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.
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.
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.