Alarm calls of house wrens (Troglodytes aedon bonariae) elicit responses of conspecific and heterospecific species

Behaviour ◽  
2021 ◽  
pp. 1-19
Author(s):  
Mariana E. Carro ◽  
Gustavo J. Fernández

Abstract Nesting house wrens (Troglodytes aedon bonariae) use two basic alarm calls (Type I and Type II) when detect a threat near the nest. We experimentally analysed if calls distract predators or serve to recruit other birds to create a mobbing flock to deter predators. The results show that individuals preferentially position themselves in front of the threat, disclosing the location of the nest. Also, using playbacks of house wren alarm calls we found that these calls recruited both conspecific and heterospecific individuals to create a mobbing response. The alarm calls of house wrens seem to fulfil multiple functions, not only conveying information about the threat to their mates and nestling as revealed in previous studies, but also as a signal that attracts the attention of other conspecific and heterospecific individuals and can trigger a mobbing response to deter the predator.

2019 ◽  
Vol 97 (1) ◽  
pp. 50-56
Author(s):  
C.L. Gable ◽  
T.J. Underwood ◽  
G.P. Setliff

House Wrens (Troglodytes aedon Vieillot, 1809) regularly add spider egg cases (Arachnida: Araneae) to their nests, which may be an example of heterospecific cleaning. This behavior involves one animal employing another to remove parasites from their nests. In House Wren nests, juvenile spiders hatching from egg cases may facilitate the reduction of mites that feed on nestlings. We tested this ectoparasite reduction hypothesis by monitoring House Wren nests for spider egg cases and by collecting completed nests to compare the number of spider egg cases and Dermanyssus hirundinis (Hermann, 1804) mites. No significant relationship was found between the number of spider egg cases and number of D. hirundinis mites in nests. We also found no significant relationship between the number of D. hirundinis mites in nests and the body condition of nestlings. Finally, no significant difference was found between the number of D. hirundinis mites in early versus late season nests, but significantly more spider egg cases were added to late season nests. Of a subsample of spider egg cases dissected, we found that 28% contained spider eggs or embryos. We also identified three species of juvenile spiders from House Wren nests using DNA barcoding. Overall, we found no evidence that spider egg cases reduce the number of D. hirundinis mites or engender better quality offspring in House Wren nests.


1997 ◽  
Vol 75 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Stanislav Pribil ◽  
Jaroslav Picman

We tested five hypotheses that may explain why House Wren (Troglodytes aedon) nests are rarely parasitized by Brown-headed Cowbirds (Molothrus ater). House Wrens may prevent parasitism in five ways: (1) by choosing to nest in cavities with small entrances (inaccessible-entrance hypothesis), (2) by restricting the size of the entrance with nest material (nest-structure hypothesis), (3) by puncturing and ejecting parasitic eggs (puncture–ejection hypothesis), (4) by burying the parasitized clutch under a new nest (egg-burial hypothesis), or (5) by abandoning the parasitized nest altogether (nest-desertion hypothesis). We tested these hypotheses in field experiments and found that (i) female cowbirds cannot enter circular entrances smaller than 38 mm in diameter, (ii) wrens prefer cavities with small entrances (inaccessible to cowbirds) to those with large entrances (accessible to cowbirds), (iii) when forced to breed in cavities with large entrances, wrens do not reduce the entrance size with nest material, (iv) despite the unusual strength of cowbird eggs, wrens are physically capable of puncture–ejecting them, (v) wrens do not puncture–eject cowbird eggs from their own nests, (vi) wrens do not abandon parasitized nests or bury the parasitized clutches under new nests. These results are consistent with the inaccessible-entrance hypothesis. We propose that additional nesting adaptations, as well as active cowbird avoidance of House Wrens, may contribute to the low frequency of cowbird parasitism.


2010 ◽  
Vol 7 (1) ◽  
pp. 127-130 ◽  
Author(s):  
Brian S. Masters ◽  
L. Scott Johnson ◽  
Bonnie G. P. Johnson ◽  
Jessica L. Brubaker ◽  
Scott K. Sakaluk ◽  
...  

Microsatellite loci have high mutation rates and high levels of allelic variation, but the factors influencing their mutation rate are not well understood. The proposal that heterozygosity may increase mutation rates has profound implications for understanding the evolution of microsatellite loci, but currently has limited empirical support. We examined 20 microsatellite mutations identified in an analysis of 12 260 meiotic events across three loci in two populations of a songbird, the house wren ( Troglodytes aedon ). We found that for an allele of a given length, mutation was significantly more likely when there was a relatively large difference in size between the allele and its homologue (i.e. a large ‘allele span’). Our results support the proposal of heterozygote instability at microsatellite loci.


The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 183-187 ◽  
Author(s):  
Brian L. Morrison ◽  
L. Scott Johnson

Abstract This study asked whether parent House Wrens (Troglodytes aedon) in a Wyoming population increased rates of food delivery to broods parasitized by hematophagous blow fly larvae and mites. We observed no significant difference in rates at which pairs fed nestlings at nests with naturally heavy infestations of fly larvae (6–19 larvae per nestling) and nests in which nestling exposure to larvae was experimentally eliminated or severely reduced (0–2 larvae per nestling). The apparent failure of parents to compensate nestlings for resources lost to parasites may, in part, explain the reduced rates of mass gain by parasitized nestlings that we observed and the presence of reduced hemoglobin levels in parasitized nestlings documented in a companion study. Parasitized nestlings may be too weak or anemic to intensify begging activity which would alert parents to their increased need for food. Alimentación de Polluelos de Troglodytes aedon Afectada por Ectoparásitos Hematófagos: Una Prueba de la Hipótesis de Compensación Parental Resumen. Nos preguntamos si los individuos parentales de Troglodytes aedon de una población de Wyoming aumentan las tasas de alimentación sobre polluelos parasitados por ácaros y larvas de moscas hematófagas. No observamos diferencias significativas en la tasa a la cual las parejas alimentaron a los polluelos entre nidos altamente infectados naturalmente por la larva de la mosca (6–19 larvas por polluelo) y nidos en que la exposición a las larvas fue eliminada o severamente reducida experimentalmente (0–2 larvas por polluelo). En parte, la aparente falta de compensación por parte de los padres sobre la pérdida de recursos de los polluelos infectados puede explicar sus bajas tasas de ganancia de peso y los niveles reducidos de hemoglobina documentados en un estudio asociado al presente. Los polluelos parasitados probablemente se encuentran muy débiles o anémicos como para intensificar la actividad de reclamo lo que alertaría a los padres sobre su mayor necesidad de alimento.


2001 ◽  
Vol 79 (8) ◽  
pp. 1527-1531 ◽  
Author(s):  
L Scott Johnson ◽  
Jennifer E Leyhe ◽  
Caryn Werner

The substantial inter- and intra-specific variation that occurs in the shape of birds' eggs remains largely unexplained. Several researchers have hypothesized that selection will favour a shape that results in the most compact fit of eggs under the incubating parent. Mathematical modeling has suggested that optimal egg shape depends on the number of eggs laid. We tested predictions of one previously published model by comparing the shape of eggs in clutches of 4, 5, 6, 7, and 8 eggs in a Wyoming, U.S.A., population of the house wren (Troglodytes aedon), a small, cavity-nesting songbird whose eggs vary considerably in shape. Contrary to predictions of the model, the typical shapes of eggs from different-sized clutches were very similar. Moreover, slight differences in shape detected were not in directions predicted by the model. There may be less selection on house wrens to adjust egg shape to clutch size because they lay eggs that are small relative to female body size, because eggs are placed in a deep spherical cup that conforms to the shape of the female's abdomen and because nests are to some degree insulated, being located in tree cavities. Full evaluation of the model will require comparisons of egg shape and clutch size in a large set of species that differ in natural-history characteristics such as egg size, nest shape, and nest placement.


2014 ◽  
Vol 92 (1) ◽  
pp. 1-7 ◽  
Author(s):  
C.F. Thompson ◽  
S.K. Sakaluk ◽  
B.S. Masters ◽  
B.G.P. Johnson ◽  
L.A. Vogel ◽  
...  

Adult male and female birds typically respond differently to immunological challenges, but whether this difference is present in altricial nestlings is not well-documented. Furthermore, the timing of the development of different axes of the immune system might vary in nestlings and also be affected by differences in condition and health state. We tested for sex-related differences in the immune response of nestling House Wrens (Troglodytes aedon Vieillot, 1809) to the injection of phytohaemagglutinin (PHA) and in the bacteria-killing capacity of their plasma. Based on prior work, we predicted that if there were sex-related differences in immune responsiveness, they would most likely occur when the sexes differed in some measure of condition or health state. Female nestlings had a stronger response to the injection of PHA than males in the one of three breeding seasons in which the condition of nestling females exceeded that of males, suggesting that the response to PHA injection is condition-dependent rather than sex-dependent. The sexes, however, did not differ in bactericidal activity, suggesting that different axes of the immune system may not be affected to the same degree by differences in sex or in condition.


