Hogan D.,Simon Fraser University |
Esler D.,Simon Fraser University |
Thompson J.E.,Ducks Unlimited Canada
Auk | Year: 2013
Molt is a metabolically demanding process in the annual cycle of birds, particularly for species that undergo simultaneous remigial molt because nutritional and energetic costs occur during a short period. Birds that molt remiges simultaneously utilize many different body-mass and foraging strategies to meet the nutritional and energetic costs of remigial molt, and documentation of interspecific variation has contributed to understanding species-specific risks associated with molt. However, little is known about intraspecific variation in body-mass and foraging strategies among birds that molt remiges simultaneously. We documented body-mass dynamics and foraging effort of Barrow's Goldeneyes (Bucephala islandica) during simultaneous remigial molt at two important postbreeding sites, including a large, hypereuthrophic lake and a small, mesotrophic lake in Alberta, to determine whether strategies for meeting nutritional costs of remigial molt varied across sites, years, and cohorts. Average body mass of all age and sex cohorts on both lakes increased during remigial molt in both 2009 and 2010. Birds were heavier on the smaller lake, and heavier in 2010 than in 2009, and adult males were heavier than subadult males. Radiomarked adult males exhibited similar foraging effort on each lake in each year (approximately 120-140 min day-1); however, birds foraged primarily diurnally on the large lake and nocturnally on the small lake. We conclude that Barrow's Goldeneyes exhibit considerable intraspecific variation in body-mass and foraging dynamics during remigial molt across sites, years, and cohorts, which suggests that these components of molt strategy are plastic and responsive to local environmental conditions. © 2013 by The American Ornithologists' Union. All rights reserved.
White L.,Canada Center for Mapping and Earth Observation |
Brisco B.,Canada Center for Mapping and Earth Observation |
Pregitzer M.,Canada Center for Mapping and Earth Observation |
Tedford B.,Ducks Unlimited Canada |
Boychuk L.,Ducks Unlimited Canada
Canadian Journal of Remote Sensing | Year: 2014
Abstract: Synthetic Aperture Radar (SAR) is well known for its ability to map surface water. There are a number of SAR satellites providing data for this application including the Canadian RADARSAT-2 system. RADARSAT-2 has a wide range of beam modes and some users may be intimidated by the variety of choices and have a difficult time deciding on the most appropriate beam mode. This technical note addresses some issues behind beam mode and polarization selection for surface water mapping with RADARSAT-2 and the upcoming RADARSAT Constellation Mission (RCM). This includes the impacts of resolution, wind effects, and the best mode for flooded vegetation detection. The results show that high resolution modes like the single polarized Spotlight are best for accurately delineating the surface water edge and small patches of flooded terrain. The addition of the cross-polarization available in other beam modes can provide useful surface water information in windy or rough surface conditions because there is little effect on the RADAR backscatter compared to the HH single polarization. For accurately delineating flooded vegetation, a polarimetric or compact polarimetric mode is best because the phase is maintained, which allows the user to apply polarimetric decompositions models to help separate the RADAR backscatter. © 2014, Copyright © Crown Copyright 2014.
Shook K.,University of Saskatchewan |
Pomeroy J.W.,University of Saskatchewan |
Spence C.,National Water Research Institute |
Boychuk L.,Ducks Unlimited Canada
Hydrological Processes | Year: 2013
The contributing areas of streams in the Prairie regions of Canada and the northern U.S. are dominated by complexes of wetlands which store and release water. Prior research has suggested the existence of hysteresis between the total volume of water stored in prairie wetlands within a drainage basin and the basin's contributing area. To simulate the relationship between storage and contributing area in a way that accounts for hysteresis, two wetland hydrology models with vastly different levels of complexity were devised. The fully distributed Wetland Digital Elevation Model (DEM) Ponding Model (WDPM) applies simple fluxes of runoff and evaporation to a DEM of a prairie wetland complex. The parameterized Pothole Cascade Model (PCM) applies simulated fluxes of water to collections of conceptual models of wetlands and is less demanding in computations and data. Prior research showed that both models produced hysteretic relationships between water storage and contributing area, but the PCM produced smaller estimates of contributing area than did the WDPM, likely due to its spatial simplification. Using sequential remote sensing observations of wetland area after snowmelt, this study shows that the frequency distribution of the open water areas of prairie wetlands is similar to that produced by the WDPM when the wetlands are close to being completely filled. The remotely sensed observations show evidence of hysteresis in the open water area frequency distributions, as predicted by the fully distributed WDPM. To enable the parameterized PCM to produce the same type of hysteretic relationships as the WDPM, scaling relationships between the maximum area of a wetland and the area of upland draining into it were included. The parameterized PCM is suitable for application with prairie snow redistribution, snowmelt, infiltration, runoff and evapotranspiration routines as part of semi-distributed hydrological modelling of prairie wetland basins such as that implemented in the Cold Regions Hydrological Model. © 2013 John Wiley & Sons, Ltd.
Brisco B.,Canada Center For Remote Sensing |
Li K.,CAS Institute of Remote Sensing Applications |
Tedford B.,Ducks Unlimited Canada |
Charbonneau F.,Canada Center For Remote Sensing |
And 2 more authors.
