Blackbird Species Research Articles

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.

Breeding Performances of the European Blackbird (Turdus merula) in Morocco: Habitat Selection, Breeding Phenology, and Breeding Success

The European Blackbird (Turdus merula) is a widespread species. In Morocco, available knowledge on this species is limited to a few descriptive pieces of information with no detailed data provided. With climate change and the intensification of agricultural activities, the study of the breeding performances of this species is indispensable for management purposes. This study investigates breeding biology, nesting habitats, breeding chronology, and reproductive success of the European Blackbird in both apple orchards and surrounding woody vegetation at Ait Ayach (Morocco) between March and August 2016. We monitored weekly nest status, nesting sites, breeding dates, and failure factors. Results showed that the European Blackbird nests mainly in apple orchards, on Golden Delicious and Starkrimson Delicious trees. Nest height above the ground was 214.15 ± 0.09 cm. Blackbird nests were cup-shaped with medium size dimensions and built from twigs, including dry leaves, stems, and roots walled by the mud. Breeding activities started firstly by nest construction during the last week of April, secondly by egg laying during the first week of May, and thirdly by hatching during the second week of May. Among the 74 surveyed nests, 100% were active during the nesting phase and 88.38% of eggs have succeeded during the incubation phase. In total, 69.03% of chicks have been emancipated. In short, 15.9% of clutches were attacked by predators, 14.35% of clutches were failed due to nest desertion, and 8.75% of chicks were dead. Our study provides the first and only detailed data on reproductive parameters of the European Blackbird in Moroccan ecosystems. Data collected from this study provide valuable information for long-term monitoring of the Moroccan Blackbird population. Additionally, our data offer a possibility of large-scale comparative studies of the reproductive ecology of the Blackbird species.

Spatially explicit modeling of blackbird abundance in the Prairie Pothole Region

Knowledge of factors influencing animal abundance is important to wildlife biologists developing management plans. This is especially true for economically important species such as blackbirds (Icteridae), which cause more than $100 million in crop damages annually in the United States. Using data from the North American Breeding Bird Survey, the National Land Cover Dataset, and the National Climatic Data Center, we modeled effects of regional environmental variables on relative abundance of 3 blackbird species (red-winged blackbird, Agelaius phoeniceus; yellow-headed blackbird, Xanthocephalus xanthocephalus; common grackle, Quiscalus quiscula) in the Prairie Pothole Region of the central United States. We evaluated landscape covariates at 3 logarithmically related spatial scales (1,000ha, 10,000ha, and 100,000ha) and modeled weather variables at the 100,000-ha scale. We constructed models a priori using information from published habitat associations. We fit models with WinBUGS using Markov chain Monte Carlo techniques. Both landscape and weather variables contributed strongly to predicting blackbird relative abundance (95% credibility interval did not overlap 0). Variables with the strongest associations with blackbird relative abundance were the percentage of wetland area and precipitation amount from the year before bird surveys were conducted. The influence of spatial scale appeared small—models with the same variables expressed at different scales were often in the best model subset. This large-scale study elucidated regional effects of weather and landscape variables, suggesting that management strategies aimed at reducing damages caused by these species should consider the broader landscape, including weather effects, because such factors may outweigh the influence of localized conditions or site-specific management actions. The regional species distributional models we developed for blackbirds provide a tool for understanding these broader landscape effects and guiding wildlife management practices to areas that are optimally beneficial. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Migratory New World Blackbirds (Icterids) Are More Neophobic than Closely Related Resident Icterids

Environments undergo short-term and long-term changes due to natural or human-induced events. Animals differ in their ability to cope with such changes which can be related to their ecology. Changes in the environment often elicit avoidance reactions (neophobia) which protect animals from dangerous situations but can also inhibit exploration and familiarization with novel situations and thus, learning about new resources. Studies investigating the relationship between a species’ ecology and its neophobia have so far been restricted to comparing only a few species and mainly in captivity. The current study investigated neophobia reactions to experimentally-induced changes in the natural environment of six closely-related blackbird species (Icteridae), including two species represented by two distinct populations. For analyses, neophobic reactions (difference in number of birds feeding and time spent feeding with and without novel objects) were related to several measures of ecological plasticity and the migratory strategy (resident or migratory) of the population. Phylogenetic relationships were incorporated into the analysis. The degree of neophobia was related to migratory strategy with migrants expressing much higher neophobia (fewer birds feeding and for a shorter time with objects present) than residents. Furthermore, neophobia showed a relationship to diet breadth with fewer individuals of diet generalists than specialists returning when objects were present supporting the dangerous niche hypothesis. Residents may have evolved lower neophobia as costs of missing out on opportunities may be higher for residents than migrants as the former are restricted to a smaller area. Lower neophobia allows them approaching changes in the environment (e.g. novel objects) quickly, thereby securing access to resources. Additionally, residents have a greater familiarity with similar situations in the area than migrants and the latter may, therefore, initially stay behind resident species.

