Orchard Oriole Research Articles

Sex-specific responses to simulated territorial intrusions provide evidence for relaxed selection pressure on female song in Orchard Orioles

Sex-specific responses to simulated territorial intrusions provide evidence for relaxed selection pressure on female song in Orchard Orioles

The Campsis-Icterus association as a model system for avian nectar-robbery studies

Avian nectar-robbing is common in some floras but its impact on plant-pollinator mutualisms, flowering phenology, and the evolution of floral traits remains largely unexplored. Surprisingly, there have been no quantitative studies of the topography and extent of floral damage inflicted on any flowering species by nectar-robbing birds. I studied nectar-robbing of orchard oriole (Icteridae: Icterus spurius) on the large reddish-orange flowers of trumpet creeper (Bignoniaceae: Campsis radicans), an ornithophilous liana of eastern North America. Floral traits that inhibit nectar-robbery by hummingbirds and bees, such as the thickened calyx and sympetalous corolla, are ineffective in deterring orioles. Orioles target the zygomorphic trumpet-shaped corollas at the 11:00 h or 01:00 h positions with a closed-bill puncture and then enlarge the incision with bill-gaping to reach the nectary. More than 92% of flowers were robbed when orioles were present. Fruit set was nil until orioles departed on fall migration in late July-early August. The timing suggests oriole nectary-robbery may be a potent selection agent for an extended flowering season or delay in the onset of flowering. The biological and geographic attributes of the Campsis-Icterus association make it a promising model system for studying the consequences of avian nectar-robbery on pollination biology and floral trait evolution.

Female song is structurally different from male song in Orchard Orioles, a temperate-breeding songbird with delayed plumage maturation

Moyer, M. J., E. M. Rose, D. A. Moreland, A. Raza, S. M. Brown, A. L. Scarselletta, B. Lohr, K. J. Odom, and K. E. Omland. 2022. Female song is structurally different from male song in Orchard Orioles, a temperate-breeding songbird with delayed plumage maturation. Journal of Field Ornithology 93(1):3. https://doi.org/10.5751/JFO-00073-930103

Nuclear locus divergence at the early stages of speciation in the Orchard Oriole complex

As two lineages diverge from one another, mitochondrial DNA should evolve fixed differences more rapidly than nuclear DNA due to its smaller effective population size and faster mutation rate. As a consequence, molecular systematists have focused on the criteria of reciprocal monophyly in mitochondrial DNA for delimiting species boundaries. However, mitochondrial gene trees do not necessarily reflect the evolutionary history of the taxa in question, and even mitochondrial loci are not expected to be reciprocally monophyletic when the speciation event happened very recently. The goal of this study was to examine mitochondrial paraphyly within the Orchard Oriole complex, which is composed of Icterus spurius (Orchard Oriole) and Icterus fuertesi (Fuertes' Oriole). We increased the geographic sampling, added four nuclear loci, and used a range of population genetic and coalescent methods to examine the divergence between the taxa. With increased taxon sampling, we found evidence of clear structure between the taxa for mitochondrial DNA. However, nuclear loci showed little evidence of population structure, indicating a very recent divergence between I. spurius and I. fuertesi. Another goal was to examine the genetic variation within each taxon to look for evidence of a past founder event within the I. fuertesi lineage. Based on the high amounts of genetic variation for all nuclear loci, we found no evidence of such an event – thus, we found no support for the possible founding of I. fuertesi through a change in migratory behavior, followed by peripheral isolates speciation. Our results demonstrate that these two taxa are in the earliest stages of speciation, at a point when they have fixed differences in plumage color that are not reflected in monophyly of the mitochondrial or nuclear DNA markers in this study. This very recent divergence makes them ideal for continued studies of species boundaries and the earliest stages of speciation.

Divergence in calls but not songs in the orchard oriole complex: Icterus spurius and I. fuertesi

Birdsong has important functions in attracting and competing for mates, and song characteristics are thought to diverge rapidly during the process of speciation. In contrast, other avian vocalizations that may have non‐reproductive functions, such as calls, are thought to be more evolutionarily conserved and may diverge more slowly among taxa. This study examines differences in both male song and an acoustically simpler vocalization, the ‘jeet’ call, between two closely related taxa, Icterus spurius and I. fuertesi. A previous study comparing song syllable type sharing within and between I. spurius and I. fuertesi indicated that their songs do not differ discernibly. Here we measured 18 acoustic characteristics of their songs and found strong evidence supporting this prior finding. In contrast, we measured 17 acoustic characteristics of jeet calls and found evidence of significant divergence between the two taxa in many of these characteristics. Calls in I. fuertesi have a longer duration, a larger frequency bandwidth, a lower minimum frequency, a lower beginning frequency, and greater levels of both frequency and amplitude modulation in comparison to the calls of I. spurius. In addition, I. fuertesi calls contain two distinct parts, while the calls of I. spurius have only one part. Thus, we find evidence of divergence in the calls of the two taxa but not their songs challenging the widespread assumption that complex bird song evolves more rapidly than other types of vocalizations. Understanding divergence in multiple vocalization types as well as other behavioral, morphological, and molecular traits is important to understanding the earliest stages of speciation.

Irrigation and avifaunal change in coastal Northwest Mexico: has irrigated habit attracted threatened migratory species?

Irrigation in desert ecosystems can either reduce or increase species diversity. Groundwater pumping often lowers water tables and reduces natural wetlands, whereas canal irrigation often creates mesic habitat, resulting in great increases in avian diversity from irrigation. Here we compare a dataset of potential natural vegetation to recent datasets from areal and satellite imagery to show that 60% of the land in the coastal plain of southern Sonora and northern Sinaloa lying below 200 m elevation has been converted by irrigation to more mesic habitats. We then use the record of bird specimens in the world’s museums from this same region of Mexico to examine the avian community before and after the development of extensive irrigation. In general these museum records show an increase in the abundance and diversity of breeding birds associated with mesic habitats. Although thorn forest birds have likely decreased in total numbers, most are common enough in the remaining thorn forest that collection records did not indicate their probable decline. Four migrants having most of their breeding ranges in the US or Canada, Yellow-billed Cuckoo, Cliff Swallow, Bell’s Vireo, and Orchard Oriole, apparently have increased dramatically as breeders in irrigated habitats of NW Mexico. Because these species have decreased or even largely disappeared as breeding birds in parts of the US or Canada, further research should assess whether their increases in new mesic habitats of NW Mexico are linked to their declines as breeding birds in Canada and the US For Bell’s Vireo recent specimens from Sinaloa suggest its new breeding population in NW Mexico may be composed partly of the endangered Least Bell’s Vireo.

Avian occupancy varies with habitat structure in oak savanna of the south-central United States

Oak savanna, once widespread across central North America, has functionally vanished from most of its range because of land conversion or fire suppression, but much oak savanna remains in the Cross Timbers ecoregion of the south-central United States. We quantified avian habitat associations across a gradient from open oak savanna to woodland, to closed canopy forest in the Cross Timbers of southeastern Kansas. We surveyed breeding bird species in 2012 and 2013 and modeled species-specific occupancy in relation to habitat variables. Several species, including the northern bobwhite (Colinus virginianus), yellow- billed cuckoo (Coccyzus americanus), downy woodpecker (Picoides pubescens), Bewick's wren (Thryomanes bewickii), northern mockingbird (Mimus polyglottos), field sparrow (Spizella pusilla), dickcissel (Spiza americana), and orchard oriole (Icterus spurius) were associated with lower levels of tree density or canopy cover (i.e., savanna-woodland). Species associated with greater levels of tree density or canopy cover at some spatial scale included eastern wood-pewee (Contopus virens), white-breasted nuthatch (Sitta carolinensis), blue-gray gnatcatcher (Polioptila caerulea), and indigo bunting (Passerina cyanea). Occupancy of eastern wood-pewee and blue grosbeak (Passerina caerulea) were highest at intermediate levels of canopy cover (50- m radius) and tree density, respectively. Occupancies of eastern wood-pewee, northern mockingbird, lark sparrow (Chondestes grammacus), indigo bunting, and brown-headed cowbird (Molothrus ater )w ere variously related to shrub density, which was unrelated to tree cover or density across the savanna-forest gradient. We expect the savanna-associated species would benefit from reduction in tree density to savanna-like habitat (tree canopy cover � 25%) within forests that were formerly savanna. 2015 The Wildlife Society.

Adiciones al inventario avifaunístico del estado de Querétaro, México

Reportamos por primera vez nueve especies de aves para el estado de Querétaro, México, cinco de ellas nativas (Cyrtonyx montezumae, Buteo lineatus, Phalaropus fulicarius, Falco mexicanus e Icterus spurius) y cuatro introducidas (Streptopelia roseogrisea, Cyanoliseus patagonus, Amazona finschi yCalocitta colliei). El inventario avifaunístico del estado incluye ahora 430 especies, de las cuales 418 son nativas y 12 introducidas. Consideramos que el estudio de la avifauna en la zona oeste de Querétaro, que corresponde a la Faja Volcánica Transmexicana, se ha venido completando en los últimos años con un importante esfuerzo de muestreo, por lo que con los presentes registros se conocen 271 especies de aves en ella.

Abundant Early-Summer Breeding In Sinaloa Does Not Suggest Post-Migration Breeding In Three Potential Double Breeders

Abstract Rohwer et al. (2009) present isotopic evidence of migratory double breeding by five species of birds that were breeding in July and August in northwestern Mexico. The presence of old brood patches in these species, combined with their late breeding in Mexico, suggested that these species had bred earlier in the north. Here we present data showing that Orchard Orioles and Yellow-breasted Chats breed as commonly in coastal Sinaloa in late May and early June as they do later in the summer; further, many females of these species examined in early June 2011 had downy ventral apteria, indicating that they were breeding for the first time in their annual cycle in Sinaloa. Thus, the old brood patches observed in these species in July and August, when they are still breeding in northwestern Mexico, may reflect earlier breeding attempts by those same individuals in Mexico. Yellow-billed Cuckoos seldom call and are uncommon in northwestern Mexico until late June and likely do not begin breeding until July. ...

Incomplete song divergence between recently diverged taxa: syllable sharing by Orchard and Fuertes’ orioles

Orchard Orioles (Icterus spurius) and Fuertes' Orioles (I. fuertesi) recently diverged from each other, making them an ideal system for investigating trait evolution and mechanisms of reproductive isolation during the early stages of speciation. These taxa differ in adult male plumage coloration and in their breeding and wintering ranges, but quantitative comparisons of their song characteristics have revealed no discernible differences. We assessed evolutionary song divergence in this group by investigating patterns of syllable-type sharing within and between populations. Of 529 distinct syllable types, 142 (26.8%) were shared among individuals, and sharing appeared to decrease with geographic distance. The total number of syllables shared between Orchard and Fuertes' orioles (26; 4.9% of the total) was similar to levels of sharing between populations of Orchard Orioles. Furthermore, hierarchical cluster analyses showed individuals of the two taxa intermixed. Syllables also used as calls were shared more frequently within and between taxa, suggesting that they have evolved more slowly than those used exclusively in songs. Our results show that at least some aspects of song have not yet diverged between these incipient species, either due to cultural exchange or because songs have evolved relatively slowly compared to plumage colors. RESUMEN. La divergencia incompleta de canci´

Breeding Bird Relationships to Landscape Metrics in Coastal Plain Georgia

Some avian species in the southeastern United States are declining, and population decreases may arise from changes in vegetation type area or structural condition. Our objective was to compare abundance of conservation priority bird species with landscape variables. We found, even in the highly forested Coastal Plain of Georgia, that areal extent and core area of cover types were related to abundance for certain bird species. Acadian flycatcher and field sparrow had models that incorporated positive area variables. Downy woodpecker, northern parula, orchard oriole, prairie warbler, and summer tanager had models that included positive area and edge associations with varying scales and vegetation types. Edge appeared in models for red-bellied woodpecker, blue jay, and brown-headed cowbird. More than half of all species did not have models that met prediction thresholds. Systematic assessment of area requirements for declining species provides information for management, conservation, and research.

Assessing Migratory Double Breeding through Complementary Specimen Densities and Breeding Records

Abstract. We re-evaluate the plausibility that five species of birds that breed in late summer in northwestern Mexico are migratory double breeders that first bred earlier in the same season to the north. We use data aggregated from scientific collections to generate abundance indices that adjust counts of specimens in collections by collecting effort, which we measure as the number of passerines collected in the same region and time period as the species of interest. Our abundance indices generally show displaced phenologies, such that presumed double breeders arrive and breed early in the north, then later in northwestern Mexico. We also compare breeding records for these regions, but these records could not be corrected for effort. Our phenologies suggest that the breeding populations of the Yellow-billed Cuckoo (Coccyzus americanus) from the western U.S. and northwestern Mexico may be derived from birds that bred earlier in eastern North America. Similarly, Orchard Orioles (Icterus spurius) breeding i...

Environmental Niche Modeling Reveals Climatic Differences among Breeding Ranges of Orchard Oriole Subspecies

Environmental niche parameters of breeding ranges for two subspecies in the Orchard Oriole complex (Icterus spurius spurius and I. s. fuertesi) were characterized via ecological niche modeling. Niche models formulated from museum specimen collections largely agree with published breeding ranges of both taxa. Furthermore, our findings identify likely suitable habitat of migratory double breeding in I. s. spurius. Models successfully identify suitable habitat as illustrated by threshold dependent and independent statistical tests and overlap very little in geographic space. Principal component analysis (PCA) identifies two axes explaining 99.0% of variation in the climate data and reveals that each breeding range exhibits unique ecological characteristics, as they occur in nonoverlapping PCA space. Multivariate analysis of variance (MANOVA) identifies significant differences along both axes (PC1, P , 0.0001; PC2, P , 0.0001). A newly formulated metric for niche similarity (I) agrees with PCA and ENM results and, further, indicates that environmental niche differences are more likely a result of differences in habitat availability than habitat preference. Our results may indicate rapid change in environmental niche within the Orchard Oriole group as these taxa have been diverging for approximately 200,000 y. The Orchard Oriole group provides an example of niche lability that contrasts with evidence of niche conservatism between many other Mexican species pairs.

Late pleistocene passerine birds from Sonora, Mexico

Songbirds (Passeriformes) have a very limited fossil record in spite of making up more than one-half of the world's 10,000 living species of birds. From the late Pleistocene fossil site of Térapa in east-central Sonora, Mexico, the identifiable fossils of songbirds consist exclusively of species of Icteridae. The seven extant species (Red-winged Blackbird Agelaius phoeniceus, Yellow-headed Blackbird Xanthocephalus xanthocephalus, Brewer's Blackbird Euphagus cyanocephalus, Great-tailed Grackle Quiscalus mexicanus, Bronzed Cowbird Molothrus aeneus, Brown-headed Cowbird M. ater, and Orchard Oriole Icterus spurius) still occur in Sonora, either as residents or migrants. The eighth fossil icterid from Térapa is an extinct genus and species of cowbird, Pandanaris convexa. The genus Pandanaris was known formerly only from late Pleistocene sites in southern California ( P. convexa A. H. Miller) and Florida ( P. floridana Brodkorb). We synonymize P. floridana with P. convexa because their supposed differences either cannot be substantiated or can be attributed to sexual dimorphism in size within a single species. Among the few Pleistocene sites from Mexico or the United States with well-studied and substantial assemblages of fossil passerines, Térapa is unique in its dominance of icterids (which may be common elsewhere but not dominant) and in its absence of corvids. Today, tropical “foothills thornscrub” is the vegetation type at Térapa except for riparian forest along the río Moctezuma. The icterid fossils are compatible with previous evidence (from plant, invertebrate, and other vertebrate fossils) that tropical/subtropical marsh, savanna, and riparian forest existed at Térapa during the late Pleistocene. Just as the two extant species of cowbirds associate today with large grazing mammals, the extinct Pandanaris convexa may have foraged in association with Pleistocene mammals whose extinction led to the demise of P. convexa as well.

Return Rates in Two Temperate Breeding Orioles (Icterus)

Abstract We monitored two migratory oriole species, Baltimore (Icterus galbula) and Orchard (I. spurius) orioles, for information on return rate and pair fate over 4 years. The return rate after migration for Baltimore and Orchard orioles was low (38 and 35%, respectively). Pairs were more likely to dissolve due to non-return of one or both members than they were to reunite or change mates. Pair members infrequently returned to the study site and previous pairs had little opportunity to reunite in the next year. Birds with non-returning mates appeared to take advantage of the first available mating opportunity instead of waiting for the return of their previous partners.

Using Color to Define Species Boundaries: Quantitative Analysis in the Orchard Oriole Complex Supports the Recognition of two Species

Abstract Abstract. The recent divergence of Orchard (Icterus spurius spurius) and Fuertes's Orioles (I. s. fuertesi) makes them an ideal system for investigating species boundaries. Orchard and Fuertes's Orioles differ in several respects. They have distinct breeding ranges—Fuertes's Orioles breed in eastern coastal Mexico, whereas Orchard Orioles breed throughout eastern and central North America—and differ in plumage coloration, with adult male Orchard Orioles appearing “chestnut” and Fuertes's Orioles “ochre.” However, no detailed quantitative color analyses have been conducted. To characterize these differences we quantitatively measured plumage color using reflectance spectrometry. The colored plumages of adult male Orchard and Fuertes's Orioles have unique spectral characteristics, with no color overlap between them. Combined with life history differences and previous molecular studies, these findings support the classification of Orchard and Fuertes's Orioles as separate species. Additionally, this study demonstrates the utility of quantitative color measurement as a tool for examining species boundaries.

Incidence of Nest Material Kleptoparasitism Involving Cerulean Warblers

Abstract We document 21 observations of interspecific stealing of nesting material involving Cerulean Warblers (Dendroica cerulea), Red-eyed Vireos (Vireo olivaceus), Blue-gray Gnatcatchers (Polioptila caerulea), Northern Parulas (Parula americana), Black-throated Green Warblers (D. virens), American Redstarts (Setophaga ruticilla), and Orchard Orioles (Icterus spurius) that occurred during studies of Cerulean Warbler breeding biology. These incidents involved a variety of combinations of nest owner and nest material thief suggesting that each of these species is both a perpetrator and recipient of this behavior in our study areas. Kleptoparasitic incidents occurred at all stages of the nesting cycle from nest-building through post-fledging. Two possible motivations for this behavior are related to saving time in finding nest materials and collecting this material for nest construction.

Melanin coloration in New World orioles I: carotenoid masking and pigment dichromatism in the orchard oriole complex

Carotenoids produce the brilliant red, orange, and yellow colors of many animals. However, melanin pigments can also confer some of these same hues. Because carotenoid and melanin colors are produced in different ways and may serve different signaling functions, either within or between species, it is important to establish whether one or both types of pigment are responsible for coloration. We have discovered what appears to be an evolutionary switch from carotenoid‐ to melanin‐based color in two sexually dichromatic New World orioles. Using a combination of reflectance spectrometry and chromatographic analyses of plumage pigments, we found that the chestnut plumage of adult male orchard oriolesIcterus spuriusis produced predominantly by phaeomelanins. Orchard oriole feathers also contain carotenoids, which appear to be masked by the high concentration of phaeomelanins. In contrast, both carotenoids and phaeomelanins appear to contribute to color in adult male Fuertes's oriolesI. fuertesi. Moreover, yellow yearling male and female plumage in both species is produced by carotenoids alone. The masking of carotenoids with phaeomelanins in orchard orioles is interesting in light of the signaling roles that carotenoids are thought to play. In addition, these plumage differences produce a unique case of age and sexual pigment dimorphism in orchard and Fuertes's orioles.

Melanin coloration in New World orioles I: carotenoid masking and pigment dichromatism in the orchard oriole complex

Melanin coloration in New World orioles I: carotenoid masking and pigment dichromatism in the orchard oriole complex

USING COLOR TO DEFINE SPECIES BOUNDARIES: QUANTITATIVE ANALYSIS IN THE ORCHARD ORIOLE COMPLEX SUPPORTS THE RECOGNITION OF TWO SPECIES

Abstract Abstract. The recent divergence of Orchard (Icterus spurius spurius) and Fuertes's Orioles (I. s. fuertesi) makes them an ideal system for investigating species boundaries. Orchard and Fuertes's Orioles differ in several respects. They have distinct breeding ranges—Fuertes's Orioles breed in eastern coastal Mexico, whereas Orchard Orioles breed throughout eastern and central North America—and differ in plumage coloration, with adult male Orchard Orioles appearing “chestnut” and Fuertes's Orioles “ochre.” However, no detailed quantitative color analyses have been conducted. To characterize these differences we quantitatively measured plumage color using reflectance spectrometry. The colored plumages of adult male Orchard and Fuertes's Orioles have unique spectral characteristics, with no color overlap between them. Combined with life history differences and previous molecular studies, these findings support the classification of Orchard and Fuertes's Orioles as separate species. Additionally, this...