House Wrens Troglodytes Aedon Research Articles

Density‐dependent natal philopatry in southern House Wrens

Staying or leaving the natal site is a decision that not only affects the individual but may have profound implications at the population level. Many studies have analysed natal philopatry in passerines, albeit mostly migratory species in the northern hemisphere. Here we explore the potential ecological drivers of the individual decision to remain or leave the natal site in a southern hemisphere sedentary species, the southern House WrenTroglodytes aedon bonariae. Using a 14‐year database, we assessed if juvenile local recruitment was affected by demographic and/or social factors. Average annual juvenile recruitment was 18.4%, but it varied between years (range 9.3–44%), and male recruitment was higher than female recruitment. Juvenile recruitment was negatively associated with adult breeding abundance in the hatching year, but was not related to variation in adult sex ratio, adult breeding abundance in the breeding year or nesting success. Also, we found no evidence of inbreeding avoidance. The results seem to support the hypothesis that philopatry rate is regulated by intraspecific competition for resources. Juveniles that fledge in years when the density of breeding adults is low may have advantages in obtaining territories and mates early, benefiting from settling in familiar areas and reducing dispersal costs.

Genetic structure in neotropical birds with different tolerance to urbanization

Gene flow in birds can be affected by urbanization depending on natural history traits and adaptability to habitat change. Contrasting results can be expected when comparing species with opposite resilience to urbanization. In this study, we assessed genetic diversity and structure for two bird species, the urban avoider white-eared ground-sparrow, Melozone leucotis, and the urban dweller house wren Troglodytes aedon. We used seven microsatellite loci and sampled five locations with differing levels of urbanization in Costa Rica. We found considerably higher genetic structure in white-eared ground-sparrows than in house wrens. Circuit theory analyses proved a higher isolation from urban resistance for the white-eared ground-sparrow than for house wrens. These results support that urbanization is a significant barrier for gene flow in urban avoiders, in contrast to urban dweller species that showed little to no impact. Differences could be attributed to a higher plasticity in habitat and nesting site preferences in the house wren, and significant dispersal limitation for the white-eared ground-sparrow. These results emphasize the need for conservation strategies towards white-eared ground-sparrows and other urban avoider species whose habitat and connectivity have been reduced by the recent urban expansion.

Preferential Begging Responses of Shiny Cowbirds to the Conspecific Chatter Call

Avian brood parasites lay their eggs into the nests of other species, which incubate them and raise the chicks until their independence. Despite living their early weeks of life surrounded by heterospecifics, young brood parasites have the ability to recognize and associate to conspecifics after independence. It has been proposed that the initial conspecific recognition develops when a young parasite encounters a unique species-specific signal that triggers the learning of other aspects of the producer of the signal. For cowbirds (Molothrus spp.), this species-specific signal is hypothesized to be the chatter call. Young birds also could express auditory biases, which in some cases lead to discrimination in favor of conspecific songs. Therefore, the perceptual selectivity for chatters might be also present in nestlings. Our aim was to assess if nestlings of the shiny cowbird (M. bonariensis) present a preferential begging response to conspecific chatter calls. We evaluated if they respond more to the parasitic vocalization than host chicks and if they respond more to the chatter than to heterospecific nonhost calls. We tested shiny cowbird chicks reared by chalk-browed mockingbirds (Mimus saturninus) or house wrens (Troglodytes aedon) and host chicks, as control species. We randomly presented to 6-day-old chicks the following playback treatments: (1) conspecific chatter calls, (2) host calls, used as positive controls, and (3) nonhost calls, used as negative control. We measured if chicks begged during the playback treatments and the begging intensity. When responding to the playback of chatter calls, shiny cowbird chicks begged at a higher frequency and more intensively than host chicks. Shiny cowbird chicks reared by mockingbirds begged more intensively to playbacks of conspecific chatter calls than to host calls, while those reared by wrens begged with a similar intensity to playbacks of conspecific chatter and host calls. On the contrary, wren nestlings begged more intensively to playbacks of the wren call than to chatter calls. Mockingbird nestlings did not beg during any treatment. None of the three species begged during the playback of nonhost calls. Our results show that the chatter call produced a preferential begging response in cowbird nestlings, which may be the beginning of a process of conspecific recognition.

