The increasing encroachment of anthropogenic noise into natural environments is a source of signi... more The increasing encroachment of anthropogenic noise into natural environments is a source of significant concern for wildlife conservation (Shannon, McKenna, et al., 2016), and both spatial extent and complexity of anthropogenic noise from activities related to natural resource extraction are expected to rise as development increases across the world. This noise pollution may increase risks to species reliant on acoustic communication that are already experiencing significant population declines (Barber et al.
Urban rights-of-way may be potential reservoirs of tall-grass prairie plants and butterflies. To ... more Urban rights-of-way may be potential reservoirs of tall-grass prairie plants and butterflies. To determine if this is true, in 2007–2008, we conducted vegetation surveys of species richness and cover, and butterfly surveys of species richness and abundance, along 52 transmission lines and four remnant prairies in Winnipeg, Manitoba. We detected many prairie plants and butterflies within transmission lines. Some unmowed and infrequently managed transmission lines had native plant species richness and total percent cover of native plants comparable to that of similar-sized remnant tall-grass prairies in the region. Although we did not find significant differences in overall native butterfly numbers or species richness between rights-of-way and remnant prairies, we found lower numbers of some prairie butterflies along frequently mowed rights-of-way than within remnant tall-grass prairies. We also observed higher butterfly species richness along sites with more native plant species. By reducing mowing and spraying and reintroducing tall-grass prairie plants, urban rights-of-way could serve as extensive reservoirs for tall-grass prairie plants and butterflies in urban landscapes. Eventually, managing urban rights-of-way as reservoirs for tall-grass prairie plants and animals could contribute to the restoration of tall-grass prairie in the North American Midwest.
Proceedings of The Royal Society B: Biological Sciences, Sep 21, 2022
Human activities may impact animal habitat and resource use, potentially influencing contemporary... more Human activities may impact animal habitat and resource use, potentially influencing contemporary evolution in animals. In the United Kingdom, COVID-19 lockdown restrictions resulted in sudden, drastic alterations to human activity. We hypothesized that short-term daily and long-term seasonal changes in human mobility might result in changes in bird habitat use, depending on the mobility type (home, parks and grocery) and extent of change. Using Google human mobility data and 872 850 bird observations, we determined that during lockdown, human mobility changes resulted in altered habitat use in 80% (20/25) of our focal bird species. When humans spent more time at home, over half of affected species had lower counts, perhaps resulting from the disturbance of birds in garden habitats. Bird counts of some species (e.g. rooks and gulls) increased over the short term as humans spent more time at parks, possibly due to human-sourced food resources (e.g. picnic refuse), while counts of other species (e.g. tits and sparrows) decreased. All affected species increased counts when humans spent less time at grocery services. Avian species rapidly adjusted to the novel environmental conditions and demonstrated behavioural plasticity, but with diverse responses, reflecting the different interactions and pressures caused by human activity.
Anthropogenic noise may be detrimental to many bird species, and manipulative experiments would h... more Anthropogenic noise may be detrimental to many bird species, and manipulative experiments would help us understand these effects. We present the design and validation of a self-sustaining solarpowered broadcasting system that will allow researchers to disentangle acute or chronic effects of noise from effects of the presence of infrastructure, even in remote areas. We tested the broadcasting system using a case study on noise from oil well infrastructure in southern Alberta, Canada. Recordings from 2 types of oil wells were obtained and then broadcasted through 6 independent playback units continuously for a period of 3 months in 2013, at sites undisturbed by oil development. Sound measurements at real oil wells and at sites with broadcasting systems simulating the noise from these oil wells demonstrated that real and projected noise had very similar sound pressure levels, attenuation trends, and spectral composition. Throughout this long-term playback experiment, the system produced power and noise reliably and consistently. In conjunction with bird surveys, this experimental design and infrastructure can be used to allow researchers to dissociate the presence of anthropogenic development from associated noise, providing us with information that will help decrease the environmental impacts of human activities.
Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, b... more Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (δ 2 H) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high intrafeather isotopic variance and mean δ 2 H values higher than predicted from δ 2 H isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of δ 2 H analysis of sawwhet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006-2007. Values of δ 2 H in saw-whet owl feathers were higher than predicted from a δ 2 H isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of δ 2 H in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in δ 2 H values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater 2 H enrichment in adult feathers. These results indicate that current δ 2 H isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of 2 H enrichment in owl feathers is required.
Bioacoustics-the International Journal of Animal Sound and Its Recording, Mar 3, 2017
Abstract Organisms encounter noise naturally in the environment. However, increasing prevalence o... more Abstract Organisms encounter noise naturally in the environment. However, increasing prevalence of human-caused noise seems to be resulting in behavioural changes in many animals that can affect survival and reproduction. Not all species react the same way to noise; some adjust their vocal signals while others do not. We hypothesized that species with more variability in their vocal signals would be better able to adjust their signals to be audible over anthropogenic noise. We tested this within a large-scale manipulative experiment by recording songs of two grassland songbirds, Baird’s sparrow (Ammodramus bairdii) and Savannah sparrow (Passerculus sandwichensis), both of which are found in areas increasingly affected by energy extraction noise. We compared these species because Savannah sparrows have more variability in their songs geographically and temporally compared to Baird’s sparrows. We recorded both species’ songs before, during and after high-fidelity playbacks of oil well drilling noise. Surprisingly, both species changed parts of their songs in the presence of noise (Baird’s sparrow usually decreasing frequency and Savannah sparrow increasing frequency) and these changes were not related to seasonal, song, or syllable variability. We suggest instead that acoustically heterogeneous environments may favour the evolution of species that are capable of adjusting their songs in response to variable ambient noise.
Anthropogenic noise is a pervasive pollutant altering behaviour of wildlife that communicates aco... more Anthropogenic noise is a pervasive pollutant altering behaviour of wildlife that communicates acoustically. Some species adjust vocalisations to compensate for noise. However, we know little about whether signal adjustments improve communication in noise, the extent to which effectiveness of adjustments varies with noise source, or how individual variation in physiology varies with response capacity. We played noise-adjusted and unadjusted songs to wild Passerculus sandwichensis (Savannah Sparrows) after measurements of adrenocortical responsiveness of individuals. Playbacks using songs adjusted to noisy environments were effective in restoring appropriate conspecific territorial aggression behaviours in some altered acoustic environments. Surprisingly, however, levels of adrenocortical responsiveness that reduced communication errors at some types of infrastructure were correlated with increased errors at others. Song adjustments that were effective in communicating for individuals with lower adrenocortical responsiveness at pumpjacks were not effective at screwpumps and vice versa. Our results demonstrate that vocal adjustments can sometimes allow birds to compensate for disruptions in communication caused by anthropogenic noise, but that physiological variation among receivers may alter effectiveness of these adjustments. Thus mitigation strategies to minimize anthropogenic noise must account for both acoustic and physiological impacts of infrastructure. Anthropogenic noise from industrial activities such as petroleum extraction 1 is widespread and alters soundscapes, behaviour and stress responses in many wildlife species 2-4. This acoustic pollution could result in extensive impacts to wildlife in critically threatened ecosystems such as grasslands 5. Noise can impact fitness by altering physiological costs 2 and disrupting behaviours crucial for defending territories and attracting mates 6-8 by preventing signals from being detected or recognised 9. However, these effects may vary among industrial activities, as spectral characteristics of noise produced by different activities can vary greatly 4,10. This suggests that ecological impacts of many different industrial activities might be mitigated by preferentially implementing infrastructure that produces noise at frequencies and amplitudes that produce the least disturbance and allow for the most compensatory behaviours from nearby animals. Vocalisations can be altered to make signals audible in noisy environments 9,11 but this can change signal content 6-8 and compromise communication efficacy 12. While many studies have demonstrated that the signalling animals can alter vocalisations to compensate for noise 10-13 , the literature has only recently focused on effects of anthropogenic noise