| experimental transmission of sarcocystis from icterid birds to sparrows and canaries by sporocysts from the opossum. | cowbirds (molothrus ater) and grackles (cassidix mexicanus) infected with muscle cysts of sarcocystis were fed to opposums (didelphis virginiana) and fecal sporocysts from the latter were given to sparrows (passer domesticus, family ploceidae), canaries (serinus canarius, family fringillidae) and ducks (anas platyrhynchos, family anatidae). asexual parasites were found in the endothelium of sparrows and canaries but not in ducks. when birds were kept 10 weeks or more after infection, muscle cyst ... | 1978 | 98622 |
| comparison of direct and modified direct complement-fixation and agar-gel precipitin methods in detecting chlamydial antibody in wild birds. | detection of chlamydial antibody in serums of wild birds was compared for the following methods: direct complement-fixation (dcf), modified dcf (mdcf), and agar-gel precipitin (agp). the birds species used were great-tailed grackles (cassidix mexicanus), common grackles (quiscalus quiscula), brown-headed cowbirds (molothrus ater), bronzed cowbirds (tangavius aeneus), and mourning doves (zenaida macroura). the birds were either inoculated with an isolate of chlamydia psittaci obtained originally ... | 1978 | 100098 |
| the opossum (didelphis virginiana) as a host for sarcocystis debonei from cowbirds (molothrus ater) and grackles (cassidix mexicanus, quiscalus quiscula). | sarcocystis-infected muscles from ducks, cowbirds, and grackles were fed to cats, opossums, rats, and a dog. only the opossum (didelphis virginiana) was a suitable definitive host. all opossums that were fed sarcocystis-infected cowbirds (molothrus ater) and grackles (cassidix mexicanus and quiscalus quiscula) passed sporocysts in their feces. opossums that ate the cowbirds had prepatent periods of 5 and 10 days and remained patent for at least 105 days. opossums that ate the grackles became pat ... | 1978 | 417165 |
| experimental transmission of chlamydia psittaci to turkeys from wild birds. | wild birds were inoculated with chlamydia psittaci to determine species that could be potential hosts and vectors in transmitting the agent to domestic turkeys. infection occurred in turkeys exposed to starlings (sturnus vulgaris), common grackles (quiscalus quiscula), brown-headed cowbirds (molothrus ater), and inca doves (cardafella inca). mourning doves (zenaidura macroura) shed the agent sparingly, but turkeys exposed to them did not become infected, these findings and knowledge of the habit ... | 1979 | 546413 |
| chlamydia shedding by four species of wild birds. | four wild bird species--great-tailed grackle (cassidix mexicanus), common grackle (quiscalus quiscula), brown-headed cowbird (molothrus ater), and mourning dove (zenaidura macroura)--were either inoculated intratracheally with chlamydia psittaci or exposed indirectly as uninoculated cagemates. shedding of chlamydiae was monitored by inoculating mice with suspensions of material eluted from cloacal swabs collected from all birds, usually at 3-day intervals. sporadic shedding of chlamydiae was dem ... | 1978 | 749892 |
| community ecology of helminth parasitism in an insular passerine avifauna. | three hundred and thirty specimens of 7 species of passerine birds from south bass island, ottawa county, ohio, were examined for helminth parasites. the total number of helminth specimens collected was 4,333. forty-one helminth taxa were identified. ten species of helminths were identified as having foci of infection on the island. an index of association for these 10 species is presented. the low association revealed between helminth species utilizing common species of intermediate hosts indic ... | 1976 | 1255354 |
| characterization and assessment of an avian repetitive dna sequence as an icterid phylogenetic marker. | the first tandemly repeated sequence examined in a passerine bird, a 431-bp psti fragment named pmat1, has been cloned from the genome of the brown-headed cowbird (molothrus ater). the sequence represents about 5-10% of the genome (about 4 x 10(5) copies) and yields prominent ethidium bromide stained bands when genomic dna cut with a variety of restriction enzymes is electrophoresed in agarose gels. a particularly striking ladder of fragments is apparent when the dna is cut with hinfi, indicativ ... | 1992 | 1572527 |
| relationships between elevation, reproduction and the hematocrit level of brown-headed cowbirds. | hematocrit, furcular fat level and oviducal egg presence were determined for 267 brown-headed cowbirds (molothrus ater) at eight sites ranging from 15 to 2390 m above sea level in california. near the end of the breeding season males at a mid-elevation site (1250 m) possessed higher hematocrits than females, but there was no difference between yearling and adult males. birds were bled during three 11-day periods beginning 1 may 1984 at one montane site (2075 m). the percentage of females with ov ... | 1986 | 2870867 |
| vocalizations of juvenile cowbirds (molothrus ater ater) evoke copulatory responses from females. | the functional attributes of the vocalizations produced by young male cowbirds during their first fall and winter, termed "vocal precursors," were tested by playing the sounds back to female cowbirds. five classes of vocalizations were tested: subsong, plastic, formatted, and stereotyped song, and songs of nonconspecifics. females responded selectively to the four classes of cowbird vocalizations. stereotyped songs evoked the most responding but the key eliciting element was the inclusion of not ... | 1988 | 3169379 |
| female visual displays affect the development of male song in the cowbird. | the role of social stimulation in avian vocal learning is well documented. the separate contribution of social, as opposed to vocal, stimulation has been difficult to address, however, because in almost all cases both tutor and pupil sing. the opportunity to isolate such effects arose in cowbirds (molothrus ater ater) after discovering that males housed with non-singing female cowbirds made vocal changes which related directly to the female preferences for native song. here we report how females ... | 1988 | 3398921 |
| effects of noise on pure-tone thresholds in blackbirds (agelaius phoeniceus and molothrus ater) and pigeons (columba livia). | blackbirds and pigeons were trained to detect tones in quiet and in broadband noise by using positive-reinforcement techniques. in experiment 1, thresholds in noise were obtained in blackbirds as a function of both tone frequency and noise intensity for a pulsed noise masker (noise gated on and off with tone). for blackbirds, critical ratios (the ratio of the power of the just-detectable tone in noise to the power of the noise masker) obtained in pulsed noise showed no consistent relation to ton ... | 1987 | 3568604 |
| different outcomes of synergy between song production and song perception in the same subspecies (molothrus ater ater). | here we report data requiring a reinterpretation of published results on the female cowbird's (molothrus ater ater) ability to identify male song (king, a. p., and west, m. j. (1983). female perception of cowbird song: a closed developmental program. dev. psychobiol., 16:335-342). previously we stated that naive females, given extensive social experience with males from a distant cowbird subspecies, showed the same degree of preference for native song as did naive females reared with local males ... | 1987 | 3582779 |
