ORCID Profile
0000-0001-9314-6700
Current Organisations
University of Windsor
,
University of Windsor Faculty of Science
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Publisher: The Company of Biologists
Date: 11-2011
DOI: 10.1242/JEB.060194
Abstract: Anthropogenic noise can mask animal signals that are crucial for communicating information about food, predators and mating opportunities. In response to noise masking, signallers can potentially improve acoustic signal transmission by adjusting the timing, frequency or litude of their signals. These changes can be a short-term modification in response to transient noise or a long-term modification in response to chronic noise. An animal's ability to adapt to anthropogenic noise can be crucial to its success. In this study, we evaluated the effects of anthropogenic noise on the structure of red-winged blackbird song. First, we manipulated the presence of anthropogenic noise by experimentally broadcasting either silence or low-frequency white noise to subjects inhabiting quiet marshes located away from roadsides. Subjects exhibited increased signal tonality when temporarily exposed to low-frequency white noise, suggesting that red-winged blackbirds can alter their signals rapidly in response to sudden noise. Second, we compared songs produced in quiet marshes located away from roadsides with songs produced during quiet periods at roadside marshes that are normally noisy. This allowed us to test whether birds that are exposed to chronic anthropogenic noise exhibit altered song structure during temporarily quiet periods. Subjects residing in roadside marshes that are normally polluted with anthropogenic noise sang songs with increased tonality during quiet periods. Overall, our results show that anthropogenic noise influences the structure of birdsong. These effects should be considered in conservation and wildlife management.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 10-2012
Publisher: Oxford University Press (OUP)
Date: 19-04-2022
DOI: 10.1093/ORNITHAPP/DUAC018
Abstract: Many breeding birds produce conspicuous sounds, providing tremendous opportunities to study free-living birds through acoustic recordings. Traditional methods for studying population size and demographic features depend on labor-intensive field research. Passive acoustic monitoring provides an alternative method for quantifying population size and demographic parameters, but this approach requires careful validation. To determine the accuracy of passive acoustic monitoring for estimating population size and demographic parameters, we used autonomous recorders to s le an island-living population of Savannah Sparrows (Passerculus sandwichensis) over a 6-year period. Using the in idually distinctive songs of males, we estimated the male population size as the number of unique songs detected in the recordings. We analyzed songs across 6 years to estimate birth year, death year, and longevity. We then compared the estimates with field data in a blind analysis. Estimates of male population size through passive acoustic monitoring were, on average, 72% of the true male population size, with higher accuracy in lower-density years. Estimates of demographic rates were lower than true values by 29% for birth year, 23% for death year, and 29% for longevity. This is the first investigation to estimate longevity with passive acoustic monitoring and adds to a growing number of studies that have used passive acoustic monitoring to estimate population size. Although passive acoustic monitoring underestimated true population parameters, likely due to the high similarity among many male songs, our findings suggest that autonomous recorders can provide reliable estimates of population size and longevity in a wild songbird.
Publisher: Informa UK Limited
Date: 19-08-2013
Publisher: Elsevier BV
Date: 06-2010
Publisher: Oxford University Press (OUP)
Date: 02-2015
Abstract: Many territorial animals exhibit reduced aggression towards neighbours. Known as “the dear enemy effect”, this phenomenon has been documented among conspecific animals across a wide range of animal taxa. In theory, the dear enemy effect can also exist between in iduals of different species, particularly when those species compete for shared resources. To date, a heterospecific dear enemy effects has only been documented in ants. In this study, we test for both a conspecific and heterospe-cific dear enemy effect in neotropical rufous-and-white wrens Thryophilus rufalbus. This species competes for resources with banded wrens Thryophilus pleurostictus, a closely related sympatric congener. We used acoustic playback to simulate ruf-ous-and-white wren and banded wren neighbours and non-neighbours at the edges of rufous-and-white wren territories. Ruf-ous-and-white wrens responded more strongly to signals from their own species, demonstrating that resident males discriminate between conspecific and heterospecific rivals. They did not, however, exhibit a conspecific dear enemy effect. Further, they did not exhibit a heterospecific dear enemy effect. This could be due to neighbours and non-neighbours posing similar levels of threat in this system, to the possibility that playback from the edges of the subjects’ large territories did not simulate a threatening signal, or to other factors. Our study provides the first test of a heterospecific dear enemy effect in vertebrates, and presents a valuable experimental approach for testing for a heterospecific dear enemy effect in other animals.
Publisher: The Royal Society
Date: 09-05-2018
Abstract: Understanding how climate change will shape species distributions in the future requires a functional understanding of the demographic responses of animals to their environment. For birds, most of our knowledge of how climate influences population vital rates stems from research in temperate environments, even though most of Earth's avian ersity is concentrated in the tropics. We evaluated effects of Southern Oscillation Index (SOI) and local temperature and rainfall at multiple temporal scales on sex-specific survival of a resident tropical bird, the rufous-and-white wren Thryophilus rufalbus , studied over 15 years in the dry forests of northwestern Costa Rica. We found that annual apparent survival of males was 8% higher than females, more variable over time, and responded more strongly to environmental variation than female survival, which did not vary strongly with SOI or local weather. For males, mean and maximum local temperatures were better predictors of survival than either rainfall or SOI, with high temperatures during the dry season and early wet season negatively influencing survival. These results suggest that, even for species adapted to hot environments, further temperature increases may threaten the persistence of local populations in the absence of distributional shifts.
