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SpATS Related Studies 
In conjunction with the SpATS research, other Ducks Unlimited Canada (DUC) studies are being conducted in the Prairie Pothole Region (PPR). This allows different studies to share resources, making research much more cost-effective.
To date, several additional studies have been undertaken. In 2003, chemical fallow fields were evaluated as duck nesting habitat in southwestern Saskatchewan. In 2004, the relationships between duck nesting and cattle grazing in southeastern Saskatchewan were examined. Between 2004-2009 a double-observer technique for enumerating pair densities was evaluated. In 2007-2009 landscape factors influencing shorebird nest-site selection and nesting success were examined in cooperation with a two-year Master’s project. In 2011 northern pintail duckling survival was examined thanks to generous funding provided by Bayer Crop Science.
SpATS has also cooperated with DUC research addressing the roles of wetlands and agriculture in mitigating climate change, with a Bird Studies Canada initiative to develop a Marsh Bird Monitoring Program for the Prairie Habitat Joint Venture (PHJV), and by evaluating a standardized brood survey protocol in conjunction with the PHJV and Prairie Pothole Joint Venture.
Chemical Fallow Study
Background
In agriculture, summerfallow is when a crop/field is left unplanted for a year. This is sometimes used as a part of annual crop rotations. Summerfallow may help to manage weeds and nutrients, and save moisture for the following crop year.
Traditionally, summerfallow is tilled (plowed), which is called tillage-fallow (TF). However, nest destruction during tillage is high. Chemical fallow (CF) involves using herbicides only, or a combination of herbicides and late tillage. Using CF instead of TF may decrease nest destruction.
This would increase nesting success for waterfowl species such as the northern pintail, a species of special concern.
The study objectives were to determine waterfowl nesting success and nest density in CF fields versus other habitat types, primarily other cropland stubble types (i.e., spring-seeded crop fields and tillage-fallow).
Study Area and Methods
The study was conducted in conjunction with the 2003 SpATS study area in southwestern Saskatchewan. Nest searching techniques were used, following SpATS protocol. Nest-searched fields included all available crop stubble on each SpATS focal quarter.
Results and Discussion
The study’s initial results suggest that replacing TF with CF may increase duck productivity. Both overall nesting success and nest density were higher in CF fields compared to TF fields.
Nesting success in CF fields also was higher than in spring-seeded stubble. More nests in CF fields hatched after June 20 (the date after which we indicated farmers could till these fields) than before. Therefore, delaying tillage may result in higher numbers of hatched nests.
The results presented here are from one year of data only. Further, it must be noted, that CF uses herbicides to control weed growth. Glyphosate is the herbicide of choice on the Prairies, and although it is typically regarded as relatively “safe”, little research has been conducted on potential impacts in wetland ecosystems.
A potential ongoing problem for nesting hens is that much of the crop stubble they encounter each spring will be seeded shortly after they begin nesting. Fall planted cereal crops (fall rye, winter wheat) have been shown to be productive waterfowl nesting habitat, while offering good financial returns for farmers. To reduce nest loss caused by spring-seeding, the planting of fall cereals is recommended.
Grazing Study
Background
Cattle can have an effect on waterfowl nesting habitat. Cattle in a pasture may decrease the area’s suitability for upland nesting waterfowl. As grazers, cattle naturally feed on the same plants that waterfowl use for nesting cover. Having lots of cattle in an area, such as a pasture, may impact its suitability for waterfowl nesting.
Heavy grazing can also negatively impact brood and duckling survival. It can decrease the quantity and quality of brood-rearing wetland habitat.
However, there is some evidence that nesting success is increased under moderate grazing. Wetland habitat, too, may be improved under moderate grazing by ‘opening up’ thick stands of vegetation.
The grazing study objectives were to:
- Evaluate relationships among nesting success, grazing and grassland type; and
- Evaluate relationships between nest-site selection and grazing.
Study Area and Methods
The grazing study was conducted in conjunction with the 2004 SpATS study area in southeastern Saskatchewan. Grazed lands in and surrounding the SpATS study sites were sorted according to grass type (tame or native/naturalized) and range health.
An experienced range agrologist selected pastures to be included in the study. The target was to have 50 per cent of the selected pastures with moderate grazing pressure and 50 per cent with heavy grazing pressure. Pastures with light or no grazing pressure were evaluated as part of normal SpATS protocols.
Methods used on the grazing study followed SpATS protocol, with additional data being collected to account for the effects of grazing. For example, the presence/absence of cattle was recorded and additional vegetation measurements were taken.
Results and Discussion
A total of 50 waterfowl nests were found during the study with the majority of nests being blue-winged teal (30), mallard (8) and gadwall (5).
Pastures with abundant standing vegetation were much more attractive (i.e., nest densities were highest) to nesting ducks than pastures where heavy grazing removed most of the vegetative biomass. In contrast, nesting success was highest in pastures with less vegetation.
Successful habitat management requires creating habitat types that satisfy the dual objectives of being attractive to nesting ducks and affording high nesting success. In the pastures we studied, these attributes seem to be at odds—the most attractive pastures were the ones with the lowest nesting success.
When we examined the product of nest density and nesting success (hatched nests/unit area) we observed the highest productivity in pastures with moderate amounts of vegetative standing biomass.
We observed no relationship between Range Health (i.e., community structure, hydrologic function, nutrient cycling, site stability, etc.) and nesting success.
While our results may suggest that management should target grazing regimes that retain moderate amounts of vegetation and that Range Health is unimportant, it is important to remember that this study represents a single group of sites observed for a single year, and that sample sizes were modest (southeastern Saskatchewan was in drought at the onset of the study). The general pattern, though, of increased nest densities with increased vegetation and the converse for nesting success is consistent with other research.
