Noise, predation risk compensation and vigilance in the chaffinch Fringilla coelebs

Background noise should in theory hinder detection of auditory cues associated with approaching danger. We tested whether foraging chaffinches Fringilla coelebs responded to background noise by increasing vigilance, and examined whether this was explained by predation risk compensation or by a novel stimulus hypothesis. The former predicts that only inter-scan interval should be modified in the presence of background noise, not vigilance levels generally. This is because noise hampers auditory cue detection and increases perceived predation risk primarily when in the head-down position, and also because previous tests have shown that only interscan interval is correlated with predator detection ability in this system. Chaffinches only modified interscan interval supporting this hypothesis. At the same time they made significantly fewer pecks when feeding during the background noise treatment and so the increased vigilance led to a reduction in intake rate, suggesting that compensating for the increased predation risk could indirectly lead to a fitness cost. Finally, the novel stimulus hypothesis predicts that chaffinches should habituate to the noise, which did not occur within a trial or over 5 subsequent trials. We conclude that auditory cues may be an important component of the trade-off between vigilance and feeding, and discuss possible implications for anti-predation theory and ecological processes.     

Evolution of the chaffinch, Fringilla coelebs, on the Atlantic Islands

Chaflinches have differentiated within the last million years on the Canary Islands and the Azores. All island populations differ more from mainland relatives than from each other. The characteristics of island birds are large body size, short wings, long legs and beaks, and blue dorsal colour. Beak depth and width have increased on the Azores but not on the Canaries. As a consequence the Azores chaffinch has evolved more in the direction of the Canary Island F. teydea than have Canary Island chaflinches. Character displacement may have occurred on the Canaries. Most of the evolutionary shifts are not predicted from a knowledge of clinal variation on the mainland. Populations have differentiated more on the Canaries than on die Azores, but are less variable regardless of whether ecologically restricted (by teydea) or not. Similarly, within the Azores archipelago the most differentiated populations are die least variable. On the Azores, but not on the Canaries, differentiation increases with isolation, whereas wimin-population variation decreases with isolation and increases with elevation. A model for diese patterns is proposed in terms of gene flow between populations, which reduces differentiation but enhances variation, and directional selection and random genetic processes which have the opposite effects.     

Testing the flexibility of song type bout duration in the chaffinch, Fringilla coelebs

Many songbird species with small song type repertoires repeat each type a few times before switching to the next. Thus, their singing style may constrain their ability to switch. However, the proximate causation of song type switching is poorly understood. We exposed male chaffinches to (nonoverlapping) playbacks of single renditions of their own songs rather than a series of songs, thus stimulating them with a single external auditory event. The most prominent effect of the playback was an increase in the duration of the current song type bout. If the song type played back was different to that the subject was singing at the time, bout duration increased less than if it was of the same song type. The short-term changes induced by the playback suggest that the auditory input increases the motivational level for a particular song type. In the chaffinch this results in a delayed switch rather than in song type matching as a reaction to acoustic stimulation by conspecific song. Copyright 2000 The Association for the Study of Animal Behaviour.     

Genetic diversity and morphological variation of the common chaffinch Fringilla coelebs in the Azores

We present new insights into the genetic diversity and phylogeography of the common chaffinch Fringilla coelebs from the Azores, based on sequences of mitochondrial and nuclear genes from 44 individuals and an outgroup/comparison of 44 birds from Madeira, the Canary Islands and the Continental Western Palearctic. To understand the level of concordance between the genetic data and morphometric variability we analysed eight morphometric characters from 413 adult living birds from all the Azores islands and compared the population genetic distances with quantitative morphometric traits. Our results indicate the occurrence of gene flow among the common chaffinch populations in the archipelago revealing the lack of current genetic structure within it and the existence of two co‐occurring lineages. Results also indicate the existence of morphometric differences among islands that could be due to ecological features instead of island isolation. This study also confirms the genetic distance among the common chaffinch populations within Macaronesia and between these archipelagos and the Continental Western Palearctic.     