Anthropogenic noise, song, and territorial aggression in southern house wrens

Anthropogenic noise constrains the transmission of birdsong and alters the behavior of receivers. Many birds adjust their acoustic signals to minimize the interference of anthropogenic noise on signal transmission. Birds may also change their acoustic signals to exchange information during aggressive interactions. However, it is unclear how birds deal with a potential trade‐off between adjusting their acoustic signals to better transmit in noisy environments versus mediating aggressive interactions. Additionally, we do not know how urbanization and anthropogenic noise alters the territorial behavior of receivers. We investigated the interplay among song, territorial aggression, urbanization, and anthropogenic noise, in males of the southern house wren Troglodytes aedon musculus, using recordings of spontaneous songs (non‐aggressive context) and a playback experiment simulating a male territorial intrusion (aggressive context). We found that urban wrens behaved more aggressively in response to the intruder by singing more and spent more time closer to the intruder than rural wrens regardless of noise. Males produced songs with lower minimum frequency and trills with wider frequency bandwidth and higher vocal performance under acute (playback) than relaxed (post‐playback) aggressive encounters. These results suggest that males use songs to communicate aggressive intent or fighting ability. Urban wrens produced higher‐pitched songs and trills than rural wrens irrespective of aggressive context. Urban wrens in the noisiest territories also produced the highest‐pitched trills but only in the non‐aggressive context. Rural wrens in the noisiest territories tended to produce the longest songs (non‐aggressive context) or produced the shortest songs (aggressive context). Results suggest that urbanization affects territorial and vocal behaviors in southern house wrens. Males in this species seem to primarily adjust acoustic signals in response to the territorial intruder rather than noise.

Urban resources limit pair coordination over offspring provisioning

The amount of care parents provide to the offspring is complicated by an evolutionary conflict of interest (‘sexual conflict’) between the two parents. Recent theoretical models suggest that pair coordination of the provisioning may reduce this conflict and increase parent and offspring fitness. Despite empirical studies showing that pair coordination is common in avian species, it remains unclear how environmental and ecological conditions might promote or limit the ability of parents to coordinate care. We compared the level of pair coordination, measured as alternation and synchrony of the nest visits, of house wrens Troglodytes aedon pairs breeding in a rural (10 nests) and a suburban (9 nests) site and investigated how differences in parental behaviours were related to habitat composition, prey abundance and how they ultimately related to reproductive success. We found that parents alternated and synchronized their nest visits more in the rural site compared to the suburban one. The suburban site is characterized by a more fragmented habitat with more coniferous trees and less caterpillar availability. Offspring from the rural site were heavier at fledging than at the suburban site. Taken together, these results suggest that environmental conditions play an important role on the emergence of coordinated parental care and that considering environmental variables is pivotal to assess the fitness consequences of parental strategies.

Anthropogenic noise and social context affect vocal plasticity in a common urban passerine

Vocal communication shapes animal social networks, connecting individuals over space and time via information, facilitating mate attraction and resource defense. Despite evidence that both the physical and social environment affect signaling behavior, few studies consider variation in individual responses to environmental change within a social context. We test the hypothesis that male House wrens (Troglodytes aedon) plastically adjust songs and song sections structured for short-and long-distance transmission in response to change in their immediate noise environment, but that both social context and noise affect singing patterns at the population level. We recorded paired males prior to clutch initiation, quantified ambient noise in the moments before singing, and define social context within pairs as female fertile status and between males as number of conspecific neighbors. Among males, adjustment patterns varied depending on transmission properties, social context, and noise. In response to immediate change in noise, males plastically adjust some, but not all, song traits. We show that not all males adjust signals in the same way, and that consideration of social context and signal function are crucial for understanding variation in signal structure. This is an essential step towards understanding how both the social and physical environment may drive selection on vocalizations.

