Clayton H. Riddell Faculty of Environment, Earth, and Resources Scholarly Works

Permanent URI for this collectionhttp://hdl.handle.net/1993/36337

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Access status: Open Access ,
Earth Sciences Graduate Symposium Program with Abstracts
(2024-04-15) Brink, Kirstin; Brueckner, Stefanie
Abstract book for the Earth Sciences Graduate Symposium
Access status: Open Access ,
Do beluga whales truly migrate? Testing a key trait of the classical migration syndrome
(BMC, 2023-08-30) Storrie, Luke; Loseto, Lisa; Sutherland, Emma L.; MacPhee, Shannon A.; O’Corry-Crowe, Greg; Hussey, Nigel E.
Background Migration enables organisms to access resources in separate regions that have predictable but asynchronous spatiotemporal variability in habitat quality. The classical migration syndrome is defined by key traits including directionally persistent long-distance movements during which maintenance activities are suppressed. But recently, seasonal round-trip movements have frequently been considered to constitute migration irrespective of the traits required to meet this movement type, conflating common outcomes with common traits required for a mechanistic understanding of long-distance movements. We aimed to test whether a cetacean ceases foraging during so-called migratory movements, conforming to a trait that defines classical migration. Methods We used location and dive data collected by satellite tags deployed on beluga whales (Delphinapterus leucas) from the Eastern Beaufort Sea population, which undertake long-distance directed movements between summer and winter areas. To identify phases of directionally persistent travel, behavioural states (area-restricted search, ARS; or Transit) were decoded using a hidden-Markov model, based on step length and turning angle. Established dive profiles were then used as a proxy for foraging, to test the hypothesis that belugas cease foraging during these long-distance transiting movements, i.e., they suppress maintenance activities. Results Belugas principally made directed horizontal movements when moving between summer and winter residency areas, remaining in a Transit state for an average of 75.4% (range = 58.5–87.2%) of the time. All individuals, however, exhibited persistent foraging during Transit movements (75.8% of hours decoded as the Transit state had ≥ 1 foraging dive). These data indicate that belugas actively search for and/or respond to resources during these long-distance movements that are typically called a migration. Conclusions The long-distance movements of belugas do not conform to the traits defining the classical migration syndrome, but instead have characteristics of both migratory and nomadic behaviour, which may prove adaptive in the face of unpredictable environmental change. Such patterns are likely present in other cetaceans that have been labeled as migratory. Examination of not only horizontal movement state, but also the vertical behaviour of aquatic animals during directed movements is essential for identifying whether a species exhibits traits of the classical migration syndrome or another long-distance movement strategy, enabling improved ecological inference.
Access status: Open Access ,
A systematic scoping review of Indigenous governance concepts in the climate governance literature
(Springer, 2022-04-25) Wilson, Nicole J.; Lira, Maria G.; O'Hanlon, Grace
While Indigenous peoples have governed their territories for millennia, mainstream climate governance literature underrepresents Indigenous governance roles in climate governance. The objective of this study is to systematically document the extent to which Indigenous governance concepts are incorporated into the climate governance literature. Using a systematic scoping search and screening process, we identified 195 references. To be included, references had to be published between 2010 and 2020, in English, explicitly mention Indigenous peoples, have a substantial focus on human responses to experienced or anticipated effects of climate change and governance, and be based on primary data or a review of primary data. Relevant references were analyzed using a data extraction questionnaire. Our results indicate that despite the growing number of publications, only two-fifths fully incorporated Indigenous governance concepts. We found that Indigenous governance concepts were more likely to be incorporated in references that included an author affiliated with an Indigenous organization, used qualitative methods, and focused on protected areas or climate transformation. Finally, most references incorporated Indigenous Knowledge systems, but this did not correspond to greater attention to Indigenous governance. Based on our findings, we make three recommendations for the climate governance literature: (i) follow Indigenous research protocols, (ii) move beyond a narrow focus on the “supplemental value” of Indigenous Knowledge systems to acknowledge the “governance value,” and (iii) engage with transformational climate responses that address the systemic inequalities created by historical and ongoing colonialism.
