Journal of Ornithology最新文献

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.

In the premigration period, weather plays a role in the ability of animals to accumulate energy stores before the onset of migration, affecting survival. In the context of rapidly changing climate, our goal was to study the effect of short-term weather conditions on the Common Crane (Grus grus) movement in the premigration period. We analyzed the daily distances and the maximum displacements using GPS telemetry data. We studied the relationship between weather conditions (average daily temperature, daily precipitation, and wind speed), age, the presence of offspring, and crane daily movements. The study was conducted at premigration staging areas in the European part of Russia. We found no differences in daily movement distance between adults with and without chicks and subadult individuals. A positive relationship between daily distances and maximum displacements and wind speed, and a negative relationship with average daily temperature and precipitation was observed. The influence of weather conditions on movement patterns can further affect the quality of migration in the rapidly changing climate.