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I used 20 years of nest records and predation at silent control and begging-call playback nests to determine whether begging calls of Red-winged Blackbirds (Agenais phoenixes) attract predators. Survival analysis provided no evidence that vocal begging affected nest predation. Survival schedules during egg and nestling periods were not significantly different, and vocal begging activity was not significantly correlated with daily nest survival. I found that predation at 35 no-longer-active nests at which begging calls were played at natural volume, at a typical rate, and following a normal schedule was slightly but not significantly higher than at 35 silent control nests. Selection may have favored adaptations of nestling Red-winged Blackbirds' begging calls that reduce the risk of predation. Received 16 November 2015. Accepted 14 February 2016. Key words: Agenais phoenixes, ant predator adaptation, begging calls, nest predation, nest survival, playback study, Red-winged Blackbird., Begging by dependent young is common in animals with parental care (Clutton-Brock 1991) and is especially well studied in birds (Wright and Leonard 2002). Begging by nestlings has clear benefits [...]

The Red-winged Blackbird (Agelaius phoeniceus', redwing) is a commonly used accepter host species that incubates eggs and cares for nestlings and fledglings of the obligate brood parasitic Brown-headed Cowbird (Molothrus ater; cowbird). This host species, however, may reduce the risk of parasitism with a frontloaded antiparasite strategy in which it attacks parasites that approach active host nests. To test this ffontloaded parasite-defense hypothesis (FPDH), we presented taxidermic models of a female Northern Cardinal (Cardinalis cardinalis), which represents no threat to redwings, a male cowbird, which cannot lay a parasitic egg, and a female cowbird, together with species- and sex-specific vocalization playbacks for 5 min. We conducted these presentations at 25 active redwing nests at Newark Road Prairie in south-central Rock County, Wisconsin, USA, where 18% of redwing nests were parasitized by cowbirds in 2015. As predicted by the FPDH, the female cowbird mount elicited the most aggressive responses and the female cardinal mount the least aggressive, as measured by number of times more than one male redwing responded and number of times the male host attacked the mount, and by Principal Component Analyses yielding the highest redwing aggressive behavior and intimidation scores. Contrary to the predictions of FPDH regarding the success of nest defense behaviors, male redwings responding at naturally parasitized nests were significantly more likely to attack the mount than males with nests that were not parasitized, although our sample size was small. We also compared our results with those of a study using the same methods in New York State where cowbird parasitism was rare. Redwings in Wisconsin were more aggressive toward the female cowbird mount than redwings in New York. Red-winged Blackbirds appear to frontload their antiparasite defenses, but the success of those defenses depends on individual and population-level experience with parasites. Received 20 October 2015. Accepted 21 January 2016. Key words: Agelaius phoeniceus, antiparasite behavior, brood parasitism, Brown-headed Cowbird, Molothrus ater, Redwinged Blackbird., About 1 % of bird species are obligate brood exclusively on host species to build nests, incubate parasites, whose reproductive strategy depends eggs, and care for nestlings and fledglings (Davies [...]

The effect of spatial and temporal patterns of brown-headed cowbird parasitism on the nest desertion or parasite egg ejection in host birds, like warblers and red-winged blackbirds, is examined.

We identified bacteria collected from the ejaculates and cloacae of male Redwinged Blackbirds (Agelaius phoeniceus) and from the cloacae of their mates during two breeding seasons and at three geographic locations with two distinct breeding habitats in each. In all, 42% of 233 ejaculates contained at least one bacteria species. Analysis of control samples suggested that some bacteria come from contamination during collection, but most are either carried within the ejaculate or are present on the male cloaca. As in an earlier study of Agelaius phoeniceus, we recorded many different species with considerable diversity between samples. We tested several explanations for this diversity. We found no overlap in either the presence of bacteria or the species found in multiple ejaculates obtained from the same male. We also found no association between bacteria in the ejaculate and those in the cloaca from the same male, or in samples collected from a male and those from the females nesting on his territory. Surveys of ejaculates from three locations, Kentucky, New York, and Wisconsin, yielded similar patterns of prevalence and diversity. Ejaculate samples from males inhabiting relatively dry upland habitats contained a similar number of bacteria and array of species as males inhabiting relatively wet, marshy territories. Many of the isolated bacteria are probably benign, but pathological effects of some species have been recorded in some circumstances. Our results suggest that acquiring pathogenic bacteria represents a potential cost to multiple mating by females, but the potential benefits of some microbes may offset these risks. Key words: Agelaius phoeniceus, bacteria, extra-pair copulations, microorganisms, multiple mating, Red-winged blackbirds, sexually transmitted diseases.