| modes of perceiving and processing information in birdsong (agelaius phoeniceus, molothrus ater, and homo sapiens). | in a previous study i examined the abilities of red-winged blackbirds and brown-headed cowbirds trained with a go-right/go-left procedure to identify conspecific and alien song themes (sinnott, 1980). results showed that each bird species exhibited superior identification of conspecific final "trill" or "whistle" elements, relative to the alien species. the present study extends these results by examining human perception of these same song stimuli, by examining the effects of tutoring birds wit ... | 1987 | 3691059 |
| song repertoire development in male cowbirds (molothrus ater): its relation to female assessment of song potency. | two studies were conducted to investigate the relation between the male cowbird's (molothrus ater ater) development of a song repertoire and the female cowbird's assessment of song potency. male development was assayed by vocal copying and female assessment by copulatory responsiveness to song playback. the results demonstrate that males do not copy most often the particular songs that females respond to most often. whereas rank orderings of potency were highly correlated across two independent ... | 1986 | 3769448 |
| enterobacteriaceae isolated from cowbirds (molothrus ater) and other species of wild birds in michigan. | | 1972 | 4552674 |
| arthropod parasites of the brown-headed cowbird, molothrus ater ater, in ohio. | | 1974 | 4850642 |
| ectoparasites from the cowbird, molothrus ater (boddaert), at london, ontario. | | 1968 | 5749477 |
| residues of ddt in brains and bodies of birds that died on dosage and in survivors. | residues of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane (ddt) and 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethane (ddd) in brains of cowbirds (molothrus ater) killed by dietary dosage of ddt were similar in birds that died after various lengths of time on dosage and in birds that died of delayed effects after as much as 40 days on clean food. residues of ddt and ddd, but not of 1,1-dichloro-2,2-bis-(p-chlorophenyl)-ethylene (dde), were much lower in survivors 112 days after dosage. the relative i ... | 1966 | 5909590 |
| oxychlordane, hcs-3260, and nonachlor in birds: lethal residues and loss rates. | oxychlordane reached lethal levels in birds given dietary dosages of hcs-3260 (70.75% cis-chlordane and 23.51% trans-chlordane) at 6 levels from 50 to 500 ppm. oxychlordane ranged from 9.4 to 22.1 ppm in brains of cowbirds (molothrus ater), grackles (quiscalus quiscula), and red-winged blackbirds (agelaius phoeniceus) that died on dosage and from 1.3 to 4.8 ppm in sacrificed birds, providing a clear diagnostic separation. among starlings (sturnus vulgaris), however, oxychlordane ranged from 5.0 ... | 1983 | 6668611 |
| ultrastructure of sarcocystis sporocysts from passerine birds and opossums: comments on classification of the genus isospora. | sporocysts were obtained from the feces of opossums (didelphis virginiana) which had been fed muscles of passerine birds (molothrus ater and cassidix mexicanus) infected with sarcocystis. sporocysts were examined by phas microscopy and scanning and transmission electron microscopy. ridges on the surface of the sporocysts outlined four plates. thin sections of the sporocyst wall showed thickened regions and gaps interpreted as cross sections of the ridges. the sporocyst wall has four major layers ... | 1980 | 6767835 |
| sarcocystis of passerine birds: sexual stages in the opossum (didelphis virginiana). | sexual stages of a sarcocystis of passerine birds were demonstrated by feeding muscle cysts from cowbirds (molothrus ater) and grackles (cassidix mexicanus) to opossums (didelphis virginiana). opossums were examined at necropsy at 36 h, 13.5 days, and 29.5 days post-inoculation (pi). large numbers of macro- and microgamonts were present in the small intestine 36 h pi, while only sporocysts and oocysts were present 13 days or more pi. microgamonts in different stages of development were in the in ... | 1980 | 6776294 |
| effects of dde and pcb (aroclor 1260) on experimentally poisoned female little brown bats (myotis lucifugus): lethal brain concentrations. | adult female little brown bats (myotis lucifugus) were collected in a church attic in north east, cecil county, md. mealworms (tenebrio molitor) containing organochlorine pollutants were fed to the bats as follows: 5 bats were dosed at 480 ppm dde, 12 at 150 ppm dde, 5 at 1000 ppm polychlorinated biphenyl (pcb; aroclor 1260), and 12 at 15 ppm pcb. seven other bats were fed untreated mealworms. the objective was to elevate brain levels of dde and pcb to lethality and measure these concentrations. ... | 1981 | 6790723 |
| female perception of cowbird song: a closed developmental program. | to investigate the modifiability of the brown-headed female cowbird's (molothrus ater ater) response to male song, we reared m.a. ater females with either m.a. ater or m.a. obscurus males, whose songs differ in geographic origin. the females were later tested for their responsiveness to playbacks of m.a. ater and m.a. obscurus song. rearing with m.a. obscurus males had no effect on the female's preference for her native song variant, suggesting a closed program for receptive development. the dat ... | 1983 | 6884582 |
| aspects of frequency discrimination in passerine birds and pigeons. | with the use of a positive reinforcement operant technique, pulsed-tone, frequency difference limens (dls) were measured in two icterid passerine species, the redwing blackbird (agelaius phoeniceus) and the brown-headed cowbird (molothrus ater). direct comparisons were made with two nonpasserine control (pigeon) subjects. blackbirds were more sensitive than pigeons to frequency changes above 1.0 khz but less sensitive below 1.0 khz. measured dls in all these birds were within the range of nonhum ... | 1980 | 7391279 |
| fat of the wild avian filarial nematode chandlerella quiscali (onchocercidae: filarioidea) in the domestic chicken. | chandlerella quiscali is a filarial nematode parasitizing the brain of the common grackle (quiscalus quiscula versicolor), blue jay (cyanocitta cristata bromia), brown-headed cowbird (molothrus ater ater), and starling (sturnus vulgaris). filarial infections of many wild bird species are common but natural infections of domestic fowl are rare. the habits of many wild birds commonly bring them in close association with domestic poultry. because of the high prevalence of c. quiscali in grackles (9 ... | 1980 | 7393850 |
| lateralization and motor stereotypy of song production in the brown-headed cowbird. | song production in adult brown-headed cowbirds (molothrus ater ater) is lateralized, with a slight right syringeal dominance. the left side of the syrinx produces low-frequency (200-2000 hz) notes within the introductory note clusters, while the right side produces the higher-frequency (1500-6000 hz) introductory notes, the interphrase unit (10-12 khz), and the final high-frequency whistle (5-13 khz). cross-correlation analyses reveal that individual cowbirds produce each of their four to seven ... | 1994 | 7815070 |
