DOCSLIB.ORG

Pair Formation in Cowbirds; Evidence Found for Screaming but Not Shiny

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Pair Formation in Cowbirds; Evidence Found for Screaming but Not Shiny The Condor 89:349-356 0 The Cooper Ornithological Society 1981 PAIR FORMATION IN COWBIRDS: EVIDENCE FOUND FOR SCREAMING BUT NOT SHINY COWBIRDS PAUL MASON Department of BiologicalSciences, University of California, Santa Barbara, Santa Barbara. CA 93106 Abstract. Sixty ScreamingCowbirds (Molothrus rufoaxillaris) and 150 Shiny Cowbirds (M. bonariensis)were trapped and banded in Buenos Aires Province, Argentina. Analysis of recapturesprovided statistical evidence for pair formation in Screamingbut not Shiny cowbirds, a result supportedby observationsof free-living birds. Pairs of ScreamingCow- birds were stable throughout the breeding season.They are probably monogamous. Shiny Cowbirds showed no pattern of associationbetween the sexes. This is consistent with a promiscuousmating system, although this conclusionis tentative. I also present ancillary data on sexual size dimorphism, sex ratio, and related aspectsof behavior. Both speciesare dimorphic in size to a similar extent, although the Screaming Cowbird is slightly larger. Neither speciesdeparts from an adult (quatemary) sex ratio of unity. Pairs of ScreamingCowbirds are conspicuousnear host nests.Female Shiny Cowbirds are not accompaniedby males at nests, but may be accompanied by other females. Shiny Cowbird females were surreptitious near nests. Differences in host selection behavior may have profound effects on other aspectsof the speciesbreeding biology. Key words: ScreamingCowbird; Shiny Cowbird;pair formation; mating systems;brood parasitism;Argentina. INTRODUCTION with respect to host selection behavior and this The unusual extent of behavioral and morpho- single difference might be responsible for con- logical variation in Icterinae has served to make trasts in a variety of other traits. The Screaming this subfamily a compelling example of adaptive Cowbird is a host specialist, thought to use the radiation in birds (Lack 1968, Selander 1972). communally breeding Bay-winged Cowbird (M. Study of these birds has contributed substantially badius) almost exclusively (Friedmann and Kiff toward the construction of a general theory of 1985; but see Hudson 1874, 1920; Grant 1911, sexual selection and mating systems (Selander 1912; Pereyra 1938; Hoy and Ottow 1964; Sick 1965, 1972; Orians 1969, 1972). I add further 1985). The Shiny Cowbird lays its eggs in the detail to this panorama by contrasting the pairing nests of many species, and the pattern of host behavior of two brood parasites, the Screaming selection, at least in the Rio de La Plata region Cowbird (Molothrus rufoaxillaris) and the Shiny (Argentina and Uruguay), seems to vary with the Cowbird (M bonariensis) at a site in Buenos Aires structure of the host community (Mason 1986a). Province, Argentina, where the species are sym- A total of 20 1 species of birds are known as hosts panic. I also present ancillary data on sexual (Friedmann and Kiff 1985). dimorphism, sex ratio, and other related aspects Another difference is in the extent of plumage of behavior. dimorphism. Screaming Cowbirds are mono- On the one hand, we might expect the species morphic in plumage (both sexes a dull black), to resemble each other very closely. First, taxo- while Shiny Cowbirds are strongly dimorphic nomic differences are minimal between conge- (females are drab gray, while males are black with ners. Second, habitat differences are minimized a blue gloss). This difference is associated with in areas of sympatry for species with similar feed- a putative difference in mating system: Hudson ing ecologies. Finally, the species are brood par- (1874, 1920) and Friedmann (1929) described asites. Screaming Cowbirds as monogamous since they On the other hand, the species differ greatly typically travelled in pairs, but Shiny Cowbirds as promiscuous since they apparently lacked any regular association between the sexes. Both au- I Received 19 May 1986. Final acceptance 10 De- thors drew these conclusions without the aid of cember 1986. individually marked birds. 