Quiscalus Quiscula Research Articles

Subspecies limits based on morphometry and mitochondrial DNA genomics in a polytypic species, the common grackle, Quiscalus quiscula

Abstract Nearctic migratory songbirds have demonstrated low levels of genetic differentiation and weak phylogeographical structure in mitochondrial DNA lineages compared with resident species. The common grackle, Quiscalus quiscula, is a widespread, partially migratory, North American icterid composed of three currently recognized subspecies. In this study, mensural characters (external and skeletal measurements) and the complete mitochondrial genome together with two mitochondrial genes, Cytb and ND2, were used to investigate subspecific differentiation and demographic history of the common grackle. The results showed substantial variation in body size among subspecies, mostly distributed between the ‘Florida grackle’, Quiscalus quiscula quiscula, and the two other subspecies. Analysis of mitochondrial DNA indicated low levels of genetic variation, but we found distinct haplotypes in Florida that form a clade in the phylogenetic tree. This suggests that the nominate subspecies in Florida is a distinct evolutionary unit. The sharing of haplotypes among the other subspecies (Quiscalus quiscula versicolor and Quiscalus quiscula stonei) in the north suggests high levels of gene flow, making the status of these two subspecies equivocal. Gene flow between nominate Q. q. quiscula, Q. q. versicolor and putative Q. q. stonei is probably attributable to historical changes in distribution and abundance following climate change events. We therefore recognize only two subspecies in the common grackle complex.

Bird species define the relationship between West Nile viremia and infectiousness to Culex pipiens mosquitoes.

The transmission cycle of West Nile virus (WNV) involves multiple species of birds. The relative importance of various bird species to the overall transmission is often inferred from the level and duration of viremia that they experience upon infection. Reports utilizing in vitro feeding techniques suggest that the source and condition of blood in which arboviruses are fed to mosquitoes can significantly alter the infectiousness of arbovirus to mosquitoes. We confirmed this using live hosts. A series of mosquito feedings with Culex pipiens was conducted on WNV-infected American robins and common grackles over a range of viremias. Mosquitoes were assayed individually by plaque assay for WNV at 3 to 7 days after feeding. At equivalent viremia, robins always infected more mosquitoes than did grackles. We conclude that the infectiousness of viremic birds cannot always be deduced from viremia alone. If information concerning the infectiousness of a particular bird species is important, such information is best acquired by feeding mosquitoes directly on experimentally infected individuals of that species.

Apparent wing-assisted incline running in a Common Grackle (<i>Quiscalus quiscula</i>)

Wing-assisted incline running (WAIR) has been observed in bird taxa from multiple clades. Its wide phylogenetic distribution in modern birds suggests that it is an ancestral trait for class Aves. WAIR as a behaviour is speculated to predate the evolution of full-powered flight, and to have formed a behavioural and physiological stepping stone between terrestrial and aerial life. Here I report an observation of apparent WAIR in a Common Grackle (Quiscalus quiscula) photographed incidentally on a trail camera deployed in an urban backyard in Guelph, Ontario, Canada. To my knowledge this is the first documented observation of apparent WAIR for the family Icteridae. Furthermore, it highlights the value of non-systematic use of trail cameras for making unique natural history observations.

LOW INCIDENCE OF HELMINTH PARASITES IN BROWN-HEADED COWBIRDS (MOLOTHRUS ATER) FROM EAST TEXAS

LOW INCIDENCE OF HELMINTH PARASITES IN BROWN-HEADED COWBIRDS (<i>MOLOTHRUS ATER</i>) FROM EAST TEXAS

An instance of hybridization with Common Grackle (Quiscalus quiscula) and male parental care by Great-tailed Grackle (Q. mexicanus)

