Browsing by Author "Davis, Stephen"

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Open Access
Breeding Biology of Grassland Songbirds and the Effects of Oil and Natural Gas Development on Their Density and Reproductive Success
(Faculty of Graduate Studies and Research, University of Regina, 2013-05) Ludlow, Sarah Maureen; Brigham, R. Mark; Davis, Stephen; Vetter, Mary; Lockhart, Wallace
Understanding the breeding ecology of grassland birds is vital for identifying the mechanisms underlying their widespread population declines. I describe the breeding biology of and quantify the effects of nest predation and brood parasitism on Savannah Sparrow (Passerculus sandwichensis), Baird’s Sparrow (Ammodramus bairdii), Vesper Sparrow (Pooecetes gramineus), Western Meadowlark (Sternella neglecta), and Sprague’s Pipit (Anthus spragueii) in south-eastern Alberta. Nest predation was the primary cause of nest failure, accounting for 75% of all nest losses. For the three sparrow species, daily survival rates were higher during the incubation compared to the nestling stage. For all five species, clutch size, hatching success, and fledging success were within the range of values previously reported for these species in other parts of their range. Brown-headed Cowbirds parasitized nests of all species except Sprague’s Pipit, with 4- 11% of nests containing cowbird eggs. Savannah Sparrow experienced the highest frequency of brood parasitism and was the only species to successfully fledge cowbird young. Parasitized Savannah Sparrow nests experienced reduced hatching success, productivity, and clutch size compared to non-parasitized nests. The overall cost of parasitism to Savannah Sparrow was 1.7 young per successful nest. This information provides a basis for future comparisons regarding the influence of anthropogenic alterations to native grassland habitat on grassland songbird reproductive success and nest survival. Despite dramatic increases in oil and gas development over the last decade, research about the effects of this activity on grassland songbird reproductive success and density is lacking. I assessed how the density and reproductive success of five species of grassland songbirds in south-eastern Alberta varied with distance to oil and gas wells, roads, trails, and patches of introduced crested wheatgrass, along with percent cover of crested wheatgrass. Savannah Sparrow density was 2.5 times higher within 100 m of wells than further away and was almost twice as high in areas without crested wheatgrass compared to those with 60% cover. Sprague’s Pipit nest survival decreased with increased cover of crested wheatgrass. The proportion of Baird’s Sparrow eggs that hatched within 50 m of wells and trails were reduced by 33% and 46%, respectively, compared to areas further from these structures. Hatching success more than doubled for both Sprague’s Pipit and Western Meadowlark as percent cover of crested wheatgrass increased from 0-60%. The number of young fledged from successful Baird’s Sparrow nests was lower near trails. Savannah Sparrow fledging success was higher near wells and in areas with greater cover of crested wheatgrass. The number of young fledged from successful Western Meadowlark nests doubled as distance from crested wheatgrass increased from 0-800 m. There was no relationship between the frequency of brood parasitism and distance to oil and gas infrastructure. Overall, my results indicate that oil and gas development has mixed effects on the density and reproductive success of grassland songbirds. To mitigate potential negative effects, future development by the energy industry should attempt to minimize the amount of edge habitat created, continue to eliminate exotic vegetation in their reclamation protocols, and take precautions to avoid the spread of crested wheatgrass, and other invasive plants, into native grassland.
