January 2025
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6 Reads
Hormones and Behavior
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January 2025
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6 Reads
Hormones and Behavior
November 2024
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49 Reads
Behavioral Ecology
The evolution of mating systems reflects a balance of the often-conflicting interests of males and females. Polygyny, a mating system in which males have multiple mates, presents a fitness benefit to males, but the consequences for females are less clear. Females with polygynous social mates may suffer reduced fitness, especially secondary females who typically receive less male support. We used 32 years of detailed reproductive data on a population of Savannah sparrows (Passerculus sandwichensis) breeding on Kent Island, NB, Canada, to investigate the effects of females’ social mating status on six indices of female fitness: survival, clutch size, fledging success, number of fledglings produced per nest and annually, and recruitment of offspring. Secondary females produced fewer fledglings per nest and annually than did monogamous or primary females, and their young were less likely to recruit into the breeding population. Yearling secondary females also had lower survival rates than older secondary females. Combined with higher rates of partial brood loss among secondary females, our results suggest that secondary females are unable to provide enough care to consistently fledge all nestlings in their broods, likely due to reduced male provisioning. Given that the sex ratio of breeders in the population is female-biased, we suggest that polygyny persists despite its fitness costs because some females must mate polygynously to “make the best of a bad situation.” Our study demonstrates the value of detailed, long-term population monitoring data for understanding mating systems and using multiple indices of fitness to analyze the costs of polygyny.
September 2024
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10 Reads
Journal of herpetology
June 2024
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26 Reads
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3 Citations
Ornithology
The size and shape of an animal’s breeding territory are dynamic features influenced by multiple intrinsic and extrinsic factors and can have important implications for survival and reproduction. Quantitative studies of variation in these territory features can generate deeper insights into animal ecology and behavior. We explored the effect of age, breeding strategy, population density, and number of neighbors on the size and shape of breeding territories in an island population of Passerculus sandwichensis (Savannah Sparrow). Our dataset consisted of 407 breeding territories belonging to 225 males sampled over 11 years. We compared territory sizes to the age of the male territorial holder, the male’s reproductive strategy (monogamy vs. polygyny), the number of birds in the study population (population density), and the number of immediate territorial neighbors (local density). We found substantial variation in territory size, with territories ranging over two orders of magnitude from 57 to 5727 m2 (0.0057–0.57 ha). Older males had larger territories, polygynous males had larger territories, territories were smaller in years with higher population density, and larger territories were associated with more immediate territorial neighbors. We also found substantial variation in territory shape, from near-circular to irregularly-shaped territories. Males with more neighbors had irregularly shaped territories, but shape did not vary with male age, breeding strategy, or population density. For males that lived two years or longer, we found strong consistent individual differences in territory size across years, but weaker individual differences in territory shape, suggesting that size has high repeatability whereas shape has low repeatability. Our work provides evidence that songbird territories are highly dynamic, and that their size and shape reflect both intrinsic factors (age and number of breeding partners) and extrinsic factors (population density and number of territorial neighbors).
June 2024
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29 Reads
Animal Behaviour
January 2024
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57 Reads
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3 Citations
Animal Behaviour
Male songbirds of many species sing local song dialects that are restricted to defined geographical areas. In most tests of responses to local versus foreign dialects, males respond more aggressively to songs from their own dialect, presumably because local males represent more of a threat to their success. We asked how hearing foreign songs during development and territory establishment affects discrimination of the local dialect in wild Savannah sparrows, Passerculus sandwichensis. After foreign songs had been heard from loudspeakers in the study area in at least two consecutive breeding seasons, males reduced the intensity of their responses to the local version of the population-specific buzz segment of the song. Four years after the foreign songs were last broadcast on the study area, males again responded more aggressively to the local version of the buzz. As for the basis of these responses, we found no evidence that birds discriminated among dialects by comparing them to their own songs. However, auditory experience with a foreign song, whether during song development (from speaker-simulated song tutors) or during the current breeding season (from neighbours' songs), reduced the intensity of birds’ responses to the local buzz type. Both familiarity, in the form of auditory experience with a song type, and homogeneity, when a song type is sung by all or nearly all of the population, appear to contribute to heightened aggressive responses to a local song dialect.
