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Prairies Ecozone+ Evidence for Key Findings Summary

Theme: Habitat, Wildlife and Ecosystem Processes


Agricultural landscapes as habitat

Key finding 16
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
The potential capacity of agricultural landscapes to support wildlife in Canada has declined over the past 20 years, largely due to the intensification of agriculture and the loss of natural and semi-natural land cover.

The agricultural landscapes of Canada include a variety of land cover types: native rangeland, tame pasture, summerfallow, and 24 types of cropland, as well as woodlots, wetlands, windbreaks, and other non-farmed areas.Footnote30 Footnote223 The agricultural landscape of the Prairie provinces increased from 35 to 55 million km2 between 1921 and the early 1970s. Javorek and Grant,Footnote84 in a more detailed analysis of recent trends for this report, found that the agricultural landscape expanded by 13,000 km2 between 1986 and 1996, then remained generally stable through to 2006. They found that close to 93% of the ecozone+ in 2006 was used for some form of agriculture (Figure 37). Approximately 55% of this was cropland, with the most common crops being wheat, cereal, oilseed, and pulses (chickpeas, dry beans, dry peas, and lentils). The area of land seeded to annual crops has increased steadily since 1921 (Figure 38) and cropland increased from 42% in 1971 to 55% in 2006.Footnote84

Figure 37. Percentage of land defined as agricultural in the Prairies Ecozone+, 2006.
Map (see long description below)
Soil Landscapes of Canada polygons were the base unit used for this analysis.
Source: Javorek and Grant, 2011Footnote84

Long description for Figure 37

This heat map presents the percentage of land defined as agricultural in the Prairies Ecozone+ in 2006. Soil Landscapes of Canada polygons were the base unit used for this analysis. The map also delineates the six ecoregions within this ecozone+ (Fescue Grassland, Cypress Upland, Mixed Grassland, Moist Mixed Grassland, Lake Manitoba Plain, and Aspen Parkland). In 2006, the vast majority of the ecozone+ was defined as 90–100% agricultural, with small areas located throughout the ecozone+ as being defined 60–90% agricultural. Only small patches of the ecozone+ were defined as less than 60% agricultural.

Figure 38. Trends in total farmland area and of land seeded to annual crops in the three Prairie provinces, 1921–2006
Graph (see long description below)
Data shown are for whole provinces and include areas outside of the Prairies Ecozone+.
Source: Statistics Canada, 2007Footnote224

Long description for Figure 38

This line graph presents the following information (km2)

YearTotal farmlandLand in crops
1921355,847130,329
1931444,274161,932
1941486,147155,316
1951501,216184,004
1956512,721190,270
1961525,339191,120
1966540,158216,181
1971540,544220,773
1976544,166220,879
1981526,715246,025
1986549,949270,077
1991554,015275,120
1996553,304286,443
2001549,349298,189
2006548,166292,827

Wildlife habitat capacity on agricultural land

The capacity of agricultural landscapes to provide habitat for wildlife depends upon the land cover type and management. Agricultural land in the Prairies Ecozone+ consists mainly of cultivated cropland with some extensive areas of tame pasture and native rangeland (Figure 39).Footnote84 With agriculture as the dominant land use, the population viability and persistence of many species depends upon the availability of suitable habitat on agricultural land. One way to measure the potential of these lands to support wildlife is through the Wildlife Habitat Capacity on Agricultural Land Indicator developed by Agriculture and Agri-Food Canada.Footnote84 Footnote225 The indicator ranks potential capacity of 15 “habitat categories” for terrestrial vertebrates based on the percent of the agricultural landscape occupied by 31 land cover types (e.g., cereal crops, summerfallow, tame hay, improved pasture, unimproved pasture, natural lands) and a rating of the value of each cover type as habitat to 588 species of birds, mammals, reptiles, and amphibians.Footnote84

Using the index, Javorek and GrantFootnote84 found that 340 species (245 birds, 71 mammals, 13 reptiles, 11 amphibians) could use agricultural land in the Prairies. Of these, 78% could use the All Other Land category (natural and semi-natural land including wetlands, riparian vegetation, and wooded areas within the agricultural landscape) for breeding and feeding, and 30% could use Unimproved Pasture (that is native rangeland) for both breeding and feeding. In contrast, only 4% were able to utilize cropland for breeding and feeding. However, when other suitable habitat was present to provide for partial life history requirements, 32% could use cropland. Godwin et al.Footnote128 showed the greatly reduced diversity in several taxonomic groups on cultivated land compared to even small remnants of native prairie.

The biggest change in land use has been the increase in area seeded to annual crops from 1971 to 2006, linked to the decrease in area of summerfallow (Figure 39). The total area of annually cultivated land, including both crops and summerfallow, declined from 66 to 62% of the agricultural landscape from 1986 to 2006, largely due to a shift of some cropland to seeded pasture (Figure 39).Footnote84 Cultivated land, offering comparatively little wildlife habitat, still represented the dominant portion of the agricultural landscape in 2006. Natural land for pasture (also known as unimproved pasture) was the second most abundant cover type and remained stable from 1971 to 2006 at about 25% of the agricultural landscape . The all other land category was also stable over that time period at about 5% of the landscape. The latter two cover types play a crucial role in determining the viability of wildlife populations in this ecozone+. It is the lower proportions of these cover types that are the primary reason for the overall low habitat capacity.

Figure 39. Trends in land cover types on agricultural land in the Prairies Ecozone+, 1971–2006.
Graph (see long description below)
Percentages were calculated as percentage of total agricultural land.
Source: Agriculture and Agri-Food Canada, 2009Footnote226

Long description for Figure 39

This line graph presents the following information:

Percentage of total farmland
Yearcropssummerfallowtame or seeded pasturenatural land for pastureall other land
197141%21%4%26%2%
197641%22%4% 2%
198147%20%5%26%2%
198650%17%4%24%4%
199150%17%5%24%4%
199653%13%5%23%5%
200156%10%6%24%4%
200655%7%8%24%5%

In 1986, 1996, and 2006, the average wildlife habitat capacity was "low" or "very low" on over 80% of the farmland in the Prairies Ecozone+ (over 10% of this was ranked as "very low") (Figure 40). Despite slight shifts in the relative percentage among habitat capacity categories, there was no significant change in habitat capacity at the ecozone+ level.Footnote84 Wildlife habitat capacity was constant on 92% of farmland, increased on 5%, and decreased on 3%. However, conversion of small parcels, such as grasslands on field margins and small wetlands in the Prairies,Footnote24 can represent significant degradation of habitat capacity even when little change is detected at broader scales as was found hereFootnote84 (see Grasslands key finding on page 16 and Wetlands key finding on page 24 for discussion of loss of these habitats). Wildlife habitat capacity among ecoregions varied considerably; Moist Mixed Grassland Ecoregion had the lowest capacity and Cypress Upland Ecoregion had the highest, which was moderate capacity (Figure 40).Footnote84

Figure 40. Wildlife habitat capacity on agricultural land in the Prairies Ecozone+ in 1986 (top) and 2006 (bottom).
Graph (see long description below)
HC means average Habitat Capacity for the ecoregion. All Soil Landscapes of Canada polygons with >5% agricultural land were included in the analysis.
Source: Javorek and Grant, 2011Footnote84

