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The costs and benefits of dispersal are often assessed by comparing fitness between dispersing and non‐dispersing individuals. Importantly, individuals that disperse between their natal and first breeding site may subsequently be more likely to disperse between breeding sites compared to those that remained philopatric to their natal site. Such within‐individual consistency in dispersal behaviour can bias local survival estimation, and thus the survival comparison between dispersing and non‐dispersing individuals, if breeding dispersal leads to permanent emigration from the study area. We examined whether adult survival correlates with natal dispersal in a migratory shorebird, the southern dunlin Calidris alpina schinzii, in two isolated patchy populations where permanent emigration is expected to be extremely rare. To assess whether local adult survival could be biased by non‐random breeding dispersal, we analysed between‐patch breeding dispersal probability and quantified within‐individual consistency in dispersal. Among females, natal dispersers were more likely to disperse again as adults compared to non‐dispersers, while no difference was observed in males which were always highly site faithful. Yet, adult survival did not differ between natal dispersing and non‐dispersing individuals in either sex. Breeding dispersal probability was higher in failed compared to successful breeders. Breeding dispersal often resulted in dispersal back to the natal patch, i.e. delayed natal philopatry. Our results suggest no survival costs of dispersal after first reproduction. Despite individual consistency, survival estimates of dispersing individuals were not biased because nearly all available breeding habitat was covered. We show that consistency in dispersal can occur even in site faithful species like the southern dunlin. Studies of the effects of dispersal on survival should therefore account for within‐individual consistency in dispersal if not all available breeding habitat is monitored in open populations. In particular, delayed natal philopatry may lead to biased local survival estimates for immigrants when compared with philopatric individuals. [ABSTRACT FROM AUTHOR]

Quaternary climatic oscillations have been considered decisive in shaping much of the phylogeographic structure around the Mediterranean Basin. Within this paradigm, peripheral islands are usually considered as the endpoints of the colonization processes. Here, we use nuclear and mitochondrial markers to investigate the phylogeography of the blue tit complex (blue tit Cyanistes caeruleus, Canary blue tit C. teneriffae and azure tit C. cyanus), and assess the role of the Canary Islands for the geographic structuring of genetic variation. The Canary blue tit exhibits strong genetic differentiation within the Canary Islands and, in combination with other related continental species, provides an ideal model in which to examine recent differentiation within a closely related group of continental and oceanic island avian species. We analysed DNA sequences from 51 breeding populations and more than 400 individuals in the blue tit complex. Discrepancies in the nuclear and mitochondrial gene trees provided evidence of a complex evolutionary process around the Mediterranean Basin. Coalescent analyses revealed gene flow between C. caeruleus and C. teneriffae suggesting a dynamic process with multiple phases of colonization and geographic overlapping ranges. Microsatellite data indicated strong genetic differentiation among the Canary Islands and between the Canary archipelago and the close continental areas, indicating limited contemporary gene flow. Diversification of the blue tit complex is estimated to have started during the early Pliocene (≈ 5 Ma), coincident with the end of Messinian salinity crisis. Phylogenetic analyses indicated that the North African blue tit is derived from the Canary blue tits, a pattern is avian 'back colonization' that contrasts with more traditionally held views of islands being sinks rather than sources. [ABSTRACT FROM AUTHOR]

Decline of migrant wader populations worldwide implies that their demography may be affected by phenomena occurring in a large geographical scale. Knowledge about vital rates affecting population growth and viability helps in finding the processes behind the declines. We estimated the rate of population growth (λ) of a dramatically declined population of Temminck's stints Calidris temminckii using a ten year capture–recapture data. We assessed the viability of the population by projections based on λ and its variation. We also studied sensitivity of λ to changes in vital rates (breeding success, recruitment and adult survival). Both adult and juvenile survival and breeding success were lower than c. 30 years earlier. Adult survival seemed to have dropped during the study period. Population growth appeared strongly negative and viability analyses predicted an almost certain extinction within a few decades. Adult survival formed the main component of the growth rate suggesting that population crash is mainly caused by a drop in adult survival. Still, sensitivity analyses showed that a moderate rise in adult survival or any other single vital rate would not make the population viable. Most probably, survival has dropped due to factors operating along migration routes and wintering areas, at sites shared by birds from other parts of the breeding range. Therefore, the observed population crash and decline in adult survival may indicate parallel changes in poorly monitored arctic populations. Migration habits (continental wide flyways and scattered wintering areas) imply that factors responsible for the drop in survival have a wide geographical range. [ABSTRACT FROM AUTHOR]