13491 350 PAUL MASON with the U statistic. Species comparisons were METHODS performed when no intersexual differenceswere The study site was conducted at Estancia El Talar found. (Site II of Mason 1986a, described in Mason Pairwise relationships were recognized using a 1985) near Magdalena, Buenos Aires Province, randomization procedure for testing the associ- Argentina from 21 September 1978 to 10 Feb- ation between two species(Pielou 1977), but sub- ruary 1979. Birds were trapped on 27 days be- stituting individuals for species. On each trap tween 6 October 1978 and 20 January 1979 in day, birds were recorded as either present or ab- a walk-in decoy trap, baited with grain and water, sent, and then 2 x 2 tables were constructed and similar in construction to that described by describing the frequency with which each bird of Carter (1986). The trap was left baited but open every possiblepair was presentor not. The entries on nontrap days, so that birds could habitually in the four cells represent the number of times enter the trap to eat. that: (1) both birds were caught together; (2) and Sixteen of the 27 trap days were in October. (3) one bird was caught but the other was not; The others occurred sporadically in the remain- and (4) neither bird was caught. The random- ing interval. Poor weather and destruction of the ization procedurethen calculatesa 1-tailed prob- trap by cattle and horsesprevented a regular trap- ability that those two particular birds enter the ping schedule. trap independently. In this sense,the procedure To identify possible pairs of birds, I occasion- is similar to Fisher’s exact test (Siegel 1956). ally observedanimals near the trap and removed Positive association is indicated by dispro- pairs immediately after entry. The trap was usu- portionate scoresin cells 1 and 4 of a particular ally left unattended. On first capture, birds were 2 x 2 table. To eliminate the possibility of in- weighed to the nearest 0.5 g with a spring scale flating the absent-absent cell (Cell 4) I made and given a unique color combination of enam- conservative assumptions about survivorship: a elled aluminum leg bands (5 2 each leg). Shiny bird was not assumed to be in the population Cowbirds were sexed by plumage. Screaming until it was trapped, and not assumedto live after Cowbirds were laparotomized (Risser 197 1). it was last trapped. Tests were carried out only Identification of pairs through the analysis of for pairs whose period of joint observation was recapturesis sensitive to any difference between at least six trap days, the minimum sample size the sexesin susceptibility to enter the trap. Two needed to show significance(P = 0.05 when both tests were performed to assesstrapability. First, birds were caught together three times, and nei- distributions describing the frequency of capture ther caught on three other days). were compared using the Heterogeneity G test Other kinds of information are made available (Sokal and Rohlf 1981). Second, probability of if the probability of independent recapture is also recapture was calculated for retrapped birds calculated for intrasexual pairs. Although com- (Darley 1971) and sexeswere compared using parison of inter- with intrasexual pairs cannot be the Mann-Whitney U-test (Siegel 1956). These construed as a control procedure, doubt would techniques have two additional benefits. First, if be cast on the entire approach if intersexual pairs no evidence is found of a sex-specific bias in were identified as frequently as intrasexual pairs capture, then the population sex ratio is esti- and no biological correspondence could be es- mated by the observed sex ratio. Sex-ratio was tablished between them. In some cases, an ap- testedfor skewnesswith the Chi-square test (Sie- propriate explanation might be available. For ex- gel 1956). Second, equivalent rates within sexes ample, if males are polygynous and hold stable