The separate scheduling of moult and breeding and of migration in birds that fly long distances between their breeding grounds and wintering areas has been recognized as an ecological adaptation permitting these events to coexist in the annual cycle. The Alpine Accentor Prunella collaris, mountain bird species, lives in harsh and cold alpine conditions. Different breeding schedules and migration strategies of females and males coincide with different moulting patterns between the sexes. Details of moult were obtained from 103 adult birds caught between the July and October (1991–2021) in the Western Carpathians (Slovak National Parks — High Tatras, Low Tatras and Low Fatra). Moult generally lasted from the second decade of July to the first decade of October but mainly during August and September. Mean primary moult duration in this species was calculated to be 36 days. Females had delayed onset of primary moult by about 12 days, of secondary moult by 8 days but moult duration was much shorter in females than in males. Mean duration of primary moult in females was 27 days, in males 43 days. Males moulted primaries over 16 days and secondaries over 10 days longer than females. Females completed primary moult two days and secondary moult one day before males. Migrants — females have adapted to the harsh alpine environment by moulting quickly, while residents — males moult more slowly than females. The alpine lifestyle of accentors leads to significant intersexual differences not only in the timing of breeding cessation, but also in the timing of moulting. This study is the first to provide a more detailed view on moulting in this species as well as discuss its wider ecological impacts on birds' annual cycle considering the alpine ecosystems.

Survival in passerine birds varies across latitudes, with survival typically greater in tropical species compared to their temperate counterparts. However, understanding of survival patterns in subtropical latitudes is limited. In this study, we provide the first apparent annual survival estimates for four sympatric passerines with different life-histories in southern and subtropical Brazil: the Star-throated Antwren Rhopias gularis, the White-rumped Swallow Tachycineta leucorrhoa, the Green-headed Tanager Tangara seledon, and the Golden-crowned Warbler Basileuterus culicivorus. We used mark-recapture and resighting data from 3–5 years of intensive population monitoring to estimate survival. We tested for potential survival trade-offs with clutch size and body weight, and whether convergence in survival rates (as predicted by the latitudinal concept of life history traits) occurs. We show important differences in apparent adult annual survival rates, rather than convergence, among the studied species. The Star-throated Antwren, with the smallest clutch size, had the greatest survival rate (0.77/yr), while the White-rumped Swallow, with the largest clutch size, had the lowest (0.49/yr), with the remaining species having intermediate clutch sizes and intermediate survival rates (0.54–0.64/yr). Our results show that survival rates of subtropical passerines differ among species, and the estimates seem to be inversely related to their clutch size. Furthermore, the observed intermediate life history traits of subtropical species compared with tropical and temperate extremes, suggests that much of this pattern may be due to local adaptation to subtropical conditions, which confound understanding in macro-scale analysis.

In 2022–2023, Europe experienced significant outbreaks of highly pathogenic avian influenza (HPAI) affecting both poultry and wild birds. These outbreaks had notable impacts on various bird species, especially those nesting in colonies. In the Odra estuary and its lower section, a particularly important area for gregarious waterbirds, 23 breeding colonies were examined in 2023. The total number of breeding pairs (bp) was 12,439. No symptoms of HPAI were found in Cormorants Phalacrocorax carbo (8,899 bp), Grey Herons Ardea cinerea (503 bp) and Pied Avocet Recurvirostra avosetta (25 bp). HPAI symptoms were found among colonies of gulls and terns, primarily in Black-headed Gull Chroicocephalus ridibundus (BHG) (2,484 bp, 14% mortality rate) and in Common Tern Sterna hirundo (CT) (656 bp, 12% mortality rate). Among the colonies of terns of the genus Chlidonias, low mortality was observed — 1 adult individual (143 bp of Black Tern Chlidonias niger, 0.2% mortality rate) and no dead individuals among Whiskered Tern Chlidonias hybrida. All samples taken from the BHG and CT (N = 20) from affected colonies contained genetic material of avian influenza A. Lower bird density in the colony results in lower mortality. Additionally, a larger area of suitable breeding habitat reduces bird mortality. There was no significant difference in mortality between artificial and natural habitats. The lowest mortality was in natural habitats with floating vegetation. There was higher mortality on natural islands compared to artificial ones. The highest mortality occurred in colonies dominated by BHG and CT. Small artificial floating platforms may contribute to episodes of mass mortality in epidemic conditions due to high density and easy virus spread. Large artificial islands may be safer, a density of 3 bp/100 m², the mortality rate was 1.1%, while on small artificial platforms with an average density of 92 bp/100 m², the mortality rate was 25%.