Publisher: Elsevier BV
Date: 04-2016
Publisher: Wiley
Date: 24-05-2012
Publisher: Elsevier BV
Date: 02-2016
Publisher: Oxford University Press (OUP)
Date: 27-09-2019
Abstract: When animals vocalize under the threat of predation, variation in the structure of calls can play a vital role in survival. The chick-a-dee calls of chickadees and titmice provide a model system for studying communication in such contexts. In previous studies, birds’ responses to chick-a-dee calls covaried with call structure, but also with unmeasured and correlated parameters of the calling sequence, including duty cycle (the proportion of the calling sequence when a signal was present). In this study, we exposed flocks of Black-capped Chickadees (Poecile atricapillus) and heterospecific birds to playback of chick-a-dee calls and taxidermic models of predators. We quantified birds’ responses to variation in number of D notes and duty cycle of the signalling sequence. Chickadees and heterospecific birds responded more intensely to high-duty-cycle treatments, and equally to treatments where duty cycle was held constant and the number of D notes varied. Although our study does not disentangle the effects of call rate and duty cycle, it is the first to investigate independently the behavioural responses of birds to variation in structural and sequence-level parameters of the chick-a-dee call during a predator confrontation. Critically, our results confirm that the pattern previously observed in a feeding context holds true in a mobbing context: variation in calling sequences, not in call structure, is the salient acoustic feature of chick-a-dee calls. These results call into question the idea that chick-a-dee call structure carries allometric information about predator size, suggesting instead that sequence-level parameters play a central role in communication in a mobbing context.
Publisher: Oxford University Press (OUP)
Date: 05-2016
Publisher: Oxford University Press (OUP)
Date: 2011
Publisher: University of Chicago Press
Date: 02-2014
DOI: 10.1086/674379
Abstract: Studies of trilled vocalizations provide a premiere illustration of how performance constraints shape the evolution of mating displays. In trill production, vocal tract mechanics impose a trade-off between syllable repetition rate and frequency bandwidth, with the trade-off most pronounced at higher values of both parameters. Available evidence suggests that trills that simultaneously maximize both traits are more threatening to males or more attractive to females, consistent with a history of sexual selection favoring high-performance trills. Here, we identify a s ling limitation that confounds the detection and description of performance trade-offs. We reassess 70 data sets (from 26 published studies) and show that s ling limitations afflict 63 of these to some degree. Traditional upper-bound regression, which does not control for s ling limitations, detects performance trade-offs in 33 data sets yet when s ling limitations are controlled, performance trade-offs are detected in only 15. S ling limitations therefore confound more than half of all performance trade-offs reported using the traditional method. An alternative method that circumvents this s ling limitation, which we explore here, is quantile regression. Our goal is not to question the presence of mechanical trade-offs on trill production but rather to reconsider how these trade-offs can be detected and characterized from acoustic data.
Publisher: Wiley
Date: 24-11-2022
DOI: 10.1002/ECY.3575
Abstract: Phenotypic plasticity allows organisms to adjust the timing of life-history events in response to environmental and demographic conditions. Shifts by in iduals in the timing of breeding with respect to variation in age and temperature are well documented in nature, and these changes are known to scale to affect population dynamics. However, relatively little is known about how organisms alter phenology in response to other demographic and environmental factors. We investigated how pre-breeding temperature, breeding population density, age, and rainfall in the first month of life influenced the timing and plasticity of lay date in a population of Savannah Sparrows (Passerculus sandwichensis) monitored over 33 yr (1987-2019). Females that experienced warmer pre-breeding temperatures tended to lay eggs earlier, as did older females, but breeding population density had no effect on lay date. Natal precipitation interacted with age to influence lay date plasticity, with females that experienced high precipitation levels as nestlings advancing lay dates more strongly over the course of their lives. We also found evidence for varied pace of life females that experienced high natal precipitation had shorter lifespans and reduced fecundity, but more nesting attempts over their lifetimes. Rainfall during the nestling period increased through time, while population density and fecundity declined, suggesting that increased precipitation on the breeding grounds may be detrimental to breeding females and ultimately the viability of the population as a whole. Our results suggest that females adjust their laying date in response to pre-breeding temperature, and as they age, while presenting new evidence that environmental conditions during the natal period can affect phenological plasticity and generate downstream, population-level effects.
Publisher: The Royal Society
Date: 13-01-2021
Abstract: Closely related species often exhibit similarities in appearance and behaviour, yet when related species exist in sympatry, signals may erge to enhance species recognition. Prior comparative studies provided mixed support for this hypothesis, but the relationship between sympatry and signal ergence is likely nonlinear. Constraints on signal ersity may limit signal ergence, especially when large numbers of species are sympatric. We tested the effect of sympatric overlap on plumage colour and song ergence in wood-warblers (Parulidae), a speciose group with erse visual and vocal signals. We also tested how number of sympatric species influences signal ergence. Allopatric species pairs had overall greater plumage and song ergence compared to sympatric species pairs. However, among sympatric species pairs, plumage ergence positively related to the degree of sympatric overlap in males and females, while male song bandwidth and syllable rate ergence negatively related to sympatric overlap. In addition, as the number of species in sympatry increased, average signal ergence among sympatric species decreased, which is likely due to constraints on warbler perceptual space and signal ersity. Our findings reveal that sympatry influences signal evolution in warblers, though not always as predicted, and that number of sympatric species can limit sympatry's influence on signal evolution.
No related grants have been discovered for Daniel Mennill.