Access status: Open Access ,
Governing water insecurity: navigating indigenous water rights and regulatory politics in settler colonial states
(Taylor & Francis, 2021-06-30) Wilson, Nicole J.; Arsenault, Rachel; Curley, Andrew; Montoya, Teresa
Indigenous peoples experience water insecurity disproportionately. There are many parallels between the injustices experienced by racialized and marginalized populations and Indigenous peoples. However, the water insecurity experienced by Indigenous peoples is distinctly shaped by settler colonialism. This article draws on examples from Canada and the United States to illustrate how jurisdictional and regulatory injustices along with the broader political and economic asymmetries advanced by settler colonial States (re-)produce water insecurity for Indigenous peoples. We conclude by engaging with how Indigenous peoples are pushing back against these arrangements using State and non-State strategies by revitalizing Indigenous knowledge and governance systems.
Access status: Open Access ,
Qualitative Methods for the Next Generation of Impact Assessment
(2023-08-01) Walker, Heidi; Pope, Jenny; Sinclair, John A.; Bond, Alan; Diduck, Alan
Sustainability-oriented IA moves beyond a primary focus on biophysical impacts to consider a broader range of potential social, health and well-being, economic, cultural, cumulative, and equity implications of proposed projects. Canadian IA under the IAA (2019), for example, now explicitly requires consideration of health, social, and economic issues; consistent use of gender-based analysis plus (GBA+); evaluation of contributions to sustainability; bridging of Indigenous and Western scientific knowledge; and meaningful public participation. Quantitative methods are typically used to examine cause and effect associated with biophysical impacts and to identify, for example, alternatives and mitigation measures. Delivering effective IA within the broadening scope of next-generation, sustainability-oriented IA, however, requires new thinking and effective methods that enable meaningful inclusion of diverse knowledges, values, and information sources. For many of the broader range of impacts considered in next-generation, sustainability-oriented IA, cause and effect can only be established—and alternatives and mitigation measures suggested—through qualitative methods that can explain the values and connections people have with the places and land where projects are proposed. While this report is primarily intended for those involved in Canadian IA, the project was implemented by an international project team and informed by experts around the globe. Therefore, we anticipate this report will also be relevant to those working in a range of IA systems and geographical contexts. Specifically, this report may be of interest to: • practitioners working for/with communities and project proponents to gather the best possible information about the potential implications of proposed developments; • decision makers with a role in evaluating and synthesizing the information received throughout an IA process; • researchers who are testing, critiquing, and pushing the boundaries of IA processes and methods; • educators fostering the upcoming generations of IA professionals; • communities and members of the public who (should) play a role in selecting and implementing the methods that best tell their stories of place, change, and impact. There is considerable opportunity for the continued integration of qualitative methods in IA, but there are also barriers that often make it difficult to implement these methods in practice. While this report presents a range of conventional, innovative, and participatory qualitative methods (17 methods categories in total), it also discusses the barriers that must be overcome if these methods are to be effective in the context of sustainability-oriented IA.