Long description for Figure 40

This graphic is composed of two heat maps that show wildlife habitat capacity on agricultural land in the Prairies Ecozone+ in 1986 and 2006. Habitat Capacity (HC) index values (± 1 standard deviation) for the whole ecozone+ and for each of six ecoregions within the ecozone+ are also provided. The Aspen Parkland Ecoregion had an HC of 39.91 ± 7.55 in 1986, and an HC of 40.72 ± 7.22 in 2006. The Lake Manitoba Plain Ecoregion had an HC of 42.25 ± 16.99 in 1986, and an HC of 42.03 ± 16.75 in 2006. The Moist Mixed Grassland Ecoregion had an HC of 37.16 ± 9.89 in 1986 and an HC of 37.96 ± 9.49 in 2006. The Mixed Grassland Ecoregion had an HC of 47.54 ± 14.32 in 1986 and an HC of 47.15±12.15 in 2006. The Cypress Upland Ecoregion had an HC of 62.45 ± 8.97 in 1986 and an HC of 61.53 ± 9.76 in 2006. The Fescue Grassland Ecoregoin had an HC of 46.72 ± 10.62 in 1986 and an HC of 49.76 ± 11.18 in 2006. Areas of Southeastern Alberta, including areas within, to the south of, and northwest of the Cypress Hills, had the highest wildlife habitat capacity (HC = 70–80) in both 1986 and 2006.

Habitat capacity is a key indicator of an ecozone+'s ability to support biodiversity and can act as an umbrella indicator of how well overall ecological processes are functioning. Management practices also influence the ability of the land to support wildlife. The development of best management practices and stewardship initiatives has had positive results in some regions and for some cover types (see Stewardship key finding on page 36).

Soil erosion on cropland

Between 1981 and 2006, the proportion of croplandFootnoteiii with very low risk of erosion increased from 64 to 84%, and the amount of land with moderate to very high erosion risk decreased from 18 to 7% (Figure 41).Footnote227 The reasons for these decreases in erosion risk are a combination of widespread adoption of conservation tillage, especially zero-till seeding, and a marked reduction in summerfallow. Further, some of the more erodible land has been converted from annual crops to perennial forages and tame pasture with associated dramatic reductions in erosion risk.Footnote227 Many of these changes are beneficial for biodiversity.

Figure 41. Soil erosion risk classes for cropland in the Prairies Ecozone+, 2006.
Map (see long description below)
All Soil Landscape of Canada polygons containing >5% cropland were included in the analysis and entire polygons are shown on the map.
Source: McConkey et al., 2011Footnote227

Long description for Figure 41

This map shows the classification of soil erosion risk (in t/ha/yr) for cropland in the Prairies Ecozone+ in 2006. Most of the ecozone+ was in the very low risk class (<6 t/ha/yr), with small patches scattered throughout the ecozone+ in the low risk class (6–11 t/ha/yr), and even fewer patches in the moderate risk class (11–22 t/ha/yr). These are located mostly in the southwestern part of the ecozone+. There were a few river basin areas in Alberta (within the ecozone+) that were classified in the very high risk category (<33 t/ha/yr).

Conservation tillage

Farmers have been working with conservation agencies to reduce the impact of tillage operations on soil erosion. Conservation tillage is the practice of minimizing plowing and retaining protective crop residues to reduce soil erosion Conservation tillage practices can also benefit waterfowl. The planting of winter wheat in the fall in a zero-till seeding practice eliminates the need for spring tillage thereby reducing disruption to nesting ducks. Application of these practices has increased since the early 1990s (Figure 42).Footnote110 Footnote228

Figure 42. Application of zero-till seeding practices in Saskatchewan, 1991–2006.
Graph (see long description below)
Source: Prairie Habitat Joint Venture, 2006Footnote228

Long description for Figure 42

This line graph presents the application of zero-till seeding practices in Saskatchewan between 1991 and 2006. In 1991, the percent of total area seeded using zero-till seeding practices was approximately 9%. Since 1991, the percent of total area seeded using zero-till seeding practices has increased steadily, reaching 60% in 2006.

Species of special economic, cultural, or ecological interest

Key finding 17
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
Many species of amphibians, fish, birds, and large mammals are of special economic, cultural, or ecological interest to Canadians. Some of these are declining in number and distribution, some are stable, and others are healthy or recovering.

Species at risk

As of 2014, 66 federally-listed species at risk were found in the Prairies Ecozone+: 25 listed as Endangered, 26 as Threatened, and 15 as Species of Special Concern.Footnote229The list is dominated by birds (20 species), plants (16 species) and insects (15 species) and many of these species are unique to the ecozone+. Most of them are found in small, localized areas, but a few are grassland endemics whose populations are steadily declining, although they are still relatively widespread at present. Many of the plants and several vertebrates are associated with open or sparsely vegetated sand environments (see Dunes key finding on page 34). Some are “peripheral” species, occurring at the edge of their range, while others may have a significant portion of their population in Canada but their numbers are declining, making them of global conservation concern.

Sprague's pipit

Sprague's pipit (Anthus spragueii) is listed as Threatened under Canada's Species at Risk Act.Footnote230 It is a native grassland birdFootnote231 and could be considered an indicator of grassland health for the Prairies Ecozone+. It breeds strictly in North America's northern Great Plains, with most of the population in Canada. Sprague's pipit has declined steadily over the past 45 years (Figure 43).Footnote232 Habitat loss and habitat degradation (due to human disturbance, invasion by shrubs and non-native plants, and area and edge effects), and climate change are among the principal threats to Sprague's pipit.Footnote152

Figure 43. Trends in abundance of Sprague's pipit as measured by the Breeding Bird Survey (BBS) in the Prairies Ecozone+ by province, 1967–2012:
Graph (see long description below)
The BBS annual index is a predicted number of birds per BBS transect based on a statistical model.
Source: Sauer et al., 2014Footnote232

Long description for Figure 43

This line graph shows the following information:

BBS annual index
YearAlbertaSaskatchewanManitoba
1967--1.11
19685.8810.280.96
19696.549.740.79
19704.459.721.02
19716.158.80.95
19725.699.350.92
19734.987.571
19744.028.120.74
19754.057.670.72
19765.477.490.58
19774.847.340.63
19783.525.880.62
19793.287.310.63
19804.976.120.77
19813.67.090.71
19824.245.970.71
19832.155.210.53
19842.14.690.52
19852.014.970.5
19862.364.920.48
19871.996.010.46
19882.214.810.44
19892.224.740.57
19901.544.420.63
19911.764.610.43
19921.663.740.51
19931.23.190.33
19941.112.980.34
19951.523.10.3
19961.43.080.32
19971.452.840.37
19981.422.840.29
19991.312.650.27
20001.292.50.26
20010.972.680.25
20021.172.830.34
20031.193.930.3
20040.852.780.29
20051.82.330.24
20061.282.120.24
20071.532.240.24
20081.242.160.23
20091.033.110.22
20100.981.880.21
20110.671.620.24
20120.621.730.25
Greater sage-grouse

