Journal of Avian Biology最新文献

As a result of a warming global climate, understanding how organisms adjust their behaviour to environmental thermal conditions has become an increasingly important question in animal biology. Temperature-driven adjustments in parental care are potentially important given the repercussions on offspring size, quality and survival. In 2015 and 2016 we monitored parental care for 83 zebra finch Taeniopygia castanotis breeding attempts in the wild with known brood sizes. We recorded the frequency of parental visits to the nest together with mean maximum ambient temperature experienced between day 7 and 14 of the nestling period. We found that for each increase of 1°C in the daytime temperature there was a 0.91% reduction in the hourly rate of parental visits, whilst also accounting for other variables such as nestling age, time of season, and wind speed. Our data suggest that nestlings may receive less food under thermally challenging conditions, which is consistent with recent studies that demonstrate offspring are smaller when reared during periods of high temperature. Understanding the behavioural drivers that may contribute to the production of smaller offspring in extreme heat conditions could prove useful to forecast long-term consequences for fitness triggered by climate change.

The social and spatial organisation of avian societies is often complex and dynamic with individuals socialising with others in a local population. Although social interactions can readily be described in colonial breeders through the location of nests, social interactions regularly take place in other contexts that are often not considered. Social behaviour in the colonially breeding zebra finch, Taeniopygia guttata, has been the focus of much work in the laboratory, but very little is known about their social organisation in free-living populations, especially outside the breeding context. Here we characterise semi-permanent gathering locations, or ‘social hotspots' in the zebra finch in the wild. We determined the use of such social hotspots and the resulting group dynamics by quantifying movements to and from these locations through direct observation and by quantifying the vocal activity at these locations using acoustic recorders. We show that, throughout the day, zebra finches regularly visit these hotspots, and the hotspots are occupied for a substantial proportion of the day. Individuals typically arrived and left in pairs, or small groups, indicating that these social hotspots do not function just for flock formation. Instead, the high levels of vocal activity at these hotspots indicate that they may potentially function as local hubs for socialisation and information exchange, whilst also perhaps providing safety-in-numbers benefits to individuals during periods of resting. These findings characterise an important component of the natural social life of one of the most widely studied birds in captivity. The characterisation of these social hotspots highlights the use of landmarks by birds to facilitate social contacts, cohesion, and behaviour, in a social bird. Similar hangouts and social hotspots may be a feature of social behaviour in other multi-level aggregative species in which the fission and fusion of groups is an important component of daily life.

We examined phylogeographic patterns and cryptic diversity within the royal flycatcher, Onychorhynchus coronatus (Aves: Onychorhynchidae), a widespread Neotropical lowland forest tyrant flycatcher. A phylogeny of the six recognized subspecies was constructed from mtDNA sequence data of the NADH dehydrogenase subunit two gene, using Bayesian Inference and Maximum Likelihood methods. Phylogenetic analyses revealed high levels of intraspecific divergence within O. coronatus, supporting the existence of at least six independent lineages. The phylogenetic results uncovered the following relationships: (O. c. swainsoni [Southern Atlantic Forest], (O. c. coronatus [western Amazonia], (O. c. castelnaui [eastern Amazonia], (O. c. mexicanus [Central America], (O. c. occidentalis [Tumbesian], O. c. fraterculus [extreme northwestern South America])))). Biogeographic and dating analyses suggest that vicariant and dispersal events acted across approximately six million years to influence lineage diversification within this genus. Some of those events include the formation of the Amazon River and its tributaries, Andean uplift, and climatically induced vegetational shifts. Phylogenetic and biogeographic analyses of O. coronatus lineages support a hypothesis of area relationships in which the first divergence event isolated the Southern Atlantic Forest from Amazonia during the Late Miocene/Early Pliocene. This event was followed by the split of western and eastern Amazonia at the Early/Late Pliocene, the divergence of cis- and trans-Andean lowland regions also at the Early/Late Pliocene, the split between Central America and the extreme northwestern South America/Tumbes at the Early/Middle Pleistocene, and the split between extreme northwestern South America and Tumbes at Middle/Late Pleistocene. Subsequent divergence of the southern and northern populations in the western and eastern Onychorhynchus lineages took place during the Pleistocene. Comparison of phylogenetic trees and patterns in Onychorhynchus with those from published work suggests that across large New World radiations such as the Suboscines, some co-distributed lineages began to diverge long before others, which exemplifies the complexity of their evolutionary history.