Access status: Open Access ,
Predation of archival tagged Dolly Varden, Salvelinus malma, reveals predator avoidance behaviour and tracks feeding events by presumed beluga whale, Delphinapterus leucas, in the Beaufort Sea
(2021-12-20) Gallagher, Colin P.; Storrie, Luke; Courtney, Michael B.; Howland, Kimberly L.; Lea, Ellen V.; MacPhee, Shannon; Loseto, Lisa
Abstract Background We report compelling evidence suggesting a predation event of a pop-up satellite archival tagged anadromous Dolly Varden (Salvelinus malma) by a marine mammal during summer in the Beaufort Sea based on abrupt changes in temperature and vertical movements. This observation provides insight on predator avoidance behaviour by Dolly Varden and the predator’s feeding frequency while the tag was ingested. Based on published distribution and ecology information, we presumed the predator was a beluga whale (Delphinapterus leucas). Supplemental satellite telemetry data from previously tagged Dolly Varden and beluga whales were used to determine the extent of spatial and vertical overlap between species in the area where predation occurred. Results Prior to the predation event, depths and temperatures occupied by the tagged Dolly Varden averaged 1.1 m and 3.1 °C, respectively. On July 7, 2020, depths remained shallow apart from a sudden dive to 12.5 m (16:45 UTC) followed by a precipitous increase in temperature from 4.4 to 27.1 °C (16:52 UTC) suggesting predation by an endotherm. Subsequent readings indicated the endotherm had a resting stomach temperature of 36.1 °C. Including the predation event, eight separate feeding events were inferred during the 20-h period the tag was ingested (before presumed regurgitation) based on subsequent declines in stomach temperatures (mean decline to 31.1 °C) that took an average of 24.1 min to return to resting temperature. The predator occupied mainly shallow depths (mean = 2.3 m), overlapping with tagged belugas that spent 76.9% of their time occupying waters ≤ 2.5 m when frequenting the area occupied by tagged Dolly Varden in the Canadian Beaufort Sea in July. Back-calculation based on tag drift and mean displacement by tagged belugas indicated the predation likely occurred west of the Mackenzie Delta. Conclusion Our findings provide new information on both anti-predator behaviour by, and marine predators of, Dolly Varden in the Beaufort Sea. We provide the first estimate of feeding frequency and stomach temperature recovery in a presumed wild beluga, and evidence for shallow foraging behaviour by belugas. Elucidating the likely predator and exploring the extent of overlap between Dolly Varden and beluga whales contributes towards knowledge on the trophic interactions in the Beaufort Sea.
Access status: Open Access ,
Distinct Ocean Responses to Greenland's Liquid Runoff and Iceberg Melt
(American Geophysical Union, 2021-11-11) Marson, Juliana M.; Gillard, Laura C.; Myers, Paul G.
While Greenland discharge has been increasing in the last decades, its impact on the Meridional Overturning Circulation (MOC) is not clearly established. Because of that, the accuracy of this discharge representation in ocean models has not been a priority in large-scale circulation studies. Many models prescribe Greenland discharge solely as liquid runoff from the coast—even though around half of this mass loss is attributed to solid discharge. In this study, we use sensitivity experiments carried out with the Nucleus for European Modeling of the Ocean general circulation model to show the most relevant impacts that different Greenland solid discharge parameterizations (transforming it to liquid runoff or explicitly representing it through an iceberg model) have on the western subpolar Atlantic. We find that icebergs act as freshwater reservoirs that affect how much, when, and where freshwater is delivered to the ocean. They carry large amounts of freshwater away from boundary currents, releasing it in the interior of the subpolar gyre. Moreover, the amount and variability of freshwater delivered to the ocean depend not only on the characteristics of Greenland discharge itself but also on the environmental conditions icebergs are subjected to. We also find a large difference in subsurface temperatures in the Gulf of Saint Lawrence, which suggests that different Greenland discharge parameterizations might have far reaching implications beyond the MOC. Although differences in ocean fields between the simulations are usually small and within their interannual variability, they might be relevant as Greenland calving rates increase with global warming.