on receivers 8,9,14-21. Thus, less is known about whether signal adjustments actually improve communication, if efficacy varies with noise source and how this interacts with intrinsic individual variation to explain capacity for populations to adjust to noise. Thus, why animals show variable behavioural responses to different types of noise 2,10,22 is not well understood. Extrinsic characteristics related to sound physics, particularly noise amplitude and frequency overlap between noise and acoustic signals, have been considered in some depth, but this does not always explain why signal alterations are necessary and effective in some systems 8 but are ineffective 7,16 in others. Behavioural responses to acoustic signals are mediated not only by the signalling environment, but also by physiological mechanisms 23 , which can both affect behavioural response patterns to novel stimuli 22 and be
Few studies have evaluated techniques for estimating detectability of prairie songbirds. We condu... more Few studies have evaluated techniques for estimating detectability of prairie songbirds. We conducted dependent double-observer point counts at 52 plots in prairie pastures in southern Alberta, Canada, in 2012, to test for species-specific, group-specific, and observer-specific differences in perceptibility. Although we did not find strong species or observer effects on perceptibility of most species in the study, we found evidence of differences in perceptibility when we pooled prairie songbirds into groups according to singing behaviors. Observers typically perceived only 40% of quiet songbirds singing from the ground (e.g., grasshopper sparrows and horned larks) but observed >89% of louder species singing from perch sites (e.g., Savannah sparrows) or in flight (e.g., Sprague’s pipits). Dependent double-observer methods would result in little increase in accuracy of abundance estimates for most species, but could be useful in studies where quiet species are more abundant or are targets for conservation management.
The rapid expansion of oil and natural gas development across the Northern Great Plains has contr... more The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds (Molothrus ater), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow (Passerculus sandwichensis) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird.
Understanding the mechanisms that explain why oil infrastructure has an effect on wildlife, and c... more Understanding the mechanisms that explain why oil infrastructure has an effect on wildlife, and comparing effects of different types of infrastructure, is necessary for determining how we may minimize or mitigate those effects. We compared the abundances of five grassland songbird species at oil well sites with different pump mechanisms and power sources, and determined the effects of exotic vegetation, perch sites, and road densities. We compared effects of wells that were active with effects of wells that were turned off to evaluate whether effects of wells were caused by noise or human activity at wells. We conducted 800-m abundance transects at 42 sites twice per year in 2013 and 2014 in Alberta, Canada. Two species at risk, Baird's sparrows (Ammodramus bairdii) and Sprague's pipits (Anthus spragueii), had significantly lower abundances at all sites that contained oil infrastructure. However, there was little evidence that noise, human activity, or traffic explained these effects. Effects of active and inactive wells were the same, and grid-powered wells had a greater effect than did generator-powered wells, although generator-powered wells are louder. Our research suggests that reducing noise, human activity or traffic would not reduce the effects of wells on grassland songbirds, and, therefore, mitigation must focus on minimizing the extent of above-ground infrastructure.
Integrating multiple disciplines to understand effects of anthropogenic noise on animal communica... more Integrating multiple disciplines to understand effects of anthropogenic noise on animal communication.
Probability of detection and accuracy of distance estimates in aural avian surveys may be affecte... more Probability of detection and accuracy of distance estimates in aural avian surveys may be affected by the presence of anthropogenic noise, and this may lead to inaccurate evaluations of the effects of noisy infrastructure on wildlife. We used arrays of speakers broadcasting recordings of grassland bird songs and pure tones to assess the probability of detection, and localization accuracy, by observers at sites with and without noisy oil and gas infrastructure in southcentral Alberta from 2012 to 2014. Probability of detection varied with species and with speaker distance from transect line, but there were few effects of noisy infrastructure. Accuracy of distance estimates for songs and tones decreased as distance to observer increased, and distance estimation error was higher for tones at sites with infrastructure noise. Our results suggest that quiet to moderately loud anthropogenic noise may not mask detection of bird songs; however, errors in distance estimates during aural surveys may lead to inaccurate estimates of avian densities calculated using distance sampling. We recommend caution when applying distance sampling if most birds are unseen, and where ambient noise varies among treatments.
