Download or read book Modelling the Spatial and Temporal Variation in Density of Breeding Black Ducks at Landscape and Regional Levels written by Alan R. Hanson and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2001 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling the Spatial and Temporal Variation in Density of Breeding Black Ducks at Landscape and Regional Levels written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2001 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Identification and Synthetic Modeling of Factors Affecting American Black Duck Populations written by Michael James Conroy and published by . This book was released on 2002 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Distribution of the Black Duck written by Robert E. Stewart and published by . This book was released on 1958 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Behavioral Ecological Perspective on Density Dependence in Breeding Waterfowl written by Kevin Michael Ringelman and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Density-dependent population regulation is observed in many taxa, and understanding the mechanisms that generate density dependence is especially important for the conservation of heavily-managed species. In one such system, North American waterfowl, density dependence is often observed at continental scales, and nest predation has long been implicated as a key factor driving this pattern. However, despite extensive research on this topic, it remains unclear if and how nest density influences predation rates. Part of this confusion may have arisen because previous studies have examined density-dependent predation at relatively large spatial and temporal scales, and have failed to account for the effects of different types of predator behavior on nest success. I used observational and experimental field research and agent-based modeling to study the relationship between nest density and predation risk across a variety of spatial scales in a population of breeding dabbling ducks in the Suisun Marsh of California. In chapter 1, my coauthors and I replicated a predation experiment 10 years after the original study, using both natural and artificial nests, comparing a year when overall rates of nest predation were high (2000) to a year with moderate nest predation (2010). We found no evidence for density-dependent predation on artificial nests in either year, indicating that nest predation was not density-dependent at the spatial scale of our experimental replicates. Using nearest neighbor distances as a measure of nest dispersion, we also found little evidence for "dispersion-dependent" predation on artificial nests. However, when we tested for dispersion-dependent predation using natural nests, we found that nest survival increased with shorter nearest neighbor distances, and that neighboring nests were more likely to share the same nest fate than non-adjacent nests. Thus, at small spatial scales, density dependence appears to operate in the opposite direction as predicted: closer nearest neighbors are more likely to be successful. In chapter 2, we built on this exciting result, and more rigorously examined the relationship between local nest clustering and nest survival. Using three years of data, we used a local measure of spatial association (Ripley's L) to assess the degree of clustering across a continuum of spatial scales for each week of the nesting season. We found that the distribution of nests was consistently clustered at small spatial scales (~50 - 400 m), especially for Mallard nests, and that this pattern was robust to yearly variation in nest density and the intensity of predation. We then used modern logistic exposure techniques to examine how nest survival changed with nearest-neighbor distance. Similar to our findings in chapter 1, we demonstrated that local nest clustering had positive fitness consequences--nests with closer nearest neighbors were more likely to be successful. Thus, nest clustering appears to effectively dilute predation risk in our California study system, possibly because the primary nest predators (Striped Skunks, Mephitis mephitis and Raccoons, Procyon lotor) at our site are only incidental predators of duck nests. Nests appear to be adaptively clustered at our site in California, but this may not be true in other areas where predators behave differently; in fact, when predators respond strongly to prey density (e.g. through area-restricted search), the optimal strategy may be for birds to disperse their nests widely across the landscape. In chapter 3, I built an agent-based model in Netlogo designed to answer that qualitative question: are clustered nests more or less successful than dispersed nests, and how does that relative benefit vary depending on predator behavior? I modeled three types of waterfowl nest predators (to emulate the foraging behavior of skunks and foxes) that differ in their degree of spatial memory and their capacity for area-restricted search, foraging on different distributions of nests. As hypothesized, well-dispersed nests survived better with fox-like predators that performed area-restricted searches. On the other hand, clustered nests survived better when incidental skunk-like predators were present, but survival was dramatically reduced in the presence of foxes; thus, small changes in the predator community (e.g. introduction of foxes) without commensurate changes in nest clustering could have important effects on waterfowl populations. On simulated landscapes containing both clustered and dispersed nests and a mixed predator community, average nest success for clustered versus randomly placed nests was the same across possible predator mixes, but the variance in success for clustered nests was much higher; this suggests that there may be risk-reward tradeoffs when nesting near conspecifics. That said, the degree to which ducks can actually assess and respond to the presence of