Access status: Open Access ,
A meta-collection of nitrogen stable isotope data measured in Arctic marine organisms from the Canadian Beaufort Sea, 1983–2013
(2021-09-06) Ehrman, Ashley; Hoover, Carie; Giraldo, Carolina; MacPhee, Shannon A.; Brewster, Jasmine; Michel, Christine; Reist, James D.; Power, Michael; Swanson, Heidi; Niemi, Andrea; Walkusz, Wojciech; Loseto, Lisa
Abstract Objectives Existing information on Arctic marine food web structure is fragmented. Integrating data across research programs is an important strategy for building a baseline understanding of food web structure and function in many Arctic regions. Naturally-occurring stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) measured directly in the tissues of organisms are a commonly-employed method for estimating food web structure. The objective of the current dataset was to synthesize disparate δ15N, and secondarily δ13C, data in the Canadian Beaufort continental shelf region relevant to trophic and ecological studies at the local and pan-Arctic scales. Data description The dataset presented here contains nitrogen and carbon stable isotope ratios (δ15N, δ13C) measured in marine organisms from the Canadian Beaufort continental shelf region between 1983 and 2013, gathered from 27 published and unpublished sources with associated sampling metadata. A total of 1077 entries were collected, summarizing 8859 individual organisms/samples representing 333 taxa across the Arctic food web, from top marine mammal predators to primary producers.
Access status: Open Access ,
The effect of crop species on DNase-producing bacteria in two soils
(2021-03-12) Kamino, Leila N; Gulden, Robert H
Abstract Purpose Extracellular deoxyribonucleases (exDNases) from microbial origin contribute substantially to the restriction of extracellular DNA (exDNA) in the soil. Hence, it is imperative to understand the diversity of bacterial species capable of performing this important soil function and how crop species influence their dynamics in the soil. The present study investigates the occurrence of DNase-producing bacteria (DPB) in leachate samples obtained from soils in which the crop species of alfalfa (Medicago sativa L.), canola (Brassica napus L.), soybean (Glycine max [L.] Merr.) and wheat (Triticum aestivum L.) were raised in a growth room. Methods Selective media containing methyl green indicator was used to screen for DPB from leachate samples, whereas the 16S rRNA sequence analysis was employed to identify the isolates. Results The proportion of culturable DPB ranged between 5.72 and 40.01%; however, we did observe specific crop effects that shifted throughout the growing period. In general, higher proportions of exDNase producers were observed when the soils had lower nutrient levels. On using the 16S rRNA to classify the DPB isolates, most isolates were found to be members of the Bacillus genera, while other groups included Chryseobacterium, Fictibacillus, Flavobacterium, Microbacterium, Nubsella, Pseudomonas, Psychrobacillus, Rheinheimera, Serratia and Stenotrophomonas. Five candidate exDNase/nuclease-encoding proteins were also identified from Bacillus mycoides genomes using online databases. Conclusion Results from this study showed that crop species, growth stage and soil properties were important factors shaping the populations of DPB in leachate samples; however, soil properties seemed to have a greater influence on the trends observed on these bacterial populations. It may be possible to target soil indigenous bacteria that produce exDNases through management to decrease potential unintended effects of transgenes originating from genetically modified organisms (GMOs) or other introduced nucleic acid sequences in the environment.