Great-tailed Grackle (Quiscalus mexicanus) and Common Grackle (Q. quiscula) are phylogenetically distant among grackles and were historically allopatric. Northward range expansion of Great-tailed Grackle and westward expansion of Common Grackle brought these species into increasing contact over the past century but has not led to notable interactions. Hybrids of Great-tailed Grackle with Boat-tailed Grackle (Q. major), Brewer's Blackbird (Euphagus cyanocephalus), and Red-winged Blackbird (Agelaius phoeniceus) have been reported, whereas hybridization of Common Grackle has never been documented with any species. We report a brood of 2 hybrid offspring of a male Great-tailed Grackle and female Common Grackle in Dillon, Montana, in 2015. For about a week after their discovery, both parents defended and fed the fledglings, the latter behavior extraordinary for a male Great-tailed Grackle. Moreover, whereas the female parent was no longer seen, the male continued to feed the young for at least another 7 weeks after they left the nest tree, during which time the trio moved ∼2 km across town and the young began prebasic molt, growing iridescent blue-black secondary coverts as expected for male Great-tailed Grackle but not for Common Grackle or female Great-tailed Grackle. Analysis of DNA from a feather of one offspring confirmed that it had hybrid nuclear DNA, had Common Grackle mitochondrial DNA, and was male. In 2016, the male Great-tailed Grackle again courted a female Common Grackle that nested in his tree, a nest which he defended, but she was also attended by a male Common Grackle. She produced 5 young, all of which were genetically pure Common Grackles, not hybrids. Also notable in 2016, another male Great-tailed Grackle in the general vicinity was observed feeding young in 1 of 3 nests that he defended, suggesting that male parental care may be more common in that species than has been appreciated.

Rapid range expansion predicted for the Common Grackle (Quiscalus quiscula) in the near future under climate change scenarios

BackgroundClimate change due to anthropogenic global warming is the most important factor that will affect future range distribution of species and will shape future biogeographic patterns. While much effort has been expended in understanding how climate change will affect rare and declining species we have less of an understanding of the likely consequences for some abundant species. The Common Grackle (Quiscalus quiscula; Linnaeus 1758), though declining in portions of its range, is a widespread blackbird (Icteridae) species in North America east of the Rocky Mountains. This study examined how climate change might affect the future range distribution of Common Grackles.MethodsWe used the R package Wallace and six general climate models (ACCESS1-0, BCC-CSM1-1, CESM1-CAM5-1-FV2, CNRM-CM5, MIROC-ESM, and MPI-ESM-LR) available for the future (2070) to identify climatically suitable areas, with an ecological niche modelling approach that includes the use of environmental conditions.ResultsFuture projections suggested a significant expansion from the current range into northern parts of North America and Alaska, even under more optimistic climate change scenarios. Additionally, there is evidence of possible future colonization of islands in the Caribbean as well as coastal regions in eastern Central America. The most important bioclimatic variables for model predictions were Annual Mean Temperature, Temperature Seasonality, Mean Temperature of Wettest Quarter and Annual Precipitation.ConclusionsThe results suggest that the Common Grackle could continue to expand its range in North America over the next 50 years. This research is important in helping us understand how climate change will affect future range patterns of widespread, common bird species.

Benefits of playa buffers as bird habitat

Playa wetlands are important for maintaining biodiversity in otherwise nondiverse landscapes in the High Plains of the western Great Plains. Vegetation buffers around playas have been documented to reduce runoff of sediments and contaminants; however, there have been few assessments of the effects of buffers on bird communities. I conducted point counts during the breeding season and sampled vegetation at playa buffer sites and control playas to assess effects of buffers on breeding birds and their habitat. Relative abundance of wetland-dependent birds and total birds was substantially greater at buffered playas than unbuffered playas. I was not able to detect a difference in upland bird relative abundance between treatments. This was likely due to the habitat requirements of the most frequently detected upland birds: Common Grackle (Quiscalus quiscula) and Horned Lark (Eremophila alpestris). Buffered playas contained more visual obstruction and percent forb cover than control playas, but I was unable to detect a difference in percent grass or bare ground. Overall, playa buffers supported more birds and provided better habitat conditions for many bird species than unbuffered sites, and I suggest further research examining survival and reproductive output of birds using playa buffers.

Why is the Common Grackle becoming less common?

Why is the Common Grackle becoming less common?

Pre-existing Microfilarial Infections of American Robins (Passeriformes: Turdidae) and Common Grackles (Passeriformes: Icteridae) Have Limited Impact on Enhancing Dissemination of West Nile Virus in Culex pipiens Mosquitoes (Diptera: Culicidae).

