scholarly journals Eavesdropping on Referential Yellow Warbler Alarm Calls by Red-Winged Blackbirds Is Mediated by Brood Parasitism Risk

2021 ◽  
Vol 9 ◽  
Author(s):  
Shelby L. Lawson ◽  
Janice K. Enos ◽  
Sharon A. Gill ◽  
Mark E. Hauber

Referential alarm calls that denote specific types of dangers are common across diverse vertebrate lineages. Different alarm calls can indicate a variety of threats, which often require specific actions to evade. Thus, to benefit from the call, listeners of referential alarm calls must be able to decode the signaled threat and respond to it in an appropriate manner. Yellow warblers (Setophaga petechia) produce referential “seet” calls that signal to conspecifics the presence of nearby obligate brood parasitic brown-headed cowbirds (Molothrus ater), which lay their eggs in the nests of other species, including yellow warblers. Our previous playback experiments have found that red-winged blackbirds (Agelaius phoeniceus), a species also parasitized by brown-headed cowbirds, eavesdrop upon and respond strongly to yellow warbler seet calls during the incubation stage of breeding with aggression similar to responses to both cowbird chatters and predator calls. To assess whether red-winged blackbird responses to seet calls vary with their own risk of brood parasitism, we presented the same playbacks during the nestling stage of breeding (when the risk of brood parasitism is lower than during incubation). As predicted, we found that blackbirds mediated their aggression toward both cowbird chatter calls and the warblers’ anti-parasitic referential alarm calls in parallel with the low current risk of brood parasitism during the nestling stage. These results further support that red-winged blackbirds flexibly respond to yellow warbler antiparasitic referential calls as a frontline defense against brood parasitism at their own nests.

2013 ◽  
Vol 91 (7) ◽  
pp. 505-511 ◽  
Author(s):  
C.A. Rock ◽  
S.P. Quinlan ◽  
M. Martin ◽  
D.J. Green

Brood parasitism by Brown-headed Cowbirds (Molothrus ater (Boddaert, 1783)) often reduces the reproductive success of their hosts. We examined whether the ability of females to avoid or mitigate the costs of brood parasitism improved with age in a population of Yellow Warblers (Setophaga petechia (L., 1766)) breeding near Revelstoke, British Columbia, between 2004 and 2011. Cowbirds parasitized 18% of Yellow Warbler nesting attempts and females rejected 24% of parasitized nests, principally by deserting the nest and initiating a new breeding attempt. We found no evidence that older females were better at avoiding parasitism or more likely to reject parasitized nests than yearlings. On average, brood parasitism reduced clutch sizes by 0.8 eggs, had no effect on nest success, but reduced the number of young fledged from successful nests by 1.3 offspring. Despite age-related improvement in some measures of breeding performance, the costs of brood parasitism at each period of the breeding cycle did not vary with age. There was, however, some evidence, that brood parasitism reduced the annual productivity (total number of young fledged) of older females less than the annual productivity of yearlings suggesting that the cumulative costs of brood parasitism varied with age.


2014 ◽  
Vol 128 (1) ◽  
pp. 44
Author(s):  
Spencer G. Sealy

Twenty cases of double brooding by colour-marked Yellow Warblers (Setophaga petechia) were recorded in 5 of 11 years (1975–1986, no data collected in 1977) during studies of breeding ecology in the dune-ridge forest at Delta Marsh, Manitoba (1 pair in 1975, 3 pairs in 1976, 3 pairs in 1984, 9 pairs in 1985, and 4 pairs in 1986). At least one member of each of the 20 pairs was marked. Eleven pairs re-used their first nest for the second attempt, whereas 9 females built a new nest, in 5 cases because the original nests had disintegrated. Four of the second nests (3 in 1985 and 1 in 1986) were parasitized by Brown-headed Cowbirds (Molothrus ater). All 20 first nests produced at least one young, a condition for double brooding, and 13 second nests, including 3 that were parasitized, were successful. Failure of about 60% of annual nesting attempts at Delta Marsh may contribute to the low number of pairs with double broods recorded in some years and the absence of double brooding in years of comparable phenology. This is the first published evidence of double brooding in the Yellow Warbler.


2012 ◽  
Vol 90 (3) ◽  
pp. 320-328 ◽  
Author(s):  
S.P. Quinlan ◽  
D.J. Green

Ecological traps arise when anthropogenic change creates habitat that appears suitable but when selected reduces the fitness of an individual. We evaluated whether riparian habitat within the drawdown zone of the Arrow Lakes Reservoir, British Columbia, creates an ecological trap for Yellow Warblers ( Setophaga petechia (L., 1766)) by investigating habitat preferences and the fitness consequences of habitat selection decisions. Preferences were inferred by examining how habitat variables influenced settlement order, and comparing habitat at nest sites and random locations. Males preferred to settle in territories with more riparian shrub and tree cover, higher shrub diversity, and less high canopy cover. Females built nests in taller shrubs surrounded by a greater density of shrub stems. Habitat preferences were positively associated with fitness: nest sites in taller shrubs surrounded by higher shrub-stem densities were more likely to avoid predation and fledge young, whereas territories with more riparian cover, higher shrub diversity, and less high canopy cover had higher annual productivity. We therefore found no evidence that riparian habitat affected by reservoir operations functions as an ecological trap. Current habitat selection decisions may be associated with fitness because Yellow Warblers are adapted to breeding in a heterogeneous environment subject to periodic flooding.


2003 ◽  
Vol 81 (10) ◽  
pp. 1685-1690 ◽  
Author(s):  
Sharon A Gill ◽  
Spencer G Sealy

During nest defence, yellow warblers (Dendroica petechia) give "seet" and "chip" calls. Seet calls are given preferentially toward brood parasitic brown-headed cowbirds (Molothrus ater) during the yellow warblers' egg-laying period, whereas chip calls are given toward mammalian and avian nest predators throughout the nesting period. In this study, we investigated two possible functions of seet and chip calls during nest defence by playing alarm calls to nesting yellow warblers. We tested whether nest owners give seet and chip calls during defence to alert their offspring and their mates about nest threats and, in the latter case, whether the alarm calls differ in function depending on nesting stage. In response to playbacks, nestlings remained inactive for a significantly longer period when chip calls were played than when seet calls were played. Female yellow warblers returned to their nesting areas more quickly when seet calls were played than when chip calls were played, but pairs were equally likely to return to the nesting area in response to both call types. These findings suggests that both seet and chip calls alert mates but that only chip calls function to alert nestlings of potential danger.


Behaviour ◽  
1996 ◽  
Vol 133 (3-4) ◽  
pp. 263-282 ◽  
Author(s):  
Sharon A. Gill ◽  
Spencer G. Sealy

AbstractYellow warblers (Dendroica petechia) were exposed to taxidermic mounts of a brood parasite (brown-headed cowbird, Molothrus ater), avian nest predator (common grackle, Quiscalus quiscula) and control (fox sparrow, Passerella iliaca) during their laying and nestling stages to determine whether nest owners distinguish between the threats of brood parasitism and predation. Yellow warblers responded more intensely to the cowbird at the laying stage, performing two unique behaviours (seet calling and nest-protection behaviour) in response to this threat. By contrast, yellow warbler responses to the grackle were greater at the nestling stage, consisting largely of alarm calls (chip, metallic chip and warble calls). The sparrow model infrequently elicited aggressive behaviour from nest owners at either stage. These responses support the hypothesis that yellow warblers discriminate between threats of brood parasitism and nest predation. Yellow warblers may perform specific behaviours to cowbirds because defensive behaviours used against predators may be incompatible with cowbird deterrence. Female nest owners responded more frequently than males at the laying stage, and more intensely than males at both nesting stages. The distance that females and males approached the models and several aggressive behaviours were positively correlated. The greater responsiveness of females may be because they dominate their mates and because females are more experienced with intruders near the nest.


2021 ◽  
Vol 17 (9) ◽  
pp. 20210377
Author(s):  
Shelby L. Lawson ◽  
Janice K. Enos ◽  
Caroline S. Wolf ◽  
Katharine Stenstrom ◽  
Sarah K. Winnicki ◽  
...  

Yellow warblers ( Setophaga petechia ) use referential ‘seet’ calls to warn mates of brood parasitic brown-headed cowbirds ( Molothrus ater ). In response to seet calls during the day, female warblers swiftly move to sit tightly on their nests, which may prevent parasitism by physically blocking female cowbirds from inspecting and laying in the nest. However, cowbirds lay their eggs just prior to sunrise, not during daytime. We experimentally tested whether female warblers, warned by seet calls on one day, extend their anti-parasitic responses into the future by engaging in vigilance at sunrise on the next day, when parasitism may occur. As predicted, daytime seet call playbacks caused female warblers to leave their nests less often on the following morning, relative to playbacks of both their generic anti-predator calls and silent controls. Thus, referential calls do not only convey the identity or the type of threat at present but also elicit vigilance in the future to provide protection from threats during periods of heightened vulnerability.


Behaviour ◽  
2001 ◽  
Vol 138 (10) ◽  
pp. 1287-1302 ◽  
Author(s):  
Aliza Le Roux ◽  
Michael Cherry ◽  
Tim Jackson

AbstractThe function of variation in single call duration and alarm calling bouts was investigated in Brants' whistling rat, Parotomys brantsii, by means of playback experiments and video analyses of the vigilance displayed. Short calls are produced in high-risk situations, and long calls in low-risk encounters, but these calls apparently do not communicate this variance in risk to conspecifics. Both short and long single calls induced heightened vigilance in receivers, but rats did not respond differentially to the two call types, and it was concluded that P.brantsii alarm calls are not functionally referential. Multiple calls maintained a state of increased alertness in receivers for a longer period than single calls, even after the bouts had ended, but long bouts (duration: 64 s) did not lead to longer periods of vigilance than short bouts (29 s). Thus the tonic communication hypothesis is only partially supported by our study.


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