| effect of motivational context on conspecific song discrimination by brown-headed cowbirds (molothrus ater). | two experiments to examine the effects of motivational context on the perception of conspecific song by cowbirds were conducted. in the first experiment, sexual displays were elicited from females by playback of normal song and rearranged sequences of the component phrases. in a second experiment, male and female cowbirds discriminated among the same songs in a food-rewarded operant procedure. in a sexual context, the birds were sensitive to both the beginning and end phrases of normal song, whe ... | 1994 | 8026169 |
| females have a larger hippocampus than males in the brood-parasitic brown-headed cowbird. | females of the brood-parasitic brown-headed cowbird (molothrus ater) search for host nests in which to lay their eggs. females normally return to lay a single egg from one to several days after first locating a potential host nest and lay up to 40 eggs in a breeding season. male brown-headed cowbirds do not assist females in locating nests. we predicted that the spatial abilities required to locate and return accurately to host nests may have produced a sex difference in the size of the hippocam ... | 1993 | 8356091 |
| sarcocystis falcatula from passerine and psittacine birds: synonymy with sarcocystis neurona, agent of equine protozoal myeloencephalitis. | equine protozoal myeloencephalitis (epm) is a neurologic disease of horses caused by sarcocystis neurona. the horse is a dead-end host for s. neurona and the definitive and intermediate hosts have not previously been identified. we hypothesized that s. neurona is actually sarcocystis falcatula, a parasite that cycles in nature between virginia opossums (didelphis virginiana) and any of a variety of avian intermediate hosts. we extracted dna from s. falcatula sarcocysts in the muscle of a brown-h ... | 1995 | 8544067 |
| social malleability in cowbirds: new measures reveal new evidence of plasticity in the eastern subspecies (molothrus ater ater). | the social experiences of young molothrus ater ater cowbirds were manipulated in a 2-year study. in the 1st year, males were housed with pairs of canaries. the males were tested in 3 social contexts. also, vocal repertoires were recorded and played back to females. in contrast to a previous study of the m. a. artemisiae subspecies, the males did not vocalize to the canaries in courtship tests (t. m. freeberg, a. p. king, & m. j. west, 1995) but showed incompetent courtship of female cowbirds. in ... | 1996 | 8851549 |
| estrogen synthesis and secretion in the brown-headed cowbird (molothrus ater). | estrogens exert profound effects on vertebrate physiology and behavior. in most vertebrates, including birds, estrogens derived from ovarian tissue circulate at high levels during discrete periods of reproductive activity, and estrogen levels in males are low. in some songbirds (passeriformes) plasma estrogens are high in both males and females. in the zebra finch, aromatase (estrogen-synthetase) is expressed abundantly in several regions of the male and female telencephalon and contributes to p ... | 1997 | 9073501 |
| a brain of her own: a neural correlate of song assessment in a female songbird. | the song control region in the avian forebrain is a series of discrete, interconnected nuclei mediating song learning and production. it has been studied in males or in species where both sexes sing. little is known about the neural correlates of song perception in nonsinging females, often the intended recipients of song. we studied cowbirds (molothrus ater), a species in which only males sing but in which females discriminate between males on the basis of song. we focused on nucleus lman becau ... | 1997 | 9398592 |
| profile: impending recovery of kirtland's warbler: case study in the effectiveness of the endangered species act | / the endangered species act (esa) has received a large amount of criticism in recent years by conservative landowners and others who believe that it has infringed on property rights. it also has been criticized by those who think it has been costly and ineffective in reaching its goal of preventing extinction and recovering species. recent evidence, however, shows that the esa has stabilized or increased the populations of over a third of the listed species. in addition, its chief administrator ... | 1998 | 9419281 |
| what cues do brown-headed cowbirds use to locate red-winged blackbird host nests? | i examined ecological and behavioural variables influencing the susceptibility of red-winged blackbird, agelaius phoeniceus, nests to brood parasitism by brown-headed cowbirds, molothrus ater, in a prairie-nesting population of redwings in southern wisconsin. i compared the following variables between parasitized and unparasitized nests: proximity of nests to trees and other prominent perches; physical characteristics of nests such as nest height and cover; and aspects of host behaviour, includi ... | 1998 | 9632503 |
| visual and song nuclei correlate with courtship skills in brown-headed cowbirds. | we assessed courtship success in 14 adult male brown-headed cowbirds, molothrus ater. volumes of song control nuclei and visual nuclei were measured in nissl stained tissue. variation in courtship success was found to be related to variation in two areas of the avian brain: the song control nucleus, area x, and the thalamic visual area, nucleus rotundus. volume of area x was negatively correlated with song potency, as assessed by female playback, and with rate of vocalizing. volume of nucleus ro ... | 1998 | 9790708 |
| the cultural transmission of courtship patterns in cowbirds, molothrus ater. | in this study, i tested whether the courtship behaviours that facilitate patterns of assortative pairing and mating could be culturally transmitted across generations of brown-headed cowbirds. in an earlier study, i housed a first generation of young south dakota cowbirds in one of two cultural backgrounds: (1) with adult social models from the same population; or, (2) with adult social models from a behaviourally distinct indiana population. during the breeding season, the first cultural genera ... | 1998 | 9819320 |
| parentage and kinship studies in an obligate brood parasitic bird, the brown-headed cowbird (molothrus ater), using microsatellite dna markers. | recent studies suggest that single-locus microsatellite dna markers have the potential to unambiguously resolve parentage among individuals in natural populations where maternity is known. however, their power for determining parentage when neither parent is known is unclear. here we investigate the usefulness of microsatellite dna markers to determine parentage in a brood parasitic bird, the brown-headed cowbird (molothrus ater), where, for a given offspring, no a priori knowledge of either par ... | 1999 | 9987928 |
| cultural influences on female mate choice: an experimental test in cowbirds, molothrus ater. | previous studies of brown-headed cowbirds molothrus ater, have shown that social learning and cultural transmission can influence courtship and mating patterns. these earlier studies did not test whether cultural background influenced mate choice in females and therefore whether culture could potentially play a role in sexual selection in this species, as has been suggested by recent theory. here, we tested whether culture influences female mate choice in brown-headed cowbirds. female cowbirds f ... | 1999 | 10049482 |