Bill M. Strausberger (1) ABSTRACT.--I studied the relationship of nesting habitat and the spatial distribution of Red-winged Blackbird (Agelaius phoeniceus) nests with the frequency of brood parasitism by Brown-headed Cowbirds [...]

There is no effect of spatial or temporal nesting aggregations on nest success in Red-winged Blackbirds, according to research focusing on the effects of aggregated nesting on blackbird nest success and brood parasitism by Brown-headed Cowbirds. The findings of this research were in line with the view that marsh-nesting populations of Red-winged Blackbirds are less vulnerable to parasitism than upland-nesting populations as high nest density allows cooperative vigilance and deterrence. However, the findings go against many studies indicating that predation is negatively correlated with nest density.

One way of preventing damage to crops by birds is to use visual stimuli which repel birds. Diurnal bids can see colors well. The way that red-winged blackbirds respond to food colors has not been researched, and this species and boat-tailed grackles are pests that damage crops in the southern US. A study has found that these species least favor blue, so this color could be used as a way of deterring birds from eating crops. More research into color perceptions by birds is needed.

Eggs of the parasitic Brown-headed Cowbird (Molothrus ater) often hatch before those of its hosts. I artificially incubated the eggs of the cowbird and the taxonomically related but nonparasitic Red-winged Blackbird (Agelaius phoeniceus) to determine if cowbird eggs have unique adaptations. To determine if cowbirds have a wider tolerance of acceptable incubation temperatures, the eggs from both species were incubated at 35, 38, and 40 [degrees] C. Neither species' eggs hatched at 35 or 40 [degrees] C, whereas 24 out of 42 cowbird eggs and 19 out of 36 redwing eggs hatched at 38 [degrees] C. When corrected for differences in mass, cowbird and redwing eggs hatched 10 and 15%, sooner than expected, respectively, suggesting that cowbirds do not have an accelerated rate of embryonic development. Cowbirds may be adapted to lay smaller eggs that generally hatch sooner. Using values obtained from allometric equations that relate body mass and egg mass, cowbird and redwing eggs were 25 and 4% smaller, respectively, than expected. For cowbirds, there was no correlation between egg mass and length of incubation period, whereas there was a positive (but not significant) correlation for redwings. Additional cowbird eggs were incubated at 36 and 39 [degrees] C to determine the effect on the length of the incubation period. The incubation periods of individual cowbird eggs ranged from 10.49 to 14.04 days at 39 and 36 [degrees] C, respectively, whereas eggs incubated at 38 [degrees] C had a mean incubation period of 11.61 days (n = 24), suggesting that cowbirds can tolerate some variation in incubation temperature and indicating a strong temperature effect. I found evidence that internal egg temperature varies with clutch composition. This may partially explain the variation in cowbird incubation periods and why cowbird eggs often hatch before host eggs.

During March 1985 male red-winged blackbirds (Agelaius phoeniceus) were marked with aerially applied fluorescent-colored pigments at two migratory roost sites in southeastern South Dakota and western Minnesota to determine their dispersal to breeding areas. Postspray samples revealed that approximately 54% (1.58 million) of the males present were marked with at least one of four pigments used. During late spring, breeding males were shot in 16 predetermined collecting areas in four N-central states in the United States and three central Canadian provinces. Of 3289 males collected, 555 (16.9%) were marked with one or more pigments; 86.8% (482) of the marked birds were from the South Dakota marking site and 13.2% (73) from the Minnesota site. The 16 collecting areas where male redwings were shot were grouped into six recovery regions for chi-square analysis. Results showed unequal proportions of marked breeding males among the recovery areas (P = < 0.001). Temporal use of the South Dakota roost site by migrating males also affected breeding male distribution (P = < 0.001). Inadequate sample sizes precluded analysis of temporal distribution of marked birds from the Minnesota marking site. Although marked redwings were dispersed over several thousand square kilometers from South Dakota to Alberta, Canada, 76% of the marked male redwings from South Dakota were concentrated in southern Saskatchewan and N-central North Dakota; 74% of the marked birds from Minnesota were concentrated more easterly in southern Manitoba, northeastern North Dakota and northwestern Minnesota. The N-northwestward distances traveled by migrating male redwings from marking sites to breeding areas was significantly different (P = 0.006) among groups marked at different time intervals at each site. Distances traveled ranged from 856 km to 1093 km., INTRODUCTION Birds, particularly blackbirds and European starlings (Sturnus vulgaris), annually cause millions of dollars worth of agricultural and property damage in North America (Pierce, 1970; Knittle and Guarino, 1974; Steenblik, [...]