When evaluating avian reproduction, life history theory examines the trade-offs between parental effort, the number and size of offspring, and the rate of nestling development. The growth rates and body sizes of developing birds vary geographically and can diverge with both latitude and migratory strategy. In terms of offspring size, growth rate can deviate in nestlings of the same or similar species due to the correlated influences of weather events, predation pressure, food availability, number of nestmates and parental provisioning. Furthermore, a longer photoperiod for species nesting at higher latitudes increases the duration over which a nestling can be fed each day, and increased nestling provisioning has been positively correlated with growth rate. Whether the amount of time a bird is fed during development drives this variation in growth rate and morphology is unknown. By removing supplemental environmental stressors (e.g. weather, predation) and standardizing feeding rate and environment, we explored the influence of daily duration of nestling provisioning on dark-eyed junco Junco hyemalis nestlings. We hand-reared 65 chicks of a sedentary junco subspecies J. h. carolinensis under both their natural photoperiod and the longer photoperiod of a closely related migratory subspecies J. h. hyemalis and compared growth rate, mass, morphology and the amount of food consumed. Average growth rate, fasted mass, wing length and total daily food consumption were all greater in birds hand-reared under the longer, more northern photoperiod treatment. These findings suggest that increased daily photoperiod at higher latitudes may allow for greater total food provisioning and thus may play a role in the ability of parents in compressed breeding seasons to produce high quality offspring. This points to a trade-off between provisioning effort and nestling growth rate in lower latitude (shorter photoperiod) populations and points to an important role of developmental plasticity on growth rate and morphology.

Bårdsen, B.-J. and Bustnes, J.O. (2022), Multiple stressors: negative effects of nest predation on the viability of a threatened gull in different environmental conditions. J Avian Biol, 2022: e02953. https://doi.org/10.1111/jav.02953

Unfortunately, we discovered that we misspecified the matrix model in our recently published article (Bårdsen and Bustnes 2022). This error did not change our overall conclusions or the original article's empirical analyses (i.e. the input values). Here, we highlight the effect of this mistake with reference to the different sections of the original article (using the same headings as in the earlier article).

The Supporting information was also incorrect and is now corrected.

We apologize for these errors.

Unaffected by the change in the model.

For an avian migrant, refueling capacity attainable during stopovers governs the entire migration schedule and, ultimately, its fitness. Specifically, timely replenishing energy stores is critical when migration involves crossing ecological barriers, within which refueling may be limited. Here, we tested the hypothesis that fuel deposition rates (FDRs) of migratory passerines within barrier-edge stopover sites are constrained by the density of potential competitors, irrespective of migration season, phenology, and local environmental conditions. We also evaluated diverse intra- and inter-specific competition scenarios and explored a potential mediation of density-dependence by environmental factors. The analyzed data, collected by us over 13 consecutive years (2009–2022), contain information on seven species of long-distance migratory insectivorous passerines measured within eight desert-edge habitats throughout autumn and spring migrations. As predicted, our analyses revealed negative density-dependence regulation of FDRs, consistent across species and migration seasons. Notably, bird density exerted its effect above and beyond the other factors known to influence FDR, such as relative ambient temperature, phenology, temporal progress of stopover, and body mass next to landfall. As expected, FDR increased at higher relative ambient temperatures and with the stopover's progress. In spring, FDR also rose as the season advanced. These findings signify the substantial impact of competition on the refueling performance of migratory passerines during their stopover on an ecological barrier's edge, acting over and above the other environmental factors. The detected importance of competition and its interrelation with other predictors provides an insight into stopover's functioning; environmentally imposed and inescapable interspecific interference is thus a significant limiting factor of FDR, a deleterious relationship potentially remediable by informed habitat restoration and planning.