1996 ◽  
Vol 74 (2) ◽  
pp. 278-282 ◽  
Author(s):  
L. Scott Johnson ◽  
Robert M. R. Barclay

The normal food of most small birds (insects, seeds, and fruit) contains relatively little calcium. Birds must therefore supplement their diets, and those of their dependent young, with bits of calcium-rich material such as bone, limestone, eggshells, and mollusk shells. In this study, the question of whether the availability of calcium constrains reproductive output in a Wyoming population of the House Wren (Troglodytes aedon), a small insectivorous passerine, was asked. A randomly selected group of breeding pairs was provided with a mix of crushed oystershell and chicken eggshell at their nests for the duration of their breeding cycles. Calcium-supplemented birds tended to lay more eggs per clutch and tended to raise fledglings with slightly longer feathers than unsupplemented control birds. Calcium-supplemented birds did not, however, lay larger eggs, produce more fledglings, or produce fledglings of greater mass than control birds. Unlike the situation in many anthropogenically acidified environments, calcium availability apparently does not constrain the reproductive output of House Wrens breeding in this one environment that appears to be relatively unaffected by acidic precipitation.


Behaviour ◽  
2018 ◽  
Vol 155 (2-3) ◽  
pp. 151-180 ◽  
Author(s):  
Cara A. Krieg ◽  
Thomas Getty

Abstract Individuals should fight hardest when they stand to lose the most. Whereas males frequently compete for fertile females, females more often compete for high quality males, male care, or resources required to breed. We asked whether established, territorial female house wrens (Troglodytes aedon) challenged by simulated female intruders fight as if they place more value on retaining (1) their nesting cavity or (2) exclusive access to other benefits offered by males. We randomly assigned house wren pairs to receive one or three nest boxes and then assayed female aggression. The relative costs to losing differed between box treatments. For one-box females, the risk of losing the cavity and territory was higher. For three-box females, the risk of losing the cavity may be lower because intruders may be able to settle as secondary females in the supplemental boxes. In this situation, females would lose exclusive access to males and their territories but would still retain the male’s assistance rearing offspring since male house wrens favour their oldest brood. We found that one-box females were significantly more aggressive. This response may be adaptive, as females that switched territories between broods were significantly more likely to lose their entire nest prior to hatching than females that retained the same territory. We interpret our results to mean that female house wrens value the nest cavity more than other benefits from exclusive access to males and their territories. This work contributes to a body of evidence that females often compete for resources required to breed.


The Condor ◽  
2002 ◽  
Vol 104 (4) ◽  
pp. 881-885
Author(s):  
Shannon M. Janota ◽  
Sheryl Swartz Soukup ◽  
Charles F. Thompson

AbstractThe sex-ratio adjustment hypothesis predicts that females should modify offspring sex ratios according to the potential reproductive success of their offspring under existing ecological conditions. We tested this hypothesis in the polygynous, sexually size-monomorphic House Wren (Troglodytes aedon). Typically, nestling House Wrens that hatch in the first half of the three-month breeding season are heavier and have higher rates of survival and recruitment than those that hatch in the second half of the season. Therefore, the sex-ratio adjustment hypothesis predicts that early broods should be more male biased than later broods, because males in good condition have higher reproductive value than females. As conditions deteriorate, broods should become less male biased because female offspring have higher reproductive value than males in poor condition. Contrary to expectation, there was no seasonal decrease in offspring condition, and the sex ratio of broods was consistently male biased throughout the breeding season. We conclude that the results are consistent with the sex-ratio adjustment hypothesis, because in the year of this study female House Wrens were able to produce offspring in similar (and presumably good) condition throughout the breeding season; therefore, they continued to produce broods that were significantly male biased.Sesgo hacia Machos en el Cociente de Sexos de la Prole en Troglodytes aedonResumen. La hipótesis sobre el ajuste del cociente de sexos predice que las hembras deberían modificar el cociente de sexos de la prole en relación al éxito potencial reproductivo de la prole bajo las condiciones ecológicas existentes. Evaluamos esta hipótesis en Troglodytes aedon, especie polígina y sin diferencias sexuales de tamaño. Típicamente, los pichones de T. aedon que eclosionan en la primera mitad de la estación reproductiva (que dura tres meses) son más pesados y presentan tasas de supervivencia y reclutamiento más altas que aquellos que eclosionan en la segunda mitad de la estación. De este modo, la hipótesis sobre el ajuste del cociente de sexos predice que las camadas tempranas deberían estar más sesgadas hacia los machos que las camadas más tardías, ya que los machos en buena condición tienen un valor reproductivo más alto que las hembras. A medida que la condición se deteriora, las camadas deberían estar menos sesgadas hacia los machos debido a que los vástagos de sexo femenino tienen un valor reproductivo más alto que los machos en mala condición. Contrariamente a lo esperado, no hubo una disminución estacional en la condición de la prole, y el cociente de sexos de las camadas estuvo consistentemente sesgado hacia los machos a lo largo de la estación de cría. Concluimos que los resultados son consistentes con la hipótesis sobre el ajuste del cociente de sexos, ya que durante el año de este estudio las hembras de T. aedon fueron capaces de producir proles en condiciones similares (y presumiblemente buenas) a lo largo de la estación de cría. De este modo, las hembras continuaron produciendo camadas que estuvieron significativamente sesgadas hacia los machos.


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