| are sarcocystis neurona and sarcocystis falcatula synonymous? a horse infection challenge. | equine protozoal myeloencephalitis (epm) is a debilitating neurologic disease of the horse. the causative agent. sarcocystis neurona, has been suggested to be synonymous with sarcocystis falcatula, implying a role for birds as intermediate hosts. to test this hypothesis, opossums (didelphis virginiana) were fed muscles containing s. falcatula sarcocysts from naturally infected brown-headed cowbirds (molothrus ater). ten horses were tested extensively to ensure no previous exposure to s. neurona ... | 1999 | 10219313 |
| cuckoos, cowbirds and the persistence of brood parasitism. | brood parasites provide a particularly good opportunity for the study of host-parasite evolution because they directly affect the reproductive success of their hosts. two parasitic species, the common cuckoo (cuculus canorus) and the brown-headed cowbird (molothrus ater), differ widely in their relationships with their hosts, yet share the attribute of having been particularly well studied by biologists. recent work on the cuckoo and the cowbird has resulted in new answers to the question begged ... | 1999 | 10441306 |
| determining the reproductive behaviour of individual brown-headed cowbirds using microsatellite dna markers. | the reproductive behaviour of brood-parasitic birds has been of long-standing interest to evolutionary biologists but key features such as the mating system, patterns of host use and degree of overlap of female egg-laying ranges are largely unknown for particular species. here we use microsatellite dna markers to obtain such information for one of the best-studied brood parasites, the brown-headed cowbird, molothrus ater. parentage analyses of young and adults from a marked population at delta, ... | 1999 | 10512663 |
| low abundance of microsatellite repeats in the genome of the brown-headed cowbird (molothrus ater). | a cosmid library made from brown-headed cowbird (molothrus ater) dna was examined for representation of 17 distinct microsatellite motifs including all possible mono-, di-, and trinucleotide microsatellites, and the tetranucleotide repeat (gata)n. the overall density of microsatellites within cowbird dna was found to be one repeat per 89 kb and the frequency of the most abundant motif, (agc)n, was once every 382 kb. the abundance of microsatellites within the cowbird genome is estimated to be re ... | 1999 | 10544500 |
| nest desertion and cowbird parasitism: evidence for evolved responses and evolutionary lag. | nest desertion with subsequent renesting is a frequently cited response to parasitism by the brown-headed cowbird, molothrus ater, yet the role of desertion as an antiparasite defence is widely debated. to determine whether desertion represents an evolutionary response to brown-headed cowbird parasitism, we searched the primary literature, yielding data on the desertion frequencies of 60 host populations from 35 species. species were categorized according to three habitat types (forest, intermed ... | 2000 | 10792938 |
| mycoplasmal conjunctivitis in songbirds from new york. | a field study was conducted to determine the prevalence of conjunctivitis and mycoplasma gallisepticum (mg) infections in house finches (carpodacus mexicanus) and other songbirds common to bird feeders in tompkins county (new york, usa). eight hundred two individuals of 23 species and nine families of birds were captured and given physical examinations during the 14 mo study beginning in february 1998. clinical conjunctivitis (eyelid or conjunctival swelling, erythema, and discharge) was observe ... | 2000 | 10813607 |
| a role of her own: female cowbirds, molothrus ater, influence the development and outcome of song learning. | previous work has shown that captive female cowbirds, molothrus ater, can influence the outcome of male song development by affecting retention or deletion of song elements and by stimulating improvization. here we looked for evidence of female influence during the process of learning, as males progress from subsong to plastic song to stereotyped song. in a longitudinal study, we measured the rate and timing of vocal development in captive, juvenile male brown-headed cowbirds, m. a. artemisiae. ... | 2000 | 11082230 |
| what's bugging brood parasites? | brown-headed cowbirds (molothrus ater) might reduce populations of the songbird species they parasitize, including endangered species. data are therefore needed on the frequency with which cowbirds use different species of foster parents. hahn et al. propose a clever new approach by which the identity of foster parents can be inferred from host-specific lice the cowbirds acquire as nestlings. we discuss the feasibility of this method and underlying assumptions. | 2001 | 11146133 |
| lead shot toxicity to passerines. | this study evaluated the toxicity of a single size 7.5 lead shot to passerines. no mortalities or signs of plumbism were observed in dosed cowbirds (molothrus ater) fed a commercial diet, but when given a more natural diet, three of 10 dosed birds died within 1 day. for all survivors from which shot were recovered, all but one excreted the shot within 24 h of dosing, whereas, the dead birds retained their shot. shot erosion was significantly greater (p < 0.05) when weathered shot were ingested c ... | 2001 | 11202707 |
| evaluation of the shedding of sarcocystis falcatula sporocysts in experimentally infected virginia opossums (didelphis virginiana). | five virginia opossums (didelphis virginiana) were fed muscles of brown-headed cowbirds (molothrus ater) containing sarcocysts of sarcocystis falcatula. shedding of sporocysts was confirmed in all five opossums by fecal flotation. counts were conducted daily for 2 weeks and then biweekly until the animals were euthanized and necropsied. the average prepatent period was 9.8 (7-16) days. the number of sporocysts shed varied greatly between the opossums with maximum mean shedding occurring at 71.6 ... | 2001 | 11223211 |
| development of sarcocystis falcatula in its intermediate host, the brown-headed cowbird (molothrus ater). | sporocysts of sarcocystis falcatula obtained from experimentally infected virginia opossums (didelphis virginiana) were inoculated orally to 60 wild-caught brown-headed cowbirds (molothrus ater). another 30 brown-headed cowbirds were not challenged and served as uninfected controls. two inoculated and one control cowbird were necropsied every 2 weeks and the pectoral and thigh muscles were examined grossly for cyst development. stained histologic sections of pectoral muscle, thigh muscle, and lu ... | 2001 | 11223213 |
| a password for species recognition in a brood-parasitic bird. | recognition of conspecifics is an essential precursor of sexual reproduction. most mammals and birds learn salient features of their parents or siblings early in ontogeny and later recognize individuals whose phenotypes match the mental image (template) of relatives closely enough as conspecifics. however, the young of brood parasites are reared among heterospecifics, so social learning will yield inappropriate species recognition templates. initially, it was inferred that conspecific recognitio ... | 2001 | 11375088 |