Open Access
Developing Grassland Songbird Management Targets for Multi-Species Conservation on Native Mixed-Grass Prairie
(Faculty of Graduate Studies and Research, University of Regina, 2018-07) Rose, Phillip Kelsey; Brigham, R. Mark; Davis, Stephen; Vetter, Mary; Sutter, Glenn
Grassland birds are declining at steeper rates than birds from nearly every other habitat type, and the primary reasons for these declines are loss and degradation of native grasslands. Moisture, along with other environmental conditions such as soil type, topography, fire, and grazing, play important roles in determining the extent of habitat features important to grassland songbirds. I examined the associations between the abundance/occurrence of 14 grassland songbird species and vegetation characteristics along a moisture gradient in southwest Saskatchewan. Associations with at least one vegetation characteristic changed along the moisture gradient for 12 of the 14 species. Songbird abundance/occurrence was typically greater in areas with dense cover at drier sites along the moisture gradient when overall cover was sparse and greater in areas with sparser cover at wetter sites when overall cover was dense; however, absolute values for vegetation characteristics associated with peak abundance/occurrence often remained similar along the moisture gradient. The umbrella species concept is based on the premise that the conservation of a single species can also aid in conservation of a wide range of other co-occurring species with overlapping habitat requirements. I examined how the vegetation attributes of greater sage-grouse (Centrocercus urophasianus) critical habitat influenced grassland songbirds, and whether sage-grouse could potentially serve as an umbrella species for the grassland songbird community at the northern extent of the sage-grouse range. I found that abundance of Sprague’s pipit (Anthus spragueii) and Baird’s sparrow (Ammodramus bairdii) was lower and abundance of lark bunting (Calamospiza melanocorys) was higher within greater sage-grouse critical habitat in comparison to a 1.6 km buffer surrounding critical habitat. The abundance of all endemic grassland songbirds, except lark bunting, was negatively associated with vegetation attributes that characterized sage-grouse critical habitat (i.e., shrub and sagebrush cover). The vegetation characteristics associated with shrub-steppe songbirds and several grassland generalists overlapped with vegetation characteristics that defined greater sage-grouse critical habitat. Greater sage-grouse conservation is likely to have a positive influence on shrub-tolerant species, such as lark bunting, and a neutral or positive effect on generalist grassland species, but will provide few benefits to other grassland species at risk.
Open Access
The Effects of natural Gas Development on Density, Reproductive Success and Nest Survival of Grassland Songbirds in South-Western Saskatchewan
(Faculty of Graduate Studies and Research, University of Regina, 2013-06) Gaudet, Carolyn Anne; Brigham, R. Mark; Davis, Stephen; Somers, Christopher; Clark, Robert G.
Natural gas development is currently expanding in south-western Saskatchewan and may be threatening the quality of the remaining grassland habitat. The effects of natural gas development on grassland birds are poorly understood but are often species-specific and vary across the species’ range. The purpose of my research is to (1) quantify aspects of grassland songbird breeding biology and (2) determine the effects of natural gas development on density and reproductive success of grassland songbirds. I found and monitored 392 nests of 7 species of grassland songbirds, including Chestnut-collared Longspur (Calcarius ornatus), Vesper Sparrow (Pooecetes gramineus), Sprague’s Pipit (Anthus spragueii), Savannah Sparrow (Passerculus sandwichensis), Baird’s Sparrow (Ammodramus bairdii), Horned Lark (Eremophila alpestris) and Western Meadowlark (Sturnella neglecta). I quantified and compared aspects of their breeding biology with published data in other parts of their range. Reproductive rates were typical of those found elsewhere. Time-specific variables (age and date) were included in the top models for nest survival for several species. Chestnut-collared Longspur nest survival increased during the incubation stage and decreased during the nestling stage and also decreased and then increased as the breeding season progressed. I also determined that Western Meadowlark nest survival increased and then decreased with increasing ambient temperature. Natural gas development features (compressor stations, gas wells, trails and fences) affected grassland songbird reproductive success, nest survival and density both negatively and positively. Vesper, Baird’s and Savannah sparrows had lower nest survival near wells, fences and trails, respectively, while Western Meadowlark experienced higher nest survival near trails. Generally, there were fewer young fledged near development, but this varied by species and type of development. Vesper and Savannah sparrows had greater densities in high disturbance plots while Chestnut-collared Longspur and Horned Lark had lower densities in high disturbance plots. Baird’s and Savannah sparrows had lower densities near compressor stations while Horned Lark density was greater near compressor stations. The density of Sprague’s Pipit and Western Meadowlark was best explained by vegetation structure. Natural gas development affected grassland songbird reproductive success, nest survival and density in both negative and positive ways or there was no effect; however, the extent of the impact may vary with the habitat and within the species’ range.