Access status: Open Access ,
The EU Horizon 2020 project GRACE: integrated oil spill response actions and environmental effects
(2019-07-16) Jørgensen, Kirsten S; Kreutzer, Anne; Lehtonen, Kari K; Kankaanpää, Harri; Rytkönen, Jorma; Wegeberg, Susse; Gustavson, Kim; Fritt-Rasmussen, Janne; Truu, Jaak; Kõuts, Tarmo; Lilover, Madis-Jaak; Seiler, Thomas-Benjamin; Hollert, Henner; Johann, Sarah; Marigómez, Ionan; Soto, Manu; Lekube, Xabier; Jenssen, Bjørn M; Ciesielski, Tomasz M; Wilms, Lonnie B; Högström, Rune; Pirneskoski, Mika; Virtanen, Seppo; Forsman, Björn; Petrich, Chris; Phuong-Dang, Nga; Wang, Feiyue
Abstract This article introduces the EU Horizon 2020 research project GRACE (Integrated oil spill response actions and environmental effects), which focuses on a holistic approach towards investigating and understanding the hazardous impact of oil spills and the environmental impacts and benefits of a suite of marine oil spill response technologies in the cold climate and ice-infested areas of the North Atlantic and the Baltic Sea. The response methods considered include mechanical collection in water and below ice, in situ burning, use of chemical dispersants, natural biodegradation, and combinations of these. The impacts of naturally and chemically dispersed oil, residues resulting from in situ burning, and non-collected oil on fish, invertebrates (e.g. mussels, crustaceans) and macro-algae are assessed by using highly sensitive biomarker methods, and specific methods for the rapid detection of the effects of oil pollution on biota are developed. By observing, monitoring and predicting oil movements in the sea through the use of novel online sensors on vessels, fixed platforms including gliders and the so-called SmartBuoys together with real-time data transfer into operational systems that help to improve the information on the location of the oil spill, situational awareness of oil spill response can be improved. Methods and findings of the project are integrated into a strategic net environmental benefit analysis tool (environment and oil spill response, EOS) for oil spill response strategy decision making in cold climates and ice-infested areas.
Access status: Open Access ,
Anthropogenic landscape changes and their impacts on terrestrial and freshwater soundscapes
(Springer, 2019) Proulx, Raphael; Waldinger, Jessica; Koper, Nicola
Purpose of review: Quantifying the effects of anthropogenic sounds on wildlife at the landscape scale of observation has been notoriously difficult because these sounds are often confounded with the presence of infrastructure and loss of habitat through resource exploitation activities. In this paper, we review how anthropogenic landscape changes affect the power level and propagation of sounds in both terrestrial and freshwater ecosystems, as well as the behavioural response of organisms to novel acoustic habitats. Recent findings: Resource exploitation and other human activities change soundscapes both directly, by affecting sound production and propagation, and indirectly, by modifying landscape structure and species distribution patterns. Intermittent anthropogenic sounds are concentrated in the lower frequencies, tend to be louder than enduring sounds of the same origin, and create more patchy soundscapes. We identified key sensorial traits that are related to the auditory acuity of species in different taxonomic groups, including fish, birds, anurans, stridulating insects, and small mammals, and which may help us understand why certain species are more sensitive to anthropogenic changes to soundscapes. Summary: Prioritizing research in an increasingly noisy world requires a proper understanding of the auditory sensitivity of species, the characteristics of anthropogenic sounds (i.e., intermittent or enduring), and how sound production and propagation is affected by landscape structure. Further research on species’ sensorial traits would provide a framework with which to scale responses to anthropogenic sounds from individuals to communities, and better predict the impact of human activities on terrestrial and freshwater ecosystems.
Access status: Open Access ,
Direct effects of cattle on grassland birds in Canada
(2014) Bleho, Barbara I.; Machtans, Craig; Koper, Nicola
Effects of grazing on grassland birds are generally thought to be indirect, through alteration of vegetation structure; however, livestock can also affect nest survival directly through trampling and other disturbances (e.g., livestock-induced abandonment). We extracted data on nest fates from 18 grazing studies conducted in Canada. We used these data to assess rates of nest destruction by cattle among 9 ecoregions and between seasonal and rotational grazing systems. Overall, few nests were destroyed by cattle (average 1.5% of 9132 nests). Nest destruction was positively correlated with grazing pressure (i.e., stocking rate or grazing intensity), but nest survival was higher in more heavily grazed areas for some species. Because rates of destruction of grassland bird nests by cattle are low in Canada, management efforts to reduce such destruction may not be of ecological or economic value in Canada.
Access status: Open Access ,
Growth, sexual maturity, and reproduction of a female Midland Painted Turtle (Chrysemys picta marginata) afflicted with kyphosis
(2015) MOLDOWAN, Patrick, D.; KEEVIL, Matthew, G.; Koper, Nicola; Brooks, Ronald, J.; Litzgus, Jacqueline, D.