Comparison of two models for estimating mortality from baitings with Compound DRC-1339 Concentrate avicide

In the U.S., DRC-1339 baitings for blackbirds (Icteridae) are generally done under the pesticide label, Compound DRC-1339 Concentrate – Staging Areas. DRC-1339 is a slow-acting avicide and gives the birds enough time to leave the baiting sites. Carcass searches and other forms of onsite counts are ineffective. Instead, linear models (LM) are used. The LM are based on esophageal analyses of several blackbird species collected while feeding at staging area bait sites. Biases and large variances can occur with this type of sampling. As an alternative to the LM, we developed a semi-mechanistic model (SM) that combined mechanistic modeling of environmental and biophysical processes with statistical modeling of DRC-1339 toxicities, avian physical and physiological traits, and foraging behavior. We used simulated baiting scenarios in Missouri and Louisiana to quantify and compare mortality between the LM and SM. The SM accounted for meteorological and regional effects on feeding rates, and we ran the SM scenarios for both mild and inclement weather conditions during January, a month when DRC-1339 baitings frequently occur. Mortality was calculated for males and females of three blackbird species. We used brown rice as the delivery substrate in a mix consisting of 11.34 kg untreated and 0.45 kg 2% DRC-1339 treated rice (1:25 dilution ratio). Compared to the LM, estimates by the SM ranged from 5% higher for male common grackles [Quiscalus quiscula L] to 59% lower for male brown-headed cowbirds [Molothrus ater Boddaert]. On average, the SM was 29% lower (x¯ = 8635, SE = 274.6) than the LM (x¯ = 12,131, SE = 1530.8, P < 0.001). Mortality estimates by the SM were 21% lower (x¯ = 7630, SE = 235.2, n = 12) under inclement than mild conditions (x¯ = 9641, SE = 276.3, P < 0.001). Latitudinal difference between the states did not affect mortality estimates produced by the SM (P > 0.65). Unlike the LM, the SM used avian physiological and behavioral responses to environmental and meteorological conditions based on individual characteristics of the modeled blackbird species. It represents a scientifically rigorous and broad-scale approach that can be applied at all staging area baitings regardless of region or time-of-year. The SM will produce much lower mortality estimates compared to the LM when brown-headed cowbirds are the major species using staging area sites.

Life History Trade-Offs Between Longevity and Immunity in the Parasitic Brown-Headed Cowbird?

Life history theory predicts evolutionary trade-offs between investing in immune defense and other traits. We investigated whether reduced longevity was associated with increased investment in immunity in an avian brood parasite, the brown-headed cowbird (Molothrus ater). Previously we had found that the brown-headed cowbird was unusually re- sistant to infection with West Nile virus and other pathogenic arboviruses when compared with three closely related spe- cies in the same Family, Icteridae, the New World blackbirds. In this study, we hypothesized that the cowbird's more ef- fective immune responses may be associated with a trade-off in somatic maintenance that results in a shorter lifespan. We measured lifespan using the North American bird banding database and compared the lifespan of the cowbird with the lifespan of red-winged blackbird (Agelaius phoeniceus) and Brewer's blackbird (Euphagus cyanocephalus), two related species whose immune defenses were previously found less effective against West Nile virus. The cowbird lifespan was significantly shorter than those of both the red-winged blackbird and Brewer's blackbird. We also found that both male and female cowbirds had a shorter lifespan than the males and females in the two non-parasitic blackbird species. These data suggest that the brown-headed cowbird is a good study species for examining the trade-offs between immunity and longevity.

Modeling Wetland Blackbird Populations as a Function of Waterfowl Abundance in the Prairie Pothole Region of the United States and Canada

Blackbirds share wetland habitat with many waterfowl species in Bird Conservation Region 11 (BCR 11), the prairie potholes. Because of similar habitat preferences, there may be associations between blackbird populations and populations of one or more species of waterfowl in BCR11. This study models populations of red-winged blackbirds and yellow-headed blackbirds as a function of multiple waterfowl species using data from the North American Breeding Bird Survey within BCR11. For each blackbird species, we created a global model with blackbird abundance modeled as a function of 11 waterfowl species; nuisance effects (year, route, and observer) also were included in the model. Hierarchical Poisson regression models were fit using Markov chain Monte Carlo methods in WinBUGS 1.4.1. Waterfowl abundances were weakly associated with blackbird numbers, and no single waterfowl species showed a strong correlation with any blackbird species. These findings suggest waterfowl abundance from a single species is not lik...