Open Access
Effects of Oil Development on Grassland Songbirds and Their Avian Predators in Southeastern Saskatchewan
(Faculty of Graduate Studies and Research, University of Regina, 2015-10) Unruh, Jason Howard; Brigham, R. Mark; Davis, Stephen; Somers, Christopher; Mahony, Nancy
The quantity and quality of Saskatchewan’s remaining grassland may be threatened by energy development such as oil extraction. Grassland songbird populations are declining and increased oil development may be contributing to their declines through habitat loss and degradation. More quantitative research is needed to inform our understanding of how grassland songbirds are affected by oil development. I examined grassland songbird abundance, vegetation structure, habitat type (native and planted grasslands), and avian predator occurrence across a gradient of oil disturbance to determine the extent to which oil well proximity, density, and cumulative habitat disturbance influences the abundance of grassland songbirds and the occurrence of avian predators. I conducted 486 point counts in 243 sample sites (259 ha) at varying distances from oil wells, and in areas with varying well densities (0-48 wells/259 ha). The abundance of seven songbird species was reduced near oil wells or in areas with higher well densities, the abundance of two species was not influenced by oil wells, and the abundance of two species increased in the presence of oil wells or with greater well density. Three species also exhibited reduced abundance with greater cumulative disturbance, while two species exhibited reduced abundance when the area covered by well pads or oil access roads increased. I also found evidence that the abundance of four species was lowest in planted grassland compared to native grassland in the presence of oil development. My results indicate that oil development influenced vegetation structure, which likely influenced grassland songbird abundance to some degree. However, structural changes in vegetation did not account for all observed variation in songbird abundance. Finally, my results provide evidence that Northern Harrier occurrence is negatively influenced by oil development but that buteos and corvids are not affected. Northern Harrier occurrence is possibly influenced by habitat fragmentation caused by oil development since they are known to be area sensitive. As oil development increases in grassland habitat, its negative impacts on grassland songbirds will likely become more pronounced. Efforts should be made to limit well density and the cumulative area of disturbance on the landscape.
Open Access
Habitat selection and nesting ecology of translocated Greater Sage-grouse
(Faculty of Graduate Studies and Research, University of Regina, 2017-02) Balderson, Kayla Lane; Brigham, R. Mark; Davis, Stephen; Somers, Christopher; Moehrenschlager, Axel
Sagebrush ecosystems are one of the most imperiled ecosystems in North America. The cumulative effects of habitat loss, fragmentation and degradation of the sagebrush ecosystem threaten the persistence of the Greater Sage-grouse. Sage-grouse depend on healthy, intact areas of sagebrush habitat throughout the year. In Alberta, the sage-grouse population is estimated to be only 5% of what it was in 1968. During the spring of 2011 and 2012, 41 sage-grouse were fitted with GPS transmitters and translocated from stable populations in Montana to active lek sites in southeast Alberta. I conducted research to improve our understanding of translocation as a management tool, and how translocated sage-grouse are affected by anthropogenic features. I examined nesting ecology including the differences in post-release movements between nesting and non-nesting hens and the extent to which nest success is affected by anthropogenic features. I also identified habitat that translocated sage-grouse select in relation to anthropogenic and natural features. My research documented some of the largest post-release movement distances, rates and areas ever recorded for grouse after being translocated. Average weekly linear distance travelled was 56 km and average area traversed was 1944 km2. Non-nesting hens had significantly higher movement rates than nesting hens. Movement rates of nesting hens decreased during the nest initiation period, whereas movement rates of non-nesting hens did not decrease until 6 weeks later. Apparent annual hen survival ranged between 31-72% across the study period. Nest initiation (53%) and nest success (29%) were low compared to other sage-grouse populations across their range. Nest success decreased with increasing distance from trees, power lines and settlements, suggesting that translocated hens are naïve to the release area and do not recognize the risks that are typically associated with certain anthropogenic features. Translocated sage-grouse were more likely to be observed, with increasing distance from all of the anthropogenic features included in the movement models: as far as 3 km from trees and gas wells, 10 km from buildings and 15 km from settlements, at least 23 km from power lines and 2.5 km from roads. Interaction models suggest that sage-grouse are avoiding anthropogenic features because of the disturbance of the features themselves, and not because the features occur in poor sagebrush habitat. My results indicate that the effects of power lines, buildings, trees and oil wells (up to 5 km) on the occurrence of sage-grouse were largest, suggesting that these features should be prioritized for removal. However, it is likely that cumulative effects of some or all anthropogenic features cause sage-grouse to select habitat further away from these features. The predicted intensity map I generated could be used to help strategically guide habitat enhancement efforts in the study area. Habitat enhancements would best be focused in areas where predicted intensity was high and suitable habitat was present yet no sage-grouse were observed, with the goal of increasing the likelihood of sage-grouse use within those areas. Future assessments of proposed developments should consider the construction of all new anthropogenic features as a potential detriment to habitat quality.