We studied the body mass variation from autumn to winter, in a free-living population of willow tits (Parus montanus), a food-hoarding passerine living year-round in boreal forests. Our aim was to find out whether this population exhibits ‘winter fattening’ as part of the annual body mass cycle. ‘True winter fattening’ is considered to be a strategic response to winter conditions. The strategy includes an increase in both the morning mass and the daily mass increase, as winter approaches. A multivariate approach was used to find which predictors (year, date, age, sex, body size, temperature and snow depth) explained the mass variation in birds measured twice per day. Morning mass variation was explained by sex, age, wing length and snow depth. Independently, date explained morning mass variation only in adult males. None of the predictors explained the variation observed in daily mass increase in any age or sex class. Therefore, we failed to detect winter fattening in our study population of willow tits. Response to increasing night length is not due to higher absolute intake, but to higher energy acquisition rate and decreased night-time energy consumption. The results suggest that willow tits at high latitudes manage increasing energy demands on a short-term basis and respond flexibly to changing conditions by adjusting foraging efficiency and especially night-time energy expenditure. [ABSTRACT FROM AUTHOR]

Summary 1. Each day small birds must build up sufficient energy reserves, largely fat deposits, for the following night and for the periods when foraging is not possible. The earlier the birds acquire the reserves and the more they carry them, the higher is the insurance value of the reserves. Still, small birds do not forage at maximal capacity during the day and, even at dusk, body reserves are usually below the physiological upper limit. A popular explanation for this is that birds’ fatness levels reflect an optimal compromise between starvation risk and risks associated with reserve carrying and acquisition. 2. Theoretical works suggest that uncertain or variable feeding conditions should promote high reserve levels, and that in the daily perspective, feeding should peak in the morning hours. In more favourable conditions, reserve levels should be smaller and the acquisition peak should be delayed towards the end of the day. These predictions were tested by experimentally manipulating winter feeding conditions and monitoring subsequent daily body mass increase in northern population of the willow tit Parus montanus (Conrad), a small-sized forest passerine. 3. The birds using feeders appeared heavier than the control birds throughout the day. This contradicts the prevailing theory, but is understandable since the feeding procedure probably not only affected food amount but may also have decreased acquisition costs in terms of predation. 4. Daily mass gain and the gain rates were fairly similar in the food-manipulated and the control birds. However, the mass gain schedules differed between the treatment groups: the food-supplemented birds gained mass at a roughly constant rate while among the control birds the gain rate was higher in the morning than in the afternoon. Probably to avoid associated costs, birds abandon early build-up of reserves if foraging conditions become favourable enough. [ABSTRACT FROM AUTHOR]

We studied the food hoarding behavior of willow tits (Parus montanus), a scatter-hoarding passerine wintering in dominance-structured flocks. We examined social influences on microhabitat selection and spatial cache distribution at temporary feeders. Dominant adult males stored food closer to die feeder and at a greater rate than did subordinates. When alone, the birds stored food closer to the feeder than when accompanied by conspecifics. Conifers were preferred over deciduous trees as cache trees. The subordinates cached more in die outer parts of branches than dominants. There were no significant differences in die relative or absolute heights of die caches, nor in the vertical or horizontal hoarding niche breadths between dominants and subordinates. We experimentally removed die dominants from die flock for 90 min and recorded the behavior of die remaining subordinates immediately after die removal. The removal resulted in a decrease in die hoarding distance of die remaining birds, indicating that die presence of dominants directly affected die behavior of subordinates and suggesting that kleptopar-asitism by dominants may be prevented by rarhing farther away. With die dominants removed, die subordinates cached at a greater rate than before die removal. The decrease in die hoarding distance and increase in die hoarding rate were die only significant effects of die experiment, perhaps suggesting that, during a short absence of dominants, die subordinates do not benefit from changing dieir caching microhabitat They might be excluded from those new, possibly safer, microhabitats after die dominant bird rejoins die flock. [ABSTRACT FROM AUTHOR]