Citizen science is critical for monitoring bird populations in the Caribbean, where logistic an... more Citizen science is critical for monitoring bird populations in the Caribbean, where logistic and resource challenges significantly limit data availability. However, observer experience and environmental characteristics can influence results of surveys, including those that make use of citizen science. To evaluate how surveys could be designed to integrate volunteer citizen scientists with different levels of experience into bird population monitoring programs in the Caribbean, we used double-observer methods with pairings of variously skilled observers to compare observer perceptibility and relative abundance estimates among potential sampling protocols. In total, we conducted 265 point counts and 140 100-m line transects with 25-m truncations on the island of Grenada in 2016–2017. Our results clearly indicated that more individuals and more species were detected per survey area during point count surveys than transect surveys. Novice observers detected as many easy-to-identify in...
Grenada is a Caribbean island with a volcanic origin and relatively low avian species diversity... more Grenada is a Caribbean island with a volcanic origin and relatively low avian species diversity, which may result in location-specific evolutionary pressures and thus locally adapted populations. Despite this, the morphology of most of its avian species has not been described. The aim of this study was to identify differences in the morphology of resident land birds on Grenada compared with other island and mainland areas. We collected morphological measurements of Bananaquits (Coereba flaveola), Black-faced Grassquits (Melanospiza bicolor), Lesser Antillean Bullfinches (Loxigilla noctis), and Common Ground Doves (Columbina passerina) in the field between 2015 and 2017, which we compared with data available from other locations (Venezuela and 23 other Caribbean islands) collated from academic papers and researchers. The morphology of Grenadian populations of our focal species differed from other islands in numerous ways; for example, Common Ground Doves had shorter wings and longe...
Short and sparse vegetation near shallow gas wells has generally been attributed to residual effe... more Short and sparse vegetation near shallow gas wells has generally been attributed to residual effects from well construction, but other mechanisms might also explain these trends. We evaluated effects of distance to shallow gas wells on vegetation and bare ground in mixed-grass prairies in southern Alberta, Canada, from 2010 to 2011. We then tested three hypotheses to explain why we found shorter vegetation and more bare ground near wells, using cattle fecal pat transects from 2012, and our vegetation quadrats. We evaluated whether empirical evidence suggested that observed patterns were driven by (1) higher abundance of crested wheatgrass (Agropyron cristatum) near wells, (2) residual effects of well construction, or (3) attraction of livestock to wells. Crested wheatgrass occurrence was higher near wells, but this did not explain effects of wells on vegetation structure. Correlations between distance to wells and litter depth were the highest near newer wells, providing support for...
ABSTRACT We screened 103 Chestnut-collared Longspurs (Calcarius ornatus) and 69 Savannah Sparrows... more ABSTRACT We screened 103 Chestnut-collared Longspurs (Calcarius ornatus) and 69 Savannah Sparrows (Passerculus sandwichensis) captured in Alberta, Canada, for infections from 3 genera of hemosporidian parasites (Haemoproteus, Plasmodium, and Leucocytozoon). We used electrophoresis to visualize bands of PCR product to code for the presence of infections and found no instances of parasitemia among the individuals we tested. To confirm that our method of blood storage and processing did not impede our ability to detect infections that were present, we screened 22 Swamp Sparrows (Melospiza georgiana) in Manitoba, Canada, using the same methods, and detected 5 infections. No previous studies have documented a lack of blood parasites in grassland songbirds, but it is possible that this is a result of publication bias against null results. As climate change shifts vector ranges, naïve populations of grassland songbirds may suffer disproportionately if vector presence or parasite transmissibility is altered.
