Shiny Cowbird (Molothrus bonariensis)

2020 ◽  
Author(s):  
Peter E. Lowther ◽  
William Post
Keyword(s):  
Molothrus Bonariensis

Flocking Behavior of Shiny Cowbirds (Molothrus bonariensis) At Feeding Areas During the Daily Cycle

2016 ◽  
Vol 128 (2) ◽  
pp. 441-445 ◽  
Author(s):  
Gustavo H. Kattan ◽  
Anamaría Posada ◽  
Diego Fernando Arenas ◽  
José Luis Moreno ◽  
Ángela Barrera
Keyword(s):  
Daily Cycle ◽  
Molothrus Bonariensis ◽  
Flocking Behavior

scholarly journals New records of pigmentary abnormalities in two species of birds in Cali, Colombia

2021 ◽  
Vol 22 (2) ◽  
pp. 147-154
Author(s):  
Giovanni Cárdenas Carmona ◽  
Juan Camilo Franco
Keyword(s):  
New Records ◽  
Bird Species ◽  
Molothrus Bonariensis

We report two bird species with pigment anomalies, which were seen in Cali, Colombia in 2020. The individuals were, a female Shiny Cowbird (Molothrus bonariensis) with partial leucism, a female Ruddy Ground-Dove (Columbia talpacoti) with partial leucism and a young nestling of the same species, with albinism. The records reported here are the first of partial leucism and albinism for Columbia talpacoti and partial leucism for Molothrus bonariensis in Colombia.

scholarly journals Variation in multicomponent recognition cues alters egg rejection decisions: a test of the optimal acceptance threshold hypothesis

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180195 ◽  
Author(s):  
Daniel Hanley ◽  
Analía V. López ◽  
Vanina D. Fiorini ◽  
Juan C. Reboreda ◽  
Tomáš Grim ◽  
...  
Keyword(s):  
Brood Parasitism ◽  
Response Curve ◽  
Discrimination Threshold ◽  
Single Component ◽  
Decision Makers ◽  
Egg Rejection ◽  
Theme Issue ◽  
Acceptance Threshold ◽  
Behavioural Responses ◽  
Molothrus Bonariensis

The optimal acceptance threshold hypothesis provides a general predictive framework for testing behavioural responses to discrimination challenges. Decision-makers should respond to a stimulus when the perceived difference between that stimulus and a comparison template surpasses an acceptance threshold. We tested how individual components of a relevant recognition cue (experimental eggs) contributed to behavioural responses of chalk-browed mockingbirds, Mimus saturninus , a frequent host of the parasitic shiny cowbird, Molothrus bonariensis . To do this, we recorded responses to eggs that varied with respect to two components: colour, ranging from bluer to browner than the hosts' own eggs, and spotting, either spotted like their own or unspotted. Although tests of this hypothesis typically assume that decisions are based on perceived colour dissimilarity between own and foreign eggs, we found that decisions were biased toward rejecting browner eggs. However, as predicted, hosts tolerated spotted eggs more than unspotted eggs, irrespective of colour. These results uncover how a single component of a multicomponent cue can shift a host’s discrimination threshold and illustrate how the optimal acceptance threshold hypothesis can be used as a framework to quantify the direction and amount of the shift (in avian perceptual units) of the response curve across relevant phenotypic ranges. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

scholarly journals Early Infestation by Bot Flies (Philornis Seguyi) Decreases Chick Survival and Nesting Success in Chalk-Browed Mockingbirds (Mimus Saturninus)

The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 898-906 ◽  
Author(s):  
Fabián L. Rabuffetti ◽  
Juan C. Reboreda
Keyword(s):  
Reproductive Success ◽  
Nesting Success ◽  
Life History Strategies ◽  
Chick Survival ◽  
Southern Limit ◽  
Growth And Survival ◽  
Molothrus Bonariensis ◽  
Bot Fly ◽  
Time Of Breeding ◽  
Host Life

AbstractBot flies (Diptera: Muscidae: Philornis spp.) are a group of flies comprising mostly species with a Neotropical distribution. Their larvae parasitize several species of birds, living subcutaneously on altricial chicks. We investigated the effect of parasitism by bot flies (P. seguyi) on the reproductive success of Chalk-browed Mockingbirds (Mimus saturninus) in temperate grasslands near the southern limit of bot fly distributions. We analyzed seasonal variation of bot fly prevalence during three consecutive years and how the timing and intensity of bot fly infestation affected growth and survival of Chalk-browed Mockingbird nestlings. Bot fly prevalence was 58.3%, 30.7%, and 45.5% each year, and in all years, it increased with time of breeding. Most of the infested nests fledged no chicks. In these nests, chicks had a lower tarsus growth rate than in noninfested nests and died 3–4 days after parasitism. The average time from hatching of the first chick until infestation was 4.4 days. The age of the chicks at the time of infestation was associated positively with nesting success and negatively with intensity of parasitism. Bot fly parasitism also reduced the survival of Shiny Cowbird (Molothrus bonariensis) chicks present in Chalk-browed Mockingbird nests, but the presence of Shiny Cowbird chicks did not affect timing of infestation or fledging success of Chalk-browed Mockingbird chicks. Our results show that an intermediate prevalence of bot fly parasitism produces an important decrease in the reproductive success of Chalk-browed Mockingbirds and suggest that bot flies may play an important role as selective agents in the evolution of host life-history strategies.La Infestación Temprana con Larvas de Philornis seguyi Disminuye la Supervivencia de los Pichones y el Éxito de Nidificación de Mimus saturninus

