Download or read book Waterfowl Nest sites and Nest Predation written by Barnet Warren Schranck and published by . This book was released on 1966 with total page 208 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 Sources of Variation in Waterfowl Nest Predation written by Karla L. Guyn and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nest loss is an important factor reducing the reproductive success of ground-nesting birds. However, it is unclear why certain nests hatch whereas others are destroyed by predators. Consequently, I performed experiments with conditioned taste aversion and measured characteristics of natural and simulated duck nests to evaluate clutch survival in relation to: i) avian and mammalian predation; ii) nest location (site, habitat, distance to edges); iii) time; iv) spatial dispersion of nests;and v) vegetative characteristics around nests. Previous studies have examined the efficacy of conditioned taste aversion (CTA) in reducing egg predation at site baited with eggs, but not at natural nests. Therefore, I evaluated whether CTA might be generalized, protecting eggs in natural nests of ducks in southcentral Saskatchewan. Consumption of eggs was monitored at baiting sites placed near nests of American crows and in locations likely to be frequented by mammals. During the treatment period, eg.

Download or read book From Individuals to Populations written by Joshua Timothy Ackerman and published by . This book was released on 2002 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Video Surveillance of Nesting Birds written by Christine Ann Ribic and published by Univ of California Press. This book was released on 2012-06-12 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Declining bird populations, especially those that breed in North American grasslands, have stimulated extensive research on factors that affect nest failure and reduced reproductive success. Until now, this research has been hampered by the difficulties inherent in observing nest activities. Video Surveillance of Nesting Birds highlights the use of miniature video cameras and recording equipment yielding new important and some unanticipated insights into breeding bird biology, including previously undocumented observations of hatching, incubation, fledging, diurnal and nocturnal activity patterns, predator identification, predator-prey interactions, and cause-specific rates of nest loss. This seminal contribution to bird reproductive biology uses tools capable of generating astonishing results with the potential for fresh insights into bird conservation, management, and theory.

Download or read book Habitat Fragmentation Striped Skunks and Waterfowl Nest Predation written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In North America, expansion of agriculture has resulted in the fragmentation of grasslands. Consequently, waterfowl populations have declined due to predation on nests. Predation on nests is an old evolutionary force affecting waterfowl, but the recent fragmentation of grasslands may have yielded a situation to which waterfowl are not yet adapted. In southcentral Saskatchewan, striped skunks are a major predator, and the interactions between fragmentation, striped skunks, and waterfowl are unknown, and were the major goal of my thesis. First, I examined the patterns of den site selection in striped skunks. Farmsteads are the most preferred habitat for den sites, and that within farmsteads, striped skunks denned under buildings. Alternatively, resting sites were preferably located in farmsteads and wetlands, whereas managed nesting areas, woodland, and cropland were avoided. When foraging within their home ranges, striped skunks preferred habitats such as wetland and woodland where their main food items, insects and small mammals, are most abundant. Cropland contained little food, and was strongly avoided. Use of specific habitats decreased with distance from the habitat edge, suggesting that large patches of nesting habitat may provide a refuge for ground nesting birds. Lastly, I performed a field experiment to assess the effects of nest density and nearest neighbours on nest predation. Density effects did not occur during the early breeding seasons of waterfowl (May 15-June 13), even across a 10-fold difference in nest density (2.5-25 nests/ha). However, density effects were significant in the late breeding season (June 15-July 14). Nearest neighbour effects were present at intermediate and high densities, but rarely observed at low density. Also, nearest neighbour effects occurred faster during the late breeding season, suggesting that striped skunks recognized and keyed on high-density nesting patches. This confirms that at current nest density (typically $