January 2024
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32 Reads
Behaviour
Animals use colouration to serve diverse functions including camouflage, thermoregulation, and communication. Recent research has revealed that many anurans exhibit drastic colour changes and growing evidence supports that these changes are sexually selected signals. Male yellow toads, Incilius luetkenii , exhibit dynamic sexual dichromatism, changing from mud-brown to lemon-yellow during their brief breeding events. Toads darken when isolated in captivity, which is hypothesized to be a stress response, although the mechanisms driving this change have yet to be experimentally investigated. We confined breeding toads to small terrariums for four hours and predicted that colour and corticosterone levels would change in isolation. We found that toads darkened during isolation, but that corticosterone levels did not change with colour. Our correlational results suggest that corticosterone is not the main driver of colour change in yellow toads and highlight avenues for future research that may enhance our understanding of colour change in anurans.
November 2023
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20 Reads
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1 Citation
Avian Research
July 2022
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157 Reads
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14 Citations
Cumulative cultural evolution, the accumulation of sequential changes within a single socially learned behaviour that results in improved function, is prominent in humans and has been documented in experimental studies of captive animals and managed wild populations. Here, we provide evidence that cumulative cultural evolution has occurred in the learned songs of Savannah sparrows. In a first step, “click trains” replaced “high note clusters” over a period of three decades. We use mathematical modelling to show that this replacement is consistent with the action of selection, rather than drift or frequency-dependent bias. Generations later, young birds elaborated the “click train” song form by adding more clicks. We show that the new songs with more clicks elicit stronger behavioural responses from both males and females. Therefore, we suggest that a combination of social learning, innovation, and sexual selection favoring a specific discrete trait was followed by directional sexual selection that resulted in naturally occurring cumulative cultural evolution in the songs of this wild animal population. Cumulative cultural evolution is ubiquitous in humans, but is rarely observed in non-human animals. Here, Williams et al. report elaboration of songs over several decades in Savannah sparrows, consistent with cumulative cultural evolution.
June 2022
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113 Reads
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11 Citations
Animal Behaviour
Social communication often involves vocal learning, whereby young animals learn their vocalizations early in life by imitating the sounds of adults. In animals that learn their vocalizations, it is common to find patterns of geographical variation known as ‘vocal dialects’, acoustic features shared within a cluster of animals that differ from the vocalizations of animals in nearby clusters. Dialects may form when animals learn their vocalizations early in life and then disperse short distances, or when they modify their vocalizations to match local vocal patterns after dispersal. Dialects are typically studied at a regional or continental scale, but they may also persist at smaller scales in so-called ‘microgeographical song dialects’ or ‘microdialects’. Microdialects have received little research attention. In this study, we investigate microdialects and dispersal distance in song-learning Savannah sparrows, Passerculus sandwichensis, through a 4-year study of birds living on three islands in the Bay of Fundy, Canada. Our analyses yield evidence of microgeographical variation: birds showed higher acoustic similarity to their neighbours than to faraway individuals in the same population. When we classified songs on the basis of their highly variable middle sections, we found that particular song types formed spatial clusters of similar-sounding individuals. Therefore, acoustic variation in Savannah sparrow song appears to show dialects across small geographical distances. In an analysis of dispersal from natal sites to breeding sites, we found a median distance of 189 m, consistent with previous findings. Our results suggest that limited dispersal distances, combined with the social processes of vocal learning (overproduction and selective attrition), likely contribute to the presence of microdialects.
... Density, in ecological terms, is the number of individuals per unit area (Mayor and Schaefer 2005). Density can be studied at many different scales, ranging from the number of individuals in a population distributed across the entire area they inhabit (i.e., "population density"; Connor et al. 2000;Gaston and Matter 2002), to a subset of a population at a smaller scale of adjacent neighbours (i.e., "local density"; Connor et al. 2000;Sharma et al. 2024). For territorial songbirds, local density is often quantified by counting the number of territorial males or territorial pairs in a relatively small area (Falls 1981;Christman 1984). ...
June 2024
Ornithology
... The auditory aspect of dialects includes not only the local vernacular used by destination residents but also destination songs and destination promotion videos. The visual landscape of dialects is primarily manifested in the form of dialect walls, sound museums, and related souvenirs [128][129][130]. Subsequent studies should expand the study of dialects in the field of tourism, such as examining the multisensory interactions between tourists and destinations through visual and auditory modalities, and comparing the impact of dialects across different sensory dimensions on tourists and tourism destinations. ...