allow the sexes to be pooled such that species harems, then significant pairwise associations comparisons can be made. should occur between the harem members as well A differencein capture frequency (which could as between the male and each female. affect the ease with which pairs could be iden- Data collected through the trapping program tified) might be due to differencesin site fidelity. were compared with observations on free-living Site fidelity wascalculated by recordinghow many birds (both marked and unmarked). I comment days separated the first and last date of obser- on the behavior of cowbirds at nests where I vation for each bird that was recaptured or re- made repeated “spot checks” of lessthan 15 min sighted. Differences between sexes were tested duration (Mason 1986b). PAIR FORMATION IN COWBIRDS 351 RESULTS TABLE 1. Frequencydistribution of captures.In both ScreamingCowbirds and Shiny Cowbirds, males and TRAPPING RESULTS females a& equally as likely to be trapped and re- traooed (GH = 0.58. df = 3. P > 0.75. GH = 3.78. I trapped 60 Screaming Cowbirds (27 females, df = 3, 6 > 0.25, respectively). Screaming Cowbirds 33 males) between 9 October 1978 and 20 Jan- are trapped more readily than Shiny Cowbirds (GH = uary 1979, and 150 Shiny Cowbirds (70 females, 42.18, df = 3, P < 0.001). 80 males) between 6 October 1978 and 29 De- cember 1978. While Shiny Cowbirds were calm No. captures I 2 3 >3 in the trap, ScreamingCowbirds (especiallymales) were restless. They typically struggled, and Screaming Females 12 6 3 6 crashed against the walls. The lores were gen- Cowbirds: Males 17 5 4 7 Total 29 11 7 13 erally bloodied and recaptured birds often pos- Shiny Females 74 5 0 1 sessedinfected lesions, a source of injury that Cowbirds: Males 59 7 1 3 may have increased mortality and made the de- Total 133 12 1 4 tection of pairs more difficult. Infections were not observed around laparotomy wounds. The ratio of male weight to female weight, an from a sex ratio of unity in either species index of sexual dimorphism, is approximately (Screaming Cowbird: x2 = 0.60 for 1 df, ns; Shiny equal between the two species, despite differ- Cowbird: x2 = 0.67 for 1 df, ns, 0.5 < P < 0.7 ences in body weight: ratio = 1.20 for the in both cases).
Load more

Recommended publications
  • Lista Roja De Las Aves Del Uruguay 1
    Lista Roja de las Aves del Uruguay 1 Lista Roja de las Aves del Uruguay Una evaluación del estado de conservación de la avifauna nacional con base en los criterios de la Unión Internacional para la Conservación de la Naturaleza. Adrián B. Azpiroz, Laboratorio de Genética de la Conservación, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318 (CP 11600), Montevideo ([email protected]). Matilde Alfaro, Asociación Averaves & Facultad de Ciencias, Universidad de la República, Iguá 4225 (CP 11400), Montevideo ([email protected]). Sebastián Jiménez, Proyecto Albatros y Petreles-Uruguay, Centro de Investigación y Conservación Marina (CICMAR), Avenida Giannattasio Km 30.5. (CP 15008) Canelones, Uruguay; Laboratorio de Recursos Pelágicos, Dirección Nacional de Recursos Acuáticos, Constituyente 1497 (CP 11200), Montevideo ([email protected]). Cita sugerida: Azpiroz, A.B., M. Alfaro y S. Jiménez. 2012. Lista Roja de las Aves del Uruguay. Una evaluación del estado de conservación de la avifauna nacional con base en los criterios de la Unión Internacional para la Conservación de la Naturaleza. Dirección Nacional de Medio Ambiente, Montevideo. Descargo de responsabilidad El contenido de esta publicación es responsabilidad de los autores y no refleja necesariamente las opiniones o políticas de la DINAMA ni de las organizaciones auspiciantes y no comprometen a estas instituciones. Las denominaciones empleadas y la forma en que aparecen los datos no implica de parte de DINAMA, ni de las organizaciones auspiciantes o de los autores, juicio alguno sobre la condición jurídica de países, territorios, ciudades, personas, organizaciones, zonas o de sus autoridades, ni sobre la delimitación de sus fronteras o límites.