Open Access
Habitat Selection by Birds in Willow-Ringed Wetlands: Management Implications for Harvesting Willow Biomass
(Faculty of Graduate Studies and Research, University of Regina, 2015-04) Mushanski, Melissa Dawn; Somers, Christopher; Davis, Stephen; Hall, Britt; Sutter, Glenn
Increase in prices of fossil fuels and escalating environmental conflicts have generated renewed interest in bioenergy production. Abundant small wetlands ringed with willow species (willow rings) growing naturally in the Prairie Ecozone of North America may provide a source of natural biomass as a bioenergy feedstock. Subsequently, a bioenergy crop from these wetlands could increase their economic value and help reduce their drainage and loss. Little is known about the importance of willow vegetation to birds, and what habitat features may be important to consider when planning biomass harvest. To address this knowledge gap, I conducted point count surveys in the spring of 2012 and 2013 at 92 willow rings in south-eastern Saskatchewan. My objectives were to determine: 1) what species make up the willow- ring bird community; 2) what wetland and vegetation characteristics influence bird abundance; and 3) whether abundance of willow-ringed wetland birds varies as a function of the surrounding upland habitat (cropland vs. grassland). I found that the willow ring community is composed of at least 66 species from 3 distinct guilds: woodland, wetland, and grassland birds, and that members of each guild responded differently to willow ring structure and habitat features. For example, American robin (Turdus migratorius) and yellow warbler (Setophaga petechia), both woodland species, increased in abundance as willow area increased. A wetland bird species, the American coot (Fulica americana), decreased in abundance as % willow cover increased. However, all other species were unaffected by changes in the willow ring structure, suggesting that willow harvest will have little impact on these birds. Woodland bird species may decrease as their habitat is lost; however, management practices such as partial harvests or rotational harvest by year may make willow harvest sustainable for all species. Furthermore, land managers should adjust harvest guidelines to reflect local bird management objectives. In doing so, willow harvest can likely be done with minimal impact on bird species associated with willow-ringed wetlands.
Open Access
La sociolinguistique pour le changement en immersion française : un examen transdisciplinaire d’idéologies linguistiques dans les prairies canadiennes
(University of New Brunswick, 2024-10-29) Adedeji, Olushola; Davis, Stephen; Roy, Sylvie; Sterzuk, Andrea
Cet article examine les discours d’enseignants1 et d’élèves en immersion française sur les idéologies linguistiques qui les empêchent d’être inclus dans les communautés francophones. Nous débutons par une recension des écrits sur certaines idéologies pour mieux connaître le travail qui se fait déjà dans le domaine. À partir de la sociolinguistique pour le changement qui prend une approche critique et réflexive sur notre rôle en tant que chercheurs ainsi que sur l’examen des relations de pouvoir chez les parlants de français langue seconde, nous examinons des extraits de nos recherches qui traitent des discours sur les idéologies présentes. Notre équipe transdisciplinaire examine donc les variétés linguistiques ; la sécurité linguistique des élèves ; la pertinence de l’immersion pour les élèves plurilingues et les rôles des répertoires linguistiques des élèves dans l’apprentissage du français en immersion. Nous constatons que les discours continuent à exclure les apprenants de français, mais que ces discours commencent à changer, surtout chez les apprenants plurilingues. Si on s’éloigne un peu de l’idée que la francophonie doit être d’une certaine façon, on conclut que des changements sont possibles.
