural and Forest Landscape and Their Use in the Slovenian Alps in the Last Centuries - A "Back to Nature" Tourism with Impacts, a Case of Western Capercaillie

“…The human disturbances at the southern edge of Western capercaillie distribution area and habitat suitability in combination with the impact of air pollution and climate change on forests in the region (Anič et al 2009;Čas & Adamič 1995Klaus et al 1997;Kutnar & Kobler 2011) and predator pressure (Čas 2010) are detrimental for the survival of Western capercaillie Blanco-Fontao et al 2009;Čas 2006, 2010Gonzales & Ena 2011;Poolo et al 2005;Storch, 1999Storch, , 2007.…”

“…Several different habitat disturbances were recognised as causes of Western capercaillie decline in temperate Europe (Adamič 1987;Čas 2001a, 2010Eiberle 1984;Klaus et al 1997;Saniga 2002Saniga , 2004Storch 1999Storch , 2007Thiel et al 2007). The populations at the southern edge of the species' distribution range have suffered the most severe population reduction (Adamič 1987;Bajc et al 2011;Blanco-Fontao et al 2009;Čas 1999, 2010Cattadori & Hudson 2000;Gonzales & Ena 2011;Poolo et al 2005;Radović et al 2003;Quedo et al 2006;Storch 2007;Zeiler 2001;Zubić 2009), and shrinkage of habitat in the last decades due to forest and climate change (Anič et al 2009;Čas 2006;Kutnar & Kobler 2011).…”