    [Show full text]
  • Nest Building and Nesting Behavior of the Brown Cacholote
    Wilson Bull., 106(l), 1994, pp. 106-120 NEST BUILDING AND NESTING BEHAVIOR OF THE BROWN CACHOLOTE ANA I. NOBES AND MANUEL NORES ’ ABsTnAcr.-we studied nesting behavior ofthe Brown Cacholote (Pseudoseisuralophotes) in Cordoba, Argentina from April 1989 to March 1993. Brown Cacholotes build many elaborate stick nests throughout the year and use each of them during the breeding period or for a short time in the non-breeding period. Nest building requires 15 to 37 days. Nests were usually built with thorny twigs, but the nature of the materials depends on availability. Usually each pair had several nests or part of them in their territory (range = l-10). Nest building requires much of the birds ’ time and energy, but Brown Cacholotes generally use the material of old nests to minimize energy expenditure in nest construction. Both sexes shared all nesting activities. The birds copulate inside the nest, which is apparently unknown among birds. Egg laying occurred from last September to late February. Mean clutch size was 2.6 eggs (range = 2-4). The incubation period lasted 18-20 days and the nestling period 18-23 days. Nesting success was 59.3%, and an average of 1.5 nestlings were reared per clutch. Parental breeding experience, rather than age, would be more important influence on clutch-size and nesting success. Juveniles remained in the parental territories for 4-l 3 months. They contributed to nest building and defense of their territory, but their help was minimal. Received7 Dec. 1992, acceptedI Sept. 1993. Although nest has been defined as a structure that aids the development of the eggs and the survival of young (Collias 1964) some birds build similar or different structures for use as dormitories throughout the year and have a close relation with them (Skutch 196 1, Collias 1964, Welty 1979).
    [Show full text]
  • The Shiny Cowbird Reaches the United States
    BREEDING RECORD The ShinyCowbird reaches the UnitedStates Will the scourge of the Caribbean impact Florida's avifauna too? P. William Smith and Alexander Sprunt IV ductinga BreedingBird Surveyon NLowerJUNE Matecumbe14,1985, Key,WHILE MonroeCON- County, Florida, Sprunt and Karen Sunderland discoveredthe first Shiny Cowbird (Molothrus bonariensis) re- ported in the United States,a male, with Red-winged Blackbirds (Agelaius phoeniceus) in mangroves near the shoulderof the OverseasHighway (U.S. 1). Its appearancein Florida was hardly unexpected. From its South American base, the Shiny Cowbird has spread northward, mostly during this century, through the Antilles; its expansionhas been particularly strongover the last 30 years(Post and Wiley 1977; Arendt and Figure 1. Three male Shiny Cowbirdsjoin Mourning Dovesand Eura•ian Collared-Dovesat Vargas 1984). By 1982, the specieshad Islamorada.Florida. July 5, 1986. Photo/P William Smith (VIREO SI4/2/003). reachedthe north coastof Cuba (Bond in the United States. This constituted On the other hand, female and ju- 1984;Cruz el al. 1985), only about 100 the first recordfor the Florida peninsula venile Shiny Cowbirds representa def- miles south of its point of discoveryin and the first definite report of a female inite identification challenge (Figs. 5- the United States. After it was relocated in the United States. Up to five male 6). An examination of specimensat the at a nearby feeder, the Lower Matec- and two female Shinies were seen to- Academy of Natural Sciences,in Phil- umbe Shiny Cowbird was observedby getherwith the Brown-headedCowbirds adelphia, reveals that except for head birders for several weeks. at Flamingo until at least late June and bill shape,there is almost complete In 1986, Smith and his wife were 1987.A juvenileShiny was present from overlap in charactersbetween female trying to capture Eurasian Collared- June 27 until late July, suggestingthe Shinies of the race minimus.