Basal metabolic rate (BMR) constitutes the lowest metabolic rate in a resting animal and is, therefore, considered to reflect the energetic cost of maintenance in endotherms. BMR is a reversible plastic trait that changes with environmental and ecological circumstances, albeit being heritable and susceptible to selection. Inter-individual variation within populations of small birds is substantial, and while many of the drivers of such variation have been identified, many remain unexplained. We studied winter BMR variation of juveniles over a 15-year period in a wild population of great tits Parus major at the northern border of their distribution. BMR during winter consistently changed between years, even after controlling for environmental factors, suggestive of a non-reversible developmental plasticity shaping the adult metabolic phenotype. BMR in cohorts of wintering great tits varied among winters as a response to minimum ambient temperatures experienced early in life, during the prehatching period. This developmental plasticity might be adaptive if temperatures experienced by growing embryos would metabolically prime them to an environment that they will likely encounter in future life. However, in line with a more unpredictable future climate, the risk of phenotype-environment mismatch is likely to lead to certain cohorts being poorly adapted to prevailing winter conditions, resulting in wider annual fluctuations in population size. [ABSTRACT FROM AUTHOR]

Investigates the effect of male and female age on the guarding behavior of the willow tit, Parus montanus. Variation in male and female quality; Relation of female interests with their mates' quality; Fertility limits; Intra-pair distances in the fertile period of juvenile male-adult female pairs; Sperm competition hypothesis; Additional function of mate guarding.

Research on winter energy management in small vertebrates has focused on the regulation of body mass (BM) within a framework of starvation-predation trade-off. Winter-acclimatized birds exhibit a seasonal increase in both BM and basal metabolic rate (BMR), although the patterns of co-variation between the two traits remain unknown. We studied this co-variation in three different species of wild titmice, great, blue and willow tits, originating from two boreal regions at different latitudes. Seasonal change in BM and BMR was inter-dependent, particularly in the great tit; however, by contrast, no seasonal change was observed in the willow tit. BMR changed non-linearly in concert with BM with a peak in midwinter for both blue and great tits, whereas such non-linear pattern in willow tit was opposite and independent of BM. Surprisingly, BMR appears to be more sensitive to ambient temperatures than BM in all three species studied. Energy management is a multifaceted strategy that cannot be fully understood without considering reserve levels and energy expenditure simultaneously. Thus, our study indicates that the prevailing conceptual framework based on variation in BM alone is insufficient to understand seasonal energy management in small wintering passerines. [ABSTRACT FROM AUTHOR]

Understanding how weather conditions affect animal populations is essential to foresee population changes in times of global climate shifts. However, assessing year-round weather impacts on demographic parameters is hampered in migratory animals due to often unknown occurrence in space and time. We addressed this by coupling tracking and weather data to explain extensive variation in apparent survival across 19 years in a northern European population of little ringed plovers (Charadrius dubius). Over 90% (n = 21) of tracked individuals followed migration routes along the Indo-European flyway to south India. Building on capture–recapture histories of nearly 1400 individuals, we found that between-year variation in precipitation during post-breeding staging in northern South Asia explained 47% of variation in apparent adult survival. Overall, the intensity of the monsoon in South Asia explained 31–33% of variability in apparent survival. In contrast, weather conditions in breeding, final non-breeding and pre-breeding quarters appeared less important in this species. The integration of multi-source data seems essential for identifying key regions and periods limiting population growth, for forecasting future changes and targeting conservation efforts. [ABSTRACT FROM AUTHOR]

Generalist predators using small mammals as their primary prey are suggested to shift hunting alternative prey such as bird nests, when small mammals are in short supply (the alternative prey hypothesis, APH). Nest survival and survival of young individuals should be positively linked to small mammal abundance and negatively linked to predator abundance, but little information exists from survival of chicks, especially until recruitment. We test these predictions of the APH using 13 years (2002–2014) of life history data from a ground nesting shorebird breeding on coastal meadows. We use small mammal abundance in the previous autumn as a proxy for spring predator abundance, mainly of mammalian predators. We examine whether small mammal abundance in the spring and previous autumn explain annual variation in nest survival from depredation and local recruitment of the southern dunlin Calidris alpina schinzii. As predicted by the APH, survival from nest predation was positively linked to spring small mammal abundance and negatively linked to autumn small mammal abundance. Importantly, local recruitment showed opposite responses. This counterintuitive result may be explained by density‐dependent survival. When nest depredation rates are low, predators may show stronger numerical and functional responses to high shorebird chick abundance on coastal meadows, whereas in years of high nest depredation, few hatching chicks lure fewer predators. The opposite effects on nest and local recruitment demonstrate the diverse mechanisms by which population size variation in primary prey can affect dynamics of alternative prey populations. [ABSTRACT FROM AUTHOR]