| cultural transmission of vocal traditions in cowbirds (molothrus ater) influences courtship patterns and mate preferences. | in this study, the authors tested the cultural transmission of vocal traditions in cowbirds (molothrus ater). young cowbirds from a south dakota (sd) population were housed over winter with adults of the sd population or with adults from an indiana (in) population. song differences between the original sd and in adult models were acquired by south dakota culture (sdc) and indiana culture (inc) males, respectively, and were transmitted to a 2nd cultural generation of birds. during playback tests ... | 2001 | 11459168 |
| nest predation by cowbirds and its consequences for passerine demography. | brood parasitism by brown-headed cowbirds (molothrus ater) reduces reproductive success in many passerines that nest in fragmented habitats and ecological edges, where nest predation is also common. we tested the hypothesis that parasitism and predation are often linked because cowbirds depredate nests discovered late in the host's nesting cycle to enhance future opportunities for parasitism. over a 20-year study period, brood parasitism by cowbirds was a prerequisite to observing marked inter- ... | 1996 | 11607677 |
| improved method for quantifying the avicide 3-chloro-p-toluidine hydrochloride in bird tissues using a deuterated surrogate/gc/ms method. | a method using a deuterated surrogate of the avicide 3-chloro-p-toluidine hydrochloride (cpth) was developed to quantify the cpth residues in the gastrointestinal (gi) tract and breast muscle tissues in birds collected in cpth-baited sunflower and rice fields. this method increased the range of a previous surrogate/gas chromatography/mass spectroscopy method from 0-2 to 0-20 microg/g in tissue samples and greatly simplified the extraction procedure. the modified method also sought to increase re ... | 2002 | 11829637 |
| parental care of a cowbird host: caught between the costs of egg-removal and nest predation. | avian brood parasites reduce host fitness through the addition of parasitic eggs and the removal of host eggs. both parasitic egg-addition and host egg-removal may be important sources of selection on host behaviour, creating fitness trade-offs with selection imposed by nest predation. however, the relative costs hosts suffer from egg-addition and host egg-removal and the responses to these costs are largely unstudied. through experimental manipulations and observations, we demonstrate that incr ... | 2002 | 11886632 |
| voice recognition technology as a tool for behavioral research. | behavioral research often requires the acquisition and processing of large volumes of data. most current techniques for recording behavior constrain the amount and type of data that can be measured. we developed and tested a system that uses voice recognition technology to collect data on the social interactions and singing patterns of cowbirds (molothrus ater) living outdoors in a semi-natural environment. we spoke observation data into a wireless microphone that transmitted the data to a compu ... | 2002 | 12060983 |
| the presumption of sociality: social learning in diverse contexts in brown-headed cowbirds (molothrus ater). | data are presented on social and vocal learning in cowbirds (molothrus ater) housed in large aviaries and given more degrees of freedom than in conventional experimental studies. the studies show that social and vocal outcomes are facultative responses to social contexts. several findings are reviewed: first, cowbirds quickly self-organize into groups by age and sex; second, opportunities to interact across age and sex do exist and affect courtship competence; third, female cowbirds organize the ... | 2002 | 12083613 |
| discrimination between host songs by brood parasitic brown-headed cowbirds ( molothrus ater). | songbirds can learn both to produce and to discriminate between different classes of acoustic stimuli. varying levels of auditory discrimination may improve the fitness of individuals in certain ecological and social contexts and, thus, selection is expected to mold the cognitive abilities of different species according to the potential benefits of acoustic processing. although fine-scale auditory discrimination of conspecific songs and calls has been frequently reported for brood parasitic brow ... | 2002 | 12357285 |
| different colors reveal different information: how nutritional stress affects the expression of melanin- and structurally based ornamental plumage. | avian plumage colors have emerged recently as model systems for investigating the types of information that can be signaled by showy sexual displays in animals. in many species, the brightness of carotenoid-based plumage reflects the health and condition of individuals and is used in mate selection. the information contained in melanin-based and structurally based ornamental colors in birds is less well resolved, however. we subjected male house sparrows passer domesticus and brown-headed cowbir ... | 2002 | 12409501 |
| cultures, genes, and neurons in the development of song and singing in brown-headed cowbirds (molothrus ater). | in brown-headed cowbirds, molothrus ater, as in many songbird species, vocalizations are fundamental to reproduction. in our studies, experiments utilizing different social housing regimes and geographic comparisons have indicated the social learning of males' vocalizations and associated abilities to use vocalizations effectively during the breeding season. here, we describe studies indicating roles of cultural and genetic background, and of social influences from females, on male vocal develop ... | 2002 | 12471496 |
| lower begging responsiveness of host versus parasitic brown-headed cowbird (molothrus ater) nestlings is related to species identity but not to early social experience. | the survival of young brood parasites depends critically on their many adaptations to exploit hosts. parasitic survival is particularly related to competitive superiorty for foster parental care whenever host young are not destroyed in parasitized nests.brown-headed cowbirds (molothrus ater) are generalist obligate parasites whose early social environments are unpredictable regarding host species and numbers of nestmates. young avian brood parasites typically beg more intensively and loudly than ... | 2003 | 12735360 |
| multimodal signals: enhancement and constraint of song motor patterns by visual display. | many birds perform visual signals during their learned songs, but little is known about the interrelationship between visual and vocal displays. we show here that male brown-headed cowbirds (molothrus ater) synchronize the most elaborate wing movements of their display with atypically long silent periods in their song, potentially avoiding adverse biomechanical effects on sound production. furthermore, expiratory effort for song is significantly reduced when cowbirds perform their wing display. ... | 2004 | 14739462 |
| social transmission of courtship behavior and mating preferences in brown-headed cowbirds, molothrus ater. | studies of the social learning of courtship behaviors and mating preferences of brown-headed cowbirds (molothrus ater) are reviewed. earlier work has suggested that cowbirds from behaviorally distinct populations mate preferentially with others from the same population. studies are described which indicate that patterns of courtship behavior that differ by population can be socially transmitted across generations are described. social background affects male songs, female preferences for males a ... | 2004 | 15161147 |