Open Access
Natural Gas Development and Grassland Songbird Abundance in Southwestern Saskatchewan: The Impact of Gas Wells and Cumulative Disturbance
(Faculty of Graduate Studies and Research, University of Regina, 2011-09-28) Bogard, Holly Jayne Kalyn; Brigham, R. Mark; Davis, Stephen; Somers, Christopher; Wellicome, Troy
The quantity and quality of remaining grasslands in southwestern Saskatchewan, Canada, are threatened by expansion of natural gas development. The number of natural gas wells nearly tripled between 1997 and 2007. Current management strategies do not consider the effect of natural gas development on grassland birds because the impacts are not known. I examined grassland songbirds and vegetation structure across an area with a gradient of gas-well densities to determine whether (1) density and proximity of gas wells influence abundance and occurrence of grassland songbirds or (2) the relative and cumulative effect of different types of anthropogenic disturbances associated with natural gas development (roads, trails, pipelines, gas well size, soil compaction, and crested wheatgrass coverage) influence the abundance and occurrence of grassland songbirds in south-western Saskatchewan. I conducted 1250 point counts in 105 plots (259 ha each) at varying distances from natural gas wells, which ranged from 0-25 natural gas wells per 259 ha per plot. I recorded 7 grassland songbird species: Horned Lark (Eremophilus alpestris), Sprague’s Pipit (Anthus spragueii), Chestnut-collared Longspur (Calcarius ornatus), McCown’s Longspur (Rhynchophanes mccownii), Savannah Sparrow (Passerculus sandwichensis), Grasshopper Sparrow (Ammodramus savannarum) and Baird’s Sparrow (Ammodramus bairdii). Responses of grassland songbirds to natural gas well density, proximity, and types of disturbance structures varied among species. Overall, Sprague’s Pipit, McCown’s Longspur and Grasshopper Sparrow responded negatively to natural gas development, Chestnut-collared Longspur, Savannah and Baird’s Sparrows exhibited mixed effects, and Horned Larks consistently responded positively to natural gas development. My results also indicate that natural gas ii development affected vegetation structure, which likely influences grassland bird abundance. The species-specific responses to natural gas disturbance seemed closely linked to the associated changes in vegetation structure. As natural gas development increases on Agriculture and Agri-Foods Canada pastures and on other grasslands, the effects on grassland songbirds will likely become more pronounced. My research is the first to quantify the relationship between songbird abundance, vegetation structure, and natural gas development. Further work is necessary to assess the effects of natural gas development on grassland songbirds and other species as energy development proceeds.