Greater sage-grouse (Centrocercus urophasianus) is an indigenous North American grouse species that occurs in Canada and eleven western U.S. states. Canada's population is the sub-species C. u. urophasianus, which occupies the silver sagebrush (Artemisia cana) grassland communities of southeastern Alberta and southwestern Saskatchewan, at the northern edge of the North American sage-grouse range.Footnote233 Greater sage-grouse is listed as Endangered under Canada's Species at Risk Act because the very small population has declined substantially.Footnote233 In 2012, based on counts of male birds at leks (areas used for courtship displays), the population was estimated at 39–58 adults in Alberta and 54–80 adults in Saskatchewan (Figure 44 ).Footnote233 Populations have declined by 98% since their highest recorded population estimates in Alberta (1968) and Saskatchewan (1988). The number of active leks has also decreased by 76% in Alberta and 93% in Saskatchewan. In 2012, there were only 5 active leks in Alberta and 3 in Saskatchewan.Footnote233

The main current and future threats to this species include drought and extreme weather conditions, West Nile virus, sensory disturbance from vertical structures and chronic noise, increased predator pressure, habitat loss and degradation, alteration of natural hydrology, and threats inherent to small populations.Footnote233

Figure 44. Population estimates for greater sage-grouse in Alberta and Saskatchewan, 1980s–2012.
Graph (see long description below)
Estimates reported above are considered high estimates and use the high count of males on leks, assume a sex ratio of 2 females: 1 male, and also that only 90% of leks are known and only 75% of males attend leks. Only estimates for years in which surveys for a province were considered complete are shown.
Source: Environment Canada, 2013Footnote233

Long description for Figure 44

This line graph presents the following information:

Number of birds
YearAlbertaSaskatchewan
19801,446-
19811,572-
19831,074432
1985624-
19871,200-
1988-2,619
19891,032282
1991723-
1994210279
1995330315
1996408369
1997366183
1998372366
1999351303
2000378378
2001342318
2002273252
2003288243
2004282180
2005285186
2006270180
2007270168
2008234153
2009198135
201093126
201139105
20123954

In 2013, the Government of Canada published an Emergency Order to protect the greater sage-grouse on crown lands in southeastern Alberta and southwestern Saskatchewan.Footnote234 The Order, which came into force on February 18, 2014, prohibits activities that are known to be harmful to the birds and their habitat. In addition to the Order, private landowners are being encouraged to undertake voluntary stewardship measures and a captive breeding program has been initiated in partnership with the Calgary Zoo.

Burrowing owl

Burrowing owl (Athene cunicularia; EndangeredFootnote230) is found across the Prairies Ecozone+ where it represents the northern limit of the species' range. Its population in Canada declined strongly from the 1960s to 2007 (Figure 45). The Canadian population of burrowing owl in 2004 was estimated at 498 birds in Saskatchewan, and 288 in Alberta, but this estimate might be low by as much as 50%.Footnote235 A variety of causes for this decline have been suggested: loss of grassland habitat (the initial cause of the decline), greater emigration than immigration of birds from Canada to the U.S., loss of burrows from declining burrowing animal populations, increased predation resulting from habitat changes, reduction in invertebrate food sources through the use of chemical pesticides, and vehicle collisions.Footnote235

Figure 45. Abundance of burrowing owls, 1969–2007.
Graph (see long description below)
Source: Canadian Wildlife Service, 2007Footnote236

Long description for Figure 45

This line graph presents the abundance of burrowing owls in Canada between 1969 and 2007. Abundance is measured by an annual index. This annual index rose from zero in 1968 to 0.118 in 1969, and then decreased to zero again in 1970. Numbers then rose again and peaked at 0.11 in 1976 before decreasing again to zero in 1978. Following another small peak of 0.045 in 1979, the annual index returned to zero and has remained at or just slightly above zero up to 2007.

Swift fox

The swift fox (Vulpes velox; ThreatenedFootnote230) is an example of a conservation success story. Originally occurring across the Prairies from Manitoba's Pembina Hills to the foothills of the Rocky Mountains in Alberta, it was extirpated from Canada by the late 1930s.Footnote237 Attempts to reintroduce it started in 1983. CarbynFootnote238 documented the release of 768 foxes from 1987 to 1995 and in 1996/1997, the Canadian population was estimated at 281 animals, of which 17% had been released and the rest were wild-born animals.Footnote239 By 2005/2006, the population had increased to an estimated 647 animals, with an additional 500 animals thought to be established in the adjacent region of Montana as a result of the Canadian reintroduction program. Although a success story so far, the population currently occupies only a small proportion of its original range, amounting to less than 300 km along the Canada-U.S. border in Alberta and Saskatchewan.

Freshwater fish

Based on data from the American Fisheries Society,Footnote240 the number of freshwater and diadromous fish taxa in this ecozone+ classified as imperilled has increased from two in 1979 to five in 2008. However, the assessment for lake sturgeon (Acipenser fulvescens) and shortjaw cisco (Coregonus zenithicus) improved between 1989 and 2008; they were downlisted to Vulnerable and Threatened, respectively.

Ungulates

Large ungulate populations have shown varying patterns of abundance and distribution, with some species increasing and others decreasing. Hunting is now regulated to prevent overharvesting, but populations continue to vary with weather fluctuations and habitat change.

Pronghorn

The pronghorn (Antilocapra americana) is a small-sized, fast-moving ungulate with two-pointed horns that is native to interior western and central North America.Footnote241 Historically found from Manitoba's Red River to the edge of the Rocky Mountains in Alberta,Footnote242 numbers were thought to equal or exceed those of bison on the Great Plains prior to European settlement. Conversion of grassland to cropland reduced pronghorn distribution to peripheral ranges, which historically supported low-density populations.Footnote243 Pronghorn numbers at the northern end of their range in Canada have always fluctuated widely because of mass emigration across the border or high winter mortalityFootnote244and were lowest at the beginning of the 20th century (Figure 46). They have recovered somewhat since then, although their range is still restricted. SheriffFootnote241 found that pronghorn abundance was strongly positively associated with native prairie. They are also highly dependent on sagebrush communities. The largest populations coincide with large expanses of remaining natural habitat. Threats include loss of movement corridors, barriers such as fences, and roads that can increase mortality risk.Footnote243

Figure 46. Pronghorn population trends in Saskatchewan (green line) and Alberta (red line), 1900–2008.
Graph (see long description below)
Source: adapted from Arsenault, 2008Footnote243 (Saskatchewan) and Alberta Forestry, Lands and Wildlife, 1990Footnote242 (Alberta)

Long description for Figure 46

This line graph presents pronghorn population trends in Alberta and Saskatchewan between 1900 and 2008. Population numbers prior to 1945 represent archive guesses while post-1945 numbers are based on systematic surveys. The line graph for Alberta shows the following information:

YearPopulation
19202,000
194530,000
19524,500
19535,000
19548,000
195510,000
195615,000
195712,500
195911,000
196012,200
196113,000
196211,500
196319,040
196420,177
196514,231
196612,428
196710,037
19689,660
19696,210
197011,400
19719,424
197210,411
197310,627
197411,115
197511,777
197616,813
197717,953
197810,919
197915,330
198018,637
198120,707
198221,202
198432,071
198524,174
198624,900
198728,209
198823,107
198922,314

In Saskatchewan, populations began at approximately 25,000 in 1900, and then dropped to a very small number in the 1920s. From the mid-1920s to 1950, the population increased after which it fluctuated but remained steady until 1975. After 1975, the population increased rapidly to just over 30,000 in 1990, before declining to approximately 15,000 in 2008.