Intraspecific variation in nest size received considerable attention in the last two decades. A number of studies of small passerines found that nests built at lower ambient temperatures were larger than those built at higher temperatures. As larger nests, although costly, provide a better thermal environment for eggs and small nestlings, this has been interpreted as adaptive phenotypic plasticity. Yet, a comparable number of studies failed to confirm the relationship between temperature and nest size. We used data from a nest box population of Great Tits Parus major breeding in central Poland to test the possible effect of temperature on nest size built by females with multiple nests measured during a 3-year study. Using the sliding window approach, we identified the exact time window for which the given weather variable best explained the variation in the nest trait, in addition to that already explained by study year, clutch type (first or second) and female identity. For each nest trait and weather variable, we tested all possible time windows over a 30-day period prior to the first egg laying date (FED). We found that for the studied Great Tit population time windows of sensitivity of nest traits to temperature opened 19–24 days before FED and closed 6–15 days before FED. Maximum daily temperature was consistently a better predictor of nest size characteristics than either minimum daily temperature or mean daily temperature. For precipitation, the only significant sensitivity window opened 27 days before FED and closed 3 days before FED. Thus, temperature sensitivity time windows opened 5–10 days before the start of nest building and lasted no longer than halfway through the building period. Temperature effects were only detectable after accounting for the strong effects of female identity on nest size. The failure to observe temperature effects on nest size in some previous studies may be explained by considering temperatures during nest building rather than some time earlier, or by ignoring persistent female effects on nest size in the analyses.

Biological invasions are among the main threats to biodiversity, yet invasive species may also have positive impacts on native taxa, such as supplementing the diet of native species when other food items are less available. Herein, we assess whether the invasive River Tamarind Leucaena leucocephala, a small Fabaceae tree, is an important food item for a genetically distinct, threatened population of the Southern Mealy Amazon Amazona farinosa in the Brazilian Atlantic Forest. We surveyed citizen science platforms and published articles for feeding records of Southern Mealy Amazon to quantify the occurrence of River Tamarind seeds in its diet throughout the year, and assess if seed consumption differed between seasons. Our results showed that, although the density of records of fruit consumption is relatively constant throughout the year, consumption of River Tamarind seeds occurs almost exclusively during the dry season. Furthermore, seed prevalence in feeding events was also significantly higher during that time of the year. Our findings indicate that L. leucocephala represents an important source of nutrition for Atlantic Forest A. farinosa during the dry season. We highlight how citizen science may help to elucidate potentially positive interactions with invasive species and emphasize the need to better understand the ecological roles between the River Tamarind and threatened seed predators at different scales in the Neotropics.

Noise pollution is one of the leading environmental risks to human health. However, noise effects on the reproduction and behaviour of wild animals have been ambiguous. The reason can be that most studies focus on the effect of one type of noise, while structurally distinct noise types with the same loudness, but with various frequencies may cause different responses due to masking effect. Hence, comparing spectrally different noises in a single study can provide valuable insight into those noise differences, as all other ecological conditions for different experiments are nearly the same. Here, we exposed free-living Great Tits Parus major breeding in nest boxes to three different noise types, such as car traffic, lawnmower, and chainsaw noise, which are common in the breeding habitats of passerines, and investigated these effects on parental provisioning behaviour. We found that noise as such had a negative effect on nest visits but the effect was not detected when analysing noise types separately. These findings do not support the acoustic masking hypothesis, given that structurally different noise types had similar effects on parental provisioning. We suggest that different anthropogenic noises may alter avian reproductive behaviour through disruption and disturbance, potentially having cumulative and negative effects on reproduction.

Competition for territories and females inevitably places males of the same species into conflict. We investigated male-male interactions within Grasshopper Warbler, Locustella naevia (later GW) and River Warbler, Locustella fluviatilis (later RW) using acoustic playback experiments. Our aim was to clarify the vocal traits employed during intraspecific encounters and to compare the territorial vocal performance between two closely related species. In total, eight GW and ten RW males were tested in May and June 2019 along the Morava River, in western Slovakia. The GW males used two call types and reduced the song duration in response to conspecific song stimuli. The RW males used four call types, reduced and accelerated songs. In each species, we found a new type of call used in territorial interaction that had never been described and visualized before. The vocal response in territorial interactions was more diverse in RW males than in GW males. This finding is consistent with the higher complexity of RW spontaneous vocal performance within the population as well as on a broader geographic scale.

Common Buzzard Buteo buteo is a raptor widely distributed in the Palaearctic Realm. Populations of a subspecies Buteo buteo vulpinus called Steppe Buzzard are strictly migratory and wintering in sub-Saharan Africa. However, detailed information about its individual movement pattern is missing. We equipped a nestling of Steppe Buzzard with a telemetry logger in eastern Ukraine in the 2021 breeding season. The bird was GPS-tracked till the end of 2022. We characterised its post-fledging period and area, periods and movement patterns of pre-migration vagrancy, two autumn and one spring migrations and winter and summer stays. The first and second autumn migrations (71 and 48 days, respectively) of the tracked bird headed south, along the east coast of the Black and Mediterranean Seas, across the Arabian Peninsula along the east coast of the Red Sea with a flight to Africa via the Bab-al-Mabdab Strait and further southeast to Zambia as wintering place. Back during the spring migration (76 days), the bird returned northeasterly along the west coast of the Red Sea and left Africa after crossing the Suez and returned to its natal area via the east coast of the Mediterranean and Black Seas. Thus, the loop migration of the Steppe Buzzard around the Red Sea was confirmed. During the summer period in 2022, the immature bird changed the area of occurrence from eastern Ukraine to western Russia supposedly as a result of war events in eastern Ukraine.