High Rates of Nest Usurpation by Grayish Baywings (Agelaioides badius) in Active Nests of House Wrens (Troglodytes aedon) in Central Andes

ABSTRACT Nest usurpation is a behavior where one individual takes over the active nest of another individual of the same or a different species. The Grayish Baywing (Agelaioides badius) has been reported as an occasional inter-specific nest usurper. In previous studies, researchers have reported usurpation of nests of House Wrens (Troglodytes aedon) by Grayish Baywings. In this paper, we report that nest usurpation by Grayish Baywings is the second cause of breeding failure in a population of House Wrens in the Central Andes.

Do interspecific image-based ageing guides produce accurate estimates of nestling ages? – progress toward development of a generalised ageing guide

ABSTRACTImage-based ageing guides of passerine nestlings can produce accurate age estimates. If different species develop similarly, but timing of development differs, creation of a generalised image-based ageing guide for use with nestlings of multiple species is justified if age estimates can be corrected to account for such differences of timing. To explore this idea, inexperienced participants used an image-based ageing guide for Tree Swallow Tachycineta bicolor nestlings to produce age estimates from images of known-age nestling Eastern Bluebirds Sialia sialis and House Wrens Troglodytes aedon. Participants also used a House Wren ageing guide to produce age estimates of nestling Eastern Bluebirds and an Eastern Bluebird ageing guide to produce age estimates of House Wren nestlings (n = 54 total participants and 2565 age estimates). Ages of nestling bluebirds were generally underestimated with the swallow and wren ageing guides, while ages of wrens were generally overestimated with the swallow and bluebird guides. Although the accuracy of age estimates (the percentage within one day of actual age) produced by interspecific guides ranged from 43% to 77% overall, accuracy of estimates corrected using regression analyses increased to better than 80% for all pairwise comparisons. Based on these results, continued development and refinement of a generalised nestling ageing guide is warranted.

Growth benefit to house wren nestlings of having an asynchronously late-hatching nestmate is greater for extra-pair offspring

Because nestling growth influences survival and future reproductive success, early-life conditions that impact growth have potentially large effects. One notable source of variation in early-life conditions for birds is the relative timing of egg hatching: hatching asynchrony leads to size hierarchies among nestlings and may affect competition for, or parental allocation of, resources. Paternity is another potentially important factor, as extra-pair offspring have been shown in some systems to be of higher quality and therefore might be better competitors. We tested whether the presence of an asynchronously late-hatched nestmate affected nestling growth in a population of house wrens (Troglodytes aedon) and whether paternity status (within-pair vs. extra-pair) affected growth either individually or in interaction with hatching synchrony. We measured mass and wing chord of nestlings repeatedly between the ages of 0 and 10 days and determined the paternity status of each nestling. Both mass and wing chord were significantly greater in nestlings who shared the nest with at least one late-hatched nestling. This effect was significantly greater for extra-pair chicks for wing chord, but not mass. We found no effect on nestling mass or wing chord of paternity status alone, hatch timing (early or late), hatch date, brood size, sex, or social father mass. Considered together, these results suggest that hatching synchrony affects nestling growth and that extra-pair nestlings may be more responsive to early-life conditions in some aspects of growth. We discuss possible mechanisms for these effects. Bird eggs can hatch synchronously or asynchronously. In nests with asynchronous hatching, nestlings are different sizes, which may affect competition among them and therefore their growth rates. If hatching asynchrony does influence nestling growth, it may have far-reaching impacts on the fitness of the nestlings. We measured mass and wing length in house wren nestlings. Nestlings with an asynchronously late-hatching nestmate were larger in both measures, demonstrating an advantage to having a younger nestmate. This advantage was greater for extra-pair nestlings for wing length. This suggests a difference between extra-pair and within-pair nestlings in their responsiveness to early-life conditions, which might be due to the genetics of the extra-pair chicks or to differences in parental investment. This study documents a previously unknown potential benefit of hatching asynchrony, as well as a context-dependent difference between extra-pair and within-pair nestlings.