Microfilariae (MF) are the immature stages of filarial nematode parasites and inhabit the blood and dermis of all classes of vertebrates, except fish. Concurrent ingestion of MF and arboviruses by mosquitoes can enhance mosquito transmission of virus compared to when virus is ingested alone. Shortly after being ingested, MF penetrate the mosquito's midgut and may introduce virus into the mosquito's hemocoel, creating a disseminated viral infection much sooner than normal. This phenomenon is known as microfilarial enhancement. Both American Robins and Common Grackles harbor MF-that is, Eufilaria sp. and Chandlerella quiscali von Linstow (Spirurida: Onchocercidae), respectively. We compared infection and dissemination rates in Culex pipiens L. mosquitoes that fed on birds with and without MF infections that had been infected with West Nile virus (WNV). At moderate viremias, about 107 plaque-forming units (pfu)/ml of blood, there were no differences in infection or dissemination rates among mosquitoes that ingested viremic blood from a bird with or without microfilaremia. At high viremias, >108.5 pfu/ml, mosquitoes feeding on a microfilaremic Grackle with concurrent viremia had significantly higher infection and dissemination rates than mosquitoes fed on viremic Grackles without microfilaremia. Microfilarial enhancement depends on the specific virus, MF, and mosquito species examined. How virus is introduced into the hemocoel by MF differs between the avian/WNV systems described here (i.e., leakage) and various arboviruses with MF of the human filarid, Brugia malayi (Brug) (Spirurida: Onchocercidae) (i.e., cotransport). Additional studies are needed to determine if other avian species and their MF are involved in the microfilarial enhancement of WNV in nature.

Late Quaternary Range Dynamics in the Common Grackle Quiscalus quiscula

Climate variability is one of the most important forces affecting the distributional range dynamics of species and consequentially plays a significant role in shaping biogeographic patterns. This study aims to infer the role of climate in the recent evolutionary history of the Common Grackle Quiscalus quiscula. Studies of other migratory North American birds have shown that their populations were isolated in two or three refugia in southern North America during the Last Glacial Maximum (LGM). In contrast, preliminary genetic work suggest that Common Grackles may have occupied a single refugium during that time. They subsequently became widespread and northern populations evolved highly migratory behaviour. We used an ecological niche modelling approach that involved the use of three general climate models for the past (the LGM, approximately 22000 years before present) and for present environmental conditions to identify climatically stable areas. Extrapolations to the past showed contraction to a large continuous refugium located in the southern part of North America, and projection to the present showed expansion that covers much of eastern and middle North America. The most important bioclimatic variable for model predictions was annual mean temperature, which explained 74% of the variation in the model. Results suggest that the Common Grackle has expanded its distributional range by more than 300% after the LGM.

Influence of different sign-post designs on avian predator perching activity

Beach-nesting shorebirds are declining due, in part, to human disturbance in nesting areas. Sign-posts are installed around nesting areas to protect nests from people, but they may serve as perches and attract avian predators. From March–August 2018, we used passive infrared game cameras to monitor perching activity on 15 variations of sign-post designs on 2 barrier islands in North Carolina. We observed 110 independent perching events dominated (70%) by common (Quiscalus quiscula) and boat-tailed grackles (Quiscalus major) and laughing gulls (25%; Leucophaeus atricilla). We compared how the number of days perching occurred was associated with sign shape, material, sign-construction (sign x shape), position on post, and presence/absence of a nail on top of the post. Position of the sign on the post had the strongest effect on the number of days perching events occurred (χ2 = 18.62 df = 2 P < 0.001). Signs positioned flush with the top of the post were most frequently perched on (10% of perching days), followed by signs positioned lower (5%) and higher (2%) than the post top. The frequency of avian predators perching on triangular signs (8%) and rectangular signs (5%) did not differ (X2 = 2.89 df = 1 P = 0.11). While sign material (metal: 12%; laminated cardboard: 11%; plastic: 13%) did not affect the probability of perching (χ2 = 1.06 df = 2 P = 0.58), triangular plastic signs (11%) had more (χ2 = 6.011 df = 2 P = 0.05) perching activity than rectangle-metal (6%) and rectangle-laminated signs (6%). Presence (3%) or absence (4%) of a nail on top of posts did not affect the number of days perching occurred on a sign-post (χ2 = 0.59 df = 1 P = 0.52). We recommend managers position signs high on the post to reduce occurrences of predatory perching. If a choice of sign shape and material is available, rectangular metal or laminated cardboard signs may also reduce perching activity.

