COMMUNITY-WIDE IMPACTS OF A GENERALIST BROOD PARASITE, THE BROWN-HEADED COWBIRD (MOLOTHRUS ATER)

I present data on the time of day of oviposition for 16 species of icterines to evaluate the idea that laying exceptionally early in the morning by the brood parasite, the Brown-headed Cowbird (Molothrus ater), is a specialization for parasitism. This cowbird, the earliest known layer among icterines, typically lays before sunrise (sunrise −9.14 ± 2.52 (SE) min, n = 36). Another brood parasite, the Shiny Cowbird (Molothrus bonariensis), also sometimes lays before sunrise. The best-known nonparasitic icterines, the Red-winged Blackbird (Agelaius phoeniceus) and the Common Grackle (Quisacalus quiscula), lay shortly after sunrise. Fragmentary records show that several other icterines lay within an hour or so after sunrise. Data are inadequate to conclude that early laying by Brown-headed Cowbirds has arisen as an adaptation for parasitism. The Brown-headed Cowbird at London, Ontario, lays earlier than most local passerines, as is shown by new data on oviposition by seven host species arranged in order of increasing lateness of oviposition: Agelaius phoeniceus, Dendroica petechia, Melospiza melodia, Cardinalis cardinalis, Vireo olivaceus, Dumetella carolinensis, and Turdus migratorius.

Download Full-text

Stable isotopes identify the natal origins of a generalist brood parasite, the brown-headed cowbird Molothrus ater

Journal of Avian Biology ◽

10.1111/j.0908-8857.2008.04170.x ◽

2008 ◽

Vol 39 (3) ◽

pp. 364-367 ◽

Cited By ~ 2

Author(s):

Karl L. Kosciuch ◽

James W. Rivers ◽

Brett K. Sandercock

Keyword(s):

Stable Isotopes ◽

Molothrus Ater ◽

Brood Parasite

Download Full-text

Temporal patterns of circulating LH and steroid hormones in a brood parasite, the Brown-headed cowbird, Molothrus ater.

Journal of Zoology ◽

10.1111/j.1469-7998.1986.tb01507.x ◽

2009 ◽

Vol 208 (2) ◽

pp. 191-203 ◽

Cited By ~ 26

Author(s):

A. M. Dufty ◽

J. C. Wingfield

Keyword(s):

Steroid Hormones ◽

Molothrus Ater ◽

Temporal Patterns ◽

Brood Parasite

Download Full-text

Nasal mites of the brood parasite brown-headed cowbird (Molothrus ater)

10.1603/ice.2016.114797 ◽

2016 ◽

Author(s):

Alexis Hilario-Pérez

Keyword(s):

Molothrus Ater ◽

Brood Parasite

Download Full-text

Community-Wide Impacts of a Generalist Brood Parasite, the Brown-Headed Cowbird (Molothrus ater)

Ecology ◽

10.2307/2680205 ◽

2001 ◽

Vol 82 (3) ◽

pp. 868 ◽

Cited By ~ 3

Author(s):

Krista L. De Groot ◽

James N. M. Smith

Keyword(s):

Molothrus Ater ◽

Brood Parasite

Download Full-text

Costs of multiple parasitism for an avian brood parasite, the Brown-headed Cowbird (Molothrus ater)

Canadian Journal of Zoology ◽

10.1139/z11-104 ◽

2011 ◽

Vol 89 (12) ◽

pp. 1237-1248 ◽

Cited By ~ 7

Author(s):

C.B. Goguen ◽

D.R. Curson ◽

N.E. Mathews

Keyword(s):