Phylogenetic perspective on ecological niche evolution in american blackbirds (Family Icteridae)

Analysis of ecological characters on phylogenetic frameworks has only recently appeared in the literature, with several studies addressing patterns of niche evolution, generally over relatively recent time frames. In the present study, we examined patterns of niche evolution for a broad radiation of American blackbird species (Family Icteridae), exploring more deeply into phylogenetic history. Within each of three major blackbird lineages, overlap of ecological niches in principal components analysis transformed environmental space varied from high to none. Comparative phylogenetic analyses of ecological niche characteristics showed a general pattern of niche conservatism over evolutionary time, with differing degrees of innovation among lineages. Although blackbird niches were evolutionarily plastic over differing periods of time, they diverged within a limited set of ecological possibilities, resulting in examples of niche convergence among extant blackbird species. Hence, an understanding of the patterns of ecological niche evolution on broad phylogenetic scales sets the stage for framing questions of evolutionary causation, historical biogeography, and ancestral ecological characteristics more appropriately. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 869–878.

Seasonal Occurrence of Blackbird Species (Icteridae) in Wild Rice (Zizania): A Response to Rice Stage or Breeding Phenology?

Author(s): Scott, Thomas A.; Marcum, Daniel B.; Lee, Pey-Yi; Shuler, James; Fry, John | Abstract: Blackbird species (Icteridae) are considered a primary cause of yield loss prior to harvest in wild rice, which equaled about $3 million in 2007. Although rice consumption should be a null model of bird damage to yield, data from cage traps and point counts indicate that blackbird flocks arrive in wild rice fields 3 to 4 weeks before rice was available for consumption, but coincidental with the time when blackbird form post-breeding flocks. Wild rice plants appear to be attractive habitat from the time the wild rice begins heading until it is harvested (c. 6 weeks), even though wild rice is a food source only for the last 2 to 3 weeks (milk stage to harvest of mature grains). The onset of occurrence in wild rice fields appears to be a function of breeding season of red-winged blackbird and Brewer’s blackbird, specifically they arrive shortly after the time when young-of-the-year become independent of parental care (first week of July). Hence, nesting phenology is the best predictor of blackbird occurrence and their potential damage to wild rice.

COMPARISON OF IMMUNE RESPONSES OF BROWN-HEADED COWBIRD AND RELATED BLACKBIRDS TO WEST NILE AND OTHER MOSQUITO-BORNE ENCEPHALITIS VIRUSES

The rapid geographic spread of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) across the United States has stimulated interest in comparative host infection studies to delineate competent avian hosts critical for viral amplification. We compared the host competence of four taxonomically related blackbird species (Icteridae) after experimental infection with WNV and with two endemic, mosquito-borne encephalitis viruses, western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV), and St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV). We predicted differences in disease resistance among the blackbird species based on differences in life history, because they differ in geographic range and life history traits that include mating and breeding systems. Differences were observed among the response of these hosts to all three viruses. Red-winged Blackbirds were more susceptible to SLEV than Brewer's Blackbirds, whereas Brewer's Blackbirds were more susceptible to WEEV than Red-winged Blackbirds. In response to WNV infection, cowbirds showed the lowest mean viremias, cleared their infections faster, and showed lower antibody levels than concurrently infected species. Brown-headed Cowbirds also exhibited significantly lower viremia responses after infection with SLEV and WEEV as well as coinfection with WEEV and WNV than concurrently infected icterids. We concluded that cowbirds may be more resistant to infection to both native and introduced viruses because they experience heightened exposure to a variety of pathogens of parenting birds during the course of their parasitic life style.

A PHYLOGENETIC PERSPECTIVE ON THE EVOLUTION OF CHROMATIC ULTRAVIOLET PLUMAGE COLORATION IN GRACKLES AND ALLIES (ICTERIDAE)

Plumage traits have been studied intensely for more than a century, especially bright and exaggerated plumage. A large body of evidence across a range of avian taxa supports sexual selection as a major evolutionary force acting on plumage colors. The discovery of ultraviolet (UV) coloration in avian plumage resulted in the extension of sexual selection hypotheses to explain the evolution of potential UV plumage traits. However, there have been no comparative evolutionary studies elucidating the origin of UV signals in birds. Here, I used a comparative phylogenetic approach to investigate the evolution of chromatic UV plumage colors in the grackles-and-allies clade of the New World blackbirds (Icteridae). On the basis of reflectance data collected from museum study skins, I have determined that UV plumage signals have evolved multiple times from an ancestral condition that lacked UV plumage signals, with very few unambiguous reversals. Although UV plumage has evolved in both males and females, there have been significantly more evolutionary changes in male UV plumage characters. Concentrated changes tests and correlations of independent contrasts reveal evidence for sexual selection of some male UV plumage characters, as well as an increase in UV plumage coloration for species found in open habitats. These results support the use of objective assessments of avian colors (i.e. spectrophotometry) to properly interpret patterns of plumage evolution generally, and they suggest the need for behavioral studies on the function of chromatic UV signals in several blackbird species. Una Perspectiva Filogenética sobre la Evolución de la Coloración Ultravioleta en los Changos y Chamones (Icteridae)