Kyphosis, a congenital humpback condition of the spinal column, has been reported across a broad range of chelonian taxa. These reports are often of single observations and lack background information about the history of the animal(s) involved. A kyphotic female Midland Painted Turtle (Chrysemys picta marginata) reported herein is a member of a long-term mark-recapture study in Algonquin Park (Ontario, Canada), providing a unique opportunity to document life-history characters of a kyphotic turtle over 18 years, and to draw comparisons to other members of her cohort and population. Despite this spinal deformity, the somatic growth, body size, age at sexual maturity, and reproduction of the kyphotic female are similar to those of normal (non-kyphotic) females in our long-term study population. This suggests that the condition has not compromised her fitness.
Access status: Open Access ,
Grazing Intensity influences Ground Squirrel and American Badger Habitat Use in Mixed-Grass Prairies
(2014) Bylo, Lindsey, N.; Koper, Nicola; Molloy, Kelsey
Ground squirrel (Spermophilus spp.) and American badger (Taxidea taxus) burrowing activities are ecologically important disturbances that contribute to the heterogeneity of prairie environments. These activities also have a strong impact on habitat suitability for many other grassland species. However, effects of cattle grazing intensity on ground squirrel and American badger burrows are not well understood. From 2006-2012, we evaluated effects of grazing intensity and vegetation type on American badger burrow occurrence and ground squirrel burrow abundance using a manipulative grazing experiment in Grasslands National Park of Canada, Saskatchewan. The study area consisted of nine 300-ha pastures at a range of stocking rates, from very low to very high for the region. Each pasture had ten plots (six upland and four lowland) where vegetation and burrow surveys were completed. Burrow abundance and occurrence, and vegetation structure, were assessed for 2 years prior to the introduction of cattle to this landscape in 2008, which followed at least 15 years without livestock, and from 2009-2012, following introduction of livestock. Data were analyzed using generalized linear mixed models. In upland habitats, ground squirrel burrow counts increased with increasing grazing intensity and decreasing vegetation biomass; conversely, badger burrow occurrence increased with decreased stocking rates and increasing average litter cover and vegetation biomass. Abundance and occurrence of both ground squirrel and badger burrows in lowland habitats was relatively independent of grazing intensity or vegetation. Vegetation composition had little impact on ground squirrel or badger burrows. A range of grazing intensities may contribute to maintaining diversity of burrowing mammals in prairie environments.
Access status: Open Access ,
Savannah sparrows (Passerculus sandwichensis) nesting close to energy infrastructure alarm call at a lower frequency
(Taylor and Francis, 2018) Antze, Bridget; Koper, Nicola
Many birds rely on alarm calls during nest defense to communicate about risk, but anthropogenic disturbance, including noisy industrial infrastructure, has the potential to disrupt alarm communication. Birds may overcome these effects by altering the structure of vocalizations to improve signal transmission. While previous work has demonstrated that birds can alter the structure of songs in the presence of noise, few have considered effects of noise-producing infrastructure on alarm call structure. Here, we tested whether Savannah sparrows (Passerculus sandwichensis) altered the structure of alarm calls in the presence of natural gas compressor stations or grid-powered or generator-powered screw pump oil wells, and in relation to overall ambient noise levels. Savannah sparrows called at a lower peak frequency and first quartile frequency close to gas compressor stations, but call structure did not differ with proximity to either type of oil well, or in response to ambient noise levels, suggesting that factors beyond noise amplitude, such as the physical footprint of the infrastructure, affected call structure close to compressor stations. Our results demonstrate that even unlearned, structurally simple avian vocalizations can vary in structure, and that the impacts of anthropogenic infrastructure on acoustic communication may be driven by factors beyond just noise.