Flight feather molt in Common Grackles (Quiscalus quiscula)

We evaluated flight feather molt of Common Grackles (Quiscalus quiscula) collected in North Dakota to determine differences by age and sex and to infer seasonal relationships with nesting and migration. On average, the HY preformative molt started and ended later than the AHY prebasic molt. Percentages of molting AHY males and females in weekly collections were ≥90% beginning the first and fourth weeks of July, respectively. Percentages of molting HY males and females reached ≥90% the first week of August. Both age classes remained >90% in molt through mid-September; thereafter percentages fell rapidly, likely caused by the passing of enough time from average onsets of molts for both resident and northern nonresident populations. By the first week of October, molting HY males and females comprised about 55% of weekly HY collections compared to 9% and 21% for AHY males and females, respectively. Extensive access to commercial sunflower fields perhaps allowed resident and nonresident AHY birds to remain in the area until molt was at or near completion.

Do Life History Traits Influence Patterns of Maternal Immune Elements in New World Blackbirds (Icteridae)?

AbstractAvian immunology developed originally by investigating domesticated poultry species (Galliformes), but in recent decades eco-immunological studies of wild bird species have revealed that avian immune systems are more diverse than initially assumed. This study compares six immunological elements in eggs of six species within the same family, the New World blackbirds (Icteridae),whose members differ most notably in two life history parameters, brood parasitism and body size. We measured the maternal immune investment of passive immune components in both yolk and albumen: lysozyme, ovotransferrin, and immunoglobulins (Igs), and LPS-specific Igs. We predicted that brood parasites would have higher levels of immune activity for both innate and adaptive immunity compared with non-brood parasites, and that increased body size could increase microbial exposure of larger animals, resulting in an increase in some adaptive immune responses, such as LPS-specific Igs. We found that brood parasites had significantly higher levels of Igs and lysozyme levels in albumen, but significantly lower levels of Igs in yolk compared with non-brood parasites. Igs in yolk scaled according to body size, with the smallest organisms (the brood parasites) having the lowest levels, and the largest organism (common grackle) having the highest. Our results confirm the findings of other studies of comparative immunity among species in a single taxon that (1) similarities in immune investment cannot be assumed among closely related species and (2) single measures of immune defense cannot be assumed to be indicators of a species’ overall immune strategy, as life history traits can differentially affect immune responses.

First Record of the Common Grackle from Sonora

First Record of the Common Grackle from Sonora

Use of cover crop fields by migratory and resident birds

Cover crops, established between the growing seasons of primary crops to improve soil and water quality, have become increasingly popular in the Midwest region of the United States; however, the impact on migratory and resident birds is largely unknown. We conducted avian surveys on four field types in east central Illinois in the spring of 2015 and 2016: maize (Zea mays L.) stubble with cover crop, maize stubble only, soybean [Glycine max (L.) Merr.] stubble with cover crop, and soybean stubble only. For each field type, we calculated relative bird abundance and the Avian Conservation Significance value (ACS). Relative bird abundance was greater in cover crop fields than non-cover crop fields, with the maize fields planted with cover crops providing the greatest value (nearly twice the number of individuals and twice the species compared with non-cover crop soybean fields). The most common species were Red-winged Blackbird (Agelaius phoeniceus), Common Grackle (Quiscalus quiscula), and American Robin (Turdus migratorius). ACS values were most influenced by the Eastern Meadowlark (Sturnella magna), a species of high conservation concern. Many agricultural landscapes lack habitat in the spring and cover crop fields may be important areas to provide shelter and forage for birds. While we documented greater use of these fields more research is needed to understand why birds use these fields; more explicitly are birds finding cover, foraging, or attempting to breed in cover crop fields? As the amount of cover crop area increases, the value of these fields for migratory and resident bird use may increase. While habitat for wildlife is a secondary consideration when planting cover crops, my research suggests the use of cereal rye and later termination of cover crops benefits birds. Cover crops will not replace natural habitats for birds, but the widespread use of cover crops may benefit some bird populations.

Assigning hatchlings to eggs: Is relative mass assignment an accurate method?