Heterospecific Infanticidal Behavior by Southern House Wrens (Troglodytes aedon musculus) Suggests Nest Site Competition

ABSTRACT Destruction of conspecific and heterospecific eggs and nestlings occurs in several species of passerines. Two main hypotheses have been proposed to explain the adaptiveness of this behavior: as a mechanism to avoid competition or to gain access to reproductive opportunities. In Colombia, Southern House Wrens (Troglodytes aedon musculus) broke eggs and/or killed nestlings of Spectacled Parrotlets (Forpus conspicillatus, 24 cases), Apical Flycatcher (Myiarchis apicalis, one case) and of other House Wrens (four cases). Wrens attacked parrotlet nests in three contexts: 1) wrens took over and used a parrotlet nestbox within their territory, 2) wrens with an active nest attacked a neighboring parrotlet nest, or 3) the attacker was unknown but was inferred to be a wren. Wrens also attacked trial nests with natural and artificial wren eggs that were placed near active wren nests. These observations suggest that infanticidal behavior by wrens at this locality may be driven by competition for nest sites. I...

Mate and territory availability affect breeding dispersal and divorce in a resident Southern House WrenTroglodytes aedon musculuspopulation

Breeding dispersal is the movement of an individual between breeding attempts and is usually associated with the disruption of the social pair bond, although mates may disperse together as a social unit. In monogamous territorial species, the decision to disperse may be affected by individual attributes such as sex, age and condition of the disperser. However, environmental and social contexts may also play a crucial role in the decision to disperse. We analysed capture‐resighting data collected over 9 years to study breeding dispersal and divorce rates of a Southern House WrenTroglodytes aedon musculuspopulation in South Temperate Argentina. Between‐season dispersal was more frequent than within‐season dispersal, with females dispersing more often than males, both between and within seasons. Both within‐season and between‐season breeding dispersal probability was affected by territory availability, but not by previous breeding success. When the adult sex ratio (ASR) was more skewed towards males, male between‐season dispersal was also affected by mating status, with widowed and single males dispersing more often than paired males. Within‐season divorce increased the reproductive success of females but not males, and was affected by the availability of social partners (with increasingly male‐skewedASR). Our results suggest that territorial vacancies and mating opportunities affect dispersal and divorce rates in resident Southern House Wrens, highlighting the importance of social and environmental contexts for dispersal behaviour and the stability of social pair bonds.

House Wren (Troglodytes aedon) provisions nestlings of Northern Cardinal (Cardinalis cardinalis)

ABSTRACT Cases of interspecific parental care are rare and pose an evolutionary puzzle. We report a male House Wren (Troglodytes aedon) regularly provisioning Northern Cardinal (Cardinalis cardinalis) nestlings in a nest located near his own. The male wren continued to provision the cardinal nestlings after his own nestlings hatched, and provisioned the cardinal nestlings more than his own nestlings during the time that their nestling periods overlapped. The adult cardinals also provisioned their own nestlings. After the cardinal chicks fledged, the male wren provisioned only his own nestlings. This is most likely a case of nonadaptive misdirection of parental behavior on the part of the wren. That the wren provisioned both nests while both were in the nestling stage, but provisioned only the wren chicks as fledglings, may suggest that kin recognition in House Wrens is mutable rather than fixed. However, this behavior is also congruent with observations of polygynous male House Wrens transferring parental...

Molecular tracking of individual host use in the Shiny Cowbird - a generalist brood parasite.