Access status: Open Access ,
Urban rights-of-way as extensive butterfly habitats: a case study from Winnipeg, Canada
(Elsevier, 2017) Leston, Lionel; Koper, Nicola
Urban rights-of-way (ROWs) offer large underused tracts of land that could be managed for plants and butterflies of threatened ecosystems like tall-grass prairies. However, built-up unvegetated urban lands might serve as barriers preventing butterflies and resource plants from settling along ROWs. Further, negative edge effects from surrounding urban lands or frequent mowing and spraying associated with urbanization may prevent butterflies from benefiting from urban ROWs as habitats. However, because ROWs often run for kilometres, they might facilitate movement from other, similar habitats by which they run close. To determine if surrounding built-up lands had a greater effect on butterflies than did the abundance of resource plants along ROWs, we surveyed butterflies and resource plants along transects in 48 transmission lines in or near Winnipeg, Manitoba, 2007 - 2009. In general, butterfly richness and abundance were better predicted by available resources than by built-up urban lands surrounding ROWs. Butterfly species richness per visit increased by 85 % with increases from 10 plant species per site to 80 species of plants per site, while abundance per species per visit increased by 100 % with increases from negligible forb cover to 5 % forb cover, and by 112 % with increases in vegetation height-density from 5 cm to 40 cm high. If appropriate resource plants are reintroduced and managed for along urban ROWs, densities of most butterfly species will increase along these lines despite surrounding built-up urban lands. Thus, urban ROWs present an opportunity for restoring habitats for prairie butterflies.
Access status: Open Access ,
Quantifying the influences of grazing, climate and their interactions using Landsat TM images
(Wiley, 2017) Xu, Dandan; Koper, Nicola; Guo, Xulin
Appropriate grazing management ensures sustainable productivities of grassland ecosystems while maintaining grassland services. Thus, it is important to understand the influences of grazing management on grassland ecosystems, which can be monitored by measuring grassland response (e.g. Leaf area index [LAI]) to grazing management. However, the measured grassland response includes the impact not only of grazing management, but also of other factors and their interactions, such as climate variability and fire. Therefore, to better study the effects of grazing management, grassland response to grazing needs to be quantified separately from that of other factors which influence grasslands and their interactions. The aim of our research was to quantify these interactions using Landsat TM images with long-term datasets at a regional scale. We studied vegetation using a manipulative grazing experiment that applied a range of low to high cattle stocking rates from 2008 to 2011 in a northern native mixed-prairie in Saskatchewan. Results show that precipitation, temperature, interaction between temperature and precipitation, cattle density, interaction between temperature and cattle density, and the interaction among cattle density and climate parameters explained 65.5, 14.5, 9.8, 1.7, 1.4 and 0.5% of the variation in grassland LAI, respectively; thus, precipitation has the dominant effect in mixed-grass prairies, while temperature and the interaction between temperature and precipitation have only moderate effects, and grazing intensity and the interaction between grazing intensity and climate variations have relatively low effects. The results also suggest that grassland response to grazing can be quantitatively separated from that of climate variability with the prior knowledge of grazing intensity, even though the influences of precipitation on LAI overrode the effects of short term grazing.
Access status: Open Access ,
The final frontier: Early-stage genetic introgression and hybrid habitat use in the northwestern extent of the Golden-winged Warbler breeding range
(2018) Moulton, Laurel; Vallender, Rachel; Artuso, Christian; Koper, Nicola
Anthropogenic changes to the landscape and climate have resulted in secondary contact between previously allopatric species. This can result in genetic introgression and reverse speciation when closely related species are able to hybridize. The Golden-winged Warbler has declined or been extirpated across much of its range where it has come into secondary contact with the Blue-winged Warbler. Genetic screening previously showed that introgression had occurred range-wide with the exception of Manitoba, Canada. Our goal was to reassess the genetic status of the Golden-winged Warbler population in Manitoba and to examine the demographics and habitat use of phenotypic and genetic hybrids. From 2011-2014, we sampled and screened mtDNA from 205 Golden-winged Warblers and hybrids in Southeast Manitoba. In 2012, we monitored all Golden-winged Warbler territories within those sites and measured territory- and landscape-level habitat variables. Of the birds screened, 195 had a phenotype that matched their mtDNA type, 2 were phenotypic hybrids, and 8 showed a phenotypic-mtDNA mismatch (cryptic hybrids). We found no difference in the habitat used by Golden-winged Warblers compared with hybrids at either scale. The low proportion of hybrids found in Manitoba and the lack of a distinguishable difference in habitat use by Golden-winged Warblers and hybrids indicates that the exclusion of hybrid birds from Golden-winged Warbler habitat is unlikely to be a successful conservation strategy. The best way to manage for Golden-winged Warblers is to slow the habitat loss and fragmentation that continues within Manitoba and to actively manage early-successional deciduous forest using tools such as fire and logging.
