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RozwĂłj badaĆ nad bocianem biaĆym Ciconia ciconia w Polsce: test trafnoĆci prognoz sprzed ÄwierÄwiecza
Age, brood fate, and territory quality affect nest-site fidelity in white stork Ciconia ciconia
Abstract Background A particular type of site fidelity is faithfulness to the nest site, where birds are not only reoccupying breeding territories but also reusing nests built in previous breeding seasons. Staying faithful to the nest site is believed to be an adaptive strategy, and based on the ability to predict an individual's own breeding success, a hypothesis of âwin-stay:loose-switchâ was proposed. In this study, we aimed to resolve which factors affect the nest-site fidelity of white stork Ciconia ciconia, species known for reusing nests available in the breeding sites. Basing on ring recoveries from 31 years of studies in Western and Southern Poland, we analysed the impact of intrinsic and extrinsic factors on nest-site fidelity. Results We found that increasing age and breeding success (i.e. producing any fledglings or not) increased the probability of reusing the nest, but in the oldest individuals, the probability decreased. In turn, the probability of breeding success increased with age, the increasing number of reproductive events on the particular nest, and the presence on the nest in the previous year. However, the oldest individuals had lower probability of success, as the relationship was curvilinear. The number of fledglings, however, was influenced only by an individual's age. The number of reproductive events on the nest was, in turn, affected by age, with the youngest and oldest individuals using the current nest for the least number of years. Conclusions Our study shows that the decision process of whether to stay faithful to the nest or switch is based on the experience from the previous breeding event, consistently with the âwin-stay:loose-switchâ hypothesis. Our results also show that site fidelity benefits white storks, as the probability of breeding success increases if the nest is reused. Results also show the senescence effect that lowers breeding success and site fidelity probabilities.
Pollinator assemblages in grasslands along river valleys depend on the urban matrix and local habitat scale variables
Brain size mediates the choice of breeding strategy in the redâbacked shrike Lanius collurio
AbstractThe brain size of vertebrates represents a tradeâoff between natural selection for enhanced cognitive abilities and the energetic constraints of brain tissue production. Processing information efficiently can confer benefits, but it also entails time costs. Breeding strategies, encompassing timing of breeding onset and nestâsite selection, may be related to brain size. In this study, we aim to elucidate the relationship between brain size, breeding timing, nestâsite choice, and breeding success in the redâbacked shrike Lanius collurio. Our findings revealed that the timing of the first eggâlaying date was associated with female head size, with largerâheaded females tending to lay eggs later in the breeding season. Additionally, we observed that breeding success was positively correlated with increased nest concealment. However, this relationship was stronger in males with smaller heads. In turn, nest concealment was not related to head size but primarily influenced breeding onset. These results suggest that the choice of breeding strategy may be moderated by brain size, with differences between sexes. Largerâheaded females may invest more time in selecting nesting sites, leading to delayed breeding onset, while largerâheaded males may compensate for suboptimal nest concealment. Our study sheds light on the intricate interplay between brain size, breeding timing, nestâsite preferences, and breeding success in passerine birds, underscoring the potential role of cognitive capacity in shaping individual decisionâmaking processes.
Are external head measurements a reliable predictor of brain size in the Common Quail (Coturnix coturnix)?
Comparative research conducted during the past two decades revealed ecological and evolutionary consequences of interspecies differences in relation to brain size. However, relatively much fewer studies have focused on intraspecific variation in brain sizes. This may arise from the lack of a reliable and universal methodology to estimate brain size that can be employed in wild populations in vivo and in a minimally invasive manner. Here, we assessed whether variation in brain mass of Common Quails ( Coturnix coturnix (Linnaeus, 1758)) was predicted by external measurements of the head. Contrary to previous work, we found that the height of the head and not the volume of the head was the best predictor of brain mass in the Common Quail. However, we found that the height of the head explained only a relatively small proportion of variance in brain masses (i.e., 74.4%). Our data suggest that the external measurements of the head may not represent a universally applicable methodology to estimate brain sizes in birds and should, therefore, be used cautiously and validated for the studied species.
Age-related nest-site segregation in a solitary nesting population of white stork Ciconia Ciconia
Abstract Background Habitat selection plays a crucial role in avian reproductive success, with nest-site characteristics and individual traits influencing breeding outcomes. This study investigates the relationship between breederâs age and nest-site selection in a population of white storks Ciconia ciconia, a long-lived, site-faithful species nesting solitarily in Western Poland. Using data collected from 2006 to 2024 on ring recoveries, nest dimensions, productivity, and habitat characteristics, we analyzed the age at which birds were first recorded on specific nests. Results Results revealed that older individuals were more likely to occupy larger nests and nests with higher productivity in previous years, suggesting the use of public information and a preference for high-quality sites. Interestingly, nest surface area, rather than height, was correlated with breederâs age, while land cover surrounding the nest had a sex-specific effect. Older individuals also appeared to prefer nests with higher occupancy rates. Older females avoided human-altered habitats, whereas no such relationship was observed for males. Contrary to expectations, age-related differences were not associated with preferred foraging habitats like meadows and pastures. Conclusions These findings highlight that age-based segregation in nest-site selection reflects experience and competition, with older birds optimizing breeding success by leveraging key environmental and social cues. The results suggest that younger individuals may occupy suboptimal habitats, possibly due to competition or inexperience. Future studies should explore the role of site fidelity, age-assortative mating, and anthropogenic influences, such as supplementary feeding, to fully understand the dynamics of nest-site selection in white storks.