1. Basal metabolic rate (BMR) is an important trait in the study of energy management of an individual, especially in small wintering passerines from the north which have one of the highest energy turnover rates in vertebrates. Laboratory studies have shown the trait to be repeatable and heritable, despite its plastic nature. However there is currently a lack of empirical data from wild passerine populations. 2. We studied within- and between-year repeatability of BMR, body mass and mass-independent BMR from two populations of wintering great tits ( Parus major) at the northern range of their distribution. 3. We found body mass, BMR and mass-independent BMR to be highly repeatable both within and between years. 4. Our results provide the first evidence from a wild small passerine that, despite a large environmentally induced variation in metabolic rate, individuals show consistent metabolic strategies over periods even longer than a year. 5. Homeotherm species exposed to new or changing environmental conditions may be able to evolve specific energetic strategies in the wild, as previously found in captive species. [ABSTRACT FROM AUTHOR]

Effects of tracking devices on survival are generally considered to be small. However, most studies to date have been conducted over a time‐period of only one year, neglecting the possible accumulation of negative effects and consequently stronger negative impacts on survival when the individuals have carried the tracking devices for longer periods. We studied the effects of geolocators in a closely monitored and colour‐ringed southern dunlin Calidris alpina schinzii population breeding in Finland. Our capture–recapture data spans 2002–2018 and includes individual histories of 338 colour‐ringed breeding adult dunlins (the term 'recapture' includes resightings of colour‐ringed and individually recognizable birds). These data include 53 adults that were fitted with leg‐flag mounted geolocators in 2013–2014. We followed their fates together with other colour‐ringed birds not equipped with geolocators until 2018. Geolocators were removed within 1–2 years of attachment or were not removed at all, which allowed us to examine whether carrying a geolocator reduces survival and whether the reduction in survival becomes stronger when geolocators are carried for more than one year. We fit multi‐state open population capture–recapture models to the encounter history data. When assessing geolocator effects, we accounted for recapture probabilities, time since marking, and sex and year effects on survival. We found that carrying a geolocator reduced survival, which contrasts with many studies that examined return rates after one year. Importantly, survival declined with the time the individual had carried a geolocator, suggesting that the negative effects accumulate over time. Hence, the longer monitoring of birds carrying a geolocator may explain the difference from previous studies. Despite their larger mass, females tended to be more strongly affected by geolocators than males. Our results warrant caution in conducting tracking studies and suggest that short‐term studies examining return rates may not reveal all possible effects of tracking devices on survival. [ABSTRACT FROM AUTHOR]

Site fidelity during the non-breeding season is beneficial if habitat quality and environmental predictability are high. In group-living species, the costs and benefits of site fidelity may be linked to the non-social (weather) and social (dominance hierarchy) environments, but little is known about factors influencing movements during the non-breeding season. We studied both within- and between-winter site fidelity of the great tit ( Parus major), a partial migrant in northern Finland. We collected mark-resight data on wintering great tits across two winters at multiple sites, and tested for the effects of age, sex, season, temperature and day length on site fidelity. Within-winter movement was lower during mid-winter and decreased during cold periods. This pattern is probably linked to energy saving and predator escaping strategies during these demanding periods when energy expenditure is high and birds have limited daylight hours to forage. Site fidelity was lower for juveniles than adults within a winter, but it was unaffected by sex. These results agree with an age related dominance structure and site-specific dominance found in great tits, but they can also be related to prior experience as young individuals still collect information during their first winter. In contrast, between-winter site fidelity was not affected by age or sex, suggesting equal benefits from site fidelity. Juveniles probably gather information on resource abundance and distribution in their first winter, and thereby gain the same benefits as adults from returning the next winter. [ABSTRACT FROM AUTHOR]

