Journal of Ornithology最新文献

Conditions encountered during early development affect future survival and reproduction in many bird species. For parents, it is important what body condition the nestlings will achieve at fledging because the condition affects the offspring’s chances to survive and reproduce in the future. However, there is a trade-off between the number of nestlings and their condition. We studied parental behaviour and nestling body condition in uniparental Penduline Tits. In this small passerine, the parental care (incubation and food provisioning) is provided by the female only (49% of clutches in the study population) or the male only (15%). In addition, over a third of clutches are deserted by both parents before the start of incubation. We found that female-only cared clutches had more eggs and nestlings and produced more fledglings than male-only cared clutches. The incubation behaviour and incubation temperature in both types of clutches were similar. The provisioning rate per brood was positively, and the provisioning rate per nestling was negatively, correlated with brood size. Although males cared for smaller clutches, parent sex was not significant in both models of provisioning rates (per brood and per nestling). Moreover, the provisioning rate did not predict the brood’s average nestling condition. However, nestlings reared in broods with male care were in better condition than those reared by females. At the age of 13 days, they had a higher scaled mass index (describes the relative size of energy reserves) and higher haemoglobin levels. The results suggest that the lower productivity of male-only cared clutches, compared to those cared for only by females, may be compensated by the higher condition of nestlings. Information about the recruitment success of broods cared for by males and females will be necessary to test this prediction.

Social learning is an important aspect of dealing with the complexity of life. The transmission of information via the observation of other individuals is a cost-effective way of acquiring information. It is widespread within the animal kingdom but may differ strongly in the social learning mechanisms applied by the divergent species. Here we tested eighteen Kea (Nestor notabilis) parrots on their propensity to socially learn, and imitate, a demonstrated sequence of steps necessary to open an apparatus containing food. The demonstration by a conspecific led to more successful openings by observer birds, than control birds without a demonstration. However, all successful individuals showed great variation in their response topography and abandoned faithfully copying the task in favour of exploration. While the results provide little evidence for motor imitation they do provide further evidence for kea’s propensity towards exploration and rapidly shifting solving strategies, indicative of behavioural flexibility.

Improving our understanding of the spatio-temporal distribution of migratory game species is pivotal for developing flyway-based management strategies. We used miniaturized GPS-Argos transmitters to analyse movement patterns, home-range, habitat use, and pre-breeding migratory dynamics of a medium-sized (~ 80 g) migratory songbird, the Fieldfare (Turdus pilaris). We focused on the population wintering in northern Italy, an area where this species is subject to intense hunting pressure during autumn–winter. Most individuals were relatively sedentary upon reaching their wintering area, with only a few performing erratic movements up to mid-January. Forest and farmland were the most used habitats during both early and late winter. We obtained partial information on pre-breeding migration from 16 individuals. Pre-breeding migration began on 21 March on average (min.: 7 March, max.: 7 April). We identified north-western Russia (longitudes 35–50° E) as the putative breeding area of six individuals, while a single individual migrated to Finland. Our novel individual-based tracking study of south-European wintering Fieldfares thus highlights that Russia, rather than Scandinavia, is likely the main origin area for Italian wintering birds, improving previous knowledge based on recoveries of ringed birds. Our findings suggest that an effective flyway-based management plan for a sustainable exploitation of the Fieldfare in southern Europe may be hindered by knowledge gaps on the conservation status of this species over its broad breeding range, which extends to distant Russian regions.

Understanding the mechanisms and the factors influencing the phenology, reproduction and biometrics of long-distance migrants are extremely important as global climate warming has induced changes in the locations of geographic ranges and dates of migration and reproduction. In this article, we compare phenology, reproductive parameters and adult biometrics of core and peripheral populations of a rare and endangered bird—the barred warbler Curruca nisoria—that inhabits the farming landscapes and makes long-distance trans-continental migrations. We predicted that: (i) individuals nesting in the core population would be larger than in the peripheral population; (ii) the reproductive parameters of the Barred Warblers in the core population would be higher than in the peripheral population. The Barred Warblers nesting in the centre of the range laid larger clutches and were clearly larger than individuals from the small, peripheral population. However, no differences in egg size and productivity were observed between the analysed populations. The Barred Warblers synchronised their breeding dates over a large geographical area as they had only a short time window for reproduction and had to lay their eggs as soon as possible. Individuals arriving earlier on the breeding grounds had larger clutches, longer wings and produced more nestlings. The pressure of the passage of time during the breeding season was a more important factor than the geographical location affecting the breeding characteristics in these populations.

Mountain habitats harbour significant breeding populations of alpine bird species, yet they can also be important from a biodiversity conservation point of view outside the breeding season. High-elevations are likely important fuelling habitats for birds during the post-breeding period due to seasonal peaks in arthropod abundance being later relative to lowlands. There is no detailed study of bird communities using high-elevations in the post-breeding migration period in Europe. In this study, we recorded birds on line transects from August to October in 2021 and 2022 across an elevational gradient in the Western Italian Alps to assess how the abundance and diversity of birds varied in time and space during the autumn migration period. We detected 104 species in total, representing 22% of the Italian list of terrestrial bird species, showing that a wide range of bird species exploit these habitats. The highest bird diversity and abundance were found during the early migration period at the end of August when long-distance migrants use high elevations. Treeline habitats and south-facing slopes held the highest abundance of migrants, probably due to the high structural diversity and relatively high solar radiation which might affect thermoregulation and prey activity. We suggest that future management of protected areas in the mountains should take these parameters into account in order to protect mountain bird diversity, not only during the breeding season, but also in other key periods of the annual cycle, such as post-breeding migration. It is also essential to counteract the effects of climate and land-use change in mountain habitats by promoting conservation strategies for Alpine biodiversity, including migrants, over the entire year.