January 2024
Animal Behaviour
... The meadows of Kent Island provide P. sandwichensis with suitable nesting sites (Mitchell et al. 2012) and males defend abutting and contiguous breeding territories from conspecific rivals by engaging in singing bouts, fights, and chases (Potter 1972, Thomas et al. 2021). The breeding population occupies a homogenous habitat made up of Vaccinium angustifolium (blueberry), Chamaenerion angustifolium (fireweed), Solidago rusa (goldenrod), Rubus idaeus (raspberry), and several species of grasses (Dobney et al. 2023). Our analyses focus on variation in territory size and shape, rather than variation in territory quality. ...
November 2023
Avian Research
... Cultural variation has also been studied in other species (Hoppitt & Laland, 2013;Rendell et al., 2011;van Leeuwen, 2021;Williams et al., 2013Williams et al., , 2022. For instance, van Leeuwen (2021) documented cultural variation in Chimpanzees' grooming styles that has remained stable over at least 12 years. ...
July 2022
... Interestingly, in bird species with small dispersal distance, the occurrence of micro-dialects can be observed. For example, in Svannah Sparrows (Passerculus sandwichensis) inhabiting islands average natal dispersal is less than 200 m, and song-sharing is higher between neighbours than between males 1 km away (Hensel et al. 2022). ...
June 2022
Animal Behaviour
... Passerculus sandwichensis are migratory songbirds that inhabit grasslands throughout North America (Wheelwright and Rising 2020). Our study population breeds on a 10-ha plot located on Kent Island, in the Bay of Fundy, New Brunswick, Canada (44.58254°N, 66.75604°W), where birds have been individually marked and studied since 1987 (Woodworth et al. 2017, Burant et al. 2021). Our study area was subdivided into 50 × 50 m squares via mowed paths, with grid markers denoting each square. ...
November 2021
... These paths have been maintained annually in the same positions and our observations suggest that the gridlines do not impact the sparrows' territorial behavior. The meadows of Kent Island provide P. sandwichensis with suitable nesting sites (Mitchell et al. 2012) and males defend abutting and contiguous breeding territories from conspecific rivals by engaging in singing bouts, fights, and chases (Potter 1972, Thomas et al. 2021). The breeding population occupies a homogenous habitat made up of Vaccinium angustifolium (blueberry), Chamaenerion angustifolium (fireweed), Solidago rusa (goldenrod), Rubus idaeus (raspberry), and several species of grasses (Dobney et al. 2023). ...
June 2021
Animal Behaviour
... The room was under a 12 : 12 white light cycle at 27°C and ca 55% humidity. I carried out the experiments on 6 April 2021 and I used identical 3D-printed models of R. ralata that were coloured with acrylic paint (figure 2a), following approaches from other studies that used 3D-printed toads to study behavioural responses [28]. A Y-maze (figure 2b) selection experiment was used to examine whether visual or non-visual cues drove the seed dispersal results. ...
April 2021
Ethology
... Such varied function has resulted in considerable phenotypic variation in colouration, both within and between species (Hofreiter and Schöneberg, 2010). Adding to this variation, colour expression in vertebrates is rarely static (Booth, 1990), with a diversity of species known to change colour (Nilsson Sköld et al., 2013;Strickland and Doucet, 2021;Zimova et al., 2018). This change can be rapid and reversible, occurring within a matter of minutes (termed 'dynamic' colour change; Kindermann et al., 2014), or take place over the entire course of an individual's life and can be irreversible (termed 'ontogenetic' colour change; Booth, 1990;Bulbert et al., 2018). ...
March 2021
... Studies in Thraupidae also indicate that coexistence in the Neotropics, interspecific interactions, and predator-prey arms race between insectivores and arthropods drive evolutionary feeding specializations [21]. At the same time, sexual selection is thought to be a critical process for speciation [93], which, in the case of Parulidae, seems to be intimately associated with plumage and song divergence for closely related species [94]. Similarly, studies suggest that sexual selection through plumage and song evolution likely drives evolution in clades like Icteridae and Passerellidae [95,96]. ...
January 2021