    [Show full text]
  • Adult Brood Parasites Feeding Nestlings and Fledglings of Their Own Species: a Review
    J. Field Ornithol., 69(3):364-375 ADULT BROOD PARASITES FEEDING NESTLINGS AND FLEDGLINGS OF THEIR OWN SPECIES: A REVIEW JANICEC. LORENZANAAND SPENCER G. SEALY Departmentof Zoology Universityof Manitoba Winnipeg,Manitoba R3T 2N2 Canada Abstract.--We summarized 40 reports of nine speciesof brood parasitesfeeding young of their own species.These observationssuggest that the propensityto provisionyoung hasnot been lost entirely in brood parasitesdespite the belief that brood parasiticadults abandon their offspringat the time of laying.The hypothesisthat speciesthat participatein courtship feeding are more likely to provisionyoung was not supported:provisioning of young has been observedin two speciesof brood parasitesthat do not courtshipfeed. The function of this provisioningis unknown, but we suggestit may be: (1) a non-adaptivevestigial behavior or (2) an adaptation to ensure adequatecare of parasiticyoung. The former is more likely the case.Further studiesare required to determinewhether parasiticadults commonly feed their genetic offspring. ADULTOS DE AVES PARAS•TICASALIMENTANDO PICHONES Y VOLANTONES DE SU PROPIA ESPECIE: UNA REVISION Sinopsis.--Resumimos40 informes de nueve especiesde avesparasiticas que alimenaron a pichonesde su propia especie.Las observacionessugieren que la propensividadde alimentar a los pichonesno ha sido totalmente perdida en las avesparasiticas, no empecea la creencia de que los parasiticosabandonan su progenie al momento de poner los huevos.La hipttesis de que las especiesque participan en cortejo de alimentacitn, son milspropensas a alimentar los pichonesno tuvo apoyo.Las observacionesde alimentacitn a pichonesse han hecho en dos especiesparasiticas cuyo cortejo no incluye la alimentacitn de la pareja. La funcitn de proveer alimento se desconoce.No obstante,sugerimos que pueda ser: 1) una conducta vestigialno adaptativa,o 2) una adaptacitn parc asegurarel cuidado adecuadode los pi- chonesparasiticos.
    [Show full text]
  • Baseline Ecological Inventory for Three Bays National Park, Haiti OCTOBER 2016
    Baseline Ecological Inventory for Three Bays National Park, Haiti OCTOBER 2016 Report for the Inter-American Development Bank (IDB) 1 To cite this report: Kramer, P, M Atis, S Schill, SM Williams, E Freid, G Moore, JC Martinez-Sanchez, F Benjamin, LS Cyprien, JR Alexis, R Grizzle, K Ward, K Marks, D Grenda (2016) Baseline Ecological Inventory for Three Bays National Park, Haiti. The Nature Conservancy: Report to the Inter-American Development Bank. Pp.1-180 Editors: Rumya Sundaram and Stacey Williams Cooperating Partners: Campus Roi Henri Christophe de Limonade Contributing Authors: Philip Kramer – Senior Scientist (Maxene Atis, Steve Schill) The Nature Conservancy Stacey Williams – Marine Invertebrates and Fish Institute for Socio-Ecological Research, Inc. Ken Marks – Marine Fish Atlantic and Gulf Rapid Reef Assessment (AGRRA) Dave Grenda – Marine Fish Tampa Bay Aquarium Ethan Freid – Terrestrial Vegetation Leon Levy Native Plant Preserve-Bahamas National Trust Gregg Moore – Mangroves and Wetlands University of New Hampshire Raymond Grizzle – Freshwater Fish and Invertebrates (Krystin Ward) University of New Hampshire Juan Carlos Martinez-Sanchez – Terrestrial Mammals, Birds, Reptiles and Amphibians (Françoise Benjamin, Landy Sabrina Cyprien, Jean Roudy Alexis) Vermont Center for Ecostudies 2 Acknowledgements This project was conducted in northeast Haiti, at Three Bays National Park, specifically in the coastal zones of three communes, Fort Liberté, Caracol, and Limonade, including Lagon aux Boeufs. Some government departments, agencies, local organizations and communities, and individuals contributed to the project through financial, intellectual, and logistical support. On behalf of TNC, we would like to express our sincere thanks to all of them. First, we would like to extend our gratitude to the Government of Haiti through the National Protected Areas Agency (ANAP) of the Ministry of Environment, and particularly Minister Dominique Pierre, Ministre Dieuseul Simon Desras, Mr.