The effect of habitat management is commonly evaluated by measuring population growth, which does not distinguish changes in reproductive success from changes in survival or the effects of immigration or emigration. Management has rarely been evaluated considering complete life cycle of the target organisms, including also possible negative impacts from management. We evaluated the effectiveness of cattle grazing in the restoration of coastal meadows as a breeding habitat for small and medium-sized ground-nesting birds by examining the size and demography of a southern dunlin ( Calidris alpina schinzii) breeding population. Using a stochastic renesting model that includes within-season variation in breeding parameters, we evaluated the effect of grazing time and stocking rates on reproduction. The census data indicated that the population was stable when nest trampling was prevented, but detailed demographic models showed that the population on managed meadows was a sink that persisted by attracting immigrants. Even small reductions in reproductive success caused by trampling were detrimental to long-term viability. We suggest that the best management strategy is to postpone grazing to after the 19th of June, which is about three weeks later than what is optimal from the farmer's point of view. The differing results from the two evaluation approaches warn against planning and evaluating management only based on census population size and highlight the need to consider target-specific life history characteristics and demography. Even though grazing management is crucial for creating and maintaining suitable habitats, we found that it was insufficient in maintaining a viable population without additional measures that increase nest success. In the presently studied case and in populations with similar breeding cycles, impacts from nest trampling can be avoided by starting grazing when about 70% of the breeding season has past. [ABSTRACT FROM AUTHOR]

Small light-level geolocators have revolutionized research on avian migration and breeding ecology. However, proper evaluations of their impact on the life history of individuals compared to control individuals that experience the same conditions are still rare. Geolocator effects may be species specific and depend on the type of mounting, sex and size of individuals. While geolocators have been used extensively and without negative effects on large shorebirds, relatively little is known about their effects on small shorebirds, especially of those attached on leg-flags. We mounted 30 leg-flagged geolocators (15 on each sex) on Southern Dunlins (Calidris alpina schinzii) -- a small, long distance migratory shorebird (40-52 grams) -- and examined the effects of geolocators on return rates and reproduction through comparisons to a control group. The whole attachment weighed 1.5-2% of an individual's body mass.We found no evidence of lowered return rates. Out of 30 birds, 22 (73%) returned from both groups. Returning birds had similar breeding probability, timing of breeding, clutch size and nesting success. The proportion of unhatched eggs was higher in the geolocator group, but this difference was not significant. Inspection of unhatched eggs from the treatment group suggested no clear damage to eggs caused by geolocators. Our results suggest that at least one small wader species can withstand the extra weight imposed by appropriately sized geolocators. However, our study lasted only for one year, and long term evaluations that capture the full suite of environmental conditions and assess impact on brood care are needed. [ABSTRACT FROM AUTHOR]

Animals should cue on information that predicts reproductive success. After failure of an initial reproductive attempt, decisions on whether or not to initiate a second reproductive attempt may be affected by individual experience and social information. If the prospects of breeding success are poor, long-lived animals in particular should not invest in current reproductive success (CRS) in case it generates costs to future reproductive success (FRS). In birds, predation risk experienced during breeding may provide a cue for renesting success. Species having a high FRS potential should be flexible and take predation risk into account in their renesting decisions. We tested this prediction using breeding data of a long-lived wader, the southern dunlin Calidris alpina schinzii. As predicted, dunlin cued on predation risk information acquired from direct experience of nest failure due to predation and ambient nest predation risk. While the overall renesting rate was low (34.5 %), the early season renesting rate was high but declined with season, indicating probable temporal changes in the costs and benefits of renesting. We develop a conceptual cost-benefit model to describe the effects of the phase and the length of breeding season on predation risk responses in renesting. We suggest that species investing in FRS should not continue breeding in short breeding seasons in response to predation risk but without time constraints, their response should be similar to species investing in CRS, e.g. within-season dispersal and increased nest concealment. [ABSTRACT FROM AUTHOR]