Microsatellite loci isolation in the Canarian common chaffinch (Fringilla coelebs) and their utility in other Canarian finches

The taxonomic classification of the common chaffinch (Fringilla coelebs) that inhabits the Canary Islands has been under debate for decades, mainly due to the absence of nuclear DNA analyses. In this study we describe the isolation and characterization of ten microsatellite loci (AAAG, AAAT and GT) from a La Palma specimen using an enrichment protocol. Two loci were monomorphic in the populations analysed (La Gomera and La Palma), but the remaining ones presented 2 or more alleles, with an average of 11.63 alleles per locus and an average observed heterozygosity of 0.735 (n = 44). All loci were tested for their utility in other Canarian populations and other finch species.     

Adaptive phenotypic and genomic divergence in the common chaffinch (Fringilla coelebs) following niche expansion within a small oceanic island

According to models of ecological speciation, adaptation to adjacent, contrasting habitat types can lead to population divergence given strong enough environment-driven selection to counteract the homogenizing effect of gene flow. We tested this hypothesis in the common chaffinch (Fringilla coelebs) on the small island of La Palma, Canary Islands, where it occupies two markedly different habitats. Isotopic (δ¹³C, δ¹⁵N) analysis of feathers indicated that birds in the two habitats differed in ecosystem and/or diet, and analysis of phenotypic traits revealed significant differences in morphology and plumage colouration that are consistent with ecomorphological and ecogeographical predictions respectively. A genome-wide survey of single-nucleotide polymorphism revealed marked neutral structure that was consistent with geography and isolation by distance, suggesting low dispersal. In contrast, loci putatively under selection identified through genome-wide association and genotype-environment association analyses, revealed a marked adaptive divergence between birds in both habitats. Loci associated with phenotypic and environmental differences among habitats were distributed across the genome, as expected for polygenic traits involved in local adaptation. Our results suggest a strong role for habitat-driven local adaptation in population divergence in the chaffinches of La Palma, a process that appears to be facilitated by a strong reduction in effective dispersal distances despite the birds' high dispersal capacity.     

Seasonal dynamics of population of the feather mite Monojoubertia microphylla (Astigmata: Analgoidea: Proctophyllodidae) in the chaffinch Fringilla coelebs

The seasonal dynamics of the Monojoubertia microphylla micropopulations in different sex and age groups of the chaffinch Fringilla coelebs (Passeriformes: Fringillidae) have been studied during the nest and migration periods in the North-West of Russia. Three bird groups were determined within the chaffinch population during the study: adult males, adult females, immature chaffinches. Total number of bird specimens examined--353. In all chaffinch groups, the mean mite numbers and age structure of mite micropopulations were similar during the spring migration. The number of mites gradually increased from April to May. During the nest and autumn migration periods the seasonal dynamics of M. microphylla micropopulations were quite different on adult males and females of the chaffinch, because of different roles of male and female in the process of infestation the young bird generation. On the adult chaffinch males, the mite number continued to increase during the breeding period (June) and began to decrease significantly in July because of the postbreeding plumage moult. The mite number slowly decreased in the end of summer and the autumn migration. On the adult chaffinch females, the mite number decreased abruptly during the nest period. During this period, the chaffinch female sits together with nestlings for a long time, and the great number of its mites (about 60% of mite micropopulation) moves from the female onto the nestlings. The mite micropopulation migrated onto nestling is represented mainly by males, females (about 25% each) and tritonymphs (38%). Total mite number on the chaffinch females continued to decrease in July under the influence of postbreeding moult and slightly increased up to the autumn migration only. On the young chaffinches, the number of M. microphylla quickly increased during the second part of summer. It is the result of the great quota of mite instars being ready for the reproduction (imago, tritonymphs) within the micropopulation migrated from the chaffinch female onto the nestlings. The decrease of the M. microphylla micropopulation on the young birds was observed in the autumn only. In the end autumn migration (October), the mean numbers of mites on all chaffinch groups became approximately similar, but did not reach the mean rate observed in the beginning of the spring migration. During both migration periods, the imago and all preimaginal instars of M. microphylla were active, the diapause was not observed. In the beginning of spring migration and the end of autumn migration the main part of the mite micropopulations was represented by females, while in all other periods of chaffinch's stay in the North-West of Russia the immature instars predominated.     