    [Show full text]
  • Screaming Cowbird Parasitism of Nests of Solitary Caciques and Cattle Tyrants
    SHORT COMMUNICATIONS 795 The Wilson Journal of Ornithology 122(4):795–799, 2010 Screaming Cowbird Parasitism of Nests of Solitary Caciques and Cattle Tyrants Alejandro G. Di Giacomo,1 Bettina Mahler,2 and Juan C. Reboreda2,3 ABSTRACT.—The Screaming Cowbird (Molothrus these events of parasitism resulted from recognition rufoaxillaris) is one of the most specialized brood errors by Screaming Cowbird females that regularly parasites with only three known hosts: Baywing parasitize Baywings and Chopi Blackbirds. The nest of (Agelaioides badius), the main host throughout most Solitary Caciques had been frequently visited by a pair of its range, and two alternative hosts in some areas of of Baywings before Screaming Cowbird parasitism its distribution, Chopi Blackbird (Gnorimopsar chopi) occurred, and the nest of Cattle Tyrants was near an and Brown-and-yellow Marshbird (Pseudoleistes vir- active Chopi Blackbird nest that had been previously escens). We studied Screaming Cowbird parasitism in parasitized by Screaming Cowbirds. Received 5 Janu- northeast Argentina where this parasite uses Baywings ary 2010. Accepted 7 April 2010. and Chopi Blackbirds as hosts. We monitored 69 nests of Baywings, 251 of Chopi Blackbirds, 31 of Solitary Caciques (Cacicus solitarius), and 30 of Cattle Tyrants (Machetornis rixosa). The frequency of Screaming The Screaming Cowbird (Molothrus rufoaxil- Cowbird parasitism on Baywing nests was 80% and laris) is a specialized brood parasite, which was 46% for Chopi Blackbirds. We recorded one event exclusively uses the Baywing (Agelaioides ba- of Screaming Cowbird parasitism on one nest of dius) as a host throughout most of its range Solitary Caciques and three events of Screaming (Mason 1980, Fraga 1998).
    [Show full text]
  • Life History Trade-Offs Between Longevity and Immunity in the Parasitic Brown-Headed Cowbird? D
    8 The Open Evolution Journal, 2011, 5, 8-13 Open Access Life History Trade-Offs Between Longevity and Immunity in the Parasitic Brown-Headed Cowbird? D. Caldwell Hahn* and Graham W. Smith USGS-Patuxent Wildlife Research Center, Laurel, MD 20708-4039, USA Abstract: 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.
    [Show full text]
  • Evoluation of Brood Parasitism in Altricial Birds
    THE CONDOR VOLUME 67 SEPTEMBER-OCTOBER NUMBER 4 EVOLUTION OF BROOD PARASITISM IN ALTRICIAL BIRDS BY WILLIAM J. HAMILTON, III, and GORDON H. ORIANS Among the 8600 living species of birds there are about 75 brood parasites which make no nest, laying their eggs in the nests of other birds. Here we wish to examine the behavior patterns and environmental circumstances which may have led to the development of this form of parasitism. This will involve comparisons with the adap- tations of nonparasitic relatives of modern brood parasites. Thus, we are attempting to evaluate not only why modern brood parasites may have developed their unusual habits but also why certain close relatives have not. Brood parasitism has evolved independently a number of times in birds. Best known are the cuckoos, with a complex of Old World species (and three less special- ized New World species) highly specialized in the parasitic habit (Friedmann, 1933, 1948). Also, all the African honey guides (Indicatoridae) whose breeding biology is known are brood parasites (Friedmann, 1955). Among passerines brood parasitism has evolved independently in African weaver birds (Ploceidae) and in several species of blackbirds (Icteridae) . The only obligate parasite in precocial species is the South American Black-headed Duck (Hetermetta atricupilZu), but the North American Redhead (Aythyu americana) has populations at various stages of parasitism, from completely independent to complete brood parasitism (Weller, 1959). The inde- pendent evolution of brood parasitism in these diverse phyletic lines is clear. But brood parasitism has not necessarily evolved only once in each group. The poly- phyletic origin of such a specialized habit within a group might seem quite improb- able, but the conditions which might lead to the development of such a habit sug- gest that this is a possibility.