International Journal of Remote Sensing | Year: 2013
Polarimetric RADARSAT-2 data of rice and wetlands are used to simulate compact polarimetry (CP) mode data from the upcoming RADARSAT Constellation Mission (RCM). The simulated CP data are then used to evaluate the information content for rice and wetland mapping using supervised classification, and the results are compared for linear and circular polarization combinations and polarimetric decompositions from the fully polarimetric data and the simulated CP data. The results are consistent for both rice and wetlands and show that the classification accuracy increases as one goes up the polarization hierarchy. The circular polarizations produced the best classification results for the polarization combinations. This result requires further research to verify. Although the CP data did not perform as well as the fully polarimetric data, the results were better than for dual polarization, and this mode may offer the best option for rice and wetland mapping applications because of swath coverage. Note that both the compact simulations and the fully polarimetric data produced operationally suitable classification accuracies. Additional research is underway to evaluate the monitoring capability of this new CP mode. This article describes the approach used for the analyses and the classification results for both rice and wetlands. © 2013 Copyright 2013 Her Majesty the Queen in Right of Canada.
Lemaitre J.,Laval University |
Darveau M.,Ducks Unlimited Canada |
Zhao Q.,Laval University |
Fortin D.,Laval University
Biodiversity and Conservation | Year: 2012
The relative contributions of habitat structure and composition to biodiversity are often scale-dependent. Although bird communities in boreal forest have been largely altered and threatened by forest harvesting, bird habitat selection in this ecosystem has not been fully understood. Our study aimed to assess the relative contributions of habitat structure and composition on the assemblages of boreal birds at multiple spatial scales characterized by radii ranging from 100 to 1,000 m. We recorded bird species occurrence at 96 stations located in an old-growth forest in the Côte-Nord region of Québec, Canada. We characterized habitat structure using the proportion of dense, open, and sparse stands, and habitat composition using the proportions of coniferous, mixedwood, and deciduous stands. We used partial canonical correspondence analyses and hierarchical variance partitioning to assess the relative contribution of habitat structure and composition on bird assemblage, and logistic regression to model the probability of occurrence for individual species in response to habitat variables. Our results revealed that habitat structure and composition explained similar proportions of the variance in bird assemblage (21.7 vs. 21.6 %), regardless of spatial scale. Whilst logistic regression yielded fair predictions in the occurrence of individual species (i. e., area under the receiver-operating characteristic curve >0.70 for 90 % of the species), it further confirmed our findings in community level analysis. Our study indicates that habitat structure and composition are both important in shaping bird assemblages, but spatial scale draws little influence on their relative contributions. © 2012 Springer Science+Business Media B.V.
Costs of reproduction in breeding female mallards: Predation risk during incubation drives annual mortality [Coûts de la reproduction chez les canards colverts femelles: Le risque de prédation durant lincubation est une facteur déterminant de la mortalité annuelle]
Arnold T.W.,University of Minnesota |
Roche E.A.,University of Minnesota |
Roche E.A.,University of Tulsa |
Devries J.H.,Ducks Unlimited Canada |
Howerter D.W.,Ducks Unlimited Canada
Avian Conservation and Ecology | Year: 2012
The effort expended on reproduction may entail future costs, such as reduced survival or fecundity, and these costs can have an important influence on life-history optimization. For birds with precocial offspring, hypothesized costs of reproduction have typically emphasized nutritional and energetic investments in egg formation and incubation. We measured seasonal survival of 3856 radio-marked female Mallards (Anas platyrhynchos) from arrival on the breeding grounds through brood-rearing or cessation of breeding. There was a 2.5-fold direct increase in mortality risk associated with incubating nests in terrestrial habitats, whereas during brood-rearing when breeding females occupy aquatic habitats, mortality risk reached seasonal lows. Mortality risk also varied with calendar date and was highest during periods when large numbers of Mallards were nesting, suggesting that prey-switching behaviors by common predators may exacerbate risks to adults in all breeding stages. Although prior investments in egg laying and incubation affected mortality risk, most relationships were not consistent with the cost of reproduction hypothesis; birds with extensive prior investments in egg production or incubation typically survived better, suggesting that variation in individual quality drove both relationships. We conclude that for breeding female Mallards, the primary cost of reproduction is a fixed cost associated with placing oneself at risk to predators while incubating nests in terrestrial habitats. © 2012 by the author(s).