The increasing encroachment of anthropogenic noise into natural environments is a source of signi... more The increasing encroachment of anthropogenic noise into natural environments is a source of significant concern for wildlife conservation (Shannon, McKenna, et al., 2016), and both spatial extent and complexity of anthropogenic noise from activities related to natural resource extraction are expected to rise as development increases across the world. This noise pollution may increase risks to species reliant on acoustic communication that are already experiencing significant population declines (Barber et al.
Urban rights-of-way may be potential reservoirs of tall-grass prairie plants and butterflies. To ... more Urban rights-of-way may be potential reservoirs of tall-grass prairie plants and butterflies. To determine if this is true, in 2007–2008, we conducted vegetation surveys of species richness and cover, and butterfly surveys of species richness and abundance, along 52 transmission lines and four remnant prairies in Winnipeg, Manitoba. We detected many prairie plants and butterflies within transmission lines. Some unmowed and infrequently managed transmission lines had native plant species richness and total percent cover of native plants comparable to that of similar-sized remnant tall-grass prairies in the region. Although we did not find significant differences in overall native butterfly numbers or species richness between rights-of-way and remnant prairies, we found lower numbers of some prairie butterflies along frequently mowed rights-of-way than within remnant tall-grass prairies. We also observed higher butterfly species richness along sites with more native plant species. By reducing mowing and spraying and reintroducing tall-grass prairie plants, urban rights-of-way could serve as extensive reservoirs for tall-grass prairie plants and butterflies in urban landscapes. Eventually, managing urban rights-of-way as reservoirs for tall-grass prairie plants and animals could contribute to the restoration of tall-grass prairie in the North American Midwest.
Proceedings of The Royal Society B: Biological Sciences, Sep 21, 2022
Human activities may impact animal habitat and resource use, potentially influencing contemporary... more Human activities may impact animal habitat and resource use, potentially influencing contemporary evolution in animals. In the United Kingdom, COVID-19 lockdown restrictions resulted in sudden, drastic alterations to human activity. We hypothesized that short-term daily and long-term seasonal changes in human mobility might result in changes in bird habitat use, depending on the mobility type (home, parks and grocery) and extent of change. Using Google human mobility data and 872 850 bird observations, we determined that during lockdown, human mobility changes resulted in altered habitat use in 80% (20/25) of our focal bird species. When humans spent more time at home, over half of affected species had lower counts, perhaps resulting from the disturbance of birds in garden habitats. Bird counts of some species (e.g. rooks and gulls) increased over the short term as humans spent more time at parks, possibly due to human-sourced food resources (e.g. picnic refuse), while counts of other species (e.g. tits and sparrows) decreased. All affected species increased counts when humans spent less time at grocery services. Avian species rapidly adjusted to the novel environmental conditions and demonstrated behavioural plasticity, but with diverse responses, reflecting the different interactions and pressures caused by human activity.
Anthropogenic noise may be detrimental to many bird species, and manipulative experiments would h... more Anthropogenic noise may be detrimental to many bird species, and manipulative experiments would help us understand these effects. We present the design and validation of a self-sustaining solarpowered broadcasting system that will allow researchers to disentangle acute or chronic effects of noise from effects of the presence of infrastructure, even in remote areas. We tested the broadcasting system using a case study on noise from oil well infrastructure in southern Alberta, Canada. Recordings from 2 types of oil wells were obtained and then broadcasted through 6 independent playback units continuously for a period of 3 months in 2013, at sites undisturbed by oil development. Sound measurements at real oil wells and at sites with broadcasting systems simulating the noise from these oil wells demonstrated that real and projected noise had very similar sound pressure levels, attenuation trends, and spectral composition. Throughout this long-term playback experiment, the system produced power and noise reliably and consistently. In conjunction with bird surveys, this experimental design and infrastructure can be used to allow researchers to dissociate the presence of anthropogenic development from associated noise, providing us with information that will help decrease the environmental impacts of human activities.
Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, b... more Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (δ 2 H) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high intrafeather isotopic variance and mean δ 2 H values higher than predicted from δ 2 H isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of δ 2 H analysis of sawwhet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006-2007. Values of δ 2 H in saw-whet owl feathers were higher than predicted from a δ 2 H isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of δ 2 H in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in δ 2 H values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater 2 H enrichment in adult feathers. These results indicate that current δ 2 H isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of 2 H enrichment in owl feathers is required.
Bioacoustics-the International Journal of Animal Sound and Its Recording, Mar 3, 2017
Abstract Organisms encounter noise naturally in the environment. However, increasing prevalence o... more Abstract Organisms encounter noise naturally in the environment. However, increasing prevalence of human-caused noise seems to be resulting in behavioural changes in many animals that can affect survival and reproduction. Not all species react the same way to noise; some adjust their vocal signals while others do not. We hypothesized that species with more variability in their vocal signals would be better able to adjust their signals to be audible over anthropogenic noise. We tested this within a large-scale manipulative experiment by recording songs of two grassland songbirds, Baird’s sparrow (Ammodramus bairdii) and Savannah sparrow (Passerculus sandwichensis), both of which are found in areas increasingly affected by energy extraction noise. We compared these species because Savannah sparrows have more variability in their songs geographically and temporally compared to Baird’s sparrows. We recorded both species’ songs before, during and after high-fidelity playbacks of oil well drilling noise. Surprisingly, both species changed parts of their songs in the presence of noise (Baird’s sparrow usually decreasing frequency and Savannah sparrow increasing frequency) and these changes were not related to seasonal, song, or syllable variability. We suggest instead that acoustically heterogeneous environments may favour the evolution of species that are capable of adjusting their songs in response to variable ambient noise.
Anthropogenic noise is a pervasive pollutant altering behaviour of wildlife that communicates aco... more Anthropogenic noise is a pervasive pollutant altering behaviour of wildlife that communicates acoustically. Some species adjust vocalisations to compensate for noise. However, we know little about whether signal adjustments improve communication in noise, the extent to which effectiveness of adjustments varies with noise source, or how individual variation in physiology varies with response capacity. We played noise-adjusted and unadjusted songs to wild Passerculus sandwichensis (Savannah Sparrows) after measurements of adrenocortical responsiveness of individuals. Playbacks using songs adjusted to noisy environments were effective in restoring appropriate conspecific territorial aggression behaviours in some altered acoustic environments. Surprisingly, however, levels of adrenocortical responsiveness that reduced communication errors at some types of infrastructure were correlated with increased errors at others. Song adjustments that were effective in communicating for individuals with lower adrenocortical responsiveness at pumpjacks were not effective at screwpumps and vice versa. Our results demonstrate that vocal adjustments can sometimes allow birds to compensate for disruptions in communication caused by anthropogenic noise, but that physiological variation among receivers may alter effectiveness of these adjustments. Thus mitigation strategies to minimize anthropogenic noise must account for both acoustic and physiological impacts of infrastructure. Anthropogenic noise from industrial activities such as petroleum extraction 1 is widespread and alters soundscapes, behaviour and stress responses in many wildlife species 2-4. This acoustic pollution could result in extensive impacts to wildlife in critically threatened ecosystems such as grasslands 5. Noise can impact fitness by altering physiological costs 2 and disrupting behaviours crucial for defending territories and attracting mates 6-8 by preventing signals from being detected or recognised 9. However, these effects may vary among industrial activities, as spectral characteristics of noise produced by different activities can vary greatly 4,10. This suggests that ecological impacts of many different industrial activities might be mitigated by preferentially implementing infrastructure that produces noise at frequencies and amplitudes that produce the least disturbance and allow for the most compensatory behaviours from nearby animals. Vocalisations can be altered to make signals audible in noisy environments 9,11 but this can change signal content 6-8 and compromise communication efficacy 12. While many studies have demonstrated that the signalling animals can alter vocalisations to compensate for noise 10-13 , the literature has only recently focused on effects of anthropogenic noise