    [Show full text]
  • Controlling Shiny Cowbirds in Puerto Rico
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Proceedings of the Thirteenth Vertebrate Pest Vertebrate Pest Conference Proceedings Conference (1988) collection March 1988 CONTROLLING SHINY COWBIRDS IN PUERTO RICO Jon F. Heisterberg USDA, APHIS, Animal Damage Control, Denver Wildlife Research Center, Bowling Green, Kentucky Fernando Nunez-Garcia U.S. Fish and Wildlife Service, Catalina Work Center, Palmer, PR Follow this and additional works at: https://digitalcommons.unl.edu/vpcthirteen Part of the Environmental Health and Protection Commons Heisterberg, Jon F. and Nunez-Garcia, Fernando, "CONTROLLING SHINY COWBIRDS IN PUERTO RICO" (1988). Proceedings of the Thirteenth Vertebrate Pest Conference (1988). 60. https://digitalcommons.unl.edu/vpcthirteen/60 This Article is brought to you for free and open access by the Vertebrate Pest Conference Proceedings collection at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Proceedings of the Thirteenth Vertebrate Pest Conference (1988) by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. CONTROLLING SHINY COWBIRDS IN PUERTO RICO JON F. HEISTERBERG, U. S. Department of Agriculture, APHIS, Animal Damage Control, Denver Wildlife Research Center, 334 15th Street, Bowling Green, Kentucky 42101. FERNANDO NUNEZ-GARCIA1, U.S. Department of Agriculture, APHIS, Animal Damage Control, Denver Wildlife Research Center, 334 15th Street, Bowling Green, Kentucky 42101. ABSTRACT: A program to trap and remove shiny cowbirds (Molothrus bonariensis) was conducted during two successive passerine nesting seasons at Roosevelt Roads Naval Station in eastern Puerto Rico. It sought to improve existing trapping techniques and to determine the effect cowbird removal has on the reproductive success of the endangered yellow-shouldered blackbird (Agelaius xanthomus).
    [Show full text]
  • Brood Parasitism of the Shiny Cowbird, Molothrus Bonariensis, on the Brown-And-Yellow Marshbird, Pseudoleistes Virescens
    The Condor 96:716-721 0 The Cooper Ornithological Society 1994 BROOD PARASITISM OF THE SHINY COWBIRD, MOLOTHRUS BONARIENSIS, ON THE BROWN-AND-YELLOW MARSHBIRD, PSEUDOLEISTES VIRESCENS MYRIAM E. MERMOZ AND JUAN C. REBOREDA Laboratorio de Biologiiade1 Comportamiento, Institute de Biologia y Medicina Experimental-CONICET, Vuelta de Obligado 2490, 1428 BuenosAires, Argentina Abstract. We studied the relationship between a generalist brood parasite, the Shiny Cowbird (Molothrus bonariensis)and one of its hosts, the Brown-and-Yellow Marshbird (Pseudoleistesvirescens). Seventy-four percent of the nestsfound were parasitized. Although the parasite lays both white and spotted eggs,most of the cowbird eggsfound in the nests of this host were spotted. Artificial parasitism experiments showed that the host rejected the cowbird white eggs.Shiny cowbird parasitism reducedthe nesting successof the Brown- and-Yellow Marshbird mainly by puncturesor cracksof the host eggs.The reduction of the nesting successof the parasite was due mostly to the loss of eggsin multiple parasitized nests. Shiny cowbird chicks were not outcompeted for food although they are smaller than the host chicks. The Brown-and-Yellow Marshbird appearsto be a very good host, capable of rearing up to four cowbird chicks in a nest. We compared the nesting successof the Shiny Cowbird in Brown-and-Yellow Marshbird nests with its nesting successin the other sym- patric hosts studied. Key words: Broodparasitism;nesting success; Shiny cowbird;Brown-and- YellowMarsh- bird; Molothrus bonariensis;Pseudoleistes virescens. INTRODUCTION Rufous-collared Sparrow, Zonotrichia capensis Interspecific brood parasitism is a breeding sys- (Sick 1958; Ring 1973; Fraga 1978, 1983), the tem in which the parasite lays its eggsin the nest Chalk-browed Mockingbird, Mimus saturninus of another species,the host, which performs all (Salvador 1984, Fraga 1985) the Yellow-shoul- the parental care.
