Species Of Cardueline Finches Research Articles

Variation among individuals in photoperiod responses: Effects of breeding schedule, photoperiod, and age-related photoperiodic experience in birds.

Many organisms use environmental cues to regulate reproductive function in order to time reproduction to coincide with favorable environmental conditions. Whereas we understand much about how environmental cues are used to time reproduction, we know relatively little about variation among individuals in responsiveness to environmental cues. However, this variation among individuals may represent a crucial component of a population's capacity to respond to changing environmental conditions. In this study, we quantify variation among individuals in photoperiod responsiveness of the avian reproductive system and investigate three potential underlying sources of this variation in environmental cue responsiveness. Specifically, we tested whether age-related photoperiodic experience, strength of the photoperiodic cue (day length), and degree of flexibility in breeding schedule influenced the degree of variation observed in experimental studies of seven species of cardueline finches. Overall, we found a high degree of variation among individuals in photoperiod response, and this was influenced by experimental photoperiod and breeding schedule. As experimental photoperiod became longer, the degree of variation declined. Opportunistic breeders showed greater variation in response compared with more seasonal breeders. We found no effect of age-related photoperiodic experience in one species for which we could examine this factor. The results of this study highlight the extent to which individuals can vary in their response to environmental cues and point to both species ecology and characteristics of the cue as important influences on the degree of this variation.

A comparison of winter stress responses in cardueline finches

ABSTRACT. We examined baseline and stress-induced changes in plasma corticosterone in relation to body condition and seasonal environmental conditions in three species of cardueline finches wintering in northeastern Oklahoma. Two of these, the Pine Siskin (Spinus pinus) and Purple Finch (Carpodacus purpureus), are irruptive migrants that winter irregularly into Oklahoma, whereas the third, the American Goldfinch (S. tristis), is considered a regular winter resident. Individual turnover of banded birds was high in all three species, which suggests comparable tendencies toward winter transience. Body mass and fat scores of incoming birds increased significantly across the season, peaking in birds captured during midwinter. Baseline corticosterone levels were comparable among species and did not differ seasonally or in relation to daily or weekly temperature fluctuations when the influence of body condition was controlled. By contrast, stress-induced levels of corticosterone secretion varied significantly am...

A comparison of the adrenocortical responses to acute stress in cardueline finches from the Tibetan Plateau, Arctic Alaska and lowland Western North America

In many avian species, it has been well demonstrated that individuals attempting to breed in harsh or unpredictable environments always express reduced adrenocortical responses to acute stress, whereas those breeding in more benign or predictable environments may show more robust responses. However, fewer studies have focused on comparing closely related species that express similar behavioral traits (e.g., territorial behavior, mating system, nestling behavior) and ecological traits (e.g., habitats, food resources) among different breeding environments. In closely related taxa, we hypothesized that those species breeding in benign environments would show greater adrenocortical responses to acute stress compared with their congeners breeding in harsh environments. In this study, we examined seasonal and sex differences in baseline and stress-induced plasma corticosterone (CORT) levels in four cardueline finch species from Arctic Alaska (reanalysis of previously published data from the Common Redpoll, Carduelis flammea, at high latitude habitats), the Tibetan Plateau (Twite, C. flavirostris, from high altitude, mid-latitude habitats), and western North America (American Goldfinch, C. tristis, and Pine Siskin, C. pinus, from mid-latitude and low altitude habitats). Our results showed that (1) Twites had lowered adrenocortical responses during the pre-basic molt stage than the early breeding stage, both sexes of American Goldfinch and Pine Siskin showed similar patterns of adrenocortical responses between the early breeding and the late breeding stages, whereas Common Redpolls expressed significantly lowered adrenocortical responses during the late breeding stage; and (2) unexpectedly, there were no significant differences in baseline or stress-induced CORT (maximal CORT, total integrated and corrected integrated CORT levels) levels among Twites, American Goldfinches, Pine Siskins, and Common Redpolls during the early breeding stage or among American Goldfinches, Pine Siskins and Common Redpolls during the late breeding stage. This similar pattern in adrenocortical responses may reflect the stability of physiological functions of CORT during long-term evolutionary adaptation. It also provides us with an opportunity to understand the potential effects of phylogenetic relationships on the modulation of adrenocortical responses to acute stress in free-living birds. Whether phylogenetic effects are a common or casual phenomenon remains to be determined in other closely related taxa.

Polymorphic microsatellite loci from the American goldfinch (Carduelis tristis) and their cross‐amplification in a variety of passerine species

AbstractCardueline finches have become important models in studies of sexual selection. Here I describe eight polymorphic microsatellite loci isolated from the American goldfinch (Carduelis tristis) that are useful in parentage and heterozygosity studies. The number of alleles per locus ranged from eight to 38 based on 252 goldfinches. The markers are polymorphic in at least four other Cardueline finch species, and several amplify in nonfinch passerines including red‐winged blackbird (Agelaius phoeniceus), black‐throated blue warbler (Dendroica caerulescens) and tufted titmouse (Baeolophus bicolor), indicating they should be useful in paternity and population studies of a variety of species.

Physiological responses to photoperiod in three cardueline finch species

Cardueline finches (canaries, goldfinches, and rosefinches, etc.) vary widely in the degree to which their natural reproductive schedules track seasonal changes in photoperiod. In this study, we tested for photo-induction of reproductive development and photorefractoriness in males of three cardueline finch species: pine siskins ( Carduelis pinus), common redpolls ( Carduelis flammea), and white-winged crossbills ( Loxia leucoptera). Exposure to long days (20L:4D) in winter induced gonadal growth and elevation of circulating luteinizing hormone (LH) in all three species. After 4.5 months on constant long days, gonadal regression was complete in redpolls and siskins, but only partial in crossbills. Feather molt was most advanced in redpolls, slightly less advanced in siskins, and least advanced in crossbills. These results indicate that the reproductive systems of all three species were stimulated by long days, but that the crossbills, which are temporal opportunists, either did not become absolutely photorefractory, or developed refractoriness more slowly than did the other two species. Reproductive development of controls held for 4.5 months on constant short days (5L:19D) was negligible in redpolls and crossbills, but substantial in siskins, suggesting that of the three species, pine siskins may be the least dependent on long days for reproductive development. Changes in fat deposition and body mass also differed among species. Short day redpolls tended to be fatter and heavier than long day redpolls, and long day crossbills tended to be fatter and heavier than short day crossbills. Body mass and fat depot of siskins remained high irrespective of photoperiod. These results illustrate substantial variation among these close relatives, and are consistent with the idea that differences in apparent reproductive flexibility among cardueline taxa relate to interspecific differences in responsiveness to environmental cues, not simply to differences in the environments experienced. This kind of information is critical to an understanding of the mechanistic bases of natural variation in reproductive schedules, and of how different species may be affected by modifications to the environment.

Evolution of sexual dichromatism: contribution of carotenoid- versus melanin-based coloration

In birds, carotenoid-based plumage coloration is more dependent on physical condition and foraging abilities and less constrained developmentally than is melanin-based coloration. Thus, female mate choice for honest signals should result in more intense sexual selection on carotenoid- than on melanin-based plumage coloration. Using variation in sexual dimorphism as an indirect measure of the intensity of sexual selection, we tested the prediction that variation in sexual dimorphism is driven more by change in carotenoid-based coloration between males and females than by change in melanin-based coloration. Examination of historical changes in carotenoid- versus melanin-based pigmentation in 126 extant species of Cardueline finches supported this prediction. We found that carotenoid-derived coloration changed more frequently among congeners than melanin-based coloration. In both sexes, increase in carotenoid-based coloration score, but not in melanin-based coloration score, was strongly associated with increase in sexual dichromatism. In addition, sexual dimorphism in carotenoid-based coloration contributed more to overall dichromatism than dimorphism in melanin-based plumage. Our results supported the hypothesis that melanin-based and carotenoid-based coloration have fundamentally different signal content and suggest that combining melanin-based and carotenoid-based coloration in comparative analyses is not appropriate.

Evolution of sexual dichromatism: contribution of carotenoid- versus melanin-based coloration

In birds, carotenoid-based plumage coloration is more dependent on physical condition and foraging abilities and less constrained developmentally than is melanin-based coloration. Thus, female mate choice for honest signals should result in more intense sexual selection on carotenoid- than on melanin-based plumage coloration. Using variation in sexual dimorphism as an indirect measure of the intensity of sexual selection, we tested the prediction mat variation in sexual dimorphism is driven more by change in carotenoid-based coloration between males and females than by change in melanin-based coloration. Examination of historical changes in carotenoid- versus melanin-based pigmentation in 126 extant species of Cardueline finches supported this prediction. We found that carotenoid-derived coloration changed more frequently among congeners than melanin-based coloration. In both sexes, increase in carotenoid-based coloration score, but not in melanin-based coloration score, was strongly associated with increase in sexual dichromatism. In addition, sexual dimorphism in carotenoid-based coloration contributed more to overall dichromatism than dimorphism in melanin-based plumage. Our results supported the hypothesis that melanin-based and carotenoid-based coloration have fundamentally different signal content and suggest that combining melanin-based and carotenoid-based coloration in comparative analyses is not appropriate.