Open Access
The response of the avian community to 40 years of land cover change within the Aspen Parkland and Moist-mixed Grassland ecoregions of the Canadian prairies
(Faculty of Graduate Studies and Research, University of Regina, 2015-03) Kovatch, Leah Catherine; Somers, Christopher; Davis, Stephen; Brigham, Mark; Piwowar, Joseph; Morrissey, Christy
Since European settlement, over 80% of grassland habitat has been lost in the Canadian prairies, primarily in the Moist-mixed Grassland and Aspen Parkland ecoregions. Native grassland continues to be lost and degraded. Reduction of fire and overgrazing by livestock has allowed woody vegetation to encroach on grasslands. Grassland bird populations in the northern extent of their range have undergone steep declines whereas woodland bird populations have increased. It is unknown whether population fluctuations over the past 40 years are a result of land cover changes during this period. The goal of my research was to address this knowledge gap with the use of long-term datasets from the Breeding Bird Survey (BBS) and remote sensing. My objectives were to: (1) assess changes in bird population trends over the past 40 years along a sub-set of representative BBS routes; (2) determine land cover change along these BBS routes from 1970 to 2012; and (3) determine if there is a relationship between land cover change and bird population trends over the past 40 years. I classified 1970 and 2012 land cover (cultivated, native grassland, and woodland) within an 800 m radius of point-count locations along nine BBS routes located in the Moist-mixed Grassland and Aspen Parkland ecoregions of Saskatchewan and Manitoba. Bird population trend estimates from 1970 to 2011 were compiled for each BBS route and I grouped species based on breeding habitat guild (grassland, scrubland, and woodland). On average, grassland and scrubland bird populations decreased by 1.5 %/yr and 0.7 %/yr, respectively, and woodland birds increased by 1.4 %/yr along routes. The amount of land cover change from 1970 to 2012 was small along routes, indicating the majority of landscape change occurred prior to 1970. Cultivated land and woodland increased on average by 2.2% and 0.1% respectively, and native grassland decreased by 2.1%. Although absolute native grassland loss was small overall, proportion of loss relative to what was present in 1970 was large. The relatively small change in woodland cover was likely a result of land being cleared for cultivation but at the same time encroaching on native grassland. Overall, I found no statistically significant relationship between land cover change and bird trend estimates. Possible explanations for a lack of a relationship include: (1) land cover change was too small to affect bird populations; (2) common and generalist species included in community analyses are less affected by the documented habitat changes; (3) factors other than recent land cover change are affecting bird populations (i.e., fragmentation, patch size, local vegetation); and (4) habitat loss is occurring on migration and winter areas. Additional research is needed to address shrub encroachment rates in my study area, as well as to investigate the effects of habitat changes on grassland specialists.
Open Access
Using Occupancy Models to Predict Grassland Bird Distributions in Southeastern Alberta
(Faculty of Graduate Studies and Research, University of Regina, 2014-10) Clements, Nathan David; Brigham, R. Mark; Davis, Stephen; Somers, Christopher; Bayne, Erin
Widespread population declines of grassland birds have stimulated a variety of conservation plans, many of which promote a landscape approach to conservation. Identifying needs for survival and reproduction, and prioritizing key habitat requirements that influence where species occur on the landscape is an essential first step to guiding long term management efforts. I used single-species, single-season occupancy models to (1) identify landscape factors influencing the distribution of grassland bird species, (2) generate predictions of species distributions in southeastern Alberta, and (3) evaluate the predictive performance of each species model with two sources of evaluation data. In 2012, I conducted three repeat surveys at each of 870 point count locations to generate occupancy models, and evaluated the predictive performance of each model using a partitioned data set from 2012 and an independent data set of 1398 point counts collected in 2011. Records of detection/non-detection were collected for: Baird's Sparrow (Ammodramus bairdii), Brown-headed Cowbird (Molothrus ater), Chestnut-collared Longspur (Calcarius ornatus), Clay-colored Sparrow (Spizella pallida), Horned Lark (Eremophila alpestris), Long-billed Curlew (Numenius americanus), Marbled Godwit (Limosa fedoa), McCown's Longspur (Rhynchophanes mccownii), Savannah Sparrow (Passerculus sandwichensis), Sprague's Pipit (Anthus spragueii), Upland Sandpiper (Bartramia longicauda), Vesper Sparrow (Pooecetes gramineus), Western Meadowlark (Sturnella neglecta), and Willet (Tringa semipalmata). Models that best explained detectability typically included both date and time of day of the survey. The amount of grassland on the landscape was a broadly useful measure in predicting occupancy. Variables describing landscape topography and the geographic location (i.e., latitude and longitude) also aided in understanding where species occur and provided a more complete explanation of resource selection. I show that the models generated for four species were accurate predictors of occupancy. The remaining models require further investigation to develop accurate predictions of occupancy, but are presented for exploratory purposes and can be used to guide and refine future predictive modelling efforts. I suggest that, depending on the application, these models and maps be used to guide local conservation plans for birds, and can be used as a valuable reference for prioritizing conservation activities in southeast Alberta. These models add to our understanding of resource selection at the landscape level, and can assist in the process of ensuring key habitats are identified and conserved.