    [Show full text]
  • Reproductive Success and Nestling Growth of the Baywing Parasitized by Screaming and Shiny Cowbirds
    Published by the Wilson Ornithological Society VOL. 122, NO. 3 September 2010 PAGES 417–634 The Wilson Journal of Ornithology 122(3):417–431, 2010 REPRODUCTIVE SUCCESS AND NESTLING GROWTH OF THE BAYWING PARASITIZED BY SCREAMING AND SHINY COWBIRDS MARI´AC.DE MA´ RSICO,1,2 BETTINA MAHLER,1 AND JUAN C. REBOREDA1 ABSTRACT.—We studied the breeding biology of the Baywing (Agelaioides badius), a shared host of Screaming (Molothrus rufoaxillaris) and Shiny (M. bonariensis) cowbirds. We monitored 193 nests from December 2002 to March 2007 in the Province of Buenos Aires, Argentina. Baywings used a wide variety of nesting sites, mainly old nests of furnarids. Their breeding season lasted from late November to February and was closely matched by that of Screaming Cowbirds. The breeding season for Shiny Cowbirds started in late September but overlapped that of Baywings. Frequency and intensity of Screaming Cowbird parasitism were 93% and 5 eggs per parasitized nest, while for Shiny Cowbirds they were 16% and 1.4 eggs. Host clutch size was 4.0 6 0.1 eggs and did not vary with time of breeding. Weight at hatching and age of maximum growth were similar for host and Screaming Cowbird nestlings. Shiny Cowbird nestlings had higher weight at hatching and lower age of maximum growth than the other two species. Screaming and Shiny cowbird nestlings had higher growth rates and asymptotic weights than host nestlings. Sex-specific growth curves of Screaming Cowbirds indicated males had higher growth rate and asymptotic weight than females. Only 19% of the nests produced fledglings. Host egg survival, hatching success, and nestling survival were 0.92, 0.88, and 0.94, respectively.
    [Show full text]
  • Patterns of Shiny Cowbird Parasitism in St. Lucia and Southwestern Puerto Rico ’
    The Condor92:461469 0 The CooperOrnithological Society 1990 PATTERNS OF SHINY COWBIRD PARASITISM IN ST. LUCIA AND SOUTHWESTERN PUERTO RICO ’ WILLIAM POST CharlestonMuseum, 360 Meeting St., Charleston,SC 29403 TAMMIE K. NAKAMURA Department of Zoology, Colorado State University,Fort Collins, CO 80523 ALEXANDER CRUZ Department of EPO Biology, Universityof Colorado, Boulder, CO 80309 Abstract. The density of Shiny Cowbirds (Molothrus bonariensis)in lowland St. Lucia and Martinique is about six individuals/km2, compared to 49/km2 in lowland southwestern Puerto Rico. Their distribution in the Antilles may be related to agriculturethat provides food for adults, as much as to availability of suitable hosts. In St. Lucia, four of eight potential host specieswere parasitized. Black-whiskeredVireos ( Vireoaltiloquus) and Yellow Warblers (Dendroicapetechia) accountedfor 90% of all parasitized nests. Patterns of par- asitism did not match host availability in either SW Puerto Rico or St. Lucia. In St. Lucia only Gray Kingbirds (Tryannus dominicensis)rejected >75% of experimental cowbird eggs. Gray Kingbirds, Northern Mockingbirds (Mimus polyglottos),and Greater Antillean Grack- les (Quiscalusniger) were rejectersin Puerto Rico. The successof parasitizedYellow Warbler nests was higher in Puerto Rico than in St. Lucia. Cowbird parasitism reduced Yellow Warbler nest successin St. Lucia, but not Puerto Rico. Comparisons with Puerto Rico indicate that neither hosts nor cowbirds in St. Lucia have evolved defenses or counter- defensesduring a 40-year period. Key words: Brood parasitism; host selection;egg rejection;Shiny Cowbird: Molothrus bonariensis;St. Lucia; Puerto Rico; Martinique. INTRODUCTION objectives were to: (1) contrast the distribution The Shiny Cowbird (Molothrusbonariensis), a and abundance of Shiny Cowbird populations in generalist brood parasite, has spread rapidly St.
    [Show full text]