| mosquito and arbovirus activity during 1997-2002 in a wetland in northeastern mississippi. | the species composition and population dynamics of adult mosquitoes in a wetland near iuka, ms, were analyzed over a 6-yr period (1997-2002) and reverse transcription-polymerase chain reaction (pcr) detection rates of arboviruses determined during five of those years. blood meals of three likely vector species were identified using a pcr-based method that allows identification of the host to species. culex erraticus (dyar & knab) composed 51.9% of the population during the 6-yr period with 295 f ... | 2004 | 15185956 |
| brood parasitic cowbird nestlings use host young to procure resources. | young brood parasites that tolerate the company of host offspring challenge the existing evolutionary view of family life. in theory, all parasitic nestlings should be ruthlessly self-interested and should kill host offspring soon after hatching. yet many species allow host young to live, even though they are rivals for host resources. here we show that the tolerance of host nestlings by the parasitic brown-headed cowbird molothrus ater is adaptive. host young procure the cowbird a higher provis ... | 2004 | 15297677 |
| density-dependent habitat selection by brown-headed cowbirds ( molothrus ater) in tallgrass prairie. | local distributions of avian brood parasites among their host habitats may depend upon conspecific parasite density. we used isodar analysis to test for density-dependent habitat selection in brown-headed cowbirds ( molothrus ater) among tallgrass prairie adjacent to wooded edges, and prairie interior habitat (>100 m from wooded edges) with and without experimental perches. eight study sites containing these three habitat treatments were established along a geographical gradient in cowbird abund ... | 2005 | 15375686 |
| patterns and coevolutionary consequences of repeated brood parasitism. | the absence of adaptive host responses to virulent parasites and pathogens is paradoxical. we explored the theoretical possibility that the evolution of antiparasitic egg-ejection strategies was delayed by avian hosts' lifetime experiences with brood parasitism. an analytical model indicated that individual hosts' repeated exposure to parasitism decreased the relative benefits of learning-based rejecter strategies when parasitism was particularly costly. because brood parasitic brown-headed cowb ... | 2004 | 15504005 |
| brood parasitism by brown-headed cowbirds and the expression of sexual characters in their hosts. | interspecific brood parasites may use the secondary sexual characters of the hosts to decide which species to parasitize. hence, species with conspicuous and well-recognisable traits may have higher chances of becoming parasitised. using north american birds and their frequent brood parasite, the brown-headed cowbird molothrus ater, we tested the relationship between features of song and plumage coloration of hosts and the frequency of brood parasitism while controlling for several potentially c ... | 2005 | 15647904 |
| patterns of avian nest predators and a brood parasite among restored riparian habitats in agricultural watersheds. | in fragmented edge-dominated landscapes, nest predation and brood parasitism may reduce avian reproductive success and, ultimately, populations of some passerine species. in the fragmented agroecosystem of northwest mississippi, placement of drop-pipe structures has been used as a restoration technique for abating gully erosion along stream banks. these actions have formed small herbaceous and woody habitat extensions into former agricultural lands. we quantified species relative abundances, spe ... | 2005 | 16160783 |
| brood parasitism increases provisioning rate, and reduces offspring recruitment and adult return rates, in a cowbird host. | interspecific brood parasitism in birds presents a special problem for the host because the parasitic offspring exploit their foster parents, causing them to invest more energy in their current reproductive effort. nestling brown-headed cowbirds (molothrus ater) are a burden to relatively small hosts and may reduce fledgling quality and adult survival. we documented food-provisioning rates of one small host, the prothonotary warbler (protonotaria citrea), at broods that were similar in age (cont ... | 2006 | 16639566 |
| songbird abundance and parasitism differ between urban and rural shrublands. | many studies have examined differences in avian community composition between urban and rural habitats, but few, if any, have looked at nesting success of urban shrubland birds in a replicated fashion while controlling for habitat. we tested factors affecting nest survival, parasitism by the brown-headed cowbird (molothrus ater), and species abundance in shrubland habitat in rural and urban landscapes. we found no support for our hypothesis that nest survival was lower in urban landscapes, but s ... | 2006 | 16705988 |
| habitat edge, land management, and rates of brood parasitism in tallgrass prairie. | bird populations in north america's grasslands have declined sharply in recent decades. these declines are traceable, in large part, to habitat loss, but management of tallgrass prairie also has an impact. an indirect source of decline potentially associated with management is brood parasitism by the brown-headed cowbird (molothrus ater), which has had substantial negative impacts on many passerine hosts. using a novel application of regression trees, we analyzed an extensive five-year set of ne ... | 2006 | 16711055 |
| genetic variation among isolates of sarcocystis neurona, the agent of protozoal myeloencephalitis, as revealed by amplified fragment length polymorphism markers. | sarcocystis neurona causes serious neurological disease in horses and other vertebrates in the americas. based on epidemiological data, this parasite has recently emerged. here, the genetic diversity of sarcocystis neurona was evaluated using the amplified fragment length polymorphism (aflp) method. fifteen s. neurona taxa from different regions collected over the last 10 years were used; six isolates were from clinically diseased horses, eight isolates were from wild-caught opossums (didelphis ... | 2006 | 16714575 |
| proximate and landscape factors influence grassland bird distributions. | ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. we examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of high conservation concern, in the sheyenne national grassland in north dakota, usa. the grassland contains a div ... | 2006 | 16827003 |
| developmental origins of sociality in brown-headed cowbirds (molothrus ater). | five variables were studied relating to the emergence of sociality in hand-reared cowbirds (molothrus ater): proximity, sex assortment, reactions to adults, head-down displays, and vocalizations. the authors were especially interested in female sociality because adult female birds influence male courtship, song content, and use through proximity, attention, and displays. the authors found that young female birds failed to show same-sex affiliation typical of the species at any point in the study ... | 2006 | 16893260 |
| to eject or to abandon? life history traits of hosts and parasites interact to influence the fitness payoffs of alternative anti-parasite strategies. | hosts either tolerate avian brood parasitism or reject it by ejecting parasitic eggs, as seen in most rejecter hosts of common cuckoos, cuculus canorus, or by abandoning parasitized clutches, as seen in most rejecter hosts of brown-headed cowbirds, molothrus ater. what explains consistent variation between alternative rejection behaviours of hosts within the same species and across species when exposed to different types of parasites? life history theory predicts that when parasites decrease the ... | 2006 | 16910987 |
