Egg mimicry by obligate avian brood parasites and host rejection of non-mimetic eggs are well-known textbook examples host–parasite coevolution. By contrast, reciprocal adaptations counteradaptations beyond the egg stage in their hosts have received less attention. The screaming cowbird ( Molothrus rufoaxillaris ) is a specialist parasite whose fledglings look identical to those its primary host, baywing Agelaioides badius ). Such resemblance has been proposed as an adaptation response...

We studied the breeding biology of Baywing (Agelaioides badius), a shared host Screaming (Molothrus rufoaxillaris) and Shiny (M. bonariensis) cowbirds. monitored 193 nests from December 2002 to March 2007 in Province Buenos Aires, Argentina. Baywings used wide variety nesting sites, mainly old furnarids. Their season lasted late November February was closely matched by that Cowbirds. The for Cowbirds started September but overlapped Baywings. Frequency intensity Cowbird parasitism were 93% 5...

The hosts of brood parasitic birds are under strong selection pressure to recognize and remove foreign eggs from their nests, but parasite may be too large grasped whole readily pierced by the host's bill. Such operating constraints on egg removal proposed force some accept eggs, as costs deserting parasitized clutches can outweigh cost rearing parasites. By fitting microcameras inside we reveal that Neotropical baywing (Agelaioides badius), a host screaming cowbird (Molothrus rufoaxillaris)...

Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or generalists. The screaming cowbird Molothrus rufoaxillaris is one of most specialized parasites, using a single host, bay-winged ( Agelaioides badius ) over its range. Coevolutionary theory predicts increasing specificity longer parasite interacts with particular community, as hosts evolve defences that cannot counteract. According this view, can be maintained if cowbirds avoid...

Obligate brood parasites should synchronize parasitism with host laying to maximize egg hatchability and chick survival. While the generalist Shiny (Molothrus bonariensis), Brown-headed (M. ater), Bronzed aeneus) Cowbirds frequently laying, specialist Screaming rufoaxillaris) very often fail do so in nests of their main host, Bay-winged Cowbird (Agelaioides badius). The poor synchronization may be result low availability at time higher nest attentiveness by during or unpredictable behavior....

The vocalizations of some young brood-parasitic birds closely resemble those their host's young. Such similarities might arise because hosts bestow the greatest parental care in response to own species' call type. We used a playback experiment assess effectiveness nestling structures 2 brood parasites, specialist screaming cowbird (Molothrus rufoaxillaris) and generalist shiny (M. bonariensis), stimulating provisioning shared host, baywing (Agelaioides badius). Screaming begging calls thus...

Brood-parasitic cowbirds (Molothrus spp.) can cause total nest failure directly by inducing desertion or destroying the host's clutch indirectly facilitating predation. We examined relationship between brood parasitism and survival in Bay-winged Cowbird (Agelaioides badius), primary host of Screaming (M. rufoaxillaris) a secondary Shiny bonariensis). used program MARK to model daily nest-survival rates, including hypothesized effects intensity parasitism, egg losses caused cowbirds, size....

Brood-parasitic cowbirds (Molothrus spp.) exploit the parental care of other species (hosts) that raise their offspring. Parasitism by reduces host reproductive success in several ways and quantifying such costs is an important step to better understand evolutionary interactions host-parasite associations. We estimated parasitism host-specialist Screaming Cowbird (M. rufoaxillaris) its primary host, Baywing (Agelaioides badius). tested effect on egg survival, hatching success, nestling...

The cowbirds (Molothrus, Icteridae) are a monophyletic group that includes five extant brood-parasitic species. Screaming (M. rufoaxillaris), Giant oryzivorus) and Shiny bonar- iensis) range mostly in South America. the ancestral most recent species of clade, respectively, therefore, differing how long they have coevolved with their hosts. We present new experimental data on egg-rejection host Cow- bird, House Wren (Troglodytes aedon), review different lines antiparasitic defenses hosts...

Young birds communicate their need to parents through complex begging displays that include visual and acoustic cues. Nestlings of interspecific brood parasites must ‘tune’ into these communication channels secure parental care from hosts. Various studies show parasitic nestlings can effectively manipulate host behaviour calls, but how manipulative signals develop in growing remains poorly understood. We investigated the influence social experience on call development a host‐specialist...

ABSTRACT Kin selection theory predicts that extrapair mating should be rare in cooperatively breeding birds. However, most cooperative breeders are not genetically monogamous and the relationship between promiscuity remains unclear. This is further complicated by a lack of data. The majority birds live tropics, their genetic systems little known. Here we studied system Grayish Baywing (Agelaioides badius), socially Neotropical blackbird which nesting pairs assisted helpers, previously...

Avian obligate brood parasites exploit the parental care of individuals other species (hosts) that rear parasitic offspring at expense their own reproductive success. The costs parasitism select for antiparasitic defences in host populations (i.e., adaptations reduce impact parasitism). This, turn, may favour counteradaptations parasite population, leading to a coevolutionary arms race between and host. We review reciprocal specialist parasite, Screaming Cowbird (Molothrus rufoaxillaris),...

Juveniles of interspecific avian brood parasites need to locate and recognize conspecifics continue their life cycle after being reared by individuals another species. However, little is known about the recognition mechanisms cues involved in this critical stage lives. It has been proposed that adult could show some kind parental behavior actively searching interacting with conspecific young, which turn serve juveniles learn and/or reinforce learning characteristics. Since acoustic...

Cooperative breeding is a reproductive system in which one or more adults (helpers) assist others rearing their offspring. occurs 9% of birds, encompassing remarkable variation mating systems and patterns social organization. Understanding how this diversity evolved requires assessing genetic relationships across broad range cooperative systems. Yet, for some geographical regions like the Neotropics, detailed studies cooperatively birds are still comparatively scarce. We used double‐digest...