Aim We study the population differentiation and phylogeography of the Temminck's Stint ( Calidris temminckii). Specifically, we seek signs of past and present population size changes and dispersal events and evaluate management and conservation unit status of the populations. We also study the possibility of introgression as the origin of two mitochondrial DNA (mtDNA) lineages found and estimate the divergence time of the lineages. Location Northern Eurasia. Methods We analysed 583 bp of mtDNA control region domains I and II and 11 microsatellite loci from 13 localities throughout the breeding range. In addition, we used mitochondrial cytochrome c oxidase subunit I ( COI), a barcoding gene, to search for signs of introgression. Results More population differentiation was found from microsatellites than from mtDNA, although differentiation was weak in both markers. Signs of past population growth were observed, in addition to more recent decline in some areas. Both control region and COI sequences revealed two maternal lineages coexisting in Fennoscandia and in north-west Siberia. No signs of introgression were detected. Lineage divergence time was estimated to have occurred during the glacial periods of Pleistocene. Main conclusions Slight differences in mtDNA and microsatellite differentiation and diversity may reflect different features - such as the mutation rate and effective population size - of the markers used, or female-biased dispersal pattern and high male site-fidelity of the species. The coexistence of the two mitochondrial lineages is most likely a consequence of post-glacial mixing of two refugial Pleistocene populations. Based on genetic information alone, global conservation concerns are not imminent. However, fast decline of a marginal Bothnian Bay population and the smallness and remoteness of a Central Yakutian population warrant conservation actions. [ABSTRACT FROM AUTHOR]

In some animal populations, immigrants have lower survival than philopatric individuals. Costs of dispersal or low phenotypic quality of dispersers may explain the pattern. However, apparent adult survival estimates, which describe real survival combined with site fidelity cannot be separated from permanent emigration. Thus, heterogeneity in breeding dispersal propensities of immigrants and philopatrics can bias fitness correlates of dispersal. Differences in breeding dispersal propensities may be caused by different strategies in response to environmental cues inducing dispersal, such as reproductive success. In such cases, the reported differences between immigrants and philopatric individuals may not reflect true variation in survival. We studied whether dispersal status specific apparent adult survival is associated with reproductive success in a Temminck's stint Calidris temminckii population. We analysed two long term capture-recapture datasets characterised by low and high nest predation levels. Philopatric individuals had higher apparent adult survival than immigrants in both datasets and the difference was highlighted during the high nest predation period. By contrasting return rates between successful and unsuccessful breeders as a proxy for dispersal, we found that unsuccessful immigrants breeding for the first time dispersed more likely than successful immigrants, but such a pattern was not found among philopatric individuals. Our results support the hypothesis that immigrant and philopatric individuals have different breeding dispersal strategies following reproductive failure and that their apparent adult survival differences are at least partly explained by different breeding dispersal propensities. Our results also suggest that the recent decline of the study population reflects a multiple response to increased nest predation through decreased local recruitment and increased emigration. [ABSTRACT FROM AUTHOR]

Due to different costs and benefits associated with dispersal and philopatry, life history traits of immigrants and philopatric individuals may differ. Despite of the apparent effects, dispersal status is only rarely considered in analyses of population dynamics. We analysed whether dispersal status explains variation in life history traits of an endangered Temminck's stint Calidris temminckii population breeding at the Baltic Sea. We also estimated the impact of immigration and dispersal status on the population growth rate (λ) with a population matrix model, in which immigrants and philopatric individuals are separated to their own stages. We found that philopatric individuals had a higher apparent survival than immigrants in both sexes. In reproductive parameters, variation due to dispersal status was not clear. Nests incubated by philopatric individuals survived better than those of immigrants, but this did not translate in hatchling production per breeding attempt. Models described a sink population in which the inclusion of both immigration rate to the population and the dispersal status of individuals into the model increased estimates of λ. When the better success of philopatric individuals was considered, the population growth appeared more stable (λ=0.972). If this was not taken into account, λ implied a strong decline (λ=0.911). The results support the hypothesis that immigrants exhibit lower components of lifetime reproductive success and therefore contribute less to population growth and the gene pool than local recruits. While we cannot distinguish whether this difference reflects higher mortality or permanent emigration, the latter explanation seems more plausible. Our results highlight the importance of considering immigration and dispersal status in population modelling. In the case of the endangered study population, the results implied that management options directed to improve local recruitment would be a profitable option. [ABSTRACT FROM AUTHOR]