A study of the relationship between paternity and paternal behavior in an eastern population of red-winged blackbirds during the four seasons shows that paternity does not influence paternal behavior. This result is suggested by the male provisioning of individual broods identically, despite the paternity of males in that brood. The level of provisioning by males with low paternity over several nests is the same as that of males with high paternity.

The effectiveness of ReJex-iT AG-36, which contains methyl anthranilate (MA), as a repellent against red-winged blackbirds which feed on rice seeds was tested in both aviary and field conditions. During aviary tests, MA-treated rice seeds were able to reduce consumption by 2.5%. During field tests, however, consumption of MA-treated rice seeds was only between 27-34% while consumption of untreated seeds were as much as 73%.

We report an apparent protective effect of neighboring Sora (Porzana carolina) nests on Red-winged Blackbird (Agelaius phoeniceus) nests in an experimental study. We suggest that quail eggs used in Sora nests acted as a supemormal stimulus drawing Marsh Wrens (Cistothorus palustris), the main predator in the system, from Red-winged Blackbird nests., Nest predation is the most significant source of mortality in many populations of nesting Red-winged Blackbirds (Agelaius phoeniceus) (Caccamise 1976, Martin 1988, Picman et al. 1988, Westneat 1992; reviewed in [...]

The importance of Brown-headed Cowbird egg coloration and maculation in the acceptance or rejection of variousobjects placed in the nests of Red-winged Blackbirds was studied. Red-winged Blackbird nests were located and marked with coded flagging tape. Various objects were then added to the nests prior to the time when Brown-headed Cowbirds normally lay their eggs. Results revealed that cowbird egg coloration helps conceal the objects so that they are eventually accepted by Red-winged Blackbirds.

Caffeine is an effective, economical, and environmentally safe avian repellent and including sodium benzoate in subsequent formulations enhances the solubility of caffeine thus proving to be an applicable, nonlethal alternative for managing blackbird impacts to agricultural production.

I monitored 382 red-winged blackbird (Agelaius phoeniceus) nests in natural (wetlands and tallgrass prairie) and human-disturbed (hayfields, roadside ditches) habitats in the vicinity of Boulder, Colorado during 1996 and 1997. I counted blackbirds in a total of 6216 ha and quantified habitat composition to determine both within-habitat population density and regional habitat availability. Population density mirrored habitat-specific productivity of red-winged blackbirds in habitats that had predictable sources of water (wetlands, roadside ditches). However, population density and habitat-specific productivity were decoupled in habitats that were unpredictable in the amount of water present during territory establishment (tallgrass prairie and hayfields, which were flood irrigated). Regional habitat productivity was estimated using data on habitat-specific productivity, habitat-specific population density and regional habitat availability. Red-winged blackbirds breeding in wetlands in the absence of yellow-headed blackbirds (Xanthocephalus xanthocephalus) contributed the most young to the regional population, whereas birds breeding in human-disturbed habitats (hayfields and roadside ditches) contributed relatively few young to the regional population. Due to the scarcity of high quality patches in the landscape (e.g., tallgrass prairie), the highest quality habitats did not always contribute the most young to the regional population., INTRODUCTION VanHorne (1983) noted that population density may be a misleading indicator of habitat quality. High population density frequently has been assumed to be correlated with high habitat quality. However, [...]