Troglodytes Aedon Research Articles

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

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.

Contrasting patterns of natal dispersal of a south temperate House Wren population at local and regional scales

Dispersal constitutes one of the main processes that shape population genetic structure and dynamics. Combining a capture-mark-resighting methodology and molecular genetics analyses, we studied the natal dispersal behaviour of House Wrens (Troglodytes aedon bonariae) inhabiting a naturally fragmented habitat in south temperate Argentina. Based on data collected over 12 breeding seasons (2005–2016), we tested if males and females differ in natal dispersal behaviour at different spatial scales. At local scale (within study sites), both resighting of banded individuals and genetic analysis showed that females dispersed greater distances than males. At a broader spatial scale (between study sites) resighting of banded individuals could not verify that females were the dispersing sex since long-distance dispersal was rare. However, genetic analyses revealed paradoxical evidence: while the females of populations separated by more than 5 km showed slight but significant genotypic differences among them, males showed genetic differences at a greater distance (> 16 km). Given that genetic analyses can provide evidence of both historical and present-day dispersal the observed genetic differentiation does not necessarily imply that the sex dispersal pattern is reversed at a regional scale. We propose that females have a higher probability of acquiring a partner/territory at closer distances due existing male-biased population sex ratio caused but higher female mortality. Also, although males are less likely to disperse, when they do, they must travel greater distances to find a suitable territory or mate. Such movements would prevent the occurrence of genetic differences among male populations.

A non-vocal alarm? Effects of wing trill playbacks on antipredator responses in the scaled dove

Animals have evolved a variety of mechanisms to detect and avoid predation. The non-vocal sounds produced by some bird species during takeoff flights have been considered to function as an alarm call, because they may convey information about predation risk. Here, we experimentally investigated the effects of the non-vocal sound (wing trills) produced by the scaled dove (Columbina squammata) on antipredation behaviours of conspecifics. We evaluated the individual response to playbacks of the wing trill stimulus and compared it to the response to other two control stimuli (vocalizations of the scaled dove and the southern house wren). We found that doves’ probability to become vigilant or to display freezing behaviour was higher after a wing trills stimulus in comparison to the other playback stimuli. These results suggest that wing trill production in scaled doves communicate potential risks and are considered by the individuals in the decision-making process, but we cannot rule out the possibility that any takeoff flight sound might also promote antipredator responses.

Effects of nest predation on a south temperate house wren population

Nest predation can have several effects on breeding birds. It reduces breeding success but also, it can strongly affect parental investment and reproductive decisions. Here we tested the extent of effects of nest predation on south temperate house wrens Troglodytes aedon bonariae by comparing the nesting success and breeding decisions of pairs breeding in plots that differed in nesting failure rates. During 2007 and 2008 breeding seasons we monitored nests built in nest boxes with a 27 mm entrance hole in a plot (E1) and with a 54 mm entrance hole in another plot (E2). At the end of the 2008 breeding season we reduced entrance holes of nest boxes at E2 to 27 mm. During 2007 and 2008 breeding seasons, nest failures were higher at E2 than E1 (70.6% and 25.8% respectively). Clutch sizes, brood sizes and number of fledgling produced per nest were smaller in E2 than in E1. However, females at E2 laid bigger eggs. Hatching success was lower at E2 than at E1, but fledgling success was similar between sites. Females nesting at E2 performed less frequently a second brood than those at E1. We did not detect differences between sites in individual breeding dispersal, mate change, apparent adult survival and offspring survival and recruitment. As a consequence of a reduced clutch size, higher hatching failures and lower frequency of double broods, individuals nesting at E2 had a lower annual productivity than those at E1. No differences in nest failure frequency and productivity were found between sites during the 2009 and 2010 breeding seasons. Our results provide experimental evidence of the existence of reproductive costs beyond nest loss associated with nesting in areas with high risk of nest predation in house wrens.

Nest predator identity and nest predation rates of three songbirds in the Central Andes of south temperate Argentina

Nest predation is the primary cause of nest failure in passerines. In order to contribute to our understanding of how nest predators shape avian nesting ecology and life history traits, we report nest predator identity and nest predation rates for 3 species of passerines in the Central Andes of south temperate Argentina. We used video cameras and opportunistic observations with photographic documentation to identify nest predators of Grass Wrens (Cistothorus platensis) breeding in a riparian grassland, as well as House Wrens (Troglodytes aedon) and House Sparrows (Passer domesticus) breeding in nest boxes in a tree plantation. From 13 nest predation events we were able to identify 3 nest predator species: mousehole snake (Philodryas trilineata), South American gray fox (Lycalopex griseus), and American Kestrel (Falco sparverius). Field observations also suggested fire ants (genera Solenopsis) as a possible nest predator. Mousehole snakes were identified at both grassland and forest plantation, representing 76.9% of the identified predation events. House Sparrows had the highest nest predation rate (43.1%), followed by Grass Wrens (30.8%) and House Wrens (29.3%). Egg predation was more frequent for House Wrens (64.2%) and House Sparrows (50.0%) than for Grass Wrens (22.1%). In contrast, nestling predation was considerably higher for Grass Wrens (77.9%) than for House Wrens and House Sparrows (34.7% and 50.0%, respectively). Knowledge of the nest predator community and information of nest predation rates of different species in temperate South America will contribute to understand nest predation effects on patterns and processes of nesting success, life history traits, and future management decisions in this region.

