Singing on the nest is a widespread behavior in incubating Northern Mockingbirds and increases probability of nest predation (original) (raw)
Related papers
Animal behaviour, 1990
Mockingbirds commonly show clutch overlap, initiating work on a subsequent brood while older young remain dependent on parental care. Several days before the male begins to build a new nest, he resumes singing. The result is a cyclic pattern of singing in which song ceases during the nestling period and recurs each time the male builds a nest. To determine if song can stimulate renesting in the presence of dependent young, and thereby regulate the amount of clutch overlap, mated males were played song earlier in the breeding cycle than they would normally begin to sing. Experimental pairs were played 140 min of mockingbird song per day in their territories beginning at nestling day 6 and continuing through the onset of renesting. They began nest building sooner and built more before the older young fledged than either males that heard no song or two that heard brown thrasher, Toxastoma rufum, song. In several pairs hearing mockingbird song, nest building continued after the stimulus song ceased, and the female laid in the nest begun in response to song. The amount of nest building was positively correlated with the male's initial aggressive reaction to the speaker playing song, but unrelated to the amount of his own song production. These data constitute the first demonstration in the field of the role of passerine song in re-initiating breeding in established pairs.
Reproductively dependent song cyclicity in mated male mockingbirds (Mimus polyglottos)
The Auk, 1983
Mockingbird (Mimus polyglottos) song has been demonstrated to function in the species' perennial territoriality. Data reported here suggest that this species' diverse song may also function intersexually in reproduction. Observations on the amount of song produced by identified males throughout the breeding season revealed a pronounced cyclicity in the occurrence of song. Further, song cyclicity was systematically associated with the nature of the breeding activity in progress. In each of six mated males, the amount of song increased substantially while the male was nest building. The amount of song decreased significantly during incubation and during the care of offspring. This relationship held even when the cycle of breeding activities was disrupted through nest loss; males resumed singing immediately, although losses often occurred during periods of very little song. Analyses indicated that the nest-building song burst did not result from the activities involved in nest construction itself but often preceded the first observed instance of nest building. Increased song during nest building cannot be explained by excess amounts of unoccupied singing time available to males not engaged in the care of offspring. The overall pattern of results indicates that Mockingbird song may function in reproductive as well as in territorial contexts. Further, the cyclic relationship between song and breeding activities suggests that song may constitute a mechanism by which the reproductive state of the female is rapidly reset in preparation for subsequent broods.
Journal of Field Ornithology, 2011
Nestling begging and parental provisioning can attract nest predators and reduce reproductive success, so parents and their offspring might be expected to respond adaptively by minimizing predator-attracting cues when predators threaten nests. Male Red-winged Blackbirds (Agelaius phoeniceus) are well known for their antipredator alarm calls that contain information about the approach of potential nest predators. We examined the begging behavior of nestlings and the provisioning behavior of females in response to antipredator alarm calls of males to test the adaptive response hypothesis. Playback experiments provided no evidence that alarm calls function to switch off vocal begging; nestlings were equally likely to beg vocally during playback and control periods. Video recordings showed that male alarm calling had no significant effect on inappropriate vocal begging (in the absence of an adult), but significantly reduced the incidence of spontaneous calling (in the absence of begging). Adult females responded to male antipredator alarm calls by delaying their provisioning visits. In addition, although having no significant effect on use of nest-arriving calls by females, male alarm calling significantly reduced their use of nest-leaving calls. We conclude that nestling and female Red-winged Blackbirds respond to male alarm calls in ways that might reduce the risk of predation, but nestlings beg vocally when females arrive to feed them, regardless of male alarm calling, perhaps to avoid a competitive disadvantage with broodmates.
Sheep in wolf's clothing: host nestling vocalizations resemble their cowbird competitor's
Proceedings of the Royal Society B: Biological Sciences, 2008
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 with a brown-headed cowbird ( Molothrus ater ) chick to evaluate how host nestlings respond. Vocalizations emitted from experimentally parasitized nests were higher in frequency, and louder, than those from unparasitized nests, consistent with the cowbird exaggerating its signalling. In response, host nestlings exaggerated the frequency and amplitude of their vocalizations, such that they resembled the cowbird's while they ‘scaled back’ on calls per parental provisioning bout. Sparr...
Calling at a cost: elevated nestling calling attracts predators to active nests
Biology Letters, 2011
Begging by nestling birds has been used to test evolutionary models of signalling but theory has outstripped evidence. Eavesdropping predators potentially impose a cost on begging that ensures signal honesty, yet little experimental evidence exists for such a cost at active nests because the use of artificial nests, long playback bouts and absence of parents may have exaggerated costs. We broadcast short periods (1 h) of either nestling vocalizations or background noise at active white-browed scrubwren, Sericornis frontalis , nests. Nestlings called naturally during both treatments, allowing us to test whether elevated calling increases risk, a key but rarely tested assumption of evolutionary models. Predators visited nests exclusively during periods of elevated calling. Furthermore, playbacks affected neither adult visits nor nestling activity, suggesting that calling alone attracted predators. Adults gave alarm calls and nestlings usually called less when predators approached nest...
Conservation Biology, 2004
Pre_&lot_' al Arlficial aml RealNests 7bol_zDso_l &Bzo+atls IC) y de 2-154% en nidos wales pot mam_Oros y ayes, respectivamente. No se pudieron utilizar los nidos artiflciales con t)uet'os de plastilina _ottf.i£1bleme_tte para identi_ltr deJ)redaeh)res. Et_ ratios _tsos, los huevos de plastilina J_teron marcados por izttones y se _lm6 a mapacbes removiendo el huevo dt. codorni_. DeOido a que los se.2gos para nidos artificialesJ_teron positivos pa_t algunos depredadoresy negativos para otros (y podrfa n compensarse) y existieron potencialmen te pa ra todos los grltpos de depredadores, se debe descottfiar en conclltsio_t£,s basadas e_l e$ltldios co_ nidos artifi'ciales (flirt clt(oldo haya el,ide?lcia de qtte las tasas generales tie depmdaci6n en nidos *_ales y artlficiales scan similares.
Mate attraction by autumnal song in the Northern Mockingbird (Mimus polyglottos)
The Auk, 1991
We do not understand what benefit, if any, accrued to the wagtail from feeding the dipper nestlings. Dawkins (1976) suggested that birds adopting alien young might benefit in gaining experience as a parent. Although this explanation might account for inexperienced birds feeding heterospecific nestlings, it seems unsuitable for the behavior of this Gray Wagtail, given that he simultaneously fed his own brood, at least one of which fledged. Instead, the prolonged investment in the dipper nestlings was more probably a realadaptive response to the proximity of loudly begging chicks. Strong responsiveness to stimuli associated with dependent young may have advantages that compensate for the rare instances in which that responsiveness results in maladaptive behavior. It may be significant that wagtail nestlings are much quieter than dipper nestlings. The dippers' calls may have acted as a "super-normal" stimulus (Tinbergen 1948) to trigger feeding of the alien young as the male passed en route to his own nest with food. One prediction of this hypothesis is that noisy nestlings would be more likely to be fed by heterospecifics than quiet nestlings, especially if the young of the adopting species are quiet. A significant aspect of our observations is that spontaneous interspecific feeding, once initiated, may be self-perpetuating. First, increased feeding by the heterospecific reduces the parents' contribution and, consequently, their activity near the nest. The interspecific aggression that might deter the adopting bird is therefore less likely to occur. Second, the sign stimuli that initially occasioned the interspecific feeding (e.g. begging calls, gaping mouths) may become associated with the sight of the alien nest and with approaches to it, thus increasing the probability that the adopting bird will return to the alien nest. A comprehensive understanding of the proximal mechanisms underlying interspecific feeding, and any ecological and evolutionary consequences, awaits additional data.
Animal Behaviour, 1989
Understanding the function of behaviour requires analysis of fitness costs and benefits, but this is difficult because methods of assessment are usually lacking. In this paper the results of an experimental analysis of costs and benefits of a vocal signal, the nest-associated call of the female red-winged blackbird are reported. Female red-winged blackbirds gave nest-associated calls during arrival and departure from their nests, and while on their nests. The intersexual 'Chit' was the call most often given in these contexts, and was frequently given in answer to the songs of mates. To assess the potential cost of nest-associated calling, mock nests containing plaster eggs were placed at suitable nest sites. Nests accompanied by playback of tape-recorded Chit calls were depredated at higher rates than nests without playback. Mock nests were also used to assess the potential benefit of nest-associated calling. Nests accompanied by playback were more strongly defended against a simulated predator by male red-winged blackbirds than nests without playback. To estimate the net benefit of nest-associated calling, the vocal behaviour of successful (produced at least one fledgling) and unsuccessful (nest depredated) females was compared. Reproductively successful females answered the songs of their mates with Chit calls from the nest more often than unsuccessful females. Nest-associated Chits thus appear to confer a net benefit on female redwinged blackbirds by maintaining the vigilance of males against nest predators.
Ethology, 2010
Parental investment and environmental conditions determine reproductive success in wild-ranging animals. Parental effort during incubation, and consequently factors driving it, has profound consequences for reproductive success in birds. The female nutrition hypothesis states that high male feeding enables the incubating female to spend more time on eggs, which can lead to higher hatching success. Moreover, both male and female parental investment during incubation might be signalled by plumage colouration. To test these hypotheses, we investigated relationships between male and female incubation behaviour and carotenoid and melanin-based plumage colouration, territory quality and ambient temperature in the Great Tit Parus major. We also studied the effect of female incubation behaviour on hatching success. Intensity of male incubation feeding increased with lower temperatures and was higher in territories with more food supply, but only in poor years with low overall food supply. Female nest attentiveness increased with lower temperatures. Plumage colouration did not predict incubation behaviour of either parent. Thus, incubation behaviour of both parents was related mainly to environmental conditions. Moreover, there was no relationship between male incubation feeding, female nest attentiveness and hatching success. Consequently, our data were not consistent with the female nutrition hypothesis.
Nest defense and parental investment in Song Sparrows (Melospiza melodia)
Canadian Journal of Zoology, 2016
Individual variation in nest defense behaviour is common in altricial birds, but despite clear predictions about why such variation exists, there is no consensus on its causes. We tested for an influence of five predictors of individual variation in nest defense behaviour, including time of season, offspring age, parental age and sex, and clutch size in a well-studied Song Sparrow (Melospiza melodia (A. Wilson, 1810)) population. We recorded parental responses to a standardized human approach and used model selection to assess support for each predictor. Parents tended to approach observers less closely and alarm-call less as the breeding season progressed, indicating a modest seasonal decline in parental nest defense, which is consistent with the hypothesis that the reproductive value of offspring influenced parental defense behaviour. Clutch size effect estimates were insignificant, but it was weakly supported as a predictor of nest defense, which is expected if parental investmen...