BackgroundAccurately assigning hatchlings to the eggs from which they hatched is a prerequisite to understanding how the composition and environment of eggs affect the growth and survival of nestlings. Correctly assigning hatchlings to their eggs can be a challenging endeavor, however, because multiple eggs within the same clutch can hatch at essentially the same time. Egg and hatchling mass are highly correlated in most bird species, and thus assigning eggs to hatchlings using their relative mass (e.g., matching the heaviest hatchling to the heaviest candidate egg) could prove extremely useful.MethodsTo assess its potential utility, I applied relative mass assignment (RMA) retrospectively to a dataset of 133 Common Grackle (Quiscalus quiscula) nests in which all egg-hatchling dyads were determined unequivocally.ResultsI found that RMA correctly assigned approximately 90% of hatchlings to their eggs when 2‒4 hatchlings were present between checks. The number of nests in which hatchlings could not be assigned to their egg, however, increased monotonically from 13 to 46 to 78% for nests containing 2, 3, and 4 hatchlings, respectively, due to the greater likelihood that the mass of hatchlings or their candidate eggs was identical.ConclusionsAlthough RMA correctly identified the vast majority of egg-hatchling dyads, researchers should use this method with caution, because it will always inflate positive egg-size effects and thus could potentially result in erroneously reporting significant effects.

Winter Habitat Associations of Blackbirds and Starlings Wintering in the South-Central United States

Birds can cause extensive crop damage in the United States. In some regions, depredating species comprise a substantial portion of the total avian population, emphasizing their importance both economically and ecologically. We used the National Audubon Society Christmas Bird Count data from the south-central United States and mixed-effects models to identify habitat factors associated with population trend and abundance for 5 species: red-winged blackbird (Agelaius phoeniceus), common grackle (Quiscalus quiscula), rusty blackbird (Euphagus carolinus), Brewer's blackbird (Euphagus cyanocephalus), and European starling (Sturnus vulgaris). Overall, we found positive associations between bird abundance and agricultural land-cover for all species. Relationships between abundance and other land-cover types were species-specific, often with contrasting relationships among species. Likewise, we found no consistent patterns among abundance and climate. Of the 5 species, only red-winged blackbirds had a significant population trend in our study area, increasing annually by 2.4%. There was marginal evidence to suggest population increases for rusty blackbirds, whereas all other species showed no trend in population size within our study area. Our study provides managers who are interested in limiting crop damage in the south-central United States with novel information on habitat associations in the region that could be used to improve management and control actions.

Bird consumption of sweet and tart cherries

Identifying species responsible for crop damage is an important fi rst step in developing management strategies. Previous studies have surveyed bird species fl ying through cherry orchards but have not documented which species were consuming cherries. We conducted traditional surveys and behavioral observations in orchards of sweet cherries (Prunus avium) and tart cherries (Prunus cerasus) in Michigan during 2010 to compare results from the 2 techniques. American robins (Turdus migratorius) were detected most frequently during sweet cherry surveys, while behavioral observations showed that cedar waxwings (Bombycilla cedrorum) consumed more sweet cherries than did robins. Chipping sparrows (Spizella passerina) were the most commonly detected species during tart cherry surveys, while observations showed that American robins and common grackles (Quiscalus quiscula) consumed the most tart cherries. Although observational work is more labor-intensive than surveys, observations are more likely to provide accurate information on the relative importance of fruit-consuming species.

Dynamics of Vector-Host Interactions in Avian Communities in Four Eastern Equine Encephalitis Virus Foci in the Northeastern U.S.