A test of sensory bias for long tails in the house finch

The sensory bias model of sexual selection proposes that female preferences for certain male traits result from biases in the female sensory system that existed prior to the evolution of the preferred trait. Phylogenetic tests of the sensory bias hypothesis have provided evidence for pre-existing bias in several species, but the hypothesis has not been tested relative to elongated tail feathers, a widespread sexually selected trait in birds. Elongated tails occur sporadically across avian taxa, including cardueline finches (family Fringillidae), suggesting that long tails evolved independently in many lineages. To determine whether a female preference for longer tails predated the evolution of long tails in cardueline finches, we tested female preferences for artificially lengthened tail feathers in male house finches,Carpodacus mexicanus. The house finch is a cardueline finch species with a tail that does not appear to be elongated or sexually selected. In mate choice experiments, females did not demonstrate a preference for lengthened tails over controls. This negative result fails to support the hypothesis that elongation of tail feathers resulted from exploitation of a widespread sensory bias.

Genetic Variability and Taxonomical Considerations about Six Species of European Cardueline Finches (Aves, Passeriformes)

Electrophoretic patterns of seven enzyme systems and two nonenzymatic proteins, albumin and haemoglobin, representing 13 loci, have been investigated in six species of cardueline finches with Palearctic distribution. A new locus, SOD-3, has been characterized in this subfamily. The two nonenzymatic proteins turned out to be the best genetic markers. From the analysis of the genetic distances it emerges that the mean values between species are higher than those reported for other groups of birds. However, the same results were obtained for other species of the same subfamily native to North America. In both cases this result is probably due to a classification that disagrees with the real cardueline phylogeny. In the present study, the attribution of the Greenfinch to the genus Carduelis raises the mean value of distance between species.

Altitudinal variation in sexual dimorphism: a new pattern and alternative hypotheses

The colder climate and disjunct distribution of nesting and foraging habitats at high elevations increases the necessity of biparental care for successful breeding in birds. If differences in parental investment between the sexes correlate with intensity of sexual selection, the intensity of sexual selection should covary with ecological factors associated with elevation. I used sexual dimorphism as an indirect measure of intensity of sexual selection and examined variation in sexual dimorphism in 126 extant species of cardueline finches. I controlled for phylogeny and potential confounding factors and tested the prediction that the extent of sexual dimorphism negatively covaries with elevation of breeding. As predicted, interspecific variation in sexual dimorphism was more strongly associated with changes in elevation than with habitat, nest dispersion and placement, and migratory status. Species occupying lower elevations were more sexually dimorphic in plumage than species at higher elevations. This variation was largely due to increased brightness of male plumage at lower elevations. I address possible explanations of this trend, which may include increased opportunities for extrapair fertilizations at lower elevations, an increase in the cost of secondary sexual trait production (i.e., molt) and maintenance at high elevations, and elevational variation in predation pressure

Breeding Site Faithfulness, Reproductive Biology, and Adult Survivorship in an Isolated Population of Cassin's Finches

We used mist nets in a capture-recapture demographic study of the birds of an isolated relict grove of ponderosa pines (Blue Sky) on Hart Mountain in southern Oregon. Cassin's Finches (Carpodacus cassinii), usually considered nomadic, returned each spring. Females were more faithful to breeding site than males. As evidenced by cloacal swelling and incubation patch formation, 96% of females laid eggs in the 18 days following 24 May. When June snow storms destroyed most nests in 1975 and 1979, many females attempted second nestings: Most apparently abandoned these second nestings in early July when the finches left Blue Sky to wander more widely over Hart Mountain while they underwent their annual molts. Most yearling females and males were sexually active and apparently nested. Although obscured by reduced mobility of females during incubation and early brooding, the sex ratio was close to 50/50. There were 20 to 25 pairs per hectare of suitable (pine) finch habitat. Breeding density may be limited by the zone around the female that is defended by the male during nestsite selection and nest building. The minimum annual survival rate for finches one year old and older was 0.64 (SE = ? 0.02) for males and 0.60 (SE = ? 0.03) for females. Cassin's Finch (Carpodacus cassinii) inhabits open conifer woodlands of the interior mountains of western North America, generally nesting above an elevation of 1,500 m. It breeds from southern interior British Columbia, Montana, and northern Wyoming south to interior southern California, northern Arizona, and northern New Mexico. The finch is at least an altitudinal migrant in parts of its range, and migrates latitudinally as well. Wintering flocks have been reported in the lowland valleys as far north as southern British Columbia. Latitudinal migrants have been recorded regularly as far south as northern Baja California and the Mexican highlands to Durango, Zacatecas, and Coahuila (AOU 1983). A limited literature (summarized by Salt 1958, Orr 1968, and Samson 1976a) conveys the impression that Cassin's Finch is an opportunistic species, characterized by a labile annual cycle, weak faithfulness to breeding site, and geared to exploit variable sources of food. The bird shares these characteristics with many other species of cardueline finches (Newton 1972). In the only systematic studies of the summer biology of the Cassin's Finch done thus far, Samson (1976a, b) found large annual fluctuations in breeding populations of northern Utah and regarded the species as nomadic. In contrast, we found that a population of Cassin's Finches on Hart Mountain in southeastern Oregon varied little in size from year t year and that individuals showed high breeding site faithfulness. This stimulated us to examine and report here several related aspects of the summer biology and demography of this relatively little-known species. Our data on Cassin's Finches were obtained as a secondary result of a more extensive, seven-year survey of year-to-year variation in the breeding avifauna of Hart Mountain, conducted by systematic capture-recapture of birds in mist nets. Our analysis is, therefore, retrospective and confined to questions that can be examined with the aid of data obtained by such methods.