A New Race of Molothrus Bonariensis from Brazil

The Auk ◽  
1927 ◽  
Vol 44 (4) ◽  
pp. 494-494 ◽  
Author(s):  
Herbert Friedmann
Keyword(s):  
Molothrus Bonariensis ◽  
New Race

scholarly journals A case of beak deformity in the Shiny Cowbird Molothrus bonariensis and a review on beak deformities in wild birds in Brazil

2019 ◽  
Vol 27 (3) ◽  
pp. 212-217
Author(s):  
Keila Nunes Purificação
Keyword(s):  
Literature Review ◽  
Bird Species ◽  
Bird Communities ◽  
Wild Birds ◽  
Mato Grosso ◽  
Molothrus Bonariensis ◽  
East Region ◽  
Beak Deformity

AbstractBeak deformities in wild birds are rarely reported. Here, I described a case of beak deformity in Shiny Cowbird, Molothrus bonariensis, and also provide a review on beak deformities recorded in wild birds in Brazil. In October 2016, I observed a M. bonariensis with a grossly elongated maxilla in the east region of the Mato Grosso state, Brazil. The literature review revealed 60 records of beak deformities in the Brazilian avifauna. The most common types of deformity were crossed maxillae or mandibles (38%), probable accidental injuries (27%), and elongations (15%). Deformities were reported in 35 bird species of 22 families. The most affected species was Ramphastos toco with 21 records. The number of published reports from Brazil was low overall, and are not related as an epizootic episode recorded in some bird communities.

scholarly journals Creamy-Bellied Thrush Defenses Against Shiny Cowbird Brood Parasitism

The Condor ◽  
2005 ◽  
Vol 107 (4) ◽  
pp. 788-796 ◽  
Author(s):  
Andrea A. Astie ◽  
Juan C. Reboreda
Keyword(s):  
Brood Parasitism ◽  
Hatching Success ◽  
Simultaneous Presentation ◽  
Control Model ◽  
Nest Attendance ◽  
Chick Survival ◽  
Molothrus Bonariensis ◽  
Egg Ejection ◽  
Cowbird Parasitism ◽  
Recognition Errors

AbstractWe studied Creamy-bellied Thrush (Turdus amaurochalinus) defenses against brood parasitism by Shiny Cowbirds (Molothrus bonariensis). Shiny Cowbirds decrease the reproductive success of Creamy-bellied Thrushes, and having historical habitats and ranges that overlap, we expected that thrushes possess antiparasitic defenses. We analyzed nest attendance during prelaying, laying and incubation; responses to the presentation of a model of a female cowbird or a control species close to the nest; nest abandonment associated with parasitism; and responses to experimental parasitism with white or spotted cowbird eggs (with or without the simultaneous presentation of a female cowbird model). Nest attendance was 58%–68% during prelaying and 83%–90% during laying and incubation. Thrushes had a shorter latency in returning near the nest and visited nests more frequently when we presented the cowbird model than the control model. The frequency of abandonment of parasitized nests was low and was not temporally associated with parasitism. Thrushes ejected white eggs more frequently than spotted eggs when parasitism was associated with the presentation of the cowbird model, but there were no differences when the model was absent. Our results indicate that Creamy-bellied Thrushes recognize cowbirds as a threat and eject white but not spotted cowbird eggs. We postulate that the low impact of cowbird parasitism on thrush hatching success and chick survival and the likelihood of recognition errors when parasite eggs resemble host eggs may have prevented the evolution of egg ejection in this host.

scholarly journals Costs of Egg Punctures and Parasitism by Shiny Cowbirds (Molothrus Bonariensis) at Creamy-Bellied Thrush (Turdus Amaurochalinus) Nests

The Auk ◽  
2006 ◽  
Vol 123 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Andrea A. Astié ◽  
Juan C. Reboreda
Keyword(s):  
Reproductive Success ◽  
Hatching Success ◽  
Nest Survival ◽  
Egg Laying ◽  
Chick Survival ◽  
Egg Survival ◽  
Lower Survival Rate ◽  
Molothrus Bonariensis ◽  
Primary Determinant ◽  
The Cost

AbstractMost studies on cowbird parasitism have focused on its effects on parasitized nests, whereas few have considered the costs at nests that cowbirds visit but at which they do not lay eggs. Shiny Cowbirds (Molothrus bonariensis) peck and puncture host eggs both in nests where they lay eggs and in unparasitized nests. We analyzed the effect of egg punctures in unparasitized and parasitized nests of a large host, the Creamy-bellied Thrush (Turdus amaurochalinus; hereafter “thrush”), as well as the costs of Shiny Cowbird eggs and chicks in this host’s nests. We determined thrush egg survival, hatching success, and chick survival in successful nests, and nest survival during the egg and nestling stages. Frequency of parasitism was 60%, and its intensity 1.6 ± 0.1 eggs nest−1. Number of host eggs punctured was positively associated with intensity of parasitism. The host’s eggs were frequently punctured in parasitized nests (71%) and in unparasitized nests (42%). Egg punctures reduced the number of eggs at hatching in 23% and 49% of unparasitized and parasitized nests, respectively. Nests with egg punctures had a lower survival rate than nests without them, but nest survival was not associated with parasitism. Presence of a Shiny Cowbird egg was associated with a decrease in the hatching success of host eggs, but presence of a Shiny Cowbird chick did not have any detrimental effect on either the survival and growth rate of host chicks in successful nests or the survival of the whole nest. Our results show that egg punctures were the primary determinant of thrush reproductive success. Consequently, comparison of unparasitized and parasitized nests gives an incomplete estimation of the effects of Shiny Cowbirds on host reproductive success, because the cost of egg punctures is also important in nests where there is no Shiny Cowbird egg laying.Costos de la Perforación de Huevos y el Parasitismo por Molothrus bonariensis en Nidos de Turdus amaurochalinus

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