The vocal behaviour of birds can change daily and seasonally. Understanding the daily and seasonal acoustic activity patterns of birds helps to understand their behavioural ecology and is crucial for designing effective monitoring protocols. We studied daily and seasonal acoustic activity patterns for a complete annual cycle of three bird species: Alström's Warbler Phylloscopus soror, Brownish-flanked Bush Warbler Horornis fortipes and Streak-breasted Scimitar Babbler Pomatorhinus ruficolli at three different sites in Yaoluoping National Nature Reserve, Anhui Province, East China. All three species displayed a peak in singing activity in the morning; however, they differed in their acoustic activity during the daytime. Alström's Warbler was vocally active for five months (April–August), with higher singing activity earlier in the season. Brownish-flanked Bush Warbler was vocally active for six months (March–August) and showed a significant variation in singing activity over time. Streak-breasted Scimitar Babbler was vocally active for nine months (March–November) and displayed a slight variation in singing activity among months at different sites. The acoustic activity of the Alström's Warbler and Brownish-flanked Bush Warbler was negatively correlated with precipitation, whereas in Streak-breasted Scimitar Babbler there was no relationship with precipitation. Overall, we found large temporal variation in singing activity within a day and between seasons. To better understand the function of the daily and seasonal pattern of singing, future studies should investigate the functioning of different song types used during daytime and morning.

Avian migration is recorded over long distances, but some species winter much closer to their breeding sites or do not migrate at all. Specifically, the family of gulls Laridae shows great within and among species variation in migration. However, the migration ecology of many gull species is still unknown, even for abundant and widespread species such as the Black-headed Gull Chroicocephalus ridibundus. Here, we aimed to map the migration of Black-headed Gulls using GPS-tracking data from eight birds from a declining colony at Griend in the Dutch Wadden Sea to study migration routes and timing as well as wintering habitat of these birds. Furthermore, we used this GPS-data and 199 colour-ring resightings of adult birds from the same colony to study their wintering locations and habitat. The GPS-tagged birds migrated away from the Dutch Wadden Sea between mid-September and late November. All migrated in western to south-western directions to wintering areas at 130 to 560 km from the breeding colony. The GPS-tagged individuals wintered in The Netherlands, France and the United Kingdom and migrated towards these wintering sites both diurnally and nocturnally. The data indicate that most movements over the North Sea were nocturnal, whereas most migratory movements over land were during the day. Colour-ring data showed that females wintered significantly further away than males. We found no indications for differences in timing of migration between males and females and also no sex-specific preference for nocturnal or diurnal migration. We argue that the hitherto undocumented prevalence of nocturnal sea crossings calls for a better assessment of the potential risks of offshore wind energy developments in the North Sea. As such, this and new GPS-tracking data of Black-headed Gulls can aid in the conservation of this common and widespread species by providing novel insights in migration behaviour and the connectivity between breeding and wintering grounds.

Northern Hemisphere species generally respond to global warming by withdrawing from the southern margins of their distributions and shifting their breeding sites northwards. However, the situation regarding the breeding populations of Goosanders Mergus merganser merganser in Europe appears to be paradoxical: in many places, an increase in the breeding population and range extension have been documented. We studied the breeding biology of this species during the breeding seasons of 1987–1996. We show that the breeding success of a Goosander population breeding in Northern Poland was higher following winters when the ice cover disappeared earlier. There was a significant positive relationship between the disappearance of ice cover and the clutch initiation date, and the breeding success of early broods was higher. The overall mean clutch initiation date was 13 April ± 15 days (SD). The yearly means of clutch initiation dates varied from the beginning of April to the beginning of May. It seems likely that, among other factors, the Goosander's adaptability in terms of the timing of breeding may be partially responsible for the expansion of the species into new areas in the last 30 years.

Ruffs Calidris pugnax migrate from wintering areas in West-Africa and Europe to breeding grounds in northern Eurasia, using stopover sites along the way. At one such stopover site in southwest Friesland (53°N, The Netherlands), we studied variation in the timing of individual stopover based on 6474 Ruffs colour-ringed in 2004–2012. 43% of males and 22% of females were recorded in the study area in March–May the years following marking. Minimal stopover duration of returning individuals showed substantial within-year heterogeneity. We distinguished two classes: (1) ‘transient’ individuals were observed only on a single day in the study area within a season (51% of observed males and 79% of females), and (2) ‘staging’ individuals were observed on multiple days. We observed two seasonal peaks in the presence of transient Ruffs, typically coinciding with the peak of arrival and departure of staging birds. Males known to winter in Europe were more likely to be observed in the study area and arrived earlier than males of unknown winter origin (3.1 days and 3.7 days earlier for transient and staging males, respectively), but departure was unrelated to winter origin. Staging and transient females arrived later than males. Between-year repeatability of individual behaviour was low, and individuals did not significantly advance their arrival date over the course of years, in contrast with a pattern of shifting arrival dates at the population level. The observation that a large proportion of Ruffs visit southwest Friesland for only a short stop suggests that many individuals rely on other sites for moulting and refuelling during spring migration. Resightings of marked individuals elsewhere in western Europe indicated that these sites are largely located between 51° and 54°N. Thus, during spring migration, Ruffs marked in southwest Friesland displayed high between- and within-individual variation in minimal stopover duration.

Studying nest construction provides insight into the functional and ecological aspects of this key behaviour of avian reproductive biology. Studies have shown that passerines construct nests out of a range of different materials, but the number of species represented in the literature remains low. This study examined nests constructed by the Eurasian Nuthatch Sitta europaea in nestboxes at various sites in North West England over the period 2011–2020. Nests were collected and weighed after breeding to quantify the materials used by the birds in order to determine whether there were any differences in nest construction behaviour among years. The study also allowed for the comparison of nests built in standard and large nestboxes. Nuthatches used mud to plaster the inside and outside of the nestbox; however, they relied heavily on bark flakes (84% of nest mass), but also included wood chips and leaves to construct the nest. Bark pieces were taken from Common Hazel Corylus avellana, Yew Taxus baccata or Scots Pine Pinus sylvestris, depending on availability in the immediate area around the nestbox, although Hazel bark was the preferred material. There was little effect of sample year on nest composition except for an increase in wood chips over the sample period. Thermal and hydrological properties of the bark flakes did not depend on the tree species. Nuthatches nesting in large nestboxes produced heavier nests, but this did not affect their reproductive success, which implies that the energy required for nest construction does not necessarily impose such an excessive burden on breeding birds that it adversely affects their fitness.

In the boreal biome, forest fires are the most important natural disturbance influencing tree substrate availability and quality for a range of specialized species. This includes the Eurasian Three-toed Woodpecker Picoides tridactylus, which is known to promptly utilize burned forest habitats. However, there are no studies addressing the foraging behaviour of this woodpecker in forests affected by wildfire. Such knowledge could assist the development of efficient post-fire management strategies which are in line with biodiversity conservation objectives. This study describes the foraging behaviour of the Eurasian Three-toed Woodpecker during the breeding season in a forest area of 13,100 ha in southcentral Sweden affected by a major wildfire in 2014. During the second breeding season after fire, we used instantaneous sampling where we observed the foraging behaviour of 28 individuals during a total of 1681 observation minutes. Our results suggest that Norway Spruce Picea abies and larger diameter trees (DBH > 25 cm) are important foraging substrates. However, data on time spent foraging on the different substrates suggest that Scots Pines Pinus sylvestris also are important. In particular, we identified the importance of the root collars, where excavation into sapwood was the main foraging method. Our study was performed during a clearly visible peak of Eurasian Three-toed Woodpecker abundance and this may suggest that the level of food resources available was very high which led to observed foraging patterns not necessarily observed in other types of habitats.

Long-term monitoring of breeding seabirds is fundamental for assessing the conservation status of their populations. Whereas traditional monitoring is often time consuming and has disadvantages, such as observer bias or disturbance to the breeding grounds, the use of uncrewed aerial vehicles (UAVs or drones) has proven to be an efficient alternative by allowing non-invasive monitoring of inaccessible areas. Nonetheless, the use of drones for monitoring wild populations brings forth a new challenge, namely the handling of large amounts of data (images), usually negating the efficiency of the previous steps. Diverse methodologies have been developed to deal with this issue, but they usually involve the use of commercial software, that reduces the accessibility of users with limited resources. We tested if the popular free software ImageJ could compete in terms of efficiency (i.e. accuracy and processing time) with other commercial software. We obtained similar values of agreement between manual and semiautomated total counts of individuals (99.1%), reducing the analysis duration fivefold. In addition, we propose a correction factor in the detection of incubating individuals based on the assessment of the individual behaviour of 10% of the birds present in each colony. Following this correction, we were able to estimate the total number of incubating birds with a 103.5% agreement with manual counts, reducing the time invested up to threefold. Thus, we show support for the use of free software (ImageJ) as a good low-cost alternative for users of drone imagery in assessing breeding birds and as a conservation tool.

Female song is widespread across songbirds, especially in tropical and subtropical species, in which females sing for resource defence, competition with intruders and mutual mate-guarding. We compared songs of males and females, produced spontaneously in a wild population of the Plain Laughingthrush Pterorhinus davidi, a songbird endemic to temperate China. We found that both sexes sing in this species and the number of notes within a song differed significantly between the two sexes. Females generally produced a longer first note than downstream notes; however, males sang in more variable frequencies than females. Males and females also differed significantly in song duration, pace and note structure. Sex-specific songs may indicate different functions and social and/or sexual selective pressures. Further studies are required to determine the functions of female song in this temperate zone passerine bird.