Barker N.K.S.,Laval University |
Cumming S.G.,Laval University |
Darveau M.,Ducks Unlimited Canada
Avian Conservation and Ecology | Year: 2014
Detailed knowledge of waterfowl abundance and distribution across Canada is lacking, which limits our ability to effectively conserve and manage their populations. We used 15 years of data from an aerial transect survey to model the abundance of 17 species or species groups of ducks within southern and boreal Canada. We included 78 climatic, hydrological, and landscape variables in Boosted Regression Tree models, allowing flexible response curves and multiway interactions among variables. We assessed predictive performance of the models using four metrics and calculated uncertainty as the coefficient of variation of predictions across 20 replicate models. Maps of predicted relative abundance were generated from resulting models, and they largely match spatial patterns evident in the transect data. We observed two main distribution patterns: a concentrated prairie-parkland distribution and a more dispersed pan-Canadian distribution. These patterns were congruent with the relative importance of predictor variables and model evaluation statistics among the two groups of distributions. Most species had a hydrological variable as the most important predictor, although the specific hydrological variable differed somewhat among species. In some cases, important variables had clear ecological interpretations, but in some instances, e.g., topographic roughness, they may simply reflect chance correlations between species distributions and environmental variables identified by the model-building process. Given the performance of our models, we suggest that the resulting prediction maps can be used in future research and to guide conservation activities, particularly within the bounds of the survey area. © 2014 by the author(s). Published here under license by the Resilience Alliance.
Bayley S.E.,University of Alberta |
Wong A.S.,University of Alberta |
Thompson J.E.,Ducks Unlimited Canada
Wetlands | Year: 2013
The ecoregions along the southern edge of the Boreal Plains have experienced rapid and extensive agricultural encroachment over the last 60 years. Over 200 wetlands and shallow lakes in central and northern Alberta and northeastern British Columbia, Canada were surveyed along an agricultural encroachment gradient to investigate the effect of land use on water quality between 2005 and 2007. Study wetlands were typically small (median 29.8 ha), shallow (median 0.8 m) and highly eutrophic (median 148 μgTP L-1). Wetlands in the southern Boreal Plains were regionally variable and dynamic. Drought in 2006 caused significant increases in TP, TN, chlorophyll a (chla), conductivity, silica and significant decreases in maximum depth and light penetration. Increased agricultural activity within a 1.6 km buffer surrounding wetlands enhanced nutrients but not chla concentrations or submersed aquatic vegetation (SAV) coverage. Wetlands with higher amounts of agriculture in the buffer zone tended to be shallower with decreased secchi depths. Due to shallow depths, SAV thrived even under hypereutrophic conditions with high agricultural encroachment in the buffer zone. Our study suggests that SAV has a significant role in maintaining clear water states in Boreal Transition Zone wetlands and shallow lakes through its ability to suppress concentrations of chla and TP. © 2012 The Author(s).
Hogan D.,Simon Fraser University |
Thompson J.E.,Ducks Unlimited Canada |
Esler D.,Simon Fraser University
Journal of Wildlife Management | Year: 2013
Postbreeding survival of waterfowl is rarely quantified, despite potential for constraints during this stage of the annual cycle that may subsequently affect population dynamics. We estimated survival of radio-marked adult male Barrow's goldeneyes (Bucephala islandica) during remigial molt and fall staging at Cardinal and Leddy Lakes in the Boreal Transition Zone of northwestern Alberta, Canada. Daily survival rate (DSR) was high during remigial molt (DSR = 0.9987, 95% CI: 0.9967-1.0000), corresponding to a 39-day period survival rate (PSR) of 0.95 (95% CI: 0.88-1.00). During fall staging, DSR was markedly lower (DSR = 0.9938, 95% CI: 0.9898-0.9978), corresponding to a PSR of 0.68 (95% CI: 0.53-0.87) over the 62-day period between the end of remigial molt and fall migration. Half of fall staging mortalities observed on Cardinal Lake were directly attributed to hunting. We conclude that remigial molt is a period with high survival in the annual cycle of Barrow's goldeneyes at our study sites. However, in light of low fall staging survival, Barrow's goldeneye harvest management strategies should be carefully evaluated with intent to reduce risk of localized high mortality at significant staging sites in western Canada. © 2013 The Wildlife Society.
Baschuk M.S.,University of Manitoba |
Koper N.,University of Manitoba |
Wrubleski D.A.,Ducks Unlimited Canada |
Goldsborough G.,University of Manitoba
Waterbirds | Year: 2012
To evaluate water-level manipulations as a management tool in boreal wetlands, marsh bird and waterfowl habitat use were studied in the Saskatchewan River Delta, Manitoba, Canada, during 2008 and 2009. Call-response and aerial surveys were used to estimate densities of marsh birds and waterfowl, respectively, within six wetland basins undergoing two different water-level treatments. Generalized linear models were used to determine relationships between presence and densities of birds to water depth, vegetation characteristics, and relative forage fish and invertebrate abundances at two spatial scales. American Bittern (Botaurus lentiginosus) and Piedbilled Grebe (Podilymbus podiceps) densities were positively influenced by water depth and relative fish abundance. American Coots (Fulica americana) and diver waterfowl (Aythya, Bucephala) also responded positively to increased water depth, whereas dabbler waterfowl (Anas, Aix) were negatively influenced by increasing water depth. Densities of Sora (Porzana Carolina) and Virginia Rail (Rallus limicola) were positively correlated with the relative abundances of invertebrates, but negatively correlated with relative fish abundance. Due to the high avian biodiversity in the region, managers should focus on providing a variety of wetland habitats. Using a combination of partial water-level drawdowns and high water, habitat for numerous avian species can be created simultaneously within wetland complexes.