One of the most critical functions of nests in parids is thermal insulation, particularly during egg incubation by females and during the first week of the hatchlings’ life when they are poikilothermic. Several avian studies reported associations between aspects of breeding success and nest parameters. In this study, we present results regarding long-term (eleven breeding seasons) impact of nest parameters on breeding characteristics in Great Tits (Parus major) and Eurasian Blue Tits (Cyanistes caeruleus) in a deciduous forest and an urban parkland study area. Our findings indicate that in Great Tits and Eurasian Blue Tits the number of fledglings (and in Eurasian Blue Tits also clutch size tended to be) was positively associated with lining mass and was influenced by the study area, with higher values observed in the forest. Additionally, there was a relationship between lining mass and higher hatching success in both tit species. We also demonstrated that both clutch size and number of fledglings were higher in Great Tits in the forest and in Eurasian Blue Tits the number of fledglings was higher in the forest. The study site also impacted hatching success, with Great Tits showing higher rates in the forest, and fledging success for Eurasian Blue Tits being higher in the forest. The number of fledglings differed between years in Great Tits and hatching success and fledging success differed between years in both Great and Eurasian Blue Tit species. We conclude that avian nests play an important role during reproduction, and the materials used to construct nests contribute to various functional properties. However, further studies are needed to establish clear relationships between nest parameters and breeding performance.

Climate change is a key driver of biodiversity loss in multiple ecosystems, which can act at multiple stages of a species life- and annual cycle. Identifying where, when, and how these impacts may happen is key to understanding, and planning for, the population-level effects of climate change. This study assesses how climate change will impact the breeding and non-breeding areas of the European Bee-eater Merops apiaster, a long-distance migratory bird, by combining correlative species distribution models with recent tracking data to account for population connectivity between breeding and non-breeding sites. The three populations studied (Iberian, German, and Bulgarian) demonstrated different levels of exposure to climate change, as well as different patterns of connectivity. The Iberian breeding population showed high exposure to climate change in both its breeding and non-breeding sites, which may result in significant, interacting impacts on this population. In contrast, breeding populations in Germany are likely to benefit from climate change, both in their breeding and non-breeding range. Connectivity also varied; while most populations demonstrated extremely high connectivity between breeding and non-breeding sites, the Iberian population was substantially more behaviourally flexible, indicating there may be some adaptive capacity of this population to change non-breeding sites if some become less suitable due to climate change. Incorporating breeding and non-breeding areas into species distribution modelling highlights how the impacts of climate change may combine into multiplicative impacts across a species’ annual cycle, and how combining methodologies and data sources can provide greater insight into the impact of climate change on migratory species and, in turn, inform conservation action.

Breeding success of birds depends on survival during two critical stages of the reproductive period: First, egg laying and incubation, and then nestling and fledgling. This essential element of avian life history mirrors an evolutionary adaptation of parents to existing environmental conditions. The main factors that determine nest survival involve weather, predation and sibling competition. Despite numerous studies documenting their impact on breeding success, only a few have analysed the issue with regard to ground-nesting birds and estimated their survival functions. Therefore, we decided to examine nest survival probability of the Crested Lark (Galerida cristata) in a population that occupies newly established roadside habitats in Central Poland. The analysis is based on 141 nests monitored between 2018 and 2022. We found that the mean survival probability of the whole nesting period was 0.376, and it was higher during the egg stage (0.836) than during the nestling period (0.392). The Cox proportional hazards model shows that nest survival in the nestling stage is mainly affected by the time of breeding and the distance from the road edge, and also by mean temperature of the whole nesting period. In other words, the probability of a brood failure in the nestling stage decreases as the breeding season advances, whereas it increases among nests located closer to the road edge. Furthermore, during the whole nesting period, nest failure decreases as the temperature rises. Our study suggests that the Crested Lark, being a multi-brood and thermophilic species inhabiting temperate regions, may benefit more if its nesting attempts begin later during the season when breeding conditions become more favourable. However, we also take into consideration a hypothesis that nesting in grassy habitats near road edges may prove to be an ecological trap, attracting high densities of nesting birds but leading to their low nest success.

The present study provides data on clutches with dwarf eggs from a large sampling in a colony of Yellow-legged Gulls (Larus michahellis) over 31 years. Their occurrence was very low, with a global percentage of 0.26%. Significant variations were not detected among periods of 10 or 11 years. In all the cases, only one dwarf egg was found per clutch. Mean volume of dwarf eggs was 34% of that of non-dwarf eggs. Their content was mostly albumen and a very reduced quantity of yolk, and they were infertile. Several results of the study (the laying order of the dwarf eggs, their mean clutch size and the mean size of the non-dwarf eggs from clutches with dwarf eggs) support the hypotheses that runt eggs occur from a temporary disturbance to the reproductive tract.

How the migration behavior of long-lived birds develops throughout their life is still a research question in ornithology that is largely unanswered. Here, we analyzed GPS data of 70 juvenile Black Storks during the first 3 years of their migration to determine the influence of age and experience on migration patterns. We focused on the choice of the migration flyway, as well as the movements in the wintering area, and the changes in departure times with increasing age. Migratory routes of German Black Storks were divided into the western (82% of all tracked individuals) and eastern flyways (16%). The central migratory flyway through Italy or Greece was taken only by two individuals and never repeatedly. In addition, we found that the wintering area decreased by almost 60% during their first 3 years of life. In addition, spring departure dates from the wintering areas also became earlier with increasing age. However, we did not find changes in departures from the breeding area in autumn. Thus, our study shows that age and migration experiences have a considerable influence on essential migratory decisions in Black Storks. Further, it also demonstrates that older storks rely strongly on previous experiences to perform their migrations efficiently.

Impacts of global climate and land‐use changes on distribution patterns and breeding sites remain today poorly studied for several vulnerable emblematic bird species, including the Golden Eagle (Aquila chrysaetos). Herein, we analyzed the potential effect of global climate changes and agricultural activities on the distribution patterns of this top predator across Mexico. We assessed the long-term role of protected areas (PAs) for safeguarding the species’ overall distribution and its breeding sites. We evaluated current and future (2040s, 2060s, and 2080s) threats from global change using ecological niche modeling and geographic information system approaches to determine the percentage of the species’ distribution area that overlaps with highly human-modified areas and PAs under each climate scenario. We also used niche overlap tests to assess whether the species’ breeding sites show equivalence or similarity of climatic conditions over time. Our findings revealed shifts in the Golden Eagle’s distributional area, with an overall size reduction (by ~ 57% in the 2040s and ~ 78% in the 2080s) due to future environmental changes, mainly attributable to increasingly dry and warm conditions. Mexican PAs cover ~ 12% of the Golden Eagle’s range across country, but this decreased by > 33% on average under the species’ future distributions. Although the hypothesis of equivalent climatic conditions at breeding sites over time was rejected, those sites did have long-term climate similarity (niche overlap: 0.75–0.83; P < 0.05). Considering the species’ nest site fidelity and that colonization of new areas within Mexico seems unlikely, protection of these breeding sites is a critical step for the long-term conservation of this emblematic species in Mexico.