conspecifics is largely unknown, and it is believed that nest sites are selected based on habitat. Results from this model, combined with empirical data suggest that commonly-used management strategies that promote nest clustering, such as restoration of small parcels of habitat, can actually create ecological traps for nesting ducks, driven by predator behavior. In my final chapter, my coauthors and I used 15 years of nesting data to explore how spatial patterns of nest density and nest success shifted across the landscape through time. Specifically, we were interested in whether there were areas of consistently high or low predation risk, and whether we could detect win-stay, lose-switch dynamics (the tendency for successful birds to return to the same area, and unsuccessful birds to disperse to new areas) at a population level. We conducted a series of analyses at a variety of spatial scales, but, surprisingly, found no spatio-temporal correlation in predation risk, and no evidence for win-stay, lose-shift dynamics. We concluded that in our system, birds are not using prior experience to select nest sites because there is little year-to-year correlation in predation risk; hence, there is no advantage to win-stay, lose-shift. We suggest that in unpredictable environments, waterfowl may use current cues, such as the presence of conspecifics, to select nest sites. This spatially- and temporally-refined investigation into density-dependent nest predation in waterfowl has underscored the importance of understanding the individual-level processes that underlie population-level patterns. It seems clear that predator behavior can have important effects, not only on patterns of nest success, but on how waterfowl adaptively select nest sites and distribute themselves across the landscape. This research highlights the need to better understand the dynamic interplay between waterfowl habitat selection and nest predator foraging behavior. From a conservation perspective, it appears that density-dependent nest predation may occur at a smaller scale than previously examined, and may be positive or negative depending on the predator community. For maximum efficacy, management actions targeted at increasing nest success should be mindful of site-specific differences in predator communities.
Download or read book American Black Duck Breeding Habitat Enhancement in the Northeastern United States written by Ronald E. Kirby and published by . This book was released on 1988 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nesting Ecology and Population Genomics of American Black Ducks in North Carolina written by Daniel M. Lawson and published by . This book was released on 2020 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: North Carolina represents the southernmost extent of the American black duck's (Anas rubripes) breeding range; however, little is known about their breeding ecology in this region. I located and monitored 140 nesting black ducks over two years (2017-18) to assess nesting productivity and quantify nesting habitat within coastal North Carolina. Specifically, I quantified nest initiation, peak nesting dates, nest success rates, and causes of failure. I further assessed genetic integrity and population structure using high-throughput DNA sequencing methods and identified Anas platyrhynchos x A. rubripes hybrids using ADMIXTURE hybrid filial generation thresholds. Nests were found in brackish marshes (n = 105, 75%) within the Pamlico Sound, and on man-made dredge spoil-islands (n = 35, 25%) along the Outer Banks. The average nest initiation date over the study was April 16 with a peak nesting date of May 7. Apparent nest success rates varied from 31% (2017) to 63% (2018). Predation rates were 42% in 2017 and 28% in 2018. Nest predators included crows (Corvidae), raccoons (Procyon lotor), American mink (Neovison vison), and bald eagles (Haliaeetus leucocephalus).Using MCestimate, I found that the majority (73%) of variability in nest success was modeled best by nest location, vegetation density, maximum vegetation height, and elevation. Nesting black ducks selected high-marsh (NWI code E2EM1P) habitats where nests were located an average of 21.81 m from open water.at mean elevation of 1.36 m. In these habitats visual obstruction readings were 0.5 m with a maximum mean vegetation height of 0.81 m mainly consisting of grass (84.61%). Nesting density was 1 nest per 22 ha. Under the threat of sea level rise, identified selected nesting habitat will increase under the most liberal simulations, allowing for 42 more black duck nests with the study area. Results from my genetic analysis reveal that introgressive hybridization is occurring from the non-western game-farm mallard genome into this population of breeding black ducks. Breeding black duck management efforts in coastal North Carolina should focus on promoting selected nesting habitat, reducing nest predators, conserving lands for future marsh travel, and reducing game-farm mallard contact with black ducks.
Download or read book Ecology Abstracts written by and published by . This book was released on 1995 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coverage: 1982- current; updated: monthly. This database covers current ecology research across a wide range of disciplines, reflecting recent advances in light of growing evidence regarding global environmental change and destruction. Major ares of subject coverage include: Algae/lichens, Animals, Annelids, Aquatic ecosystems, Arachnids, Arid zones, Birds, Brackish water, Bryophytes/pteridophytes, Coastal ecosystems, Conifers, Conservation, Control, Crustaceans, Ecosyst em studies, Fungi, Grasses, Grasslands, High altitude environments, Human ecology, Insects, Legumes, Mammals, Management, Microorganisms, Molluscs, Nematodes, Paleo-ecology, Plants, Pollution studies, Reptiles, River basins, Soil, TAiga/tundra, Terrestrial ecosystems, Vertebrates, Wetlands, Woodlands.