Elk

Abundant in the Prairies prior to settlement, elk (Cervus elaphus) became largely restricted to pockets of forestFootnote245 but, since the 1990s, have begun to rapidly re-occupy non-forest habitats.Footnote108 Footnote164 Footnote217 Footnote246 Footnote247

Moose

Moose (Alces alces), which typically occur in the Boreal Forest, have increased and extended their range into the Prairies since the late 1970s to mid-1980s.Footnote164 Footnote217 Footnote246 This expansion was likely a result of a reduction in hunter numbers, reduction or elimination of predators such as wolves and bears, and increasing amounts of woody vegetation.

Deer

Mule deer (Odocoileus hemionus) were the more common deer in the Prairies prior to European settlement, but are currently less abundant, being more restricted to open habitats with rougher topography.Footnote248 Footnote249 White-tailed deer (O. virginianus)may have been largely absent from the Prairies Ecozone+ before European settlement.Footnote245 Footnote248 They are very common, especially in the Aspen Parkland Ecoregion. Populations expanded rapidly in the 1940s and 1950s and have generally continued to expand.Footnote250 Footnote251 Footnote252 Because the Prairies Ecozone+ is near the north end of the white-tailed deer's range, winter weather is the main factor limiting current populations, with fluctuations closely linked to severe winters.Footnote252 The main reasons for expansion over the last 50 years have been reduced competition with mule deer, high quality and abundance of food provided by agriculture, and expansion of aspen.Footnote250 Footnote251 Footnote252 Footnote253

Birds

Landbirds

The Prairies Ecozone+ includes more grassland than any other ecozone+ and is the heart of range of many grassland birds in Canada. Grassland birds declined more rapidly than any other group of birds in North America since the 1970s,Footnote50 Footnote254 Footnote255 and this is reflected in the results for the Prairies Ecozone+ (Figure 47) (see the Grasslands key finding on page 16).

In contrast, forest birds in the Prairies Ecozone+ increased by 35% in overall abundance since the 1970s (Figure 47). This assemblage benefitted from increased forest habitat as a result of tree planting on farms and in other settlements as well as the increased tree cover in areas of Aspen Parkland Ecoregion (see Forests key finding on page 15).Footnote17, Footnote256 Birds of other open and shrub/early successional habitats were relatively stable and urban/suburban birds decreased as a group (Figure 47). Birds of forest, urban, and shrub/early successional habitats are a relatively small component of prairie avifauna.Footnote49

Figure 47. Change in abundance of landbirds by habitat for the Prairies Ecozone+ from 1970s to 2000s.
Graph (see long description below)
Source: adapted from Downes et al., 2011Footnote49 using data from the Breeding Bird SurveyFootnote50

Long description for Figure 47

This bar graph presents the following information:

Species AssemblagePercentage of change from 1970 index
Forest35%
Shrub-4%
Grassland-35%
Other / Open-8%
Urban-18%
Raptors

Because of their position high in the food web, raptors are indicators of ecosystem health. Data from the Breeding Bird Survey was analyzed to look at trends in raptor populations in the Prairies Ecozone+. Of the four species showing statistically significant trends, three were positive, while one, short-eared owl (Asio flammeus), was negative (Figure 48). Red-tailed hawk (Buteo jamaicensis) has increased 3.3%/yr, and it has replaced Swainson's hawk (Buteo swainsoni) as the dominant Buteo and most abundant raptor in the ecozone+.257 This is probably due to the gradual expansion of tree cover.Footnote258 Footnote259

Figure 48. Population trends for raptors showing significant change in the Prairies Ecozone+, 1973–2009.
Graph (see long description below)
Only raptors with significant trends (p<0.05) are shown.
Source: Environment Canada, 20102Footnote260

Long description for Figure 48

This line graph presents population trends for four different raptor species showing significant (p<0.05) changes in the Prairies Ecozone+ between 1973 and 2009. Abundances are represented by population index values. Red-tailed hawks, great horned owls, and merlin increased while short-eared owls decreased over the time period. Red-tailed hawk had the highest population index values, substantially higher than the other three species. Red-tailed hawk populations increased steadily over the the first part of the time period, from a population index of approximately 0.9 in 1973 to 3.5 in 1995. Between 1995 and 2009, the population remained steady before decreasing slightly to a population index of just below 3.0. Great horned owl populations increased from 0.1 in 1973 to 0.6 in 2009. Merlin numbers also increased, but with a lower population index, from 0 in 1973 to 0.3 in 2009. The short-eared owl population index was highest in 1974 but decreased steadily to almost 0 in 2009.

Waterfowl

The waterfowl found in the Prairies Ecozone+ are diverse, with a variety of different habitat requirements and migratory strategies. Some species winter on Canadian coasts while the majority winter in the U.S. and Mexico.Footnote58 The Prairie Pothole Region (U.S. and Canada) is the world's most productive waterfowl habitatFootnote62 and, although it only covers 10% of the available breeding habitat in North America, it supports the highest densities of breeding waterfowl and can account for greater than 50% of annual continental duck production.Footnote58 Footnote59 The Canadian Prairies produce 50–80% of the Prairie Pothole Region's duck population.Footnote261 The Prairies Ecozone+ is also an important area for migrating waterfowl. Many ducks and geese that nest in the Arctic, sub-Arctic, and boreal forest pass through this area during migration, stopping in staging areas.

Some waterfowl species are showing long-term population increases. For example, Canada geese populations have increased by 765% since the 1970s due to their ability to adapt to a variety of habitats including farmland and urban areas.Footnote219 Footnote262 Some species have declined significantly, such as northern pintail (Anas acuta) and American wigeon (A. americana). Other species, such as blue-winged teal (A. discors) and canvasback (Aythya valisineria), have shown little long-term change in their population size since the 1970s (Table 6).

Table 6. Abundance trends for selected breeding waterfowl species in the Prairies Ecozone+, 1970s to 2000s.
Common nameNesting habitatTrend (%/yr)PAnnual abundance index (in 1000s)
1970s
Annual abundance index (in 1000s)
1980s
Annual abundance index (in 1000s)
1990s
Annual abundance index (in 1000s)
2000s
% Change
Canvasback
(Aythya valisineria)
Overwater0.3-198146.7192.7206.24.2
Redhead
(Aythya americana)
Overwater0.7*279.2202285.1307.510.1
Ring-necked duck
(Aythya collaris)
Overwater0.6n47.455.244.157.320.8
Ruddy duck
(Oxyura jamaicensis)
Overwater1.6*145.5152.7196.7234.861.3
Bufflehead
(Buchephala albeola)
Cavity2.7*59.455.592.9112.789.9
Northern pintail
(Anas acuta)
Ground-4.1*2795.3944.8816.8835.5-70.1
American wigeon
(Anas americana)
Ground-3.6*908.6398.3356.7299.6-67
Green-winged teal
(Anas crecca)
Ground-1.5*561.3220.7346.7323.8-42.3
Mallard
(Anas platyrhynchos)
Ground-1.1*3180.118012156.92221.2-30.2
Blue-winged teal
(Anas discors)
Ground-0.1-2024.51242.21636.81835-9.4
Gadwall
(Anas strepera)
Ground1.1*814.6585.2968.4986.621.1
Northern shoveler
(Anas clypeata)
Ground1.2*899.9654.71022.9125439.3
Canada goose
(Branta canadensis)
Ground7.9*47.7107.9238.6412.4765.4

P is the statistical significance: * indicates P <0.05; n indicates 0.05<P<0.1; no value indicates not significant
Source: Fast et al., 2011Footnote219, using data from CWS and USFWS Waterfowl Breeding Population and Habitat SurveyFootnote59

Increased conversion of marginal land to cropland over the last four decades (see Agricultural landscapes as habitat key finding on page 64) has likely had continuing negative impacts on many breeding waterfowl on the Prairies through habitat loss and changes in predation patterns. For example, nest success for mallard (Anas platyrhynchos), northern pintail, northern shoveler (A. clypeata), blue-winged teal, and gadwall (A. strepera) is negatively associated with proportion of cropland.Footnote263

Climatic conditions, such as drought in the 1980s, also had a large impact on waterfowl populations; many populations steadily increased after the drought (Table 6). Wetland abundance and distribution affects several prairie breeding ducks (see Wetlands key finding on page 24).Footnote263 Footnote264 Footnote265 Footnote266 Footnote267 Footnote268 Footnote269 Northern pintail, blue-winged teal, mallard, and northern shoveler breeding densities fluctuate with numbers of prairie ponds suggesting that these species fly over the prairies in drought years and settle in more northern ecozones+.Footnote268 These species, along with green-winged teal (Anas crecca), are dabbling ducks that are typically associated with shallow temporary and seasonal wetlands (i.e., ephemeral habitats). Consequently, some of these species may be more sensitive to fluctuating water conditions (which influences wetland densities) and wetland destruction than other species such as gadwall and diving ducks (e.g., canvasback, ruddy ducks), which are more associated with semi-permanent and permanent wetlands that are less susceptible to drought conditions and drainage.Footnote268 As such, duck species that use small wetlands prone to agricultural modification or destruction and climate fluctuations are generally the species that are declining (Table 6).

Figure 49. Population trends of selected ground nesting ducks in the Prairies Ecozone+, 1970–2006.
Graph (see long description below)
Source: Fast et al., 2011Footnote219 using data from CWS and USFWS Waterfowl Breeding Population and Habitat SurveyFootnote59

Long description for Figure 49

This line graph presents the following information:

Number of breeding pairs
YearAmerican WigeonBlue-winged TealGadwallGreen-winged TealMallardNorthern PintailNorthern Shoveler
19711,099,7591,905,129819,058559,0973,750,4842,474,5341,027,842
19721,133,1601,886,066868,355590,4503,888,4432,722,1061,104,025
19731,172,2941,941,069888,119657,8124,088,1872,823,2591,169,798
19741,230,0442,109,231943,605723,3494,155,9943,085,2311,233,564
19751,271,7622,308,023985,323769,5734,281,5733,309,2611,279,341
19761,300,3422,473,4411,014,746816,8314,537,8423,499,4991,333,940
19771,293,4312,572,6441,010,169814,9644,550,7353,334,4261,275,975
19781,261,2432,481,6661,006,331815,5084,498,2973,217,7441,205,695
19791,284,0632,593,169996,531846,3084,536,7413,388,3241,228,527
19801,259,7522,659,2861,005,349819,9354,544,7953,205,0961,190,384
19811,177,3352,624,324993,747762,6174,348,9442,952,9811,168,416
19821,117,8862,539,591984,617712,0494,131,5322,747,7581,145,174
19831,073,2242,509,231962,561672,3373,945,1102,501,7151,109,443
19841,032,1442,512,685947,970622,2203,745,4872,387,7431,068,586
1985959,2472,385,437912,742568,8983,579,6042,066,4831,034,460
1986872,9902,165,389895,709520,4483,429,5341,797,232996,933
1987795,8222,014,784869,636476,8393,185,6371,532,103950,852
1988760,1371,912,946838,352476,4423,043,5971,465,360947,092
1989709,4591,875,411828,630440,9812,944,7191,335,387932,809
1990627,7281,804,095829,310398,2272,838,2191,104,554908,940
1991563,3101,742,128826,719381,2392,700,464973,040902,590
1992571,7621,769,610858,160375,0252,675,025917,161907,781
1993532,7781,765,267863,946373,9352,586,890802,509878,636
1994493,9741,763,807906,860379,9792,559,055775,509891,617
1995499,6651,770,512948,545406,6982,645,403775,190946,694
1996507,7371,873,6451,010,961457,1482,760,174781,8411,015,909
1997526,1441,974,7021,076,052521,6182,883,236856,0831,145,991
1998541,4592,055,3891,180,190528,0423,039,098850,1841,190,756
1999561,8392,180,4901,253,476555,0433,232,501917,6551,301,310
2000577,9992,313,9291,284,835617,0433,398,705915,7121,386,763
2001580,5022,347,5721,288,297630,5683,456,648926,2521,417,424
2002566,2792,301,5351,293,600642,6813,506,349920,2131,412,549
2003548,3282,312,5981,324,213649,0753,576,865978,6841,506,284
2004529,2872,373,3581,355,734649,6373,631,478982,6221,557,973
2005523,7612,479,4641,355,695666,3073,659,431982,2061,641,407
2006505,3112,642,7511,426,316680,0393,668,8861,059,0401,762,013
Case study: northern pintail

Unlike most other waterfowl species, the northern pintail population in North America has remained well below the North American Waterfowl Management Plan goal of 5.6 million birds. In 2007, the population was 40% below the plan's goal and 19% below the long-term average (Figure 50).Footnote270 Typically, the number of pintails that settled on the Prairie Pothole Region had a consistent and positive relationship with numbers of wetlands counted during May surveys. Since the early 1980s, however, the strength of this relationship had weakenedFootnote271 and there was no relationship between pintails and wetlands in the mid-1990s when water conditions were excellent. Comparison of population trends between the Canadian and U.S. portions of the Prairie Pothole Region indicate that most of the decline occurred in the southern Canadian portion of the region. A primary cause for the decline is the tendency of northern pintail to nest in standing stubble, mulched stubble, or fallow fields early in the season often prior to seeding. The reduction of summerfallow and increase of spring seeding since the 1970sFootnote84 has been linked to reduced nest success and a decline in the northern pintail population in the Canadian portion of the region.Footnote272 Footnote273

Figure 50. Comparison of northern pintail population trends in Alaska/northern Canada, southern Canada, and the northern U.S., 1961–2007.
Graph (see long description below)
Source: U.S. Fish and Wildlife Service, 2007Footnote59 and Canadian Wildlife Service Waterfowl Committee, 2008Footnote220

Long description for Figure 50

This line graph presents the following information:

Population
YearAlaska and
Northern Canada
Northern U.S.Southern Canada
19612,041,665715,5781,457,929
19621,342,4781,266,5781,014,467
19631,219,998809,6071,812,954
19641,309,236596,0331,385,958
19651,074,350894,8801,622,688
1966958,222987,1002,866,611
1967872,8301,008,8003,396,135
19681,753,379370,7001,365,320
1969850,2561,246,7003,806,958
19701,064,8981,356,1003,970,848
1971666,0791,062,1004,119,042
19721,406,4211,385,1004,187,411
19731,551,327699,9002,104,969
19741,285,561703,0004,609,543
19751,149,229933,0003,818,073
19761,179,985546,3003,749,311
19772,541,902340,4001,043,805
19781,352,6701,615,8002,139,690
19791,024,7591,122,1003,229,291
19802,141,909558,1001,808,044
19811,891,748345,5001,242,179
1982924,396880,5001,903,885
19831,368,106641,5001,501,088
19841,408,203738,800817,870
1985940,275420,7001,154,449
19861,085,765745,400908,584
19871,230,426550,400847,497
19881,358,036329,700317,746
19891,102,825315,300693,802
19901,291,647256,400708,608
19911,280,907162,200360,277
19921,194,361253,300650,558
1993979,097424,000650,413
1994905,855850,1001,216,281
1995952,363943,600861,870
1996836,867674,4001,224,706
1997840,000840,0001,600,000
19981,100,000760,000800,000
19991,214,000793,0001,052,000
20001,688,000522,000698,000
20011,611,000841,000843,000
20021,140,587362,724286,397
20031,023,592250,0731,284,562
20041,130,000379,000675,000
20051,021,000331,0001,208,000
20061,173,000521,0001,692,000
20071,374,000662,0001,299,000
Shorebirds

The Prairies Ecozone+ provides important habitat for both breeding and migrant shorebirds. This includes eight species whose breeding range in Canada is primarily or entirely in the Prairies: American avocet (Recurvirostra americana), marbled godwit (Limosa fedoa), piping plover (Charadrius melodus), Wilson's phalarope (Phalaropus lobatus), black-necked stilt (Himantopus mexicanus), willet (Tringa semipalmata), long-billed curlew (Numenius americanus) and upland sandpiper (Bartramia longicauda). Data for these species was limited to the Breeding Bird Survey. Population totals of shorebird species tend to number in the tens to hundreds of thousands, with a few in the millions.Footnote274 The only species with a significant trend was marbled godwit, which declined by 1.1% per year since the 1970s.Footnote275 This is important as approximately 60% of the world's population breeds in the Canadian Prairies.Footnote276 There is little information on population trends for the 31 species of shorebirds that regularly migrate through the Prairies in the spring and fall.Footnote277 Footnote278 Footnote279

Range changes

Major range shiftshave occurred in a number of native species including white-tailed deer (see Deer on page 75), moose (see Moose on page 75), red-tailed hawk (see Raptors on page 76), and raccoon (Procyon lotor).280 LarivièreFootnote280 documented the increase in raccoons in the Prairie provinces by examining fur sale records for each of the provinces. Sales of raccoon pelts in Manitoba climbed from near zero in 1960 to almost 1,000 in 1969, peaking at over 7,000 in the early 1970s. The increase in Saskatchewan occurred slightly later, starting in 1970, and numbers in Alberta showed little fluctuation above a low baseline through to 1985.

Climate change will also enable more warm water fish species to expand their ranges. The channel catfish (Ictalurus punctatus) is a native species that has increased its range, moving up the Qu'appelle River from Manitoba into Saskatchewan.Footnote114 Rainbow smelt (Osmerus mordax), an anadromous species of North America's east and west coasts, has appeared in Manitoba with the first report occurring in Lake Winnipeg in 1975. White bass (Morone chrysops), introduced to North Dakota in 1953, appeared in Lake Winnipeg 10 years later and by 1994 had become the most abundant spiny-rayed fish in the Lake's south basin.Footnote157

Primary productivity

Key finding 18
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
Primary productivity has increased on more than 20% of the vegetated land area of Canada over the past 20 years, as well as in some freshwater systems. The magnitude and timing of primary productivity are changing throughout the marine system.

The Normalized Difference Vegetation Index (NDVI), calculated from remote sensing data, is an indicator of the amount and vigour of green vegetation present on a landscape. Changes in NDVI are a proxy for changes in primary productivity. Trends in annual peak NDVI values over a 22-year period (1985–2006) were analyzed by Pouliot et al.Footnote281 The significant results were then summarized by ecozone+ and visually compared to 1995 land cover (derived from Advanced Very High Resolution Radiometer data by the Canadian Centre for Remote SensingFootnote282) by Ahern et al. (2011).Footnote7 Results show that, between 1985 and 2006, NDVI values increased for 157,491 km2 (35.1%) of the Prairies Ecozone+ and decreased for 1,116 km2 (0.2%) (Figure 51). Increases were distributed widely while decreases in NDVI were confined to a small area in southeastern Alberta. Broad increases in NDVI in this ecozone+ have also been shown by Slayback et al.,Footnote283 Zhou et al.,Footnote284 and Tateishi and Ebata.Footnote285

Figure 51. Change in the Normalized Difference Vegetation Index for the Prairies Ecozone+, 1985–2006.
Map (see long description below)
Trends are in annual peak NDVI, measured as the average of the three highest values from 10-day composite images taken during July and August of each year. Spatial resolution is 1 km, averaged to 3 km for analysis. Only points with statistically significant changes (p<0.05) are shown.
Source: adapted from Pouliot et al., 2009Footnote281 by Ahern et al., 2011Footnote7

Long description for Figure 51

This map shows areas of increase and decrease in the annual peak Normalized Difference Vegetation Index (NDVI) for the Prairies Ecozone+ between 1985 and 2006. Of areas showing change over this period, the vast majority had increasing trends. Only one small area in the southeastern corner of Alberta exhibited a negative trend in NDVI. The map shows that, from 1985 to 2006, NDVI values increased for 157,491 km2 (35.1%) and decreased for 1,116 km2 (0.2%) of the ecozone+. Areas with increasing values were concentrated largely in Saskatchewan and southern Alberta.

Natural disturbance

Key finding 19
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
The dynamics of natural disturbance regimes, such as fire and native insect outbreaks, are changing and this is reshaping the landscape. The direction and degree of change vary.

The main natural disturbance regimes that have historically shaped the Prairies include fire, drought, bison grazing, and large-scale native insect outbreaks.

Fire

Under pre-European settlement conditions, frequent fires were the predominant disturbance regime of grasslands in the Prairies Ecozone+. In addition to natural fires caused by lightning,Footnote286 some burning was anthropogenic.Footnote205 Footnote287 Footnote288 Footnote289 There is no way to measure historic fire frequency, but 5–10 years is a “reasonable” estimate of the natural fire-return interval.16 Under modern conditions, prairie fires still start under dry conditions,Footnote16 sometimes ignited by lightning.Footnote290 They do not travel as far as they did historically, however, as a network of firebreaks in the form of roads and cultivated fields break up the grassland,Footnote16 and accidental grass fires are aggressively suppressed to reduce damage to forage and facilities. No quantitative data were available for the extent or frequency of fires across the ecozone+.

In a review of threats to native areas in the Northern Great Plains of the U.S. and Canada, the Nature ConservancyFootnote291 rated “loss of fire regime” as the second-most serious threat to this region. Fire is a natural and essential process which, like grazing, creates and maintains variety in the prairie landscape. In tallgrass prairie, however, Collins and SmithFootnote292 found that frequently repeated burns reduce spatial variability and diversity, increasing the dominance of a few C4 grass species. In the mixed prairie, which covers most of this ecozone+, productivity is probably higher now than before European settlement, because fire causes a reduction in productivity that lasts for three years or more.Footnote16 Footnote17 Footnote293 Footnote294 Footnote295 In moister parts of the ecozone+, the reduction in fire frequency has led to increases in shrub and tree cover, because frequent fire tends to suppress woody plants and favour grasses.Footnote12 Footnote13 Footnote16 Footnote17 In some areas, woody invasion threatens native grassland communities, such as the northern fescue prairie. Fire suppression may also contribute to sand dune stabilization, reducing habitat for certain rare species associated with active dunes.Footnote99 PylypecFootnote296 found that some birds such as horned lark increase after grassland fire, while others such as Sprague’s pipit, Baird’s sparrow (Ammodramus bairdii), and western meadowlark (Sturnella neglecta) decrease after fire.

Large-scale native insect outbreaks

Insect herbivores are an integral part of prairie ecosystems, with outbreaks of some native species functioning as disturbance agents. Grasshoppers (order Orthoptera) are the most significant insect pests to grasslands and cereal crops in many parts of the Prairies.Footnote297 Their populations increase when late summers are dry and warm,Footnote298 Footnote299 and major grasshopper outbreaks occur after several consecutive years of warm, dry weather.Footnote297 No data were available on trends in the pattern of grasshopper outbreaks.

Forest tent caterpillars (Malacosoma disstria) and other insects can significantly defoliate trembling aspen in the Aspen Parkland Ecoregion in some years,Footnote300 and like the grasshoppers, outbreaks occur more frequently in warm, dry summers.Footnote301 Outbreaks were much more frequent and severe in the Aspen Parkland in the 1980s and 1990s than in the 1940s to 1970s. They peaked in the early 1980s before severity declined in the early part of the 2000s (Figure 52).Footnote302

Figure 52. Trend in estimated percentage of area of aspen defoliated in the Aspen Parkland Ecoregion, based on plots monitored by the Canadian Forest Service, 1940–2005.
Graph (see long description below)
The mean percent white rings from tree-ring analysis (blue line above) indicate years of severe insect defoliation. The orange line shows the estimated percent area with moderate to severe defoliation. The proportion of defoliated area is based on estimates from insect surveys of the area surrounding the plots. Defoliated aspen may have lower subsequent survival, potentially leading to underestimates of defoliation in early years based on white tree-ring method.
Source: Canadian Forest Service, unpublished dataFootnote302

Long description for Figure 52

This line graph presents the following information:

-% White tree-rings% Area defoliated
19416-
19425-
19432-
19471-
19485-
19492-
195001
195101
195213
195329
195401
195712
195826
195916
1960217
1961018
196208
1963010
1964317
196530
196601
196701
197010
197100
197230
197301
197401
197502
197607
1977114
197803
19791826
19802641
19811229
198238
198384
1984811
1985911
1986313
19871728
19881831
1989521
199059
199131
199283
1993109
19941810
19951513
199608
20044-

Another insect disturbance agent of the Prairies Ecozone+ is the mountain pine beetle (Dendroctonus ponderosae), which is native to the unique lodgepole pine (Pinus contorta) forests of Cypress Hills. A significant outbreak occurred in the 1980sFootnote303 and the population was beginning to increase again in 2008.Footnote304

Food webs

Key finding 20
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
Fundamental changes in relationships among species have been observed in marine, freshwater, and terrestrial environments. The loss or reduction of important components of food webs has greatly altered some ecosystems.

Changes to the food webs and trophic dynamics in the Prairies Ecozone+ have included changes in herbivore grazing patterns and intensity due to the replacement of bison herds with domestic livestock and the loss of large predators.

Herbivores

As discussed in the Grasslands key finding on page 16, the historic impacts of free-roaming bison on grasslands were thought to be very different from the impacts of confined bison herds and domestic beef cattle today. Although the relationships among grazing, grassland biodiversity, and invasive non-native plants are complex, the presence of a wide range of grazing intensities appears better for maintaining prairie biodiversity than uniform grazing management.Footnote44 Footnote45 In some areas, grazing regimes more similar to historic patterns have been implemented for conservation purposes (e.g., Grasslands National Park).Footnote305

Predators

Large predators, such as the grey wolf (Canis lupus) and grizzly bear (Ursus arctos), have been eliminated or substantially reduced as a result of European settlement (Figure 53).Footnote306 The decline of the grey wolf began with the extirpation of the plains bison in the late 1800s and continued due to over-hunting of ungulate prey and predator control.Footnote307 Across North America, the loss of the wolf has, among other impacts, resulted in increased abundances of ungulates, leading to increased browsing on vegetation.Footnote308 Although hunting has played a role similar to ungulate predation, it can also be selective based on age, sex, or other characteristics, leading to demographic effects on the overall population and decreased fecundity,Footnote309 or unintentional evolutionary consequences (e.g., selection for small antler size).Footnote310 However, studies showing these effects have not been carried out in the ecozone+.

Figure 53. Reduction in the ranges of three large carnivores in North America.
Map (see long description below)
Source: after Hummel and Ray, 2008Footnote306

Long description for Figure 53

This figure shows three maps of the current and historical distribution of the grey wolf, the grizzly bear, and the wolverine in North America. The historical distribution of the grey wolf extended south to include almost all of the U.S. The current distribution only goes as far south as the Canada–U.S. border. The historical distribution of the grizzly bear extended throughout western North America down to Mexico. The current distribution is limited to Alaska, northwestern Canada (to Hudson's Bay), and western Canada, with its southern limit being the Canada–U.S. border. The historical distribution of the wolverine was mostly delineated by the Canada–U.S. border, dipping slightly further south along the U.S. northwestern coast. The current wolverine distribution includes Alaska, the Canadian Arctic and territories, and all of B.C. and extends slightly south from BC into the Rocky Mountains.

Because wolves tend to dominate other carnivores,307 the loss of wolves has probably contributed to increased coyote (Canis latrans) populations.Footnote311 In southeastern Alberta, coyote abundance increased 135% between 1977–1989 and 1995–1996.Footnote311 Coyotes eat a wide variety of foods including rodents, rabbits, woodchucks, songbirds, fruits, and domestic livestock (especially sheep). Although they do prey upon wild ungulates, much of the ungulate meat coyotes consume is from carrion.Footnote312 The shift in top predators from wolves, that mainly hunted ungulates, to coyotes, shifted the abundance and distribution of prey species. Coyotes are also a major predator of duck nests.Footnote313 Coyotes, along with golden eagles (Aquila chrysaetos), are also the main predators of the reintroduced swift fox.Footnote311 Footnote314 Footnote315 Footnote316

Wildlife diseases and parasites

Ecozone+-specific key finding
Theme Habitat, Wildlife, and Ecosystem Processes

National key finding
Wildlife diseases and parasites was initially identified as a nationally recurring key finding and information was subsequently compiled and assessed for the Prairies Ecozone+. In the final version of the national report,Footnote3 information related to wildlife diseases and parasites was incorporated into other key findings. This information is maintained as a separate key finding for the Prairies Ecozone+.

A wide variety of diseases affect wildlife in the Prairies Ecozone+:Footnote317

  • Avian influenza in wild ducks;
  • Botulism in waterfowl;
  • Avian cholera in migrating geese;
  • Newcastle disease virus in double-crested cormorants (Phalocrocorax auritus);
  • Ranavirus in amphibians;
  • Chytrid fungus in amphibians;
  • Epizootic hemorrahic disease and Bluetongue virus in deer and pronghorns;
  • Chronic wasting disease in deer and elk;
  • Brainworm (Parelaphostrongylus tenuis) in deer, elk, and moose;
  • Winter tick in moose;
  • Tuberculosis in elk;
  • Lyme disease in deer;
  • Morbillivirus in carnivores such as the reintroduced swift fox and black-footed ferret (Mustela nigripes); and
  • Plague bacterium in colonial ground squirrels and prairie dogs, which could also spread to black-footed ferret.