on receivers 8,9,14-21. Thus, less is known about whether signal adjustments actually improve communication, if efficacy varies with noise source and how this interacts with intrinsic individual variation to explain capacity for populations to adjust to noise. Thus, why animals show variable behavioural responses to different types of noise 2,10,22 is not well understood. Extrinsic characteristics related to sound physics, particularly noise amplitude and frequency overlap between noise and acoustic signals, have been considered in some depth, but this does not always explain why signal alterations are necessary and effective in some systems 8 but are ineffective 7,16 in others. Behavioural responses to acoustic signals are mediated not only by the signalling environment, but also by physiological mechanisms 23 , which can both affect behavioural response patterns to novel stimuli 22 and be
Few studies have evaluated techniques for estimating detectability of prairie songbirds. We condu... more Few studies have evaluated techniques for estimating detectability of prairie songbirds. We conducted dependent double-observer point counts at 52 plots in prairie pastures in southern Alberta, Canada, in 2012, to test for species-specific, group-specific, and observer-specific differences in perceptibility. Although we did not find strong species or observer effects on perceptibility of most species in the study, we found evidence of differences in perceptibility when we pooled prairie songbirds into groups according to singing behaviors. Observers typically perceived only 40% of quiet songbirds singing from the ground (e.g., grasshopper sparrows and horned larks) but observed >89% of louder species singing from perch sites (e.g., Savannah sparrows) or in flight (e.g., Sprague’s pipits). Dependent double-observer methods would result in little increase in accuracy of abundance estimates for most species, but could be useful in studies where quiet species are more abundant or are targets for conservation management.
The rapid expansion of oil and natural gas development across the Northern Great Plains has contr... more The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds (Molothrus ater), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow (Passerculus sandwichensis) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird.
Understanding the mechanisms that explain why oil infrastructure has an effect on wildlife, and c... more Understanding the mechanisms that explain why oil infrastructure has an effect on wildlife, and comparing effects of different types of infrastructure, is necessary for determining how we may minimize or mitigate those effects. We compared the abundances of five grassland songbird species at oil well sites with different pump mechanisms and power sources, and determined the effects of exotic vegetation, perch sites, and road densities. We compared effects of wells that were active with effects of wells that were turned off to evaluate whether effects of wells were caused by noise or human activity at wells. We conducted 800-m abundance transects at 42 sites twice per year in 2013 and 2014 in Alberta, Canada. Two species at risk, Baird's sparrows (Ammodramus bairdii) and Sprague's pipits (Anthus spragueii), had significantly lower abundances at all sites that contained oil infrastructure. However, there was little evidence that noise, human activity, or traffic explained these effects. Effects of active and inactive wells were the same, and grid-powered wells had a greater effect than did generator-powered wells, although generator-powered wells are louder. Our research suggests that reducing noise, human activity or traffic would not reduce the effects of wells on grassland songbirds, and, therefore, mitigation must focus on minimizing the extent of above-ground infrastructure.
Integrating multiple disciplines to understand effects of anthropogenic noise on animal communica... more Integrating multiple disciplines to understand effects of anthropogenic noise on animal communication.
Probability of detection and accuracy of distance estimates in aural avian surveys may be affecte... more Probability of detection and accuracy of distance estimates in aural avian surveys may be affected by the presence of anthropogenic noise, and this may lead to inaccurate evaluations of the effects of noisy infrastructure on wildlife. We used arrays of speakers broadcasting recordings of grassland bird songs and pure tones to assess the probability of detection, and localization accuracy, by observers at sites with and without noisy oil and gas infrastructure in southcentral Alberta from 2012 to 2014. Probability of detection varied with species and with speaker distance from transect line, but there were few effects of noisy infrastructure. Accuracy of distance estimates for songs and tones decreased as distance to observer increased, and distance estimation error was higher for tones at sites with infrastructure noise. Our results suggest that quiet to moderately loud anthropogenic noise may not mask detection of bird songs; however, errors in distance estimates during aural surveys may lead to inaccurate estimates of avian densities calculated using distance sampling. We recommend caution when applying distance sampling if most birds are unseen, and where ambient noise varies among treatments.