Monomers of a satellite sequence of chaffinch (Fringilla coelebs L., Aves: Passeriformes) genome contains short clusters of the TTTAGGG repeat

A novel repeated sequence of chaffinch (Fringilla coelebs) designated as GS was isolated from genomic DNA after in vitro amplification of satellite DNA sequences using GSP-PCR technique. The proportion of this repeat in the chaffinch genome constitutes about 2%. Monomers are 176 to 199 bp in size and contain a short cluster of the TTAGGG telomeric tandem repeat. The oligomer of the telomeric hexanucleotide is flanked by the sequences that are significantly different in different monomers. The GS sequences are organized as tandemly repeated units and located in a number of chromomycin-positive blocks on the long arms of macrochromosomes 1, 2, 3, 5, and 6, as well as on several microchromosomes. The sequences homologous to the GS satellite of chaffinch were not found in the genomes of redwing (Turdus iliacus) and house sparrow (Passer domesticus).     

Mitochondrial DNA control region diversity in the endangered blue chaffinch, Fringilla teydea

The blue chaffinch (Fringilla teydea) is found only on the two central Canary Islands of Gran Canaria and Tenerife, where it is restricted to pine forest habitat. It is reasonably abundant on the latter island but endangered on the former. Here, sequence variation was studied in a fragment spanning domains I and II of the mitochondrial DNA (mtDNA) control region. Phylogenetic analysis of all haplotypes with a F. coelebs outgroup indicated the two island populations were reciprocally monophyletic, supporting their individual conservation. Unlike in other species, most within-island haplotype diversity was due to mutations in the domain II region. Surprisingly, genetic diversity was greater in the smaller Gran Canarian population. We suggest that this is unlikely to be maintained under current population sizes although it may be mitigated by incorporating genetic information into the captive breeding programme.     

Interspecific patterns of seed selection among granivorous passerines: effects of seed size, seed nutritive value and bird morphology

The relationships between seed characteristics (size and nutrient contents) and bird morphology were investigated in ten species belonging to three specialized families of granivorous passerines. Wild-caught birds were exposed in captivity to a fixed mixture of thirteen seed types before measuring their consumption rates and seed preferences. A multivariate analysis of seed characteristics showed two principal and independent gradients of covariation, namely seed nutritive value and seed size. The smaller the birds, the more nutritive the seeds they selected, this result being largely independent of the family the bird belonged to. The selected seed size was directly related to both the body and bill sizes of the birds, hut these relationships varied between families, most probably as a consequence of interfamilial differences in the structure of the ramphotheca and the associated seed handling method.     

Variation in Song Rate during the Breeding Cycle of the Chaffinch,Fringilla coelebs

The variation in song rate during the breeding season was studied in two individually marked chaffinch Fringilla coelebs populations. We gathered data to investigate especially the recently presented mate-guarding hypothesis. The active singing has been supposed to function as a form of mate guarding during the female's fertile period by announcing the high status of the male and preventing extra-pair copulations by neighbouring males. There was no clear dawn chorus in the chaffinch, i.e. a peak in the song rate before sunrise. Male chaffinches continued to sing after mating, but the song rate dropped significantly. In contrast to the mate-guarding hypothesis the song rate was lower during the fertile period of the female than during pre-mating and incubation. Thus, the males do not announce the fertility status of their mates or their own quality and status by active singing. The song does not function as a form of mate guarding in the chaffinch. One function of the song of the chaffinch is mate attraction: singing activity was highest before pair formation in early spring and decreased after mating but increased again if the male lost his mate later in the breeding season.     

Variability in seed size selection by granivorous passerines: effects of bird size,bird size variability,and ecological plasticity

The niche variation hypothesis predicts a direct relationship between intraspecific variability in feeding ecology and the variability of the morphological traits related to feeding behaviour. The following study tests this prediction by measuring in captivity the seed size preferences and the morphology of 9–11 individuals of seven specialized granivorous bird species. The average seed size preferences of these birds have previously been shown to be related to components of bill size. The ranges of seed sizes selected were related to the mean bill sizes of birds in a way that paralleled the patterns found when analysing average values. Bill and body size variability were not related, however, to the range of seed preferences after controlling for the significant mean-variance relationship showed by morphological traits. Thus, results do not support the niche variation hypothesis. the significant effect of average bill size on diet variability was consistent with the direct relationship between bird size and ecological plasticity expected on the basis of the shape of the family of functions relating seed size and seed profitability for different-sized birds. These findings suggest morphological mechanisms for ecological plasticity whose generality and evolutionary significance merit further research.     