Download or read book Alternate Prey and Habitat Characteristics Affecting Waterfowl Nest Predation written by Robert L. Crabtree and published by . This book was released on 1984 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of Waterfowl Nesting on a Lake Erie Marsh written by Ralph Andrews and published by . This book was released on 1952 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Olfactory and Visual Predators on Nest Success and Nest site Selection of Waterfowl in North Dakota written by Jennifer Suzanne Borgo and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Selecting a nest site is an important decision for waterfowl. Because most nest failure is due to depredation, the primary selective pressure in choosing a nest site should be to reduce depredation risk. This task is difficult because predators use differing tactics to locate nests, such as olfactory or visual cues. I investigated several components of waterfowl nest-site selection and success on sites with shelterbelts (planted tree-rows) in North Dakota, during the 2006 and 2007 nesting seasons. I found that meteorological conditions impacted nest depredation; artificial nests were more likely to be depredated when either temperature or dew point was high. These meteorological conditions should improve foraging efficiency for olfactory predators by increasing odor concentration. Waterfowl selected nesting sites with greater visual concealment than random locations (lateral concealment). However, the only difference found between successful and depredated nests was lateral dispersion, an olfactory concealment characteristic. Nest density was higher in areas without shelterbelts than in areas near shelterbelts. Nest success for waterfowl decreased as shelterbelt height increased. Other shelterbelt characteristics, like porosity and orientation, did not affect nest success or nest density. Given that nest predators differ in foraging habitat, temporal patterns of activity, and searching modalities, nest site characteristics that conceal the nest from 1 predator species may increase its vulnerability to another predator. For instance, risk due to olfactory predators should be reduced near shelterbelts because locating nests would be more difficult as turbulence is generated by the shelterbelts. Concomitantly, shelterbelts could also increase the presence of visual predators, by providing nesting sites and vantage points. In my study, any benefits shelterbelts provide in reducing nest depredation by olfactory predators may have been offset by increasing nest depredation from visual predators. Hence nesting near shelterbelts was neither a liability nor a benefit to ducks.

Download or read book Factors Affecting Duck Nesting in the Aspen Parklands written by David William Howerter and published by . This book was released on 2003 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Habitat fragmentation often has been cited as a cause for reduced reproductive success of grassland-nesting birds, including ducks, though results of many studies have been equivocal. As remotely sensed habitat data become increasingly available, an increased understanding of how habitat configurations affect demographic parameters will allow wildlife managers to make better decisions about habitat preservation and restoration. We used duck (Anas spp.) nesting data from 15 65-km2 study areas (n=6300 nests) dispersed throughout the aspen (Populus tremuloides) parklands of south-central Canada, to test hypotheses and build models that predict hatching rates and nest-site distributions in relation to landscape features. We constructed separate models using landscape features generated at 3 different spatial extents and using 3 different habitat classification schemes. Generalized linear mixed-modeling techniques were used to model hatching rates, and logistic regression was used to discr.

Download or read book Grazing and Haying Effects on Habitats of Upland Nesting Birds written by Leo M. Kirsch and published by . This book was released on 1986 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Influence of Landscape Characteristics on Duck Nesting Success in the Missouri Coteau Region of North Dakota written by Scott Eugene Stephens and published by . This book was released on 2003 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Dummy Waterfowl Nest as an Index to Predation written by Don Ray Perkuchin and published by . This book was released on 1964 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dabbling Duck Recruitment in Relation to Habitat and Predators at Union Slough National Wildlife Refuge Iowa written by Joseph P. Fleskes and published by . This book was released on 1991 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nest Success of Dabbling Ducks in a Human modifield Prairie written by Jaime Enrique Jimenez and published by . This book was released on 1999 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nest Site Selection Patterns of Dabbling Ducks in Response to Variation in Predation Pressure written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nesting success is an important vital rate affecting the reproductive fitness of birds, and predation typically is the single most important factor affecting nesting success. Presumably, birds should nest in locations that maximize nest survival. If specific nest characteristics increase the probability that a nest will hatch, natural (phenotypic) selection could favour use of sites with these features, producing nonrandom patterns of nest site use. Alternatively, birds that are highly selective in nest site choices might be at a disadvantage if predators learn to forage preferentially in these locations and improve their efficiency in depredating nests; in this case, random nesting patterns could be favoured. Finally, it has been hypothesized that predation pressure can influence nest site selection patterns of entire bird communities. If predators develop a search image to hunt for bird nests, then nests that are most similar to each other, irrespective of species, should sustain higher mortality. To evaluate these hypotheses, I quantified nest site selection patterns of multiple species of ground-nesting dabbling ducks in areas where predation pressure was normally high, and compared these patterns to those on areas where predation was relaxed. Predation pressure was experimentally reduced by removing common predators of duck nests and females (mainly red foxes, coyotes, skunks and raccoons) on some study areas and not on others (controls). Predator removal and natural causes produced a 10-fold difference in duck nesting across study sites, allowing for investigation of effects of predation pressure on nest site selection of ducks. Coarse scale habitat selection patterns were similar to results reported in previous studies; blue-winged teal and northern shoveler were found more often in native grassland than in other habitat types, while gadwall and mallard nests occurred more frequently in shrub patches when compared with other habitat patches. A difference in n.

Download or read book Duck Productivity and Nest Predation in Southeastern Idaho written by Randall J. Gazda and published by . This book was released on 1994 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: