Grasslands Of Alberta Research Articles

Diversity in selection patterns of five grassland songbirds in dry-mixed grasslands of Alberta

Declining grassland bird populations across North America continue to be a concern. Understanding local relationships between grassland bird abundance and vegetative and landscape characteristics will enable more prescriptive recommendations to be made to land managers. We used point count survey data collected by the MULTISAR (Multiple Species At Risk) program along with field measurements of habitat and landscape characteristics on 15 ranches in the Dry Mixed-grass Subregion in southern Alberta to improve our understandings of habitat relationships for five grassland bird species: Baird’s Sparrow (<em>Centronyx bairdii</em>), Sprague’s Pipit (<em>Anthus spragueii</em>), Thick-billed Longspur (<em>Rhynchophanes mccownii</em>), Chestnut-collared Longspur (<em>Calcarius ornatus</em>), and Grasshopper Sparrow (<em>Ammodramus savannarum</em>). We used generalized linear mixed models to examine the relationship between the predicted abundance of a species and covariates that represented vegetative structure (e.g., litter), management (e.g., range health), and anthropogenic features (e.g., energy development) of habitat site selection. Model results demonstrate four vegetation structure covariates were of most importance for predicting abundance, including litter, vegetation height, bare soil, and shrub cover. Quadratic relationships were found with litter amounts for the predicted abundance of Baird’s Sparrow, Chestnut-collared Longspur, and Grasshopper Sparrow. Contrastingly, higher amounts of litter reduced the predicted abundance of Thick-billed Longspur. The relationship of vegetation height was quadratic for Sprague’s Pipit and was positive for Baird’s Sparrow, but negative for Thick-billed Longspur. As bare soil percentage increased, the predicted abundance of Baird’s Sparrow and Chestnut-collared Longspur decreased, with Sprague’s Pipit showing a quadratic association. Negative relationships were found with increased amounts of shrub cover for Chestnut-collared Longspur, Sprague’s Pipit, and Thick-billed Longspur. Our results help to further understand individual grassland bird species’ habitat requirements, enabling us to provide land management recommendations for maintaining, improving, or creating the heterogenic environments needed for a variety of grassland birds in the Dry Mixed-grass Subregion.

Altered precipitation rather than warming and defoliation regulate short-term soil carbon and nitrogen fluxes in a northern temperate grassland

Grasslands store large quantities of organic carbon (C) and thus can markedly impact global climate change if they are disturbed. How practices such as grazing intensity and climate change interact to affect soil greenhouse gas (GHG) fluxes within native northern temperate grasslands is unclear. We investigated the responses of three major GHGs (CO2, N2O and CH4) to temperature (ambient vs. warmed), precipitation (ambient vs. reduced or increased) and defoliation (no defoliation vs. low- or high-intensity defoliation) treatments in a factorial experiment over a two-year period in a native northern temperate grassland in Alberta, Canada. Growing season mean soil gas fluxes across all treatments were 93.8 mg CO2 m−2 h−1, −0.025 mg CH4 m−2 h−1, and 0.003 mg N2O m−2 h−1, suggesting that this grassland was a source for CO2 and N2O, but a sink for CH4 over the study period. Structural equation modeling showed that increased precipitation, rather than warming or defoliation, was the primary driver directly regulating fluxes of CO2 and N2O. While increased precipitation also increased microbial biomass C (MBC), the latter had little impact on GHG fluxes, suggesting that MBC was not a critical factor regulating the precipitation-GHG flux relationship. Warming and precipitation effects on CH4 fluxes depended on the month of sampling during the growing season. Warming decreased CH4 uptake but only in mid-July, while increased precipitation reduced CH4 uptake across all sampling dates except early August, at which time increased precipitation increased CH4 uptake. Our study shows that short-term soil GHG fluxes in this native grassland are relatively resilient to moderate warming and defoliation, but sensitive to altered precipitation. Increased precipitation was the main contributor to short-term GHG fluxes in this temperate grassland via changes in CO2 efflux.

Non-Native Plant Invasions in Prairie Grasslands of Alberta, Canada

Native prairie grasslands are a fundamental part of Canada's natural heritage, but these formerly extensive ecosystems have undergone declines due to grassland conversion and fragmentation. In addition, remaining native grasslands are threatened by invasive non-native plants, which can outcompete native flora and negatively impact ecological functioning. Although several studies have reported invasions in northern prairie grasslands, only some have investigated patterns across a large spatial gradient, and few have tested their relationship with environmental predictors and anthropogenic disturbance. We surveyed 139 plots across a 938-km spatial gradient in Alberta to 1) identify the most frequent and abundant non-native species, 2) test whether levels of non-native plant invasions are linked to environmental factors or anthropogenic disturbance, and 3) inspect whether relationships differ between mesic and semiarid grasslands. Data were analyzed using generalized additive models and commonality analysis.Our results show that Kentucky bluegrass (Poa pratensis subsp. angustifolia), commonly used for agronomic purposes, is by far the most frequent and abundant non-native plant in Alberta grasslands. Across all plots, abundance and richness of non-native plants were positively linked to a shared effect by aridity, soil texture, and agricultural activity. Furthermore, the importance of predictors differed between mesic and semiarid grasslands. In mesic grasslands, non-native plant abundance and richness were highest in areas with high agricultural activity and fine-textured soils. In the semiarid prairie, topography accounted for most explained variation in the levels of invasion. In summary, climatic conditions, and to some extent agricultural activity and topography, best explain the patterns of non-native plant invasions. A priority for future research is to identify the mechanisms underlying the differences in invasion across mesic and semiarid prairie grasslands. To counteract invasions, practitioners need to diminish the propagule pressure by invasive agronomic grasses, protect and restore grasslands remnants in the mesic region, and proactively control new invaders.

Vertical size structure is associated with productivity and species diversity in a short‐stature grassland: Evidence for the importance of height variability within herbaceous communities

AbstractQuestionsLocal size structure is frequently measured in plant populations and forested systems due to its association with population‐ and community‐level processes. In contrast, size structure is rarely examined within herbaceous communities despite evidence for size‐dependent processes in these systems, suggesting an important functional vegetation property may be widely overlooked. Here, we test whether vertical size structure (a) varies within a short‐stature grassland, (b) varies along a productivity gradient, and (c) enhances the understanding of a foundational ecological pattern: the diversity–productivity relationship.LocationRough fescue grassland in Alberta, Canada.MethodsWe measured the heights of individuals within 32 plots and used average height, the Gini coefficient, and a two‐parameter Weibull distribution to estimate community‐level vertical size structure. Linear mixed models were used to test whether size structure parameters were significantly associated with productivity, species richness, and species evenness.ResultsVertical size structure varied significantly among local communities, such that some were dominated by short individuals while others were comprised of a more equal number of taller individuals. With increasing productivity, there was an increase in average plant height and a decrease in height inequality. Decreased height inequality was associated with reduced species richness with evidence that loss was not size‐dependent. The inclusion of vertical size structure parameters increased the explained variance of the diversity–productivity relationship by ~35% while also increasing its parsimony.ConclusionsEven within a short‐stature grassland, there is substantial functional variation in vertical size structure. Productivity is strongly associated with size structure patterns, and the inclusion of height inequalities greatly enhances productivity–diversity relationships, likely because they are the product of assembly mechanisms such as size‐asymmetric competition, assemblage‐level thinning, and niche complementarity. Overall, this demonstrates that vertical size structure has been a missing mechanism in most community assembly theories and models and should be included in the future.

Behavior of adult and young grassland songbirds at fledging

The behavior of adults and young at the time of fledging is one of the least understood aspects of the breeding ecology of birds. Current hypotheses propose that fledging occurs either as a result of parent-offspring conflict or nestling choice. We used video recordings to monitor the behavior of nestling and adult grassland songbirds at the time of fledging. We observed 525 nestlings from 166 nests of 15 bird species nesting in grasslands of Alberta, Canada, and Wisconsin, USA. Overall, 78% of nestlings used terrestrial locomotion for fledging and 22% used wing-assisted locomotion. Species varied in propensity for using wing-assisted locomotion when fledging, with nestling Grasshopper Sparrows (Ammodramus savannarum) and Henslow’s Sparrows (Centronyx henslowii) often doing so (47% of fledgings) and nestling Song Sparrows (Melospiza melodia), Common Yellowthroats (Geothlypis trichas), and Chestnut-collared Longspurs (Calcarius ornatus) rarely doing so (3.5% of fledgings). For 390 fledging events at 127 nests, camera placement allowed adults near nests to be observed. Of these, most young fledged (81.5%) when no adult was present at nests. Of 72 fledging events that occurred when an adult was either at or approaching a nest, 49 (68.1%) involved feeding. Of those 49 fledgings, 30 (62.1%) occurred when one or more nestlings jumped or ran from nests to be fed as an adult approached nests. The low probability of nestlings fledging while an adult was at nests, and the tendency of young to jump or run from nests when adults did approach nests with food minimize opportunities for parents to withhold food to motivate nestlings to fledge. These results suggest that the nestling choice hypothesis best explains fledging by nestlings of ground-nesting grassland songbirds, and fledging results in families shifting from being place-based to being mobile and spatially dispersed. Video clip data for this study are published at https://doi.org/10.2737/RDS-2018-0034-2.

Updating the Grassland Vegetation Inventory Using Change Vector Analysis and Functionally-Based Vegetation Indices

The Grassland Vegetation Inventory (GVI), which represents a comprehensive biophysical, anthropogenic, and land-use inventory of grasslands in Alberta, is widely used as a baseline for grassland conditions. An up-to-date GVI is essential for understanding grassland changes and for planning management or conservation actions on grasslands. In this study, a hybrid change detection method is proposed that incorporates change vector analysis and a set of vegetation indices (VIs) measuring different vegetation attributes for mapping the conversion of native grassland to cultivated agriculture, and ultimately to update the GVI based on multiseasonal and multiyear Landsat images. Vegetation indices that contribute significantly to differentiation between existing native grassland and land recently converted from native grassland to cultivated cropland were identified by using stepwise regression analyses and were used as inputs for mapping the conversion between 2006 and 2011 or 2015. The results showed that land conversion can be detected using a single image acquired during the growing season, but that the accuracy of identification is affected by the date of image collection and the nature of the VIs used. The greatest accuracy in detecting land conversion between 2006 and 2011 was achieved using the difference in VI between years (dVI) for the Shortwave Infrared Reflectance 3/2 Ratio (SWIR32) and the Enhanced Vegetation Difference Index (EVI) derived from July imagery (accuracy = 95.2 %; Kappa = 0.86). The same combination of SWIR32 and EVI was also effective, although with lower accuracy (accuracy = 86.0 %; Kappa = 0.64) when tested on a larger geographical area and for detecting land use change between 2006 and 2015. The method proposed here could be applied to detect the land cover conversion in other grassland regions, although the optimal VIs and image acquisition date may need to be modified depending on the type of land use activities implemented in each region.

Patterns of phylogenetic diversity are linked to invasion impacts, not invasion resistance, in a native grassland

AbstractQuestionThere are often more invasive species in communities that are less phylogenetically diverse or distantly related to the invaders. This is thought to indicate reduced biotic resistance, but recent theory predicts that phylogenetic relationships have more influence on competitive outcomes when interactions are more pair‐wise than diffuse. Therefore, phylogenetic relationships should change when the invader becomes dominant and interactions are more pair‐wise, rather than alter biotic resistance, which is the outcome of diffuse interactions with the resident community; however both processes can produce similar phylogenetic structures within communities. We ask whether phylogenetic structure is more associated with biotic resistance or invasion impacts following Bromus inermis (brome) invasion and identify the mechanisms behind changes to phylogenetic structure.LocationNative grassland in Alberta, Canada.MethodsWe tested whether phylogenetic structure affected biotic resistance by transplanting brome seedlings into intact vegetation and quantified invasion impacts on community structure by surveying across multiple invasion edges. Additionally, we tested whether relatedness, rarity, average patch size, evolutionary distinctiveness or environmental tolerances determined species' response to brome invasion.ResultsNeither phylogenetic diversity, nor relatedness to brome, influenced the strength of biotic resistance; resource availability was the strongest determinant of resistance. However, communities did become less diverse and phylogenetically over‐dispersed following brome invasion, but not because of the loss of related species. Brome invasion was associated with declines in common species from common lineages and increases in shade‐tolerant species and rare species from species‐poor lineages.ConclusionsOur results suggest that invasion is more likely to affect the phylogenetic structure of the community than the phylogenetic structure of the community will affect invasion. However, they also suggest that the degree of relatedness between the invader and the resident community is unlikely to drive these effects on phylogenetic community structure. Consistent with previous studies, invasion effects were stronger for common species as they have reduced shade tolerance and cannot persist in a subordinate role. This suggests that invasion effects on phylogenetic community structure will depend on which species exhibit traits that enable persistence with the invader and how these traits are distributed across the phylogeny.

Using structural equation modelling to test the passenger, driver and opportunist concepts in a Poa pratensis invasion

The passenger, driver, and opportunist models are conceptual models of the invasion process used to describe alternative invasion scenarios. In the passenger model, both the invasive species and native community respond independently to environmental changes. In the driver model, changes to the native community are driven by the invasive species, while in the opportunist model invasion occurs in response to changes in the native community. In any given invasion scenario, however, it is possible that the relationships between the invasive, the native community, and the environment correspond to some combination of these invasion models acting simultaneously. We study invasion by Poa pratensis in a grassland in Alberta, Canada. Poa pratensis is a non‐native plant implicated with loss of plant diversity in the region. In a three year field experiment, we manipulate the environment though defoliation, water addition, and nitrogen addition, and measure responses of P. pratensis cover, and cover and richness of the native community. We use structural equation modelling to describe the relationships between the invasive, the native community, and the environmental changes, and then interpret these relationships using the three invasion models. We found that P. pratensis predominantly invaded via the driver model, with subsequent reductions in native plant cover, but not in species richness. Positive effects of the environmental changes on P. pratensis also aided its ability to drive native cover. As well, we found some involvement of the opportunist model, through a negative relationship between the native community and the invasive. As invasion mainly proceeded via the driver model, management actions to limit invasion should focus on efforts to control abundance of P. pratensis itself.

Simulation and quantification of pasture condition and animal performance on boreal grasslands in Alberta

We developed a computer model (PASTURE) to simulate both condition of pastures grazed by farmed wildlife and animal performance as dual measures of system performance. For representative habitat types (e.g., aspen forest and open grasslands), the model simulates herbage growth, maturation and senescence, habitat and diet selection, and nutrient intake of several wild ruminant species. The model generated seasonal patterns of pasture productivity and animal behavior expected for Bromus-Poa pastures in aspen boreal ecosystems. Model calibration was conducted using data collected from studies conducted within the aspen boreal ecosystems at the Ministik Research Station in 1997 and 1998, and Elk Island National Park and the University of Alberta greenhouse in 1999 and parameters adjusted until the predicted and observed results were visibly close. Evaluation of the model was conducted using statistical criteria of calculating average error, root mean square, root mean square error, coefficient of residual mass and modeling efficiency and comparing these statistics against optimal values. Statistical tests indicated a good fit between predicted and observed values for cumulative phytomass, herbage use and animal performance.

A comparison between Terra MODIS and NOAA AVHRR NDVI satellite image composites for the monitoring of natural grassland conditions in Alberta, Canada

Natural grasslands in Alberta are largely used for cattle grazing operations. The abundance of this feeding source is largely subject to climate variability. Given the large area of grazing pasture and grasslands (almost 9 million hectares) and its value to the livestock industry in Alberta, it would be useful for both rangeland managers and governments if a pasture insurance program could be developed based on satellite imagery. Grazing pastures and grasslands were monitored throughout the province using satellite image data for 2002 and 2003. Normalized difference vegetation index (NDVI) composites derived from National Oceanic and Atmospheric Administration (NOAA) advanced very high resolution radiometer (AVHRR) and Terra moderate resolution imaging spectroradiometer (MODIS) sensors were used and compared with in situ, natural grassland productivity data. Overall, statistical correlation between NOAA AVHRR and Terra MODIS image composite data and the in situ field data yielded similar results, with correlation coefficients of 0.71 and 0.74, respectively. Additionally, the strong correlation of 0.87 between AVHRR and MODIS NDVI images indicates that MODIS NDVI data can be used as a complementary source of NDVI data and to populate the existing AVHRR historical database.

Distribution of range and cultivated grassland plants in southern Alberta

We analysed the geographic distribution of native grassland and introduced grassland plants and the association of species abundance with climate and site characteristics in southern Alberta using a database of range and pasture assessments collected during 1991, 1992 and 1993. Distribution maps of native and introduced grassland plants could be inferred from association between site data recording botanical composition or presence and mean monthly climate surfaces for May and August. Introduced species formed three main geographical patterns with alfalfa, smooth bromegrass and crested wheatgrass most widespread, Russian wildrye restricted to the south eastern quarter and timothy, creeping red fescue, bluegrass and clovers restricted to the northern half. Native plants formed four main patterns characterised by Stipa comata and Bouteloua gracilis – south eastern; Agropyron spp. – widespread; Festuca spp. – northern and foothills; and Stipa viridula – sparse. Relative abundance of Stipa comata and Bouteloua gracilis were related primarily to latitude and longitude and variables describing temperature during the growing season. Biomass increased and range condition decreased with increasing latitude reflecting the decline in dominant native species, the increase in introduced and invader species and the better growing season moisture in northern areas. The maps provide a recent snapshot of the condition of commercially utilised native and cultivated grasslands in Alberta. They constitute a valuable reference point for comparison with future climate or management-induced change.

RUNOFF AND SEDIMENT YIELD UNDER GRAZING IN FOOTHILLS FESCUE GRASSLANDS OF ALBERTA1

ABSTRACT: Grazing can have a profound impact on infiltration and thus runoff and erosion. The objectives of this study were to quantify the effects of select grazing systems on rainfall and snowmelt induced runoff and sediment yield from sloped areas of the foothills fescue grasslands of Alberta, Canada. The effects of two grazing intensities (heavy and very heavy) for two durations (short duration and continuous throughout the growing season) were compared to an ungrazed control between June 1988 and April 1991. Runoff was measured using 1‐rn2 runoff frames and collection bucket systems. Sediment yields were then determined on samples from the collected runoff.Snowmelt was the dominant source of runoff. Snowmelt runoff was higher from the heavily grazed areas than from the very heavily grazed areas, due to the higher standing vegetation which accumulated snow in the former areas. Sediment yields as a result of snowmelt were generally low in all areas. Only a few summer storms caused runoff. Runoff volumes and sediment yields from summer rainstorms were low, due to low rainfall and to generally dry antecedent soil moisture conditions. The greatest risk of summer runoff, and thus sediment yield, appears to occur in August.

Grazing Effects on Soil Water in Alberta Foothills Fescue Grasslands

Grazing can have a profound impact on soil water through its influence on infiltration via treading and on evapotranspiration through defoliation. Hydrologic changes in rangelands are most often associated with heavy grazing intensities although these changes do not increase linearly with grazing intensity. The objectives of this study were to quantify the impacts of grazing on the soil water regimes of sloped areas of the foothills fescue grasslands of Alberta. The study site was located at the Agriculture Canada Research Station at Stavely, Alberta. The effects of 2 grazing intensities (heavy = 2.4 AUM ha-1 and very heavy =4.8 AUM ha-1) for 2 grazing treatments (short duration = 1 week in mid-June and continuous grazing = May through October) were compared to an ungrazed control. The study was initiated in June 1988 and ended in April 1991. Surface soil water and soil water with depth were measured throughout each growing season using a neutron probe. Surface soil water (0 to 7.5 cm) across slope positions was lowest in the control and highest in the continuous very heavy treatments, but the trend in profile soil water (to 50 cm) was the opposite. Total profile soil water in the short duration very heavy treatment was greater than that in the continuous very heavy treatment, while soil water in the short duration heavy treatment was similar to that in the continuous heavy treatment. Vegetation at the study site was regularly water-stressed, as evidenced by soil water that was often below permanent wilting point, generally by mid-summer each year. Soil was near or below permanent wilting point in the autumn, regardless of its status throughout the growing season. Profile soil water was similar across treatments in autumn, indicating vegetation is using all available soil water. In contrast, soil water was generally near or above field capacity every spring, indicating the importance of snowmelt infiltration in these ecosystems. Only major (greater than 75 mm) summer rainstorms recharged soil water to field capacity. Thus it is concluded that maintenance of a vegetative cover that will trap snow for potential snowmelt infiltration is critical to soil water recharge of these ecosystems. Any grazing management regime that enhances litter accumulation and carryover should facilitate such snowmelt soil water recharge.

Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada

Alberta foothills fescue grasslands are very productive ecosystems but there is concern that the traditional season-long (continuous) grazing regimes may be leading to soil deterioration due to compaction and increased soil strength. The objectives of this study were to quantify grazing effects on soil bulk density and soil strength of sloped areas in the Alberta foothills fescue grasslands at the Agriculture Canada Stavely Range Substation. The effects of two grazing intensities (heavy and very heavy) for two treatments (short duration and continuous) on these two parameters were compared to an ungrazed control. Soil bulk density and soil water to a depth of 7.5 cm were measured with a surface water/density gauge. Soil strength was measured with a hand-pushed cone penetrometer to a depth of 45 cm. Cone index, the maximum penetration resistance in a given depth interval, was used as a measurement parameter for soil strength.Grazing affected both soil bulk density and penetration resistance. Even short-duration treatments affected these soil properties, although their effects were similar for both heavy and very heavy grazing intensities. Distinction between heavy and very heavy continuous grazing treatments was clear for both bulk density and penetration resistance, with the very heavy treatment having the greatest detrimental effect on these two soil parameters for all treatments. Bulk density and soil strength values were always lowest in the spring after snowmelt and highest late in the growing season, reflecting the water status of these ecosystems. Identical treatment rankings were obtained using bulk density and penetration resistance, but cone index was a more sensitive indicator of the effects of grazing than bulk density. Key words: Grazing, fescue grasslands, bulk density, soil strength

Water Holding Capacity of Litter and Soil Organic Matter in Mixed Prairie and Fescue Grassland Ecosystems of Alberta

Litter and organic matter accumuiations can reduce soil water through interception of precipitation and subsequent evaporation of absorbed water. Interception varies with mass and water hoiding capacity (WHC) of litter and organic matter, and is highest from small precipitation events. WHC varies with vegetation type, which is affected by grazing regime. Thus long-term grazing could affect WHC of litter and organic matter and would be important in the hydrologic assessment of rangelands subjected to many small precipitation events throughout the growing season. The study was conducted in mixed prairie, parkland fescue, and foothills fescue grasslands in Alberta, Canada. Grazing regimes were of light to very heavy intensities, grazed early, Me, and continuously during the growing season. Litter and organic matter were sorted by sieving into various sized categories. Litter-soil cores were also evaluated. WHC of litter and organic matter was lower in mixed prairie than in fescue grasslands. WHC increased with increazed particle size, being higher for roots and standing and fallen litter than for organic matter. WHC of iarge particle-sized material decreased with heavy intensity and/or early season grazing. WHC was affected more by intensity than season of grazing. Grazing affected WHC through species composition changes, since species have different WHC, and through trampling which affected particle size. It was concluded that litter and organic matter WHC were important in rangeland hydrologic assessments.

Applicability of the Kostiakov Equation to Mixed Prairie and Fescue Grasslands of Alberta

The Kostiekov equation is of interest in rangeland hydrology because it is a simple 2 prrnmeter equation with values of constants easy to determine from measured infiltration data, and because of its reasonable fit to infiltration data for many soils over short time periods. There is, however, some controversy in the literature regarding its applicability to rangelands. The Kostiakov infiltration equation was examined to determine its suitability to characterize hrfiltration on mixed prairie and fescue grassland ecosystems in Alberta, Canada. The infiltration data from double ring infiltrometers fit the Kostiakov equation very well. Of 26 regressions, 10 had anRr over 0.95 while another 8 had an R* over 0.90. The average R2 for all data at a site was 0.931 for mixed prairie, 0.857 for parkland fescue, and 0.938 for foothills fescue grassland. Changes in antecedent soil water and different grazing regimes altered the 2 equation parameters. Intercepts consistently declined with intensity and earliness in the growing season of grazing, although there were no consistent treatment trends with grazing. The Kostiakov equation is considered a good equation for infiltration in the 3 grassland ecosystems studied. Although parameter m had a narrow range of values for all 3 ecosystems and an average value from this study could be used, parameter a limits the equation and field testing is required for its determination.

Mus musculus and Peromyscus maniculatus: homing ability in relation to habitat utilization

House mice displaced from established home ranges in grassland on Great Gull Island, New York, exhibited homing behaviour. This behaviour was associated with large home range, wandering before home range establishment, and forays outside the range. When both house mice and deer mice inhabiting granaries in grassland in Alberta were displaced, homing behaviour was poorly expressed in house mice, but well developed in deer mice. The poorly developed homing tendency of Alberta house mice was associated with a pattern of habitat utilization that appeared to limit familiarity with areas outside the home range. While this result does not explicitly eliminate a role for a direction-finding ability in house mouse homing, it does emphasize the importance of familiarity with terrain external to the home range.