Relationships between bird community and habitat structure in shelterbelts of Hokkaido,Japan

Summary The relationship between the bird community and habitat structure in wind shelterbelts of Ishikari district was examined.Breeding birds were classified into nesting guilds (hole, canopy, and bush) and also into foraging guilds (outside, canopy, and bush) Both density and species richness in the outside-foraging guild were positively related to forest age variables. On the other hand, bird density in all three nesting guilds and the other two foraging guilds (canopy and bush) was correlated with the vegetation cover of their nesting or foraging sites, and species richness was positively correlated with tree species complexity variables.Bird species diversity (BSD) was closely related to tree species complexity, but not to foliage height diversity (FHD) within woods. However, if woods were re-classified into two groups such as natural and artificial and these were separately analysed, the correlation between BSD and FHD was significant.From these results, it is concluded that both FHD and tree species complexity should be considered together in order to predict BSD within forests. A new index is proposed for this purpose, and its usefulness discussed.     

Lack of canonical E6 and E7 open reading frames in bird papillomaviruses: Fringilla coelebs papillomavirus and Psittacus erithacus timneh papillomavirus

Determination and analyses of the complete sequence of Fringilla coelebs papillomavirus and Psittacus erithacus timneh papillomavirus indicate that they represent a distinct and distant lineage of papillomaviruses. The lack of canonical E6-E7 open reading frames suggests that they serve adaptive functions during papillomavirus evolution.     

Interspecific and annual variation in pre-dispersal seed predation by a granivorous bird in two East Asian hackberries, Celtis biondii and Celtis sinensis

Pre-dispersal seed predation by granivorous birds has potential to limit fruit removal and subsequent seed dispersal by legitimate avian seed dispersers in bird-dispersed plants, especially when the birds form flocks. We monitored pre-dispersal seed predation by the Japanese grosbeak, Eophona personata, of two bird-dispersed hackberry species (Cannabaceae), Celtis biondii (four trees) and Celtis sinensis (10 trees), for 3 years (2005, 2007 and 2008) in a fragmented forest in temperate Japan. Throughout the 3 years, predation was more intense on C. biondii, which, as a consequence, lost a larger part of its fruit crop. Grosbeaks preferred C. biondii seeds that had a comparatively lower energy content and lower hardness than C. sinensis, suggesting an association between seed hardness and selective foraging by grosbeaks. In C. biondii, intensive predation markedly reduced fruit duration and strongly limited fruit removal by seed dispersers, especially in 2007 and 2008. In C. sinensis, seed dispersers consumed fruits throughout the fruiting seasons in all 3 years. In C. biondii, variation in the timing of grosbeak migration among years was associated with annual variation in this bird's effects on fruit removal. Our results demonstrate that seed predation by flocks of granivorous birds can dramatically disrupt seed dispersal in fleshy-fruited plants and suggest the importance of understanding their flocking behaviour.     

Multiscale assessment of the influence of habitat structure and composition on bird assemblages in boreal forest

The relative contributions of habitat structure and composition to biodiversity are often scale-dependent. Although bird communities in boreal forest have been largely altered and threatened by forest harvesting, bird habitat selection in this ecosystem has not been fully understood. Our study aimed to assess the relative contributions of habitat structure and composition on the assemblages of boreal birds at multiple spatial scales characterized by radii ranging from 100 to 1,000?m. We recorded bird species occurrence at 96 stations located in an old-growth forest in the C?te-Nord region of Québec, Canada. We characterized habitat structure using the proportion of dense, open, and sparse stands, and habitat composition using the proportions of coniferous, mixedwood, and deciduous stands. We used partial canonical correspondence analyses and hierarchical variance partitioning to assess the relative contribution of habitat structure and composition on bird assemblage, and logistic regression to model the probability of occurrence for individual species in response to habitat variables. Our results revealed that habitat structure and composition explained similar proportions of the variance in bird assemblage (21.7 vs. 21.6?%), regardless of spatial scale. Whilst logistic regression yielded fair predictions in the occurrence of individual species (i.e., area under the receiver-operating characteristic curve >0.70 for 90?% of the species), it further confirmed our findings in community level analysis. Our study indicates that habitat structure and composition are both important in shaping bird assemblages, but spatial scale draws little influence on their relative contributions.