Gathering demographic information on rare species is critical to understanding their population dynamics and implementing efficient conservation measures. Using integrated models, we jointly analyzed multiple data sets, including capture–recapture, GPS tracking and nest monitoring data collected over the last 10 years, to provide the first demographic insights for one of the world's rarest raptors, the endemic Reunion harrier Circus maillardi. We estimated key demographic rates including annual survival and breeding parameters (clutch size, hatching and fledging success), and used population projection models to assess population growth rate and quasi-extinction risk. In order to guide future conservation actions for the population, we evaluated the effects of different management scenarios that improve survival, fecundity, or both, on population growth and quasi-extinction risk. Comparison of the estimated annual survival (juvenile and subadult survival: 0.66; adult survival: 0.71) and breeding parameters (clutch size: 2.3; hatching success: 0.45; fledging success: 0.83) with those of other harrier species suggests that adult survival and breeding parameters of Reunion harriers are low. A small data set collected 40 years ago suggests that the probability of an egg producing a fledgling was higher and has declined to the current low level. The population models project that the Reunion harrier population is declining and faces a high risk of quasi-extinction in the next 40 years. Only management measures that simultaneously improve adult survival and fecundity could lead to a recovery of the population. These alarming results call for immediate conservation action aimed at rapidly improving the demographic rates.

Brood parasites are expected to lay only one egg per parasitized nest, as the existence of several parasitic nestlings in a brood increases competition and can lead the starvation of some of them. However, multiparasitism (laying of two or more eggs by one or more parasitic females in a single host nest) is surprisingly frequent. Here, we study multiparasitism by different females or by the same female (repeated parasitism) in the great spotted cuckoo Clamator glandarius, a non-evictor brood parasite that mainly parasitizes the magpie Pica pica, and whose chicks may be raised together with host nestlings in the same nest. We used a total of 262 magpie nests found during four breeding seasons. Multiparasitism and repeated parasitism are very frequent because this brood parasite is less virulent than other cuckoo species and magpie hosts can successfully raise more than one parasitic nestling per nest. The total number of cuckoo chicks fledged was higher in multiparasitized nests than in single- or double-parasitized magpie nests. Magpie breeding success (i.e. the proportion of eggs that produce young that leave the nest) did not differ between single-, double-, and multiparasitized magpie nests. These results suggest that multiparasitism is an adaptation in the great spotted cuckoo. The intensity of parasitism (number of cuckoo eggs per nest), after controlling for the potential effect of year, did not affect nest desertion or nest predation rate, neither during the incubation nor the nestling periods. This implies that nest concealment does not affect the susceptibility of one nest being parasitized and predated, as nest predation rate was similar regardless of the intensity of parasitism. Predation rate during the nestling phase did not vary according to intensity of parasitism, which does not support either the ‘mutualism' hypothesis or the ‘predation cost of begging' hypothesis.

This mini-review is dedicated to a critical re-appraisal of the putative hybrid origin of the grey-cheeked populations of the ashy-throated parrotbill Sinosuthora alphonsiana that was postulated based on the results of a clustering analysis using a set of five nuclear loci. However, the number of genetically admixed individuals is lower than 10% in the proposed hybrid form and largely restricted to a single population in closest vicinity of one proposed parental taxon. Based on total evidence from mitochondrial and nuclear markers the proposed hybrid taxon is indistinguishable from the second postulated parental taxon. Wide-range allelic introgression in a broad zone of range overlap along with incomplete lineage sorting of nuclear markers is a more plausible alternative explanation for the patterns observed. So far, there is no convincing evidence of a hybrid origin of the grey-cheeked ashy-throated parrotbill populations.

Determining the limits of species is still a major area of contention, particularly when diagnostic differentiating characters are subtle and there is a contradiction between morphological and genetic data. The lesser whitethroat (LWT) complex Curruca curruca represents an interesting study system to address this issue. Here, we use phylogeny-, admixture- and principal component analysis- (PCA-) based analyses on whole-genome sequence data of the parapatric LWT taxa C. c. curruca, C. c. halimodendri, C. c. zagrossiensis and C. c. althaea to investigate the prevalence and importance of gene flow in a geographical area where morphological evidence suggests a clinal transition between populations. The results suggest that LWT populations of the Zagros Mts zagrossiensis may represent a lineage historically diverged from topotypical curruca, the two lineages later coming into secondary contact with extensive gene flow as a result. There is no evidence of a hybrid zone or cline between zagrossiensis and althaea in the Zagros Mts. On the other hand, there is evidence for gene flow between althaea and halimodendri. The results also show possible evidence of admixture from other populations in the LWT complex, extralimital to the sampled area, but the nature of this needs to be evaluated based on a larger data set.