Introduction Seabird life history strategies are often characterised by high adult survival, delayed maturity at breeding, low clutch sizes and variable reproductive output (Schaffner 1990, Bowler et al. 2002, Hockey and Wilson 2003, Ramos et al. 2005). At low latitudes seabirds have small clutches, large eggs and long incubation and fledging periods (Hockey and Wilson 2003), and clutch size has been related to food availability and predation risk (Shea and Ricklefs 1996). Primary production in tropical marine ecosystems is generally considered to be low and seasonal, and food may be scarce, especially at oceanic islands (Hockey and Wilson 2003). Avian predators on small islands are generally few, but predators may be attracted to seabird eggs and chicks when large numbers of seabirds are breeding at high densities (Schaffner 1991, Hockey and Wilson 2003). Although most tropical islands are free of large indigenous mammalian predators, predation by smaller terrestrial predators like crabs and skinks occurs (Schaffner 1991, Ramos et al. 2005). Intra- and interspecific competition between breeding birds may also lower breeding success (Bowler et al. 2002, Ramos et al. 2005). Cousine Island is one of the smallest islands in the Seychelles archipelago. Seven tropical seabirds breed at the island; two of the least common are the White Tern Gygis alba and the White-tailed Tropicbird Phaethon lepturus. An estimated 1 000–1 500 pairs of White Terns and 450–850 pairs of White-tailed Tropicbirds breed on this island (Skerret et al. 2001). White Terns are tree-nesting birds that lay a single egg on an exposed fork or in an artificial structure, whereas White-tailed Tropicbirds are ground nesters that breed in a shady and sheltered crevice (Schaffner 1991, del Hoyo et al. 1996, Bowler and Pillay 2000). The incubation period of White Terns is 34–36 d (five weeks) and the nestling period 68 d (seven weeks), whereas the incubation period of the White-tailed Tropicbird is 40–42 d (six weeks) and the nestling period 77–85 d or 11–12 weeks (del Hoyo et al. 1996, Higgins and Davies 1996). Both species exhibit life-history traits specific to tropical island breeding. Each species has a clutch size of one and nesting success is generally low, from 30–50% for White-tailed Tropicbirds (Schaffner 1991, Ramos and Pacheco 2003) and 29–40% for White Terns (Vanderwerf 2003). The aim of this study was to compare the reproductive parameters of White Terns and White-tailed Tropicbirds on Cousine Island and investigate if egg or chick failures were associated with different stages of the incubation and nestling periods. The study also examined the associations between reproductