Journal of Ornithology最新文献

The frequency of extreme climatic and weather events has increased since 1950 due to global changes induced by human influence. These events can have significant impacts at the individual, population, and community levels across various taxonomic groups. They can be particularly detrimental to bird populations during their breeding season, affecting specific breeding parameters. This study originated from an exceptionally rare breeding season of a resident Great Tit population recorded in spring 2002 when an unusual mortality of nestlings was observed. We quantified weather conditions (temperature, rainfall) from the end of April, a few days before we started detecting failed nests, and compared them with previous and subsequent years. In early May, when many pairs were incubating or caring for newly hatched chicks, we detected unusually low ambient temperatures and unusually high rainfall. This event likely caused that many first clutches failed completely, and that, compared with previous and subsequent years, fledging and breeding success was relatively low in those which were successful. There was also an increased proportion of replacement clutches that year. Anyway, the overall production of fledglings per breeding pair over the breeding season was 2.39, lower than other years. Although recruitment rate in 2003 was similar to other years, the lower production of fledglings in 2002 probably resulted in a decrease in the number of breeding pairs in the following years.

The pectoralis major is the muscle required for migratory flight in songbirds, and has been believed to be exclusively composed of fast oxidative glycolytic (FOG) fibers in most small songbirds (< 20 g). Here, we investigated the effect of season (migratory versus non-migratory) and migratory distance (within North America versus to South America) on muscle fiber type in three songbird families: vireos (Vireonidae), warblers (Parulidae), and thrushes (Turdidae). FOG and fast glycolytic (FG) fibers were identified using myosin-ATPase staining. Short-distance migrants within the vireo and warbler families altered their pectoralis muscle to contain FG fibers during non-migratory conditions, while long-distance migrants maintained exclusively FOG fibers, regardless of season. Thrushes, a family of larger songbirds, exhibited mixed fibers regardless of season or migratory distance. This study is one of the first to identify FG fibers in small North American songbirds and highlights the potential role of migratory distance and season on muscle phenotype.

After a range contraction in the south-east of its European range during the twentieth century, Black Woodpecker (Dryocopus martius) is re-colonizing this area since the 1970s. Our analysis of published data revealed average expansion rate 70–180 km per decade, first through well-connected forests along major river systems, and later spreading to isolated forest clusters in East Ukraine. Field studies confirmed that mature Populus stands in riverine and upland broadleaved forests were preferably settled by the recolonizers. A consequence of this recolonization is the re-appearance of large excavated cavities; observations in one territory showed their fast accumulation reaching 10 cavities/km² in 7 years.

The Gran Canaria Blue Chaffinch is the rarest forest passerine in the western Palaearctic with a population reduced to a single locality, Inagua, in the west of the island. After a forest fire, some birds were established in another location and a reinforcement programme was launched with the aim of consolidating this new population. Between 2010 and 2019, 194 Blue Chaffinches were released in the pine forest of La Cumbre, in the centre of the island and at a higher altitude than the previous one. Birds of two origins were used for this action: captive-bred birds were released using “soft” release methods, and wild-caught birds from the Inagua source population were released using “hard” release methods. Survival of radio-tagged birds (20–42 days of battery life) was high and similar between the two groups. Wild-caught birds occupied 12–15 times more surface area than captive-bred birds that remained close to supplementary feeding sites. All translocated birds displayed breeding behaviour in the following breeding season, although the rate of contribution to the new population was significantly lower for wild-caught birds (21% compared to 54% for captive-bred birds). This disparity can be partly attributed to nearly one-fifth of the wild-caught birds returning to Inagua. We conclude that the establishment phase of the Blue Chaffinch reinforced program in Gran Canaria has been successful. To retain wild-caught birds and deter their return to the source population, we recommend employing methods akin to the soft-release techniques utilized for captive-bred birds. Ongoing monitoring of the enhanced population, collecting data on survival and breeding success, will enable the evaluation of the long-term success of the translocation program.

Scheduling between mates in species with long-term pair bonds can be essential for positive fitness. The annual cycle in photoperiod is the primary environmental cue used by many animals to synchronize behavior and physiology among members of a population, and animals that migrate must have similar annual schedules to ensure successful breeding. However, we know little about whether members of mated pairs in migratory species experience similar photic environments across the year, which could allow for synchronization in annual phenology. Here, we used light-based geolocation to estimate positions of mated pairs of Thick-billed Murres (Uria lomvia, a seabird a.k.a. Brünnich’s Guillemot) which bred above the northern polar circle in Greenland. We tested the hypothesis that individuals in mated pairs occur in more similar locations and photic environments than randomly matched females and males. We found no difference in the amount of spatial separation or in the photic environment between mates and randomized heterosexual pairings. In general, the distance between females and males ranged from 1,198.5 km during August to 737.4 km during January. The sexes remained in photic environments with highly correlated photoperiods and moderately correlated times of solar noon in UTC. The spatial separation of, but similar photic environments experienced by, female and male murres regardless of pair status is probably adaptive by facilitating the synchronization of annual schedules between sexes, while allowing individuals in mated pairs the freedom to pursue the best foraging opportunities during migration and overwintering independent of their mate.