Drought‐Induced Changes in Avian Community Structure Along a Montane Sere

Avain community structure was studied along a meadow—aspen—fir—spruce subalpine sere in northern Utah and southern Idaho during the breeding seasons of 1976, 1977, and 1978. During 1977 one of the worst droughts of this century occurred in the western United States, and comparative changes in avian community structure were documented during and after drought in the four seral stages. The number of breeding species declining most markedly during drought in aspen. Breeding communities on the forested plots during drought were least similar to predrought communities; pre and postdrought communities were consistently most similar. Densities of singing males declined more markedly on all plots during drought than did number of species, and remained below predrought levels in 1978. Changes were also noted in avian trophic structure during drought: insectivores generally declined in number, nectivorous hummingbirds completely disappeared, and the number of granivorous cardueline finch species increased. These changes can be related to changes in food resources. During drought, insect species composition and densities changed, flower phenology was 5 wk early, and one of the best coniferous cone crops in 30 yr occurred in northern Utah. Direct effects of lack of water were observed, and many bird species probably experienced water stress. Although difficult to document, indirect effects of drought on food resources are suggested for insectivores, nectivores, and possibly carnivores. The result indicate that a drought can represent an "ecological crunch" to and affect the structure of, temperature avain communities. However, separating the variation due to drought from inherent variation is difficult without comparative long—term studies. Avian communities in deciduous vegetation may be greatly affected by drought than those in coniferous vegetation.

The Relationships of the Hawaiian Honeycreepers (Drepaninini) as Indicated by DNA-DNA Hybridization

AbstractTwenty-two species of Hawaiian honeycreepers (Fringillidae: Carduelinae: Drepaninini) are known. Their relationships to other groups of passerines were examined by comparing the single-copy DNA sequences of the Apapane (Himatione sanguinea) with those of 5 species of cardueline finches, 1 species of Fringilla, 15 species of New World nine-primaried oscines (Cardinalini, Emberizini, Thraupini, Parulini, Icterini), and members of 6 other families of oscines (Turdidae, Monarchidae, Dicaeidae, Sylviidae, Vireonidae, Corvidae). The DNA-DNA hybridization data support other evidence indicating that the Hawaiian honeycreepers shared a more recent common ancestor with the cardueline finches than with any of the other groups studied and indicate that this divergence occurred in the mid-Miocene, 15-20 million yr ago.The colonization of the Hawaiian Islands by the ancestral species that radiated to produce the Hawaiian honeycreepers could have occurred at any time between 20 and 5 million yr ago. Because the honeycreepers captured so many ecological niches, however, it seems likely that their ancestor was the first passerine to become established in the islands and that it arrived there at the time of, or soon after, its separation from the cardueline lineage. If so, this colonist arrived before the present islands from Hawaii to French Frigate Shoal were formed by the volcanic "hot-spot" now under the island of Hawaii. Therefore, the ancestral drepaninine may have colonized one or more of the older Hawaiian Islands and/or Emperor Seamounts, which also were formed over the "hot-spot" and which reached their present positions as the result of tectonic crustal movement. The cardueline-drepaninine lineage probably diverged from the Fringilla lineage in the late Oligocene, from the New World nine-primaried oscines in the early Oligocene, and from the other oscines in the early Eocene.During this study we also obtained evidence that the vireos (Vireonidae) are not closely related to the New World nine-primaried oscines.

Vocal Imitation and Individual Recognition of Finch Calls

American goldfinch females recognize individual males by their individually distinctive flight calls. Goldfinches and other cardueline finch species are also capable of learning new flight calls by imitation during pair and flock formation. Vocal imitation can occur between members of different species as well as between members of the same species. Learning of new flight calls differs in several respects from typical passerine song learning.

Testicular Responses of House Sparrows and White-Crowned Sparrows to Short Daily Photoperiods with Low Intensities of Light

Testicular Responses of House Sparrows and White-Crowned Sparrows to Short Daily Photoperiods with Low Intensities of Light

Testicular Response of the House Sparrow, Passer Domesticus, to Short Photoperiods and Low Intensities

Testicular Response of the House Sparrow, Passer Domesticus, to Short Photoperiods and Low Intensities