New Mexico ◽

Intraspecific Competition ◽

Molothrus Ater ◽

Brood Parasite ◽

Egg Survival ◽

Host Nest ◽

Egg Mortality ◽

Nest Desertion ◽

Nestling Period ◽

Polioptila Caerulea

The Brown-headed Cowbird ( Molothrus ater (Boddaert, 1783)) is a generalist brood parasite that often lays into nests that contain conspecific eggs. Although it has often been assumed that this multiple parasitism reduces Cowbird survival, this has rarely been evaluated. We measured Cowbird survival in nests of the Blue-gray Gnatcatcher ( Polioptila caerulea (L., 1766)), Plumbeous Vireo ( Vireo plumbeus Coues, 1866), and Western Tanager ( Piranga ludoviciana (A. Wilson, 1811)) in New Mexico, USA. Our objectives were to measure the costs of intraspecific competition on Cowbird survival in multiply-parasitized nests, evaluate if these costs were related to host size, and to compare the costs of multiple parasitism relative to other mortality sources that occur over the entire nesting cycle. Intraspecific competition reduced Cowbird survival during the nestling period in nests of all three hosts, and was of particular importance in nests of the two smaller hosts. When all sources of egg mortality were considered, however, the costs of multiple parasitism were small compared with the large effects of predation and nest desertion. Given that multiple parasitism reduces Cowbird egg survival, it is unclear why Cowbirds multiply-parasitize. Possible explanations depend on an improved understanding of fecundity and level of host nest selectivity by female Cowbirds.

Download Full-text

Stable isotopes identify the natal origins of a generalist brood parasite, the brown-headed cowbird Molothrus ater

Journal of Avian Biology ◽

10.1111/j.0908-8857.2008.4170.x ◽

2008 ◽

Vol 0 (0) ◽

pp. 080319062618140-???

Author(s):

Karl L. Kosciuch ◽

James W. Rivers ◽

Brett K. Sandercock

Keyword(s):

Stable Isotopes ◽

Molothrus Ater ◽

Brood Parasite

Download Full-text

Persistence of host defence behaviour in the absence of avian brood parasitism

Biology Letters ◽

10.1098/rsbl.2011.0268 ◽

2011 ◽

Vol 7 (5) ◽

pp. 670-673 ◽

Cited By ~ 30

Author(s):

Brian D. Peer ◽

Michael J. Kuehn ◽

Stephen I. Rothstein ◽

Robert C. Fleischer

Keyword(s):

Brood Parasitism ◽

New World ◽

Molothrus Ater ◽

Egg Rejection ◽

Brood Parasite ◽

Bombycilla Cedrorum ◽

Defence Behaviour ◽

Cedar Waxwing ◽

Host Parasite

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 Bombycilla japonica were sister taxa, and this clade was sister to the cedar waxwing Bombycilla cedrorum . In addition, there was support for a split between Old and New World Bohemian waxwings. Our molecular clock estimates suggest that egg rejection may have been retained for 2.8–3.0 Myr since New World Bohemian waxwings inherited it from their common ancestor with the rejecter cedar waxwings. These results support the ‘single trajectory’ model of host–brood parasite coevolution that once hosts evolve defences, they are retained, forcing parasites to become more specialized over time.

Download Full-text

Shared transcriptional responses to con- and heterospecific behavioral antagonists in a wild songbird

10.1101/795757 ◽

2019 ◽

Author(s):

Matthew I. M. Louder ◽

Michael Lafayette ◽

Amber A. Louder ◽

Floria M. K. Uy ◽

Christopher N. Balakrishnan ◽

...

Keyword(s):

Behavioral Plasticity ◽

Molothrus Ater ◽

System Response ◽

Brood Parasite ◽

Functional Responses ◽

Transcriptional Responses ◽

Free Living ◽

Brood Parasites ◽

Singing Behavior ◽

Immune System Response

AbstractThe recognition of and differential responses to salient stimuli are among the main drivers of behavioral plasticity, yet, how animals evolve and modulate functional responses to novel classes of antagonistic stimuli remain poorly understood. We studied free-living male red-winged blackbirds (Agelaius phoeniceus) to test whether gene expression responses in blood are distinct or shared between patterns of aggressive behavioral responses directed at simulated conspecific versus heterospecific intruders. In this species, males defend territories against conspecific males and respond aggressively to female brown-headed cowbirds (Molothrus ater), a brood parasite that commonly lays eggs in blackbird nests. Both conspecific songs and parasitic calls elicited aggressive responses from focal subjects and caused a downregulation in genes associated with immune system response, relative to control calls of a second, harmless heterospecific species. In turn, only the conspecific song treatment elicited an increase in singing behavior and an upregulation of genes associated with metabolic processes relative to the two heterospecific calls. Our results suggest that aspects of antagonistic responses to both conspecifics and brood parasites can be based on similar physiological responses, suggestive of shared molecular and behavioral pathways involved in the recognition and reaction to both evolutionarily old and new enemies.

Download Full-text