EFFECT OF PREDATION AND COWBIRD PARASITISM ON THE NESTING SUCCESS OF TWO SYMPATRIC NEOTROPICAL MARSHBIRDS

We compared the effect of nest predation and cowbird parasitism on the breeding success of two simultaneously nesting ecologically similar blackbird species that differ in their breeding strategies. The Scarlet-headed Blackbird (Amblyramphus holosericeus) is a monogamous species that performs territorial defense. In contrast, the Brown-and-yellow Marshbird (Pseudoleistes virescens) is a non-territorial monogamous breeder that performs mate guarding and has helpers at the nest. Both species suffered similar nest predation rates throughout their nesting cycle. However, the Brown-and-yellow Marshbird suffered higher parasitism from Shiny (Molothrus bonariensis) and Screaming cowbirds (M. rufoaxillaris) than the Scarlet-headed Blackbird (62.6% vs 15.4%). Brood parasitism accounted for most of the egg losses and hatching failures in Brown-and-yellow Marshbird. Parasitized nests had lower egg survival and hatching success than non-parasitized ones. Mean clutch size was 1.5 eggs larger in Brown-and-yellow Marshbird than in Scarlet-headed Blackbird. However, Scarlet-headed Blackbird had higher hatching success than Brown-and-yellow Marshbird and similar fledging success. Consequently, both species produced similar numbers of fledglings. We did not detect any relationship between the reproductive success of these species and their breeding strategies. The presence of helpers at Brown-and-yellow Marshbird nests did not affect nest defense or chick survival, but helpers might account for reduced parental effort by supplementing food delivery to chicks/fledglings.

Preferences of three blackbird species for sunflower meats, cracked corn and brown rice

We offered sunflower meats, cracked corn and brown rice to individuals and small groups ( n = 4–5) of red-winged blackbirds ( Agelaius phoeniceus), yellow-headed blackbirds ( Xanthocephalus xanthocephalus) and common grackles ( Quiscalus quiscula) to determine their food preference. Common grackles (sexes combined) preferred cracked corn over sunflower meats and brown rice. Male and female yellow-headed blackbirds preferred brown rice or a combination of brown rice and cracked corn or sunflower meats. Female red-winged blackbirds chose brown rice; whereas, male red-winged blackbirds did not show a consistent food preference. Either brown rice or a brown rice and cracked corn combination should be used to bait blackbirds.

An evaluation of phenol methylcarbamates as taste aversion producing agents in caged blackbirds

Mesurol, 3,5-dimethyl-4-(methylthio) phenol methylcarbamate, is registered as a repellent for bird damage control on cherries and grapes, and several field evaluations have suggested decreased damage with Mesurol application. This laboratory experiment with a colony of mixed blackbird species suggests that Mesurol-dusted sunflower meats consumed by blackbirds alters the subsequent palability of untreated seeds rather than the presence of the Mesurol serving directly to repel birds from the crop. In a second experiment, methylcarbamate-impregnated seeds and non-treated seeds were evenly spread in different sunflower plots containing blackbirds. Reduced rates of sunflower damage in treated areas compared to the control areas suggest this technique may be promising.

Comparison of audiograms and song spectra in two blackbird (Icterid) species

Dooling [J. Acoust. Soc. Am. 50, 706 (1971)] has hypothesized that avian songs, which are broadcast signals adapted to distant communication, should fall in the frequency region for which a songbird has maximum auditory sensitivity. Using operant conditioning procedures, we have compared behavioral audiograms in two blackbird species belonging to the same family (Icteridae) with significantly different song spectra: The redwing blackbird (Agelaius phoeniceus), whose song energy is concentrated in the 2–4‐kHz region, and the brown‐headed cowbird (Molothrus ater), whose song consists of unusually high frequencies in the 6–10‐kHz region. Results revealed maximum auditory sensitivity for both species to be at 2–4 kHz, with no tendency for the cowbird to be more sensitive than the redwing in the region of its own song (6–10 kHz). Therefore the cowbird, unlike the redwing, does not show the predicted match between song spectrum and region of maximum auditory sensitivity. One factor contributing to this mismatch may be that the cowbird, a brood parasite who lays its eggs in the nests of smaller species such as sparrows and warblers, imitates the high frequencies in the sounds of these birds. [Research supported by NIH Grant No. R01 NS12112.]