Predation on the nonnative Puerto Rican crested anole ( Anolis cristatellus ) by the Dominican House Wren ( Troglodytes aedon rufescens ) on the Commonwealth of Dominica

Predation on vertebrate species by insect-eating birds is rarely recorded, with only one report for the House Wren (Troglodytes aedon). On 4 January 2019, we observed a Dominican House Wren (T. a. rufescens) consume a juvenile of the nonnative Puerto Rican crested anole (Anolis cristatellus) in Roseau, Commonwealth of Dominica. This observation suggests the Dominican House Wren could additionally prey on the endemic Dominican anole (Anolis oculatus). This record aids our understanding of the ecosystem-wide impact of the A. cristatellus invasion.

Incubation Behavior Differences in Urban and Rural House Wrens, Troglodytes aedon

As global land surfaces are being converted to urban areas at an alarming rate, understanding how individuals respond to urbanization is a key focus for behavioral ecology. As a critical component of avian parental care, incubating adults face a tradeoff between maintaining an optimal thermal environment for the developing embryos while meeting their own energetic demands. Urban habitats are biotically and abiotically different from their rural counterparts,i.e., in food availability, predator compositions, and the thermal environment. Therefore, urban birds may face different incubation challenges than their natural counterparts. We measured incubation behavior of rural and urban house wrens,Troglodytes aedon, with temperature loggers throughout the 12-day period. We found that urban females had more incubation bouts of shorter duration and spent less total time incubating per day than rural females. Results could provide evidence of behavioral shifts of wrens in cities, which have implications for the evolution of parental care. Our findings contribute to our understanding of the behavioral traits needed for city life and possible environmental pressures driving urban adaptations.

Anthropogenic noise and atmospheric absorption of sound induce amplitude shifts in the songs of Southern House Wren (Troglodytes aedon musculus)

Birdsong is an important feature that mediates several aspects of bird reproduction, such as mate choice, territory defense, and individual recognition. Any factor that impairs vocal transmission through the environment may also impair conspecific recognition and thus reduce the effectiveness of reproduction. In this scenario, birds inhabiting urban environments might be subject to different selective pressures on their vocal amplitude due to acoustic barriers in the song transmission, such as excessive background noise and abnormal atmospheric absorption of sound. Therefore, we measured the amplitude of the song of the Southern House Wren (Troglodytes aedon musculus), to determine the relationships between the variation in vocal intensity and the environmental features. We expect divergence in vocal amplitude according to the noise levels, with song intensity responding to the increasing noise. We found that birds sang with higher amplitude in areas where traffic noise is elevated. Multiple linear regression showed a positive relationship between song amplitude and background noise and a negative relationship between vocal intensity and atmospheric attenuation. Our findings suggest a direct influence of urban environmental structures on the vocal behavior of wrens, which may challenge the effectiveness of communication between subjects and affect the behavioral ecology of the species.

Female birds monitor the activity of their mates while brooding nest-bound young.

In addition to food and protection, altricial young in many species are ectothermic and require that endothermic parents provide warmth to foster growth, yet only one parent-typically the female-broods these young to keep them warm. When this occurs, reduced provisioning by males obliges females to forage instead of providing warmth for offspring, favoring the temporal mapping of male activities. We assessed this in a wild house wren population while experimentally feeding nestlings to control offspring satiety. While brooding, females look out from the nest to inspect their surroundings, and we hypothesized that this helps to determine if their mate is nearby and likely to deliver food to the brood (males pass food to brooding females, which pass the food to nestlings). Females looked out from the nest less often when their partner was singing nearby and when his singing and provisioning were temporally linked, signaling his impending food delivery. Females also left to forage less often when their mate was nearby and likely to deliver food. Nestling begging did not affect these behaviors. Females looking out from the nest more often also provisioned at a higher rate and were more likely to divorce and find a new mate prior to nesting again within seasons, as expected if females switch mates when a male fails to meet expectations. Our results suggest anticipatory effects generated by male behavior and that brooding females temporally map male activity to inform decisions about whether to continue brooding or to leave the nest to forage.

An opportunist predator hidden in the vegetation: on the predation of birds by Philodryas olfersii (Serpentes: Dipsadidae)

ABSTRACT Snakes are common predators of birds. However, reported cases of snake predation on Troglodytes musculus are scarce. Here, we report a predation attempt of a Troglodytes musculus nestling by the dipsadid snake Philodryas olfersii. We also present a list with bird species recorded as prey of this snake species. We found 25 predation events of P. olfersii on adult, juvenile, and nestling birds. A total of 19 bird species from 14 families have been reported as prey of P. olfersii. Most predation events occurred on the vegetation, while some others were observed on the ground, cage, and artificial nest.

Conventional and network analyses of song organization and complexity in northern House Wrens (Troglodytes aedon parkmanii)

Conventional and network analyses of song organization and complexity in northern House Wrens (<i>Troglodytes aedon parkmanii</i>)

Variation in song structure of house wrens living in urban and rural areas in a Caribbean small island developing state

ABSTRACT Most research on how birds adapt to urban environments has been conducted in cities in developed (Global North) countries, which differ structurally and acoustically from cities in developing (Global South) countries; therefore, optimal behavioural strategies of animals living in urban landscapes may also differ based on the economic status of the country in which they live. We studied Grenada’s house wren population (Troglodytes aedon grenadensis) to investigate song plasticity of this subspecies in response to urbanisation. Grenada, a Small Island Developing State in the Caribbean, is under increasing pressure from tourism, urbanisation, and climate change, and little is known about its avian community. We recorded 33 Grenada house wrens at five urban and five rural sites across Grenada, and analysed effects of urbanisation using generalised estimating equations. Grenada house wrens used a mix of strategies to compensate for urbanisation. In urban habitats, house wrens sang shorter introductions, faster trills, and increased the low frequencies of the introduction and the whole song. Grenada’s house wrens use some unusual song alterations in urban environments, emphasising the importance of studying animal behaviour in Small Island Developing States to help us understand the unique anthropogenic pressures faced by species in these vulnerable regions.

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.

Borrelia genospecies in Ixodes sp. cf. Ixodes affinis (Acari: Ixodidae) from Argentina

Borrelia genospecies in Ixodes sp. cf. Ixodes affinis (Acari: Ixodidae) from Argentina

Anthropogenic noise affects female, not male house wren response to change in signaling network

AbstractVocal signals mediate social relationships, and among networks of territorial animals, information is often shared via broadcast vocalizations. Anthropogenic noise may disrupt communication among individuals within networks, as animals change the way they vocalize in noise. Furthermore, constraints on signal transmission, including frequency masking and distance, may affect information exchange following a disruption in social networks. We tested the hypothesis that signaling interactions within networks of breeding male and female house wrens (Troglodytes aedon) depend on distance, ambient noise, and receiver nesting stage. We used playback experiments to simulate territorial intrusions with and without noise playbacks on the territories of established males and simultaneously recorded the vocal responses of neighbors. To examine whether intrusions impacted interactions between males, we used randomization tests to determine whether treatment, distance, noise, or nesting stage affected vocal coordination between challenged and neighboring males. We also quantified singing patterns to explore whether intrusions on territories of challenged males affected singing by males and females on neighboring territories. Males sang at the lowest rates and were less likely to overlap songs with the challenged male when their partner was laying, compared to males during early and late nesting stages. Noise and distance did not affect vocal coordination or male singing rates. Fewer females sang during the intruder‐only treatment compared to the control and intrusions with noise. Added noise in the territories of challenged males may have masked signals, and as a result, females only changed their behavior during the intruder‐only treatment. Our results suggest that the fertility of breeding partners may be more important to males than short‐term changes on rival male territories. Elevated noise did little to alter male responses to threats within networks. Females appeared to eavesdrop on interactions involving neighboring males, but noise may have prevented detection of their interactions.

Social context and noise affect within and between male song adjustments in a common passerine

AbstractAcross populations, animals that inhabit areas with high anthropogenic noise produce vocalizations that differ from those inhabiting less noisy environments. Such patterns may be due to individuals rapidly adjusting their songs in response to changing noise, but individual variation is seldom explored. Therefore, we tested the hypothesis that male house wrens (Troglodytes aedon) immediately adjust their songs according to changing noise and that social context further modifies responses. We recorded songs, quantified noise, and defined social context within pairs as female fertile status and between males as number of conspecific neighbors. We used a reaction-norm approach to compare song trait intercepts (between-male effects) and slopes (within-male effects) as a function of noise. Individuals immediately adjusted song duration in response to changing noise. How they achieved adjustments varied: some sang shorter and others longer songs with greater noise, and individuals varied in the extent to which they adjusted song duration. Variation in song duration could be affected by competition as between-male noise levels interacted with number of neighbors to affect syllable duration. Neither within- nor between-male noise effects were detected for frequency traits. Rather, males with fertile mates sang lower-frequency songs and increased peak frequency with more neighbors. Among males, social context but not noise affected song frequency, whereas temporal structure varied between and within individuals depending on noise and social factors. Not all males adjusted signals the same way in response to noise, and selection could favor different levels of variation according to noise.

House Wrens Troglodytes aedon reduce repertoire size and change song element frequencies in response to anthropogenic noise

Anthropogenic noise (≤ 3 kHz) can affect key features of birds’ acoustic communication via two different processes: (1) song‐learning, because songbirds need to hear themselves and other birds to crystallize their song, and (2) avoidance of song elements that overlap with anthropogenic noise. In this study we tested whether anthropogenic noise reduces the number of song elements in the repertoire of House Wren Troglodytes aedon, an urban species. Additionally, we tested whether the proportion of high‐frequency elements (i.e. elements where the minimum frequency is above 3 kHz) is related to anthropogenic noise levels, and how the frequencies and duration of shared elements between males change with different levels of anthropogenic noise. We recorded 29 House Wren males exposed to different anthropogenic noise levels (36.50–79.50 dB) during two consecutive breeding seasons from four locations. We recorded each male on 2 days during each season continuously for 50 min (we collected 104 h of recordings) and measured anthropogenic noise levels every 10 min inside each male territory during the recording period. In general, individuals inhabiting noisier territories had smaller repertoires. However, only in two locations with anthropogenic noise levels between 38.60 and 79.50 dB did males inhabiting noisier territories have smaller repertoires. In the other two locations with lower anthropogenic noise (36.50–66.50 dB), the anthropogenic noise inside each territory was not related to the repertoire size. Individuals inhabiting the noisiest location showed a tendency to include more high‐frequency elements in their songs. In 26% of the elements, the anthropogenic noise affected their frequency features. Our results showed that not all House Wrens inhabiting urban environments modify their songs at the highest level of organization (i.e. repertoire) to reduce the masking effect of anthropogenic noise on acoustic communication.

Urbanization has opposite effects on the territory size of two passerine birds

BackgroundUrban expansion has been identified as one of the leading drivers of biodiversity change or loss. For birds, urbanization is specifically related to survival, breeding success, and territory size. Understanding how different birds adjust territory size in response to urbanization is essential for their conservation in urban environments and to better understand why some species are lost and others persist under this condition. We evaluated the effect of urbanization on the territory size of an urban avoider species, White-eared Ground-Sparrow (Melozone leucotis), and an urban adapter species, House Wren (Troglodytes aedon), at five Costa Rican sites.MethodsWe measured the size of 30 ground-sparrow and 28 wren territories using a total of 296 h of observation. We followed each individual for at least 1 h per day for at least 2 days of two consecutive years, and geo-referenced their locations. Territory size was estimated using the minimum convex polygon method. We measured the urban surfaces (roads, buildings, any other paved area, soccer fields, lawns, and gardens with short grass) within territories.ResultsGround-sparrow territories were larger at the highly urbanized site than at the non-urbanized site. Wren territories were larger at the low urbanized site than at the highly urbanized site. We found a positive relationship between urban surface and territory size for the ground-sparrow, but not for the wren.ConclusionsOur results showed that not all birds adjust territory size in the same way in response to urbanization. We showed that urban avoiders probably need to defend larger territories in urban environments to find all the resources required to survive because urban environments may provide insufficient resources such as food or shelter. Urban adapters on the other hand defend smaller territories in urban environments because even small territories may provide sufficient resources. These results suggest specific behavioral adaptations developed by Neotropical birds inhabiting urban environments.

Connecting the dots: avian eggshell pigmentation, female condition and paternal provisioning effort.

Differences in avian eggshell pigmentation could be an honest signal of female quality that males use to inform their nestling provisioning effort. We investigated whether among-individual variation in protoporphyrin-based eggshell pigmentation in house wrens (Troglodytes aedon) reflects female fitness-associated traits and whether males use that information. Females laying lighter clutches were older and larger than females laying darker clutches. Nestlings hatching from lighter clutches had greater size-corrected mass on post-hatch day 11, a measure that strongly predicts survival and recruitment to the breeding population. To test whether male provisioning effort responds to clutch pigmentation, we used a reciprocal clutch cross-fostering design, swapping dark with light clutches and light with dark; in controls, we swapped light with light clutches and dark with dark. Shortly before hatching, clutches were returned to their original nest to avoid confounding effects of nestling quality on male provisioning. Contrary to the sexual selection hypothesis, clutch pigmentation had no effect on male provisioning. Males were probably able to observe eggshell pigmentation and thus had information about female quality, but they did not use this information to modulate their nestling provisioning. This may be because of constraints on species-specific reproductive opportunities, or because variation in eggshell protoporphyrin serves other functions.

Spatial and temporal variation in breeding parameters of two south‐temperate populations of House Wrens

Spatial and temporal variation in breeding parameters of two south‐temperate populations of House Wrens