Analysis of additional information collected by SpATS from 2002-2009 is complete; write-up is currently underway. This information will be useful to confirm or refute these findings.
Double-Observer Study
Background
The use of indices to estimate abundance is coming under increasing scrutiny and criticism in the wildlife literature. Precise estimates of breeding populations of ducks are fundamental to many aspects of ecological study and management.
Current techniques to estimate resident populations of breeding ducks assume that the likelihood of seeing a duck (detection probability) remains constant among survey dates and locations. However, various factors may influence detection probabilities. Furthermore, current techniques are indices that provide no estimate of precision, and the timing of standard counts is somewhat ambiguous because social groups vary throughout the course of a single day as females leave their mates to perform nesting activities.
A potential solution is a double-observer technique where two observers, working in tandem, independently survey each wetland. This approach allows the estimation of detection probability, how detection probabilities vary with a number of variables, breeding population, and a measure of precision for the breeding population estimate. This approach does not provide an improvement to the ambiguity associated with varying social groups; however, it may be possible to minimize that ambiguity by conducting pair surveys when females are more likely to be with their mates (i.e., in the afternoon).
The double-observer study objectives were to:
- Determine if a double-observer survey is logistically feasible for duck counts, and to develop protocols
- Determine if all birds are counted and if detection probability varied by
- observer
- wind speed
- study site
- duck species
- Determine if breeding population estimates derived from standard counts fall within the range derived from double-observer counts
- Determine if counts conducted late in the day reduced the proportion of males seen alone or in small groups, thereby reducing ambiguity.
Study Area and Methods
During the 2004 field season, we performed a test of the double-observer technique at the SpATS study area in southeastern Saskatchewan.
Counts were performed on 3 different study sites within 3 days of standard pair counts, during the afternoon/evening. At each wetland, one observer surveyed each wetland using the same protocols as our standard counts while the second observer waited out-of sight. When the first observer finished surveying a pond the second observer would begin, again following standard protocols. At some large ponds with many pairs of ducks, both observers conducted the surveys simultaneously to reduce flushing birds. Following the survey, counts were reconciled to determine birds that were counted or not counted by both observers.
Results and Discussion
Despite relatively high detection probabilities and no evidence of investigator, weather or study site differences in detection, estimates of abundance differed substantially from those derived using standard count protocols. We did find evidence that detection probability differed among species, and that double-observer counts conducted in the afternoon resulted in proportionally fewer indicated breeding pairs resulting from males alone or in small groups.
Both observers in this preliminary test were very experienced. Observer effects may be more pronounced for a typical field crew with varying degrees of experience identifying waterfowl. The counts were conducted under generally windy conditions (Beaufort scale 4-6). It is possible that counts performed under a broader range of wind conditions might have resulted in a “wind effect” on detection probability. We did find evidence for differences in detection probability among green-winged teal (more were missed than any other species), but detection probabilities for other species were uniformly high. Additional testing over a broader geographic range may also be warranted.
The timing of double-observer counts may have contributed to discrepancies from standard counts. A high degree of movement by migrating/resident pairs may also have caused the discrepancies. Or, differences may have been simply error resulting from relatively small sample sizes.
A double-observer technique for counting ducks appears to be a logistically feasible method for estimating duck breeding populations. However, enough uncertainty remains about the results that the study was extended through the 2005 and 2006 field seasons on a subsample of 2 quarter-sections at each SpATS site. A slightly modified double-observer technique, where both observers conducted the surveys simultaneously at all ponds, was tested in 2007 - 2009. Analysis is underway.
Shorebird Study
Background
Forty-seven species of shorebirds breed or migrate through the Canadian Prairies.
Shorebirds are experiencing worldwide declines. Reasons for these losses are complex and relatively unexplored, but include habitat fragmentation and loss. These are similar to threats facing duck populations.
Currently, efforts are underway to develop conservation plans for prairie-breeding shorebirds. Gaining a better understanding of factors affecting productivity has been identified as a priority conservation action.
The study will be a spatial analysis of factors affecting the nesting ecology of 4 shorebird species (long-billed curlew, marbled godwit, upland sandpiper, and willet) in the Canadian prairie-parklands.
The shorebird study objectives are to:
- Determine the patterns of nesting success for 4 species of upland nesting shorebirds
- Determine patterns of nest-site selection for these species using patterns of nesting success.
- Evaluate the hypothesis that nesting success is highest in areas where measures of habitat fragmentation are lowest.
- Recommend future conservation actions.
Study Area and Methods
The shorebird study was conducted in conjunction with the 2007 - 2009 SpATS study areas in Alberta, Saskatchewan and Manitoba. Additional data was available from the Pintail Project where shorebird nests encountered during 2005 to 2007 were monitored. Methods used on the shorebird study followed SpATS protocol with additional data being collected as needed. Incubation was determined by floating eggs.
Results and Discussion
A total of 69 shorebird nests (long-billed curlew [0], marbled godwit [4], upland sandpiper [37], and willet [28]) were found at SpATS study sites during 2007, and 30 shorebird nests were monitored during 2008 (long-billed curlew [0], marbled godwit [1], upland sandpiper [25], and willet [4]). Preliminary analysis indicates 49% and 34% of nests hatched in 2007 and 2008, respectively.
Analysis and write-up is complete. For additional information see: Garvey, M. E. 2011. A spatial analysis of factors affecting the nesting ecology of shorebirds in the Canadian Praire-Parklands. Thesis, Trent University, Peterborough, Ontario, Canada.
Disclaimer:
SpATS data presented on this Web site cannot be used without written permission from the authors.