Citizen science is critical for monitoring bird populations in the Caribbean, where logistic an... more Citizen science is critical for monitoring bird populations in the Caribbean, where logistic and resource challenges significantly limit data availability. However, observer experience and environmental characteristics can influence results of surveys, including those that make use of citizen science. To evaluate how surveys could be designed to integrate volunteer citizen scientists with different levels of experience into bird population monitoring programs in the Caribbean, we used double-observer methods with pairings of variously skilled observers to compare observer perceptibility and relative abundance estimates among potential sampling protocols. In total, we conducted 265 point counts and 140 100-m line transects with 25-m truncations on the island of Grenada in 2016–2017. Our results clearly indicated that more individuals and more species were detected per survey area during point count surveys than transect surveys. Novice observers detected as many easy-to-identify in...
Grenada is a Caribbean island with a volcanic origin and relatively low avian species diversity... more Grenada is a Caribbean island with a volcanic origin and relatively low avian species diversity, which may result in location-specific evolutionary pressures and thus locally adapted populations. Despite this, the morphology of most of its avian species has not been described. The aim of this study was to identify differences in the morphology of resident land birds on Grenada compared with other island and mainland areas. We collected morphological measurements of Bananaquits (Coereba flaveola), Black-faced Grassquits (Melanospiza bicolor), Lesser Antillean Bullfinches (Loxigilla noctis), and Common Ground Doves (Columbina passerina) in the field between 2015 and 2017, which we compared with data available from other locations (Venezuela and 23 other Caribbean islands) collated from academic papers and researchers. The morphology of Grenadian populations of our focal species differed from other islands in numerous ways; for example, Common Ground Doves had shorter wings and longe...
Short and sparse vegetation near shallow gas wells has generally been attributed to residual effe... more Short and sparse vegetation near shallow gas wells has generally been attributed to residual effects from well construction, but other mechanisms might also explain these trends. We evaluated effects of distance to shallow gas wells on vegetation and bare ground in mixed-grass prairies in southern Alberta, Canada, from 2010 to 2011. We then tested three hypotheses to explain why we found shorter vegetation and more bare ground near wells, using cattle fecal pat transects from 2012, and our vegetation quadrats. We evaluated whether empirical evidence suggested that observed patterns were driven by (1) higher abundance of crested wheatgrass (Agropyron cristatum) near wells, (2) residual effects of well construction, or (3) attraction of livestock to wells. Crested wheatgrass occurrence was higher near wells, but this did not explain effects of wells on vegetation structure. Correlations between distance to wells and litter depth were the highest near newer wells, providing support for...
ABSTRACT We screened 103 Chestnut-collared Longspurs (Calcarius ornatus) and 69 Savannah Sparrows... more ABSTRACT We screened 103 Chestnut-collared Longspurs (Calcarius ornatus) and 69 Savannah Sparrows (Passerculus sandwichensis) captured in Alberta, Canada, for infections from 3 genera of hemosporidian parasites (Haemoproteus, Plasmodium, and Leucocytozoon). We used electrophoresis to visualize bands of PCR product to code for the presence of infections and found no instances of parasitemia among the individuals we tested. To confirm that our method of blood storage and processing did not impede our ability to detect infections that were present, we screened 22 Swamp Sparrows (Melospiza georgiana) in Manitoba, Canada, using the same methods, and detected 5 infections. No previous studies have documented a lack of blood parasites in grassland songbirds, but it is possible that this is a result of publication bias against null results. As climate change shifts vector ranges, naïve populations of grassland songbirds may suffer disproportionately if vector presence or parasite transmissibility is altered.
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Papers by Nicola Koper