Access status: Open Access ,
Effects of Weather and Land Management on the Western Prairie Fringed-orchid (Platanthera praeclara) at the Northern Limit of its Range in Manitoba, Canada
(2015) Bleho, Barbara I.; Koper, Nicola; Borkowsky, Christie L.; Hamel, Cary D.
The western prairie fringed-orchid is a rare North American orchid restricted to a few remnants of wet to mesic tallgrass prairie. It is federally listed in both Canada and the United States and both countries have developed a recovery plan for the species. Two key management objectives are to monitor population trends and identify beneficial management practices. We used 21 y of data from the Manitoba metapopulation to assess effects of weather and land management on this species. Our results suggest the metapopulation in Manitoba is relatively stable. Western prairie fringed-orchids appear to benefit most from a combination of warm temperatures in the previous growing season followed by cool snowy but short winters and wet springs. Periodic burning ( e.g., every 2-3 y) may benefit fringed-orchids, whereas grazing may be detrimental. This was not a controlled experiment, however, and gaps in the data may have influenced our results. Prescribed burning is a viable management tool for curtailing woody invasion and both burning and grazing reduce litter and grass cover, but careful consideration of timing, frequency, and intensity of application is required so management does not hinder fringed-orchid reproduction or reduce survival, while also recognizing management requirements may vary among years depending on weather. Long-term studies are particularly valuable for the western prairie fringed-orchid due to its erratic life cycle and fluctuating populations, which complicate studies of environmental and management effects on this species.
Access status: Open Access ,
Managing Mixed-grass Prairies for Songbirds Using Variable Cattle Stocking Rates
(Elsevier, 2015) Sliwinski, M.S.; Koper, N.
Most remaining grasslands are used for livestock grazing; stocking rates could be managed to help stop declining songbird populations. We examined the effects of stocking rates on grassland songbirds in northern mixed-grass prairies using a beyond Before-After-Control-Impact manipulative experiment in Canada’s Grasslands National Park and adjacent community pastures. The study area consisted of nine 300-ha pastures grazed at a range of stocking rates starting in 2008. We conducted songbird surveys at six upland plots in each pasture from 2006‒2010, and measured vegetation structure within each plot from 2008‒2010 (n = 54). We evaluated the effects of stocking rates on habitat structure and songbird abundance using linear and generalized linear mixed models. Baird’s sparrow (Ammodramus bairdii) relative abundance declined with increasing stocking rates. Chestnut-collared longspur (Calcarius ornatus) relative abundance increased only at higher stocking rates indicating a possible threshold effect. Savannah sparrow (Passerculus sandwichensis) relative abundance decreased with stocking rates above 0.4 AUM after a year of grazing. Sprague’s pipit (Anthus spragueii) relative abundance declined with grazing, but the effect was weak and only significant in one year. Western meadowlark (Sturnella neglecta) abundance was unaffected by grazing. Stocking rates may be used to benefit grassland songbirds and may alter avian communities after as little as one month of livestock grazing. Applying a range of stocking rates regionally may provide habitat for many species.

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