The constituent habitat use by remotely tracked tagged Short-eared Owls Asio flammeus on moorland and other dwarf shrubland–grassland mosaics was assessed in Britain and Norway. A preference for the owls to hunt over patches of graminoids within managed moorland in Britain contrasted with a tendency to hunt more over dwarf shrubs in Norway. The observed differences likely reflect the availability of small mammal prey and how this contrasts between largely single-species stands of managed heather Calluna vulgaris in Britain and more naturally diverse (species and structure) dwarf shrubland in Norway. Diurnal patterns of landscape use differed between areas, with owls in Scotland and Norway tending to hunt over ground at higher elevations at night but the reverse being observed in England. The difference demonstrates behavioural plasticity of Short-eared Owls, potentially driven by minimising risks from predation within different areas. Conservation implications include increased and proportionate priority for grassland management on British moorlands and the restoration of natural montane dwarf shrublands, both routes to enhance conditions for and the availability of small mammal prey. As a generality, site protection for Short-eared Owls and their monitoring need to acknowledge uncertainties around variations in abundance and occupation by this nomadic species.

Bird species depending on seeds from masting trees face large temporal and spatial variation in food availability and perform nomadic or irruptive movements to locate food. In northern Europe, the Common Crossbill (Loxia curvirostra) is specialized on seeds from Norway Spruce (Picea abies) which usually has peak years followed by crop failure. Common Crossbills breed in mast years and emigrate when spruce seeds are no longer available. On the other hand, the Parrot Crossbill (L. pytyopsittacus) is specialized on seeds from Scots Pine (Pinus sylvestris) in which seed production is more stable from year to year. The Parrot Crossbill is therefore thought to be more sedentary. However, both species may switch food if there is low abundance of their 'own' seed type, but little is known about the relative importance of crop size of the two tree species on breeding population size and migration of the two crossbill species. Here, we analyse time series (up to 36 years) of crossbills and crop size of spruce and pine in Norway and Sweden to investigate this. We found that breeding population sizes of both species were positively related to spruce crop size. Surprisingly, pine crop size had no positive influence, not even on the Parrot Crossbill. Emigration of both crossbill species (based on autumn migration counts in southern Sweden) increased when there were small seed crops of spruce, but pine crop size had no influence, not even on the Parrot Crossbill. There was no influence of population size on emigration. These results suggest that alternative food resources had an asymmetric effect, only influencing the Parrot Crossbill. This asymmetry explains why the two crossbill species often have synchronous eruptions despite being specialized on different tree species with different seed crop size dynamics.

Parent–offspring communication mediates parental provisioning rates through nestling begging. Although begging can be energetically costly and it potentially attracts predators to the nest, it is critical to nestling survival. Parent-absent begging is a behavior that has similar costs as parent-present begging but lacks the immediate benefits and yet occurs among several passerine species. We recorded European Starling (Sturnus vulgaris) nestling begging vocalizations at 18 nest boxes on days 2, 7, 12, 17 of the nestling period and the day before fledging to examine whether parent-absent begging occurred, and if so, whether the frequency of parent-absent begging changed with nestling age. We predicted that, like other cavity-nesting species, European Starling nestlings would spend more time begging in the absence of parents as they aged. We found that the average proportion of time nestlings spent parent-absent begging increased significantly from days 2 and 7 to days 12 and 17, then declined significantly on the day prior to fledging. Offspring provisioning rates remained high on the day before fledging, when growth rates have slowed, and did not differ significantly from the early and middle stages of the nestling period. Parent-absent begging may function in advertising hunger.

We analysed primary and secondary feather moult and fat reserves in 539 Common Snipes captured in the middle Pripyat River Valley, an important stopover site for waders in Central Europe, between 2002 and 2022. The average daily rate of feather growth was 1.89% in primaries and 2.27% in secondaries, being one of the highest documented in waders. The estimated duration of growth for a single flight feather varied from 11 to 21 days in primaries and from 8 to 11 days in secondaries. Moreover, multiple flight feathers (up to 14) were replaced simultaneously. As a result, the wing moult in Common Snipes was rapid with the mean primary moult duration estimated at 53 days (28 June–20 August) according to the Underhill–Zucchini model, and only 20 days in secondaries (31 July–20 August) based on moult estimates of individual secondaries. Hence, although secondary feathers began to grow when primary moult was already advanced, moulting of both flight feather groups was completed in most birds at almost the same time. Our study shows that Common Snipe in the middle Pripyat River Valley exhibit very rapid wing moult with large wing gaps. Fat reserves and thus body mass of Common Snipes were the lowest when the wing gap was greatest, compensating for their reduced wing area. Late and slow movement towards wintering grounds, allows them to moult rapidly at the early stage of autumn migration, which is likely to occur only in sites with abundant food resources.

Many empirical studies have focused on highly ornamented species to identify ecological factors that maintain the ornamentation or favour its exaggeration. By contrast, although reduction or loss of ornamentation appears to be widespread, species with reduced/lost ornamentation and its relationship with ecological factors are rarely focused on. Here, based on data collected over 4 years, we studied outermost tail feather length, i.e. a well-known sexual ornamentation in this clade, in relation to roosting location in the Pacific Swallow Hirundo tahitica during winter. In contrast to congeners, this species has inconspicuous tail ornamentation, i.e. very shallowly forked tails with vestigial streamers, providing a rare opportunity to study the ecological factors driving reduced ornamentation. We found that Pacific Swallows mainly roost in old nests under bridges over rivers, which resemble their original roosting sites, but some roost in much warmer sites, i.e. old nests under the eaves of houses above the ground. Individuals roosting under the eaves of houses had significantly longer outermost (but not central) tail feathers than those roosting under bridges. Individuals roosting under the eaves of houses were heavier and showed lower physiological stress, and thus might better endure the maintenance cost, favouring ornament elaboration. Because we controlled for the effects of sex and age, these factors would not confound the observed pattern. Reduced ornamentation, as found in Pacific Swallows roosting under their original roosting sites, could become elaborated in benign environments (i.e. under eaves, here), stressing the importance of balance between the costs and benefits of ornamentation.