Population growth rate ( λ) and its components (adult survival, local recruitment, immigration and their relative contributions to λ) were studied in the declining willow tit Parus montanus in Northern Finland. Capture–recapture models for open populations were used to estimate the population parameters and their process variation. Adult survival was fairly high with low variation (0.593, CV=0.067). As expected, local recruitment was lower and more variable (0.063, CV=0.610). During the 12-year study, the population growth rate averaged to one (0.988, CV=0.197; calculated as $$ {\hat{\sigma }_{{{\text{process}}}} } \mathord{\left/ {\vphantom {{\hat{\sigma }_{{{\text{process}}}} } {{\text{mean}}}}} \right. \kern-\nulldelimiterspace} {{\text{mean}}}). $$ However, if the present processes continue, population projections show that the population is likely to decline. There was considerable temporal variation in the relative contributions of demographic parameters to λ. In all years, adult survival had the highest relative contribution (mean 64%) to the population growth rate and it was the least variable trait. Immigration had a higher relative contribution (22%) to λ than local recruitment (14%). Based on the results for the contributions to λ, the main conservation concern for willow tits is adult survival. Due to low variation, adult survival may be difficult to enhance, but at least it should be prevented from declining. High stochasticity in local recruitment and immigration is probably an inherent characteristic of highly seasonal environments, making these traits difficult to address for conservation practices. [ABSTRACT FROM AUTHOR]

Predation risk is thought to be highly variable in space and time. However, breeding avian predators may create locally fixed and spatially fairly predictable predation risk determined by the distance to their nest. From the prey perspective, this creates predation risk gradients that potentially have an effect on fitness and behavioural decisions of prey. We studied how breeding avian predators affect habitat selection (nest location) and the resulting fitness consequences in a northern population of resident willow tit ( Parus montanus). Data included 429 willow tit nests over a four year period in a landscape containing a total of 33 avian predator nests. Willow tit nests were located randomly in the landscape and no predator avoidance in habitat selection or emptying of territories in proximity to predators was observed. Nestling size, however, was positively associated with distance from predator nests (n=252). Nestling mass and wing length were about 4.5% smaller close to predator nests compared to nestlings raised far from predator nests. Tarsus length also exhibited a positive relationship with increasing distance from predator nest but this was limited to habitats of young forests and pine bogs or dense mixed forests (4% increase). It is likely that habitat structural complexity influenced the perception of predation risk in different habitats. Our results indicate that willow tits do not provide reliable cues of predator free habitats for settling migrants. Nonetheless, breeding avian predators may create predictable predation risk in the landscape which is an important factor affecting reproductive success and potentially the demography of prey populations. [ABSTRACT FROM AUTHOR]

Abstract It is expected that through flexibility in behaviour, flock living birds respond to the asymmetries in resource access derived from dominance relationships. We analysed the microhabitat use of willow tits in winter flocks and assessed possible factors which shape habitat segregation between adults and juveniles in different temperature regimes. When foraging in mild conditions (ambient temperature > 0°C), flocks split up into subgroups with adults foraging in inner parts of trees more often than juveniles. However, no differences were recorded in the vertical position occupied in trees. In harsh conditions (< - 4°C), flocks re-united and juveniles further moved to outer parts of trees, increasing horizontal segregation between age classes. In mild conditions, vigilance behaviour was not related to the position of birds in trees, but in harsh conditions, scanning frequency was higher in outer parts of trees only for adults. In mild weather, juvenile position in trees was associated with body size and mass. The foraging microhabitat segregation detected in harsh conditions fits the age-related hoarding distribution previously described in the same population. This supports the hypothesis that hoarded food is important in determining future foraging habitat use. Adult preference and intraspecific competition for safer or richer inner parts of trees as foraging sites during harsh conditions seems to determine the habitat segregation between adults and juveniles. Furthermore, we suggest that in mild weather, when foraging in the absence of adults, juveniles balance the costs of using a potentially dangerous microhabitat with the benefits of building energetically cheap and large food reserves through hoarding. The expected patterns of microhabitat segregation may differ in parids, depending on whether predation risk or other factors such as food availability are the main factors controlling habitat quality. [ABSTRACT FROM AUTHOR]