| growth strategies of passerine birds are related to brood parasitism by the brown-headed cowbird (molothrus ater). | sibling competition was proposed as an important selective agent in the evolution of growth and development. brood parasitism by the brown-headed cowbird (molothrus ater) intensifies sibling competition in the nests of its hosts by increasing host chick mortality and exposing them to a genetically unrelated nestmate. intranest sibling competition for resources supplied by parents is size dependent. thus, it should select for high development rates and short nestling periods, which would alleviat ... | 2006 | 17017069 |
| dermal insecticide residues from birds inhabiting an orchard. | the us environmental protection agency conducts risk assessments of insecticide applications to wild birds using a model that is limited to the dietary route of exposure. however, free-flying birds are also exposed to insecticides via the inhalation and dermal routes. we measured azinphos-methyl residues on the skin plus feathers and the feet of brown-headed cowbirds (molothrus ater) in order to quantify dermal exposure to songbirds that entered and inhabited an apple (malus x domestica) orchard ... | 2007 | 17171236 |
| retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs. | why do many hosts accept costly avian brood parasitism even when parasitic eggs and nestlings differ dramatically in appearance from their own? scientists argue that evolutionary lag or equilibrium can explain this evolutionary enigma. few, however, consider the potential of parasitic birds to enforce acceptance by destroying eggs or nestlings of hosts that eject parasitic eggs and thereby reject parasitism. this retaliatory "mafia" behavior has been reported in one species of parasitic cuckoo b ... | 2007 | 17360549 |
| fragmention by agriculture influences reproductive success of birds in a shrubsteppe landscape. | shrubsteppe communities are among the most imperiled ecosystems in north america as a result of conversion to agriculture and other anthropogenic changes. in the intermountain west of the united states, these communities support a unique avifauna, including several species that are declining and numerous others that are of conservation concern. extensive research in the eastern and central united states and in scandinavia suggests that fragmentation of formerly continuous forests and grasslands ... | 2007 | 17494408 |
| constructing culture in cowbirds (molothrus ater). | in past work, the authors produced divergent patterns of courtship and communication in juvenile male cowbirds (molothrus ater) by providing them with different social experiences during their 1st year. here the authors determined whether these different social patterns could be transmitted to new generations of juvenile males. in experiment 1, the authors exposed groups of juveniles to adult males who differed in the amount of male-male competition they produced. in experiment 2, they gave grou ... | 2007 | 17516790 |
| molothrus ater and his hostesses. | | 1893 | 17774609 |
| individual patterns of habitat and nest-site use by hosts promote transgenerational transmission of avian brood parasitism status. | brood parasitic birds impose variable fitness costs upon their hosts by causing the partial or complete loss of the hosts' own brood. growing evidence from multiple avian host-parasite taxa indicates that exposure of individual hosts to parasitism is not necessarily random and varies with habitat use, nest-site selection, age or other phenotypic attributes. for instance, nonrandom patterns of brood parasitism had similar evolutionary consequences to those of limited horizontal transmission of pa ... | 2007 | 17922717 |
| sheep in wolf's clothing: host nestling vocalizations resemble their cowbird competitor's. | nestlings of many avian brood parasites are virtuosos at mimicking host nestling vocalizations, which, like egg mimicry, presumably ensures acceptance by host parents. having been accepted, parasitic nestlings then often exaggerate the aspects of the host's display to increase parental care. host nestlings may, in turn, exaggerate their vocalizations to keep up with the parasite, though this possibility has not been evaluated. we experimentally parasitized song sparrow (melospiza melodia) nests ... | 2008 | 18252675 |
| brown-headed cowbirds (molothrus ater) harbor sarcocystis neurona and act as intermediate hosts. | we tested the hypothesis that brown-headed cowbirds (molothrus ater) harbor sarcocystis neurona, the agent of equine protozoal myeloencephalitis (epm), and act as intermediate hosts for this parasite. in summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with sarcocystis spp. by macroscopic inspection. seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. histopathology revealed two classes of sa ... | 2008 | 18342449 |
| cowbird removals unexpectedly increase productivity of a brood parasite and the songbird host. | generalist brood parasites reduce productivity and population growth of avian hosts and have been implicated in population declines of several songbirds of conservation concern. to estimate the demographic effects of brood parasitism on bell's vireos (vireo bellii), we removed brown-headed cowbirds (molothrus ater) in a replicated switchback experimental design. cowbird removals decreased parasitism frequency from 77% and 85% at unmanipulated plots to 58% and 47% at removal plots in 2004 and 200 ... | 2008 | 18488614 |
| sex differences in the effects of captivity on hippocampus size in brown-headed cowbirds (molothrus ater obscurus). | in brood parasitic cowbirds, hippocampus (hp) size is correlated with environmental spatial memory demands. searching for host nests is the presumed causal factor influencing cowbird hp size, because hp volumes vary across species, sexes, and seasons according to nest-searching participation. brown-headed cowbirds have female-only nest searching and, at least in the eastern subspecies, a larger hp in females than in males, suggesting that nest searching influences cowbird hp size. we predicted t ... | 2008 | 18513123 |
| behavioral compatibility and reproductive outcomes in two distant populations of captive brown-headed cowbirds (molothrus ater). | increased understanding of geographic variation in courtship behavior in animal species can provide insight into the ways behavior may influence evolutionary change. here, the relationship of geographic variation in courtship behavior to reproductive outcomes was tested in two distant and behaviorally distinct populations of brown-headed cowbirds, molothrus ater, by comparing rates of copulation and egg production. females from an indiana (in) population and a south dakota (sd) population were h ... | 2008 | 19014267 |
| acoustic mate copying: female cowbirds attend to other females' vocalizations to modify their song preferences. | we conducted a tutoring experiment to determine whether female brown-headed cowbirds (molothrus ater) would attend to vocalizations of other females and use those cues to influence their own preferences for male courtship songs. we collected recordings of male songs that were unfamiliar to the subject females and paired half of the songs with female chatter vocalizations-vocalizations that females give in response to songs sung by males that are courting the females effectively. thus, chatter im ... | 2009 | 19535371 |
