© 2024 The Authors. This is an Open Access article. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited., Knowing the location and movements of individuals at various temporal and spatial scales is an important facet of behavior and ecology. In threatened populations, movements that would ensure gene flow and population viability are often challenged by habitat fragmentation. Also in those endangered populations capturing and handling individuals to tag them, or to obtain tissue samples, can present additional challenges. DNA tagging, i.e. non-invasive individual identification of samples, can reveal movement patterns. We used fecal material genetically assigned to individuals to indirectly track movements of a large-bodied, endangered forest bird, Cantabrian capercaillie (Tetrao urogallus cantabricus). We wanted to know how the birds were using the fragmented forest landscape, and whether they showed fidelity to display areas. We used multi-event capture−recapture models to estimate fidelity to display areas among three consecutive mating seasons. We identified 127 individuals, and registered movements of 22 females and 48 males. Most observed movements were as expected relatively short, concentrated around display areas. We did not find differences in movement distances between females and males within mating seasons, or between them. Fidelity to display areas among seasons was 0.62 (± 0.12 SE) for females and 0.77 (± 0.07 SE) for males. The best CR model suggested no sex or season effects. Several longer movements, up to 9.9 km, linked distant display areas, demonstrating that Cantabrian capercaillies were able to move between different parts of the study area, complementing previous studies on gene flow. Those longer movements may be taking birds out of the study area, and into historical capercaillie territories, which still include substantial forest cover. The non-invasive DNA tagging approach provided a much larger sample size than would have been feasible with direct tracking. Lack of information on the social status of individuals, and timing of movements, are some disadvantages of DNA tagging., The study was funded by grants IB08-158 (FICYT, Asturian Government) to MJ Bañuelos and CGL2010-15990 (MICINN, Spanish Government) to MJ Bañuelos and M Quevedo. Mario Quevedo was partially supported by grant AYUD/2021/51261 (FICYT, Gobierno del Principado de Asturias, FEDER) to S. Suárez-Seoane., Peer reviewed

Knowing the location and movements of individuals at various temporal and spatial scales is an important facet of behavior and ecology. In threatened populations, movements that would ensure gene flow and population viability are often challenged by habitat fragmentation. Also in those endangered populations capturing and handling individuals to tag them, or to obtain tissue samples, can present additional challenges. DNA tagging, i.e. non-invasive individual identification of samples, can reveal movement patterns. We used fecal material genetically assigned to individuals to indirectly track movements of a large-bodied, endangered forest bird, Cantabrian capercaillie (Tetrao urogallus cantabricus). We wanted to know how the birds were using the fragmented forest landscape, and whether they showed fidelity to display areas. We used multi-event capture-recapture models to estimate fidelity to display areas among three consecutive mating seasons. We identified 127 individuals, and registered movements of 22 females and 48 males. Most observed movements were as expected relatively short, concentrated around display areas. We did not find differences in movement distances between females and males within mating seasons, or between them. Fidelity to display areas among seasons was 0.62 (± 0.12 SE) for females and 0.77 (± 0.07 SE) for males. The best CR model suggested no sex or season effects. Several longer movements, up to 9.9 km, linked distant display areas, demonstrating that Cantabrian capercaillies were able to move between different parts of the study area, complementing previous studies on gene flow. Those longer movements may be taking birds out of the study area, and into historical capercaillie territories, which still include substantial forest cover. The non-invasive DNA tagging approach provided a much larger sample size than would have been feasible with direct tracking. Lack of information on the social status of individuals and timing of movements are some disadvantages of DNA tagging., Ministerio de Ciencia e Innovación : CGL2010-15990; Foundation for the Promotion of Applied Scientific Research and Technology in Asturias : IB08-158; Foundation for the Promotion of Applied Scientific Research and Technology in Asturias : AYUD/2021/51261, Peer reviewed

Effective population size (Ne) is a useful parameter to evaluate the long-term viability of populations. While obtaining enough field data from wild populations to estimate Ne directly is challenging, molecular techniques applied to non-invasive samples provide an appealing alternative. However, Ne estimates may be biased by both ecological and sampling-related factors. In polygamous species, the monopolization of mating tends to reduce the ratio between the effective population and the census population (Ne:Nc) compared to idealized populations. Ne estimates may also be affected by sample size, spatial structure, and relatedness, factors that are often overlooked in studies of wild populations. We investigated how sample size, spatial structure, and relatedness impact Ne estimates in an endangered population of a polygynous forest grouse, the Cantabrian capercaillie inhabiting the mountains of north-western Spain. We studied 135 capercaillie individuals based on DNA extracted from droppings and shed feathers. We estimated contemporary Ne based on linkage disequilibrium. Ne estimates stabilized at sample sizes of ~ 20 individuals, with confidence intervals markedly narrowing beyond 30 individuals, i.e. at 23 to 35% of the estimated population size. Samples taken in specific valleys yielded consistently lower Ne values compared to similar-sized random samples from the entire study area, indicating that the spatial structure of the sampling design also affected Ne. We observed a negative correlation between Ne and relatedness, which highlighted the need to account for kinship structure in sampling design. Our estimated Ne:Nc ratio (~ 15%) was not as low as expected for a polygynous species, with male-biased sex ratios, and inhabiting a fragmented habitat. However, the absolute Ne values were extremely small. We showed the relevance of integrating field-based observations of demography and spatial ecology into DNA-based estimates of Ne to improve its interpretation, and usefulness in conservation efforts., – The study was funded by grants IB08-158 (FICYT, Asturian Government) to M-JB and CGL2010-15990 (MICINN, Spanish Government) to M-JB and MQ., Peer reviewed