Download or read book Factors Influencing the Density and Distribution of Breeding Waterfowl in North Central Montana written by Sean Patrick Fields and published by . This book was released on 2011 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Continental waterfowl population declines in the early 1980s led to the development and implementation of the North American Waterfowl Management Plan. The plan identified wetland and grassland losses in the Prairie Pothole Region (PPR) of Canada and the United States as the major causes of low continental duck populations. North-central Montana is the only remaining PPR area in the United States without a ground-based annual survey to monitor breeding duck populations and quantify breeding duck habitat. The purpose of this study was to establish an annual breeding duck survey in north-central Montana to 1) develop species-specific breeding pair predictive models, and 2) apply the models to estimate the density and distribution of breeding ducks and identify priority areas for conservation actions. 1969 indicated breeding duck pairs were observed on approximately 700 wetland basins in 2008 and 2009. A competing model analysis was used to identify local- and landscape-scale habitat characteristics to predict breeding duck pairs on wetland basins. The five most commonly observed species were modeled separately; those species were mallard (Anas platyrhynchos), northern pintails (A. acuta), gadwall (A. strepera), northern shoveler (A. clypeata) and blue-winged teal (A. discors). At the local scale, wetland basin area, the square root transformation of wetland basin area and wetland basin class were important predictors for all species. Northern pintail, gadwall and blue-winged teal exhibited a strong location effect, occurring more in the northern and eastern portions of the study area. At the landscape scale, the proportion of agricultural lands surrounding a sample basin was associated with the greater abundance of all species. Northern pintail and blue-winged teal breeding pair abundance increased when the proportion of seasonal and semipermanent basin wetland surface area in the landscape around sample basin decreased. Results from this study provide land managers with initial information on where breeding waterfowl are settling across the PPR landscape of north-central Montana. The continuation of this research for several more breeding seasons will enable conservation partners to efficiently target important breeding waterfowl habitat for conservation actions.
Download or read book Breeding Duck Populations and Habitat in Wisconsin written by James R. March and published by . This book was released on 1973 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Duck Breeding A Collection of Articles on Selection Crossing Feeding and Other Aspects of Breeding Ducks written by Various and published by Frazer Press. This book was released on 2011-03-01 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains classic material dating back to the 1900s and before. The content has been carefully selected for its interest and relevance to a modern audience.
Download or read book High Tide and an East Wind written by Bruce S. Wright and published by Harrisburg, Pa : Stackpole Company and the Wildlife Management Institute, Washington. This book was released on 1954 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wisconsin Breeding Duck Populations written by and published by . This book was released on 1985 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prairie Basin Wetlands of the Dakotas written by Harold A. Kantrud and published by . This book was released on 1989 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluations of Duck Habitat and Estimation of Duck Population Sizes with a Remote Sensing Based System written by Lewis M. Cowardin and published by . This book was released on 1995 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: During 1987-90, we used high-altitude photography, aerial videography, counts, and models to estimate sizes of breeding populations of dabbling ducks (Anatinae) and duck production and to identify duck habitat on U.S. Fish and Wildlife Service land and easements and on private land pothole region of the United States. in the prairie km2). Wetland area (ha per km2) The study area contained about 3.1 million wetland basins (28,490 was highest on service-owned land; wetland-basin density was greatest on service easements. Temporary and seasonal wetlands were underrepresented and lakes were overrepresented on service-owned land. Seventy-eight percent of all basins were less than 0.41 ha. Cropland dominated private land. Pond density decreased from 4.4/km2 in 1987 to 3.4/km2 in 1990 and pond area, from 7.2 ha/km2 to 2.7 ha/km2. The density of the blue-winged teal was greatest (3.4 pairs/km) and was followed in magnitude by those of the mallard (2.1 pairs/km2), the gadwall (1.8 pairs/km2), the northern pintail (0.8 pairs/km), and the redhead (0.8 pairs/km2). Duck density was consistently highest on service-owned land. The decline of breeding-population sizes in 1987-90 closely corresponded to losses of pond numbers and pond area. The density of breeding pairs per pond was inversely related to pond density, suggesting that breeding ducks tended to concentrate on the remaining ponds as drought intensified. The production of recruits followed the same pattern as breeding-population sizes. We estimated that 2.5% of the ducklings hatched on service-owned land, which was 1.3% of the study area; 19.6% hatched on service easements, which were 14.2% of the study area; and 77.9% hatched on private land, which was 84.6% of the study area.