| identifying predators clarifies predictors of nest success in a temperate passerine. | 1. nest predation negatively affects most avian populations. studies of nest predation usually group all nest failures when attempting to determine temporal and parental activities, habitat or landscape predictors of success. often these studies find few significant predictors and interpret patterns as essentially random. 2. relatively little is known about the importance of individual predator species or groups on observed patterns of nest success, and how the ecology of these predators may inf ... | 2010 | 19656236 |
| explaining postnatal growth plasticity in a generalist brood parasite. | selection of a particular host has clear consequences for the performance of avian brood parasites. experimental studies showed that growth rate and fledging mass of brood parasites varied between host species independently of the original host species. finding correlates of this phenotypic plasticity in growth is important for assessing adaptiveness and potential fitness consequences of host choice. here, i analyzed the effects of several host characteristics on growth rate and fledging mass of ... | 2010 | 20020276 |
| community-level patterns of population recruitment in a generalist avian brood parasite, the brown-headed cowbird. | the brown-headed cowbird (molothrus ater) is a generalist brood parasite that typically parasitizes many host species in a single bird community. population recruitment in a generalist parasite should be diverse with respect to host species; however, host-specific rates of cowbird recruitment have not been reported in any host community, and the determinants of host quality are poorly known. we studied the combined influence of parasitism level, nest abundance, and host quality on community-leve ... | 2010 | 20422223 |
| retinal ganglion cell topography of five species of ground-foraging birds. | birds that forage on the ground have been studied extensively in relation to behavioral trade-offs between foraging and scanning for predators; however, we know little about the topography of their retinas, which can influence how they gather visual information. we characterized the density of retinal ganglion cells across the retina and estimated visual acuity of four passeriformes (european starling sturnus vulgaris, brown-headed cowbird molothrus ater, house sparrow passer domesticus, house f ... | 2010 | 20516656 |
| sex differences in auditory filters of brown-headed cowbirds (molothrus ater). | receiver sensory abilities can be influenced by a number of factors, including habitat, phylogeny and the selective pressure to acquire information about conspecifics or heterospecifics. it has been hypothesized that brood-parasitic brown-headed cowbird (molothrus ater) females may locate or determine the quality of potential hosts by eavesdropping on their sexual signals. this is expected to produce different sex-specific pressures on the auditory system to detect conspecific and heterospecific ... | 2010 | 20559641 |
| food supplementation leads to bottom-up and top-down food-host-parasite interactions. | 1. food-prey-predator interactions may involve both 'bottom-up' and 'top-down' processes. conventionally, food-host-parasite interactions have been seen as governed solely from the 'bottom-up', i.e. well-fed hosts can better resist parasites and so suffer less parasitism. recent studies on diverse endo- and ecto-parasites increasingly highlight that well-fed hosts provide parasites with a better resource base, and so may be more likely to be parasitized. 2. brood parasites exploit host parental ... | 2010 | 20646123 |
| mite-filled cyst on a brown-headed cowbird (molothrus ater) in florida, usa. | a large, partly pedunculated mass on the scapular area of a wild-caught captive brown-headed cowbird (molothrus ater) consisted of a multiloculated keratin cyst inhabited by a new species of harpirhynchid mite (harpirhynchus quasimodo). the mass did not interfere with flight or behavior. this is the first record of such an infestation of cowbirds in florida. | 2010 | 20966280 |
| a social ethological perspective applied to care of and research on songbirds. | the interrelationships among individuals in gregarious species can have profound effects on the animals' behavior, physiology, and even health. captive housing should address the social needs of such species because failure to do so can result in the development and expression of abnormal behavior. but determining what social stimuli to provide for any given species poses many challenges. i review recent work on brown-headed cowbirds (molothrus ater) that was designed to identify the social stim ... | 2010 | 21131715 |
| persistence of host defence behaviour in the absence of avian brood parasitism. | the fate of host defensive behaviour in the absence of selection from brood parasitism is critical to long-term host-parasite coevolution. we investigated whether new world bohemian waxwings bombycilla garrulus that are allopatric from brown-headed cowbird molothrus ater and common cuckoo cuculus canorus parasitism have retained egg rejection behaviour. we found that egg rejection was expressed by 100 per cent of bohemian waxwings. our phylogeny revealed that bohemian and japanese waxwings bomby ... | 2011 | 21493623 |
| anthropogenic resource subsidies decouple predator-prey relationships. | the extent to which resource subsidies affect food web dynamics is poorly understood in anthropogenic landscapes. to better understand how species interactions are influenced by subsidies, we studied breeding birds and nest predators along a rural-to-urban landscape gradient that varied in subsidies provided to generalist predators. we hypothesized that resource subsidies in urban landscapes would decouple predator-prey relationships, as predators switch from natural to anthropogenic foods. from ... | 2011 | 21639056 |
| two measures of temporal resolution in brown-headed cowbirds (molothrus ater). | studies of auditory temporal resolution in birds have traditionally examined processing capabilities by assessing behavioral discrimination of sounds varying in temporal structure. here, temporal resolution of the brown-headed cowbird (molothrus ater) was measured using two auditory evoked potential (aep)-based methods: auditory brainstem responses (abrs) to paired clicks and envelope following responses (efrs) to amplitude-modulated tones. the basic patterns observed in cowbirds were similar to ... | 2012 | 21987264 |
| immune function in an avian brood parasite and its nonparasitic relative. | organisms that breed multiple times must trade off resources between current and future reproduction. in many species, sexual selection can lead to reduced levels of immune function in males because they invest heavily in current reproduction at the expense of self-maintenance. much less is known about whether the same trend is seen in species such as the brood-parasitic brown-headed cowbird molothrus ater (hereafter "cowbird"), in which females invest heavily in current reproduction. we examine ... | 2012 | 23303321 |