Search

Copyright of Ardeola is the property of Sociedad Espanola de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

River systems are some of the habitats most drastically affected by climate change. Consequently, many riparian species are amongst the most threatened living organisms worldwide, making riparian areas a conservation priority. Demographic analyses destined to improve our comprehension of the population dynamics of riparian species are crucial in this context. The present work analyses the spatio-temporal demographic dynamics of a presumably well-preserved White-throated Dipper (Cinclus cinclus) population from northern Spain. Using multistate models where we considered the effects of factors such as mean water flow in winter, age, sex, hydrographical basin of origin and hatching date, we found that the population had a constant annual dispersal rate (ψ = 0.038; 95% CI: 0.022-0.065). The mean apparent survival of Dippers from first-order clutches was 0.18 (95% CI: 0.12-0.22), whereas for those hatched in second-order clutches was 0.07 (95% CI: 0.03-0.15). The mean annual apparent survival for adults was 0.64 (95% CI: 0.56-0.70). Although apparent survival varied from year to year, we found no effect of the average winter flow on this parameter. Recapture probability (p) varied among basins, probably reflecting a heterogeneous sampling effort. In conclusion, using multistate models were found that Dippers from three adjacent river basins in northern Spain had a very short-range natal dispersal rate, and a breeding dispersal close to zero, a trait that could be different from findings in other zones of Spain, where dispersal rates seem to be much higher. [ABSTRACT FROM AUTHOR]

The dynamics of migratory populations at wintering quarters can inform on population state and size because these areas act as demographic funnels, assembling birds from different origins. Previous evidence on survival probability of woodcock Scolopax rusticola wintering in northern Spain suggested a high harvesting pressure, but whether this pressure is causing a decline of woodcock occurrence at wintering quarters is still to be assessed. We used data from 3411 surveys conducted during the winter at 434 selected grasslands in the Gipuzkoa region, Northern Spain, to investigate the dynamics of woodcock occurrence probability, conditional on detection, over a period of 10 years (2009–2019). A 47% of the variation in woodcock occurrence within and across winters was explained by the monthly average minimum temperature. The remaining variation was due to a marked increase during the winters 2016 and 2017, contrary to the progressively decreasing values detected in previous years. At present, these abrupt yearly fluctuations prevent clear predictions on woodcock presence in the Gipuzkoa region. Future studies should explore woodcock occurrence probability according to scenarios of climate and habitat changes. [ABSTRACT FROM AUTHOR]

The management of mixed municipal waste can have an impact on wildlife and ecosystems. Previous studies have investigated how opportunistic species like gulls can react very fast to new landfills; however, the impact of landfill closure on bird populations is less investigated. Yet, there is a need to understand how fast and to what extent, animal populations can be adapted to new scenarios where the waste will not be deposited in landfill sites anymore. The aim is to determine the influence of landfill closures on apparent survival of a resident Yellow‐legged Gull (Larus michahellis) population, used as a model species showing short‐distance foraging movements, and with a high dependence on local food subsidies. Complementarily, we built some basic population growth models in order to determine how potential changes in survival (before/after landfill closure) will impact on population growth rate. Using a data set of 4,437 Yellow‐legged Gull chicks ringed in four colonies over a period of 13 years, we obtained evidence supporting that the apparent survival was affected by landfill closure, especially if the landfill was located within a buffer of 10 km around the colony. Landfill closure affected the survival of first‐year gulls (with a mean decrease of ~ 0.5–0.36), but not of older birds. Consequently, we did not detect a remarkable effect of landfill closures on population growth rate, probably due to the lack of effect on adult survival rates except for one of the surveyed colonies, where we found an annual decline of 7%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ornithology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Body condition of nestlings can influence their future survival. Here, we used data obtained from a colourringing program of Yellow-legged Gull Larus michahellis in two colonies from northern Iberia to quantify the relative importance of pre-fledging body size and mass on post-fledging juvenile survival. Chicks were ringed with colour-rings at their colony in June/July when they were almost ready to fledge, and, thereafter, sighting data of these birds were collected over a period of one year and analysed with Cormack-Jolly-Seber capture-recapture models. The Yellowlegged Gull in the region is resident, so sighting data were mostly collected within an area close to natal colonies, where the field effort was intensive. Monthly survival from August onwards was higher than from ringing date to August (0.59± 0.06 SE), reaching model averaged values of 0.91 ± 0.03 and 0.98 ± 0.03 for the two colonies analysed. Moreover, condition of chicks (measured as residual body mass and body size) before fledging had a positive effect on survival from ringing date to August, but not from August onwards, when survival was strongly affected by the colony of origin. [ABSTRACT FROM AUTHOR]

The authors discuss the results of their study on the role of age, colony of origin and year on the survival of yellow-legged gulls Larus michahellis in the bay of Biscay. The percentage of gulls seen alive in Gueraria range from 36% to 52%. Mean survival rate for age and classes is lowest among gulls from Izaro. Colony size was not linked with survival.