BackgroundEastern equine encephalitis (EEE) virus (Togaviridae, Alphavirus) is a highly pathogenic mosquito-borne zoonosis that is responsible for occasional outbreaks of severe disease in humans and equines, resulting in high mortality and neurological impairment in most survivors. In the past, human disease outbreaks in the northeastern U.S. have occurred intermittently with no apparent pattern; however, during the last decade we have witnessed recurring annual emergence where EEE virus activity had been historically rare, and expansion into northern New England where the virus had been previously unknown. In the northeastern U.S., EEE virus is maintained in an enzootic cycle involving the ornithophagic mosquito, Culiseta melanura, and wild passerine (perching) birds in freshwater hardwood swamps. However, the identity of key avian species that serve as principal virus reservoir and amplification hosts has not been established. The efficiency with which pathogen transmission occurs within an avian community is largely determined by the relative reservoir competence of each species and by ecological factors that influence contact rates between these avian hosts and mosquito vectors.Methodology and principle findingsContacts between vector mosquitoes and potential avian hosts may be directly quantified by analyzing the blood meal contents of field-collected specimens. We used PCR-based molecular methods and direct sequencing of the mitochondrial cytochrome b gene for profiling of blood meals in Cs. melanura, in an effort to quantify its feeding behavior on specific vertebrate hosts, and to infer epidemiologic implications in four historic EEE virus foci in the northeastern U.S. Avian point count surveys were conducted to determine spatiotemporal host community composition. Of 1,127 blood meals successfully identified to species level, >99% of blood meals were from 65 avian hosts in 27 families and 11 orders, and only seven were from mammalian hosts representing three species. We developed an empirically informed mathematical model for EEE virus transmission using Cs. melanura abundance and preferred and non-preferred avian hosts. To our knowledge this is the first mathematical model for EEE virus, a pathogen with many potential hosts, in the northeastern U.S. We measured strong feeding preferences for a number of avian species based on the proportion of mosquito blood meals identified from these bird species in relation to their observed frequencies. These included: American Robin, Tufted Titmouse, Common Grackle, Wood Thrush, Chipping Sparrow, Black-capped Chickadee, Northern Cardinal, and Warbling Vireo. We found that these bird species, most notably Wood Thrush, play a dominant role in supporting EEE virus amplification. It is also noteworthy that the competence of some of the aforementioned avian species for EEE virus has not been established. Our findings indicate that heterogeneity induced by mosquito host preference, is a key mediator of the epizootic transmission of vector-borne pathogens.Conclusion and significanceDetailed knowledge of the vector-host interactions of mosquito populations in nature is essential for evaluating their vectorial capacity and for assessing the role of individual vertebrates as reservoir hosts involved in the maintenance and amplification of zoonotic agents of human diseases. Our study clarifies the host associations of Cs. melanura in four EEE virus foci in the northeastern U.S., identifies vector host preferences as the most important transmission parameter, and quantifies the contribution of preference-induced contact heterogeneity to enzootic transmission. Our study identifies Wood Thrush, American Robin and a few avian species that may serve as superspreaders of EEE virus. Our study elucidates spatiotemporal host species utilization by Cs. melanura in relation to avian host community. This research provides a basis to better understand the involvement of Cs. melanura and avian hosts in the transmission and ecology of EEE virus and the risk of human infection in virus foci.

Cascade of ecological consequences for West Nile virus transmission when aquatic macrophytes invade stormwater habitats.

Artificial aquatic habitats are ubiquitous in anthropogenic landscapes and highly susceptible to colonization by invasive plant species. Recent research into the ecology of infectious diseases indicates that the establishment of invasive plant species can trigger ecological cascades which alter the transmission dynamics of vector-borne pathogens that imperil human health. Here, we examined whether the presence or management of two invasive, emergent plants, cattails (Typha spp.) and phragmites (Phragmites australis), in stormwater dry detention basins (DDBs) alter the local distribution of vectors, avian hosts, or West Nile virus (WNV) transmission risk in an urban residential setting. Mosquitoes and birds were surveyed at 14 DDBs and paired adjacent residential sites. During the study period, emergent vegetation was mowed by site managers in three DDBs. In the absence of vegetation management, the overall abundance and species composition of both adult vectors and avian hosts differed between residential and DDB habitats; however, WNV entomological risk indices were equivalent. Communal bird roosts composed primarily of three species, European Starlings (Sturnus vulgaris), Red-winged Blackbirds (Agelaius phoeniceus), and Common Grackles (Quiscalus quiscula), representing a broad range of WNV reservoir competence, were observed at half (three out of six) of the DDBs containing unmanaged stands of phragmites; however, their presence was associated with a lower seasonal increase in vector infection rate. Conversely, mowing of emergent vegetation resulted in a significant and sustained increase in the abundance of WNV-infected vectors in DDBs and the increase in risk extended to adjacent residential sites. These findings indicate that management of invasive plants in DDBs during the growing season can increase, while presence of communal bird roosts can decrease, WNV transmission risk.