One disease (chronic wasting disease) and one parasite (botulism) are described in more detail below as examples of the known and potential impacts on native wildlife populations, along with an example of a disease impacting tree populations (Dutch elm disease).

Chronic wasting disease

Chronic wasting disease (CWD) is a fatal disease to members of the deer family (cervids; family Cervidae) resulting from ingestion of a misfolded version of a normal body protein called the prion protein.Footnote318 Footnote319 CWD was first recognized as a clinical disease in 1967 in mule deer housed at a research station in Colorado.Footnote319 The disease has spread widely in the U.S. and Canada (Figure 54), often in association with the sale and transport of farmed cervids. CWD was first reported in Canada in 1996 in captive elk on game farms in Saskatchewan.Footnote320 In 2000 it was detected in a wild mule deer and has since been detected in four separate geographical areas of the Prairies Ecozone+ in mule deer, white-tailed deer, and elk. CWD is a serious ecological and economic concern to Canada. The approximately 1.8 million white-tailed deer, 350,000 mule deer, 100,000 elk, and 900,000 moose in Canada are susceptible to CWD and there are no natural barriers to prevent its spread from its current locations to the rest of the country.Footnote321 A CWD disease control and eradication policy was implemented by the Canadian Food Inspection Agency (CFIA) in October 2000. Testing is mandatory in Manitoba, Saskatchewan, Alberta and the Yukon. Where captive animals have tested positive, exposed herds have usually been destroyed to minimize the risk of spread.Footnote322

Figure 54. Distribution of Chronic Wasting Disease in North America, 2013.
Map (see long description below)
"Depopulated" means that all cervids on the farm were killed by government authorities as per the North American response to CWD.
Source: USGS National Wildlife Health Center, 2013Footnote323
Long description for Figure 54

This map presents the distribution of Chronic Wasting Disease (CWD) in North America in 2013. In Canada, CWD was found in free ranging populations in southern Saskatchewan and southeastern Alberta. In the U.S., it was known from free ranging populations in three major areas (although other scattered smaller areas are also known): a larger area encompassing six states centred around Wyoming and Colorado, southern Wisconsin and northern Illinois, and a small patch of on the southern New Mexico–western Texas border. Prior to 2000, CWD was only known from free-ranging populations in Wyoming and Colorado. Captive facilities previously depopulated of animals with CWD ("depopulated" means that all cervids on the farm were killed by government authorities as per the North American response to CWD) were located around the areas of CWD in free-ranging populations, including in Saskatchewan and Alberta, but also scattered more broadly throughout the northwestern U.S., southwest of the Great Lakes. In 2013, captive facilities that currently had CWD were found in Nebraska, Colorado, Minnesota, and Indiana. There were no captive facilities that currently had CWD in Canada.

Botulism

Botulism is a form of food poisoning associated with the ingestion of powerful toxins produced by various strains of the bacterium Clostridium botulinum. Although it has occurred in other ecozones+, type-C botulism has caused large and recurrent epidemics only in the Prairies Ecozone+, affecting waterfowl, especially ducks. The alkaline wetlands of the Prairies Ecozone+ are habitats favourable to type-C botulism. In the mid-1990s, repeated years of high mortality occurred in southern Alberta, Saskatchewan, and Manitoba. For example, over 100,000 ducks died in late fall at Old Wives' Lake in southern Saskatchewan in 1996, and total mortality from June to October was approximately one million birds.Footnote324 Footnote325 These outbreaks were associated with summer drought conditions during which many of the small wetlands used by waterfowl for nesting were dry and large numbers of birds were concentrated on a small number of large wetlands where suitable habitat remained available. There was a marked reduction in mortality from botulism in subsequent years when precipitation relieved drought conditions.Footnote325

Dutch elm disease

Dutch elm disease is a fungal disease of elm trees. Since its introduction to Canada in Quebec in about 1940, it has spread quickly, invading Ontario by 1946, the Maritimes by 1957, Manitoba by 1975, and Saskatchewan by 1981.Footnote326 Control measures have generally focused on urban areas and as a result, wild trees have suffered high mortality rates. In Saskatchewan, mortality rates exceeded 80%.Footnote327 In Winnipeg, 40,000 city elms were lost over the past 20 years, with 200,000 remaining.Footnote328 Isolated pockets of wild trees occur as far west as Saskatoon and Assiniboia and these are probably the only natural populations in Canada that remain uninfected.Footnote327

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Footnotes

Footnote iii

Cropland in this analysis also includes areas defined as Improved Pasture and Summerfallow in the Census of Agriculture. See McConkey et al., 2011Footnote227 for more information.

Return to footnote iii

Footnote 3

Federal, Provincial and Territorial Governments of Canada. 2010. Canadian biodiversity: ecosystem status and trends 2010. Canadian Councils of Resource Ministers. Ottawa, ON. vi + 142 p.

Return to footnote 3

Footnote 7

Ahern, F., Frisk, J., Latifovic, R. and Pouliot, D. 2011. Monitoring ecosystems remotely: a selection of trends measured from satellite observations of Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 17. Canadian Councils of Resource Ministers. Ottawa, ON.

Return to footnote 7

Footnote 12

Bailey, A.W. and Wroe, R.A. 1974. Aspen invasion in a portion of the Alberta parklands. Journal of Range Management 27:263-266.

Return to footnote 12

Footnote 13

Scheffer, E.J. and Bailey, A.W. 1972. Ecology of aspen groves and their invasion into grasslands. In 51st Annual Feeder's Day Report. University of Alberta, Department of Animal Science. Edmonton, AB. pp. 49-50.

Return to footnote 13

Reference 16

Wright, H.A. and Bailey, A.W. 1982. Fire ecology: United States and southern Canada. John Wiley and Sons. New York, NY. 501 p.

Return to footnote 16

Footnote 17

Anderson, H.G. and Bailey, A.W. 1980. Effects of annual burning on grassland in the aspen parkland of east-central Alberta. Canadian Journal of Botany 58:985-996.

Return to footnote 17

Footnote 24

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Footnote 323

USGS National Wildlife Health Centre. 2013. Distribution of Chronic Wasting Disease in North America [online]. U.S. Geological Survey. (accessed 5 November, 2013)

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Footnote 324

Rocke, T.E. and Bollinger, T.K. 2007. Avian botulism. In Infectious diseases of wild birds. Edited by Thomas, N.J., Hunter, D.B. and Atkinson, C.T. Blackwell Publishing. Ames, IA. Chapter 21. pp. 377-416. 

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Footnote 325

Canadian Cooperative Wildlife Health Centre. 2008. Canada's national wildlife disease database [online]. (accessed 23 January, 2009)

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Footnote 326

Rioux, D. 2003. Dutch elm disease in Canada: distribution, impact on urban areas, and research. XII World Forestry Congress. Natural Resources Canada, Canada Forest Service. Quebec City, QC. 

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Footnote 327

Hyde, S. 2008. Personal communication. Information on Dutch elm disease in Canada. Ecological Protection Specialist, Government of Saskatchewan.

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Footnote 328

Elm Care. 2007. Quality tree and shrub seeds. [online]. (accessed September, 2008).

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