Generalist parasites exploit multiple host species at the population level, but the individual parasite's strategy may be either itself a generalist or a specialist pattern of host species use. Here, we studied the relationship between host availability and host use in the individual parasitism patterns of the Shiny Cowbird Molothrus bonariensis, a generalist avian obligate brood parasite that parasitizes an extreme range of hosts. Using five microsatellite markers and an 1120‐bp fragment of the mtDNA control region, we reconstructed full‐sibling groups from 359 cowbird eggs and chicks found in nests of the two most frequent hosts in our study area, the Chalk‐browed Mockingbird Mimus saturninus and the House Wren Troglodytes aedon. We were able to infer the laying behavior of 17 different females a posteriori and found that they were mostly faithful to a particular laying area and host species along the entire reproductive season and did not avoid using previously parasitized nests (multiple parasitism) even when other nests were available for parasitism. Moreover, we found females using the same host nest more than once (repeated parasitism), which had not been previously reported for this species. We also found few females parasitizing more than one host species. The use of an alternative host was not related to the main hosts' nest availability. Overall, female shiny cowbirds use a spatially structured and host species specific approach for parasitism, but they do so nonexclusively, resulting in both detectable levels of multiple parasitism and generalism at the level of individual parasites.

The structure and organization of song in Southern House Wrens (Troglodytes aedon chilensis)

Studies of birdsong across very broad geographic scales, such as between the north temperate zone and the tropics, provide special opportunities to understand the role of variable ecologies, life histories and mating pressures on song structure and organization. The problem is typically studied through comparative, cross-species analyses because few species have such broad distributions to encompass both regions. The House Wren is an important exception, having the widest distribution of any native songbird in the Americas, from Canada to Tierra del Fuego. Across this range, they manifest considerable variation in life history, mating systems and migration, but there is no systematic research on corresponding song variation. Here we provide a first detailed characterization of song structure and organization for Southern House Wrens (Troglodytes aedon chilensis) in western Argentina and provide preliminary comparisons to Northern House Wrens. Songs of Southern House Wrens contained two distinct sections: an introduction of broadband noisy, or harmonic, notes followed by a louder terminal section of tonal, frequency-modulated syllables with a mean of seven syllables and three syllable types per song. The syllable repertoire was large (28), mostly shared and used to construct very large song repertoires (up to 170 song types with no evidence of a ceiling), but much smaller repertoires of commonly produced song types (24). Males tended to repeat song types many times before switching (eventual variety) but, at times, sang with immediate variety. Compared to Northern House Wrens, there were differences in the detailed form of some notes and syllables as well as in the relative emphasis of the softer introduction versus louder terminal section of songs. In broader patterns of song construction, organization, delivery, and the size of syllable and song repertoires, the two populations were very similar. These patterns are discussed in light of differences in life history, mating and migration between them.

Male House Wrens provide more parental provisioning to nests with a brighter artificial egg

ABSTRACT Recent research suggests that male birds could use eggshell color as a signal of the quality of their offspring to decide how much parental care to provide. Previous studies have found support for this hypothesis in bird species that lay blue eggs, but it has not been as thoroughly tested in species that lay brown eggs, such as House Wrens (Troglodytes aedon). In this species, brighter eggs are associated with greater female investment. We tested whether males responded to this potential cue. We experimentally manipulated clutch brightness by randomly adding a white or brown plastic egg to nests during incubation and then compared the male provisioning rates between those two treatment groups. Male House Wrens whose nests had received a white egg provisioned their nestlings at significantly higher rates than males whose nests had received a brown egg. These results suggest that male House Wrens pay attention to female investment when deciding how much energy to spend on nestling provisioning. Thi...

Diverse avian malaria and other haemosporidian parasites in Andean house wrens: evidence for regional co‐diversification by host‐switching

Recent research has revealed well over 1000 mtDNA lineages of avian haemosporidian parasites, but the extent to which this diversity is caused by host–parasite coevolutionary history or environmental heterogeneity is unclear. We surveyed haemosporidian and host mtDNA in a geographically structured, ecological generalist species, the house wren Troglodytes aedon, across the complex landscape of the Peruvian Andes. We detected deep genetic structure within the house wren across its range, represented by seven clades that were between 3.4–5.7% divergent. From muscle and liver tissue of 140 sampled house wrens we found 23 divergent evolutionary lineages of haemosporidian mtDNA, of which ten were novel and apparently specific to the house wren based on searches of haemosporidian databases. Combined and genus‐specific haemosporidian abundance differed significantly across environments and elevation, with Leucocytozoon parasites strongly associated with montane habitats. We observed spatial stratification of haemosporidians along the west slope of the Andes where five lineages were restricted to non‐overlapping elevational bands. Individual haemosporidian lineages varied widely with respect to host specificity, prevalence, and geographic distribution, with the most host‐generalist lineages also being the most prevalent and widely distributed. Despite the deep divergences within the house wren, we found no evidence for host‐specific co‐diversification with haemosporidians. Instead, host‐specific haemosporidian lineages in the genus Haemoproteus were polyphyletic with respect to the New World parasite fauna and appeared to have diversified by periodic host‐switches involving distantly related avian species within the same region. These host‐specific lineages appeared to have diversified contemporaneously with Andean house wrens. Taken together, these findings suggest a model of diffuse co‐diversification in which host and parasite clades have diversified over the same time period and in the same geographic area, but with parasites having limited or ephemeral host specificity.

Condition-dependent sex difference in nestling House Wren (Troglodytes aedon) response to phytohaemagglutinin injection

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.

Song organization and variability in Northern House Wrens (Troglodytes aedon parkmanii) in western Canada

ABSTRACT. Detailed descriptions of song structure are critical to understanding the ontogeny, evolution, and function of bird song, particularly for species with large song repertoires. We provide a first detailed characterization of song organization and variability in a migratory population of House Wrens (Troglodytes aedon) breeding in western Canada, using a sample of 15,608 songs from 15 males. Males sang with high intensity in protracted bouts prior to pairing and often resumed high-intensity singing later in the breeding cycle to attract a second mate. The high-amplitude terminal portion of songs comprised rapid trills of frequency-modulated notes organized into discrete syllable types with a mean of 10 syllables and 4 syllable types per song. The population syllable repertoire was large (n = 27) and mostly shared but was used to produce much larger repertoires of song types, most of which were unique. Individual males sang up to 194 different song types, with no evidence of a ceiling. However, mal...

Measuring consistency: spectrogram cross-correlation versus targeted acoustic parameters

Several recent studies indicate that the consistency of song or syllable repetitions signals male quality. However, the comparability and efficacy of different measurement methods is not known. Here, I compared two approaches to measuring the consistency of syllable repetitions within the trills of House Wren (Troglodytes aedon) songs. In the first approach, I calculated the coefficient of variation (CV) in standard time–frequency measurements within each trill. In the second approach, I used spectrogram cross-correlation (SPCC), which measures the maximum pixel-by-pixel similarity of two spectrograms. The two approaches gave correlated estimates of trill consistency, but SPCC was more strongly related to two putatively biologically relevant traits: specifically, SPCC differed more strongly between age classes, and more variation in SPCC could be attributed to individual differences. CV-based measures complemented SPCC measures by clarifying some of the specific acoustic features whose consistency changed with age. Although additional comparisons between measurement approaches would be useful to assess generality, it appears that researchers interested in song or trill consistency should consider using an SPCC, or a combined SPCC- and CV-based, approach.

Urban noise influences vocalization structure in the House WrenTroglodytes aedon

Urban habitats are noisy and constrain acoustic communication in birds. We analysed the effect of anthropogenic noise on the vocalization characteristics of House Wrens Troglodytes aedon at two sites with different noise levels (rural and urban). We measured in each song and song trill the frequency bandwidth, maximum amplitude, highest and minimum frequency, and trill rate. In noisy urban environments, there was a reduction in bandwidth and an increase in trill rate relative to quieter, rural environments. The whole song of birds from both populations increased in minimum frequency as noise increased, improving song transmission.