Habitat conditions surrounding individual birds are key components determining their fitness, notably by influencing effective foraging, escape from predators, and adaptation to changing environmental conditions. Birds living in dynamic habitats are particularly likely to have a high need to explore; however, spatial and temporal patterns of exploratory movements are poorly understood. We investigated the exploratory movements of adult common shelducks (hereafter Shelducks, Tadorna tadorna) in the Wadden Sea, which provides a dynamic habitat for birds. We captured nine shelducks in adjacent breeding areas and attached GPS satellite telemetry devices for 5–18 months, mostly covering the post-breeding period. We analyzed bird-movement patterns based on mean daily locations and behavioral change point analysis. All individuals explored on a median of 22% of tracking days (range = 6–39%). Individuals usually explored new areas for a short time before switching to stay in these areas for longer periods. Exploratory movements were particularly frequent before the start of the flightless period during molting. During this time, shelducks explored the traditional molting area in the Elbe estuary intensively. However, birds did not explore places within the area subsequently used for molting for longer or more often than other places. The molting area was used for a median of 59 days, i.e., about twice as long as required for the flightless period, suggesting that this area was explored not only to select a suitable molting place, but also for other purposes. Only two shelducks performed longer-distance exploration movements, i.e., > 45 km from their sedentary areas. We therefore concluded that exploratory movements by adult shelducks may enable the birds to adapt to small-scale changes in habitat conditions.

Nest cavities with suitable thermal conditions can provide fitness benefits for birds through reduced thermoregulatory cost. Insulation can however vary between natural and human-made cavities. While several studies have assessed cavity temperatures, research from high elevation habitats, where environmental conditions are particularly variable, is still scarce. We compared temperature profiles of vacant natural and human-made nest cavities of White-winged snowfinches Montifringilla nivalis, a high elevation cavity nestling species. Human-made cavities experienced more extreme temperatures, with potential consequences for offspring viability, bringing into question their suitability as conservation measure, particularly as extreme temperature events become more frequent.

Weak oscillating magnetic fields (OMF) in the radiofrequency range are known to disrupt the orientation of birds. However, until now, it has not been experimentally verified that the sensitivity to OMF is a characteristic feature specifically of the magnetic compass and OMF does not influence the celestial compass system as well. Here we studied if OMF affected the star compass of a long-distance migrant, the Garden Warbler. The birds were tested under the natural starry sky under two different conditions: in the natural magnetic field (NMF) and in radiofrequency OMF with the amplitude 20nT and frequency 1.41 MHz (matching the Larmor frequency of a freestanding electron spin in the local NMF of 50,400 nT). This amplitude is about ten times higher than the sensitivity threshold to OMF shown for this species in previous studies. Our experimental results clearly demonstrated that OMF did not influence the celestial (star) compass system: with access to the starry sky garden warblers showed migratory orientation appropriate for autumn migratory season both in the NMF and in the OMF. Thus, the OMF effect is pertinent to the magnetic compass system, not to the avian orientation in general.

Many aspects of the spatial ecology of the cinereous vulture (Aegypius monachus) are still unknown. The Iberian population is thought to be predominantly sedentary, but the spatial patterns of young individuals have been barely studied. The aim of this study was to provide a comprehensive understanding of the juvenile dispersal of the Iberian cinereous vultures. To this end, we GPS-tagged 41 Cinereous Vultures and tracked their movements during the period 2002–2021, from the end of parental care to the beginning of reproductive age. We examined the influence of age, season and sex on movement metrics (accumulated distances, distances to nest and home range sizes). During the juvenile dispersal period, cinereous vultures travelled over large areas of the Iberian Peninsula and southern Europe. Despite the high individual variability, we found a negative age-related trend in all movement metrics: the younger individuals (<1 year old) often performed farther movements and occupied larger areas, stabilising their movements during immature (1–3 years) and subadult (4 years) phases. On the other hand, season influenced the accumulated distance within all age classes; warm months positively influenced flight effort. Finally, females flew farther and occupied larger areas than males, consistently within age classes. This study did not take into account many factors which may explain part of the high variability observed: landscape, supplementary feeding sites, dumps, colony size, interspecific interactions, stochastic events, etc. Further studies are needed to investigate the influence of these factors on the dispersal of the species in more detail, but this work provides the first approach to the juvenile dispersal of the cinereous vulture in Iberia.

The Agulhas Long-billed Lark Certhilauda brevirostris is restricted to the Agulhas Plain, South Africa, a region extensively transformed for crop production and sheep grazing. We present data on nest and egg characteristics, clutch and brood size, parental care and breeding success previously undescribed for this species. During field surveys in 2020 and 2021, 29 nests were located. Of these, 16 were monitored by camera traps. Laying started in late winter (July) and continued until early summer (late November). Most nests (66%) were in Renosterveld, a unique vegetation component of the Fynbos Biome, with the remainder in human-modified landscapes. Female larks were responsible for nest construction and incubation. Both sexes provisioned nestlings, with provisioning rate related to nestling age and time of day but not brood size. Breeding success was low, with only 14% of nests fledging any young. Only one repeat nesting attempt following a predation event was observed, but the attempt was abandoned. Nest predation was the main cause of nest failure, with eight species of nest predators identified. An apparent preference for nesting in Renosterveld highlights the need for protection of this endangered habitat type. As a ground-nesting species in an agriculturally transformed landscape, this lark faces numerous threats associated with habitat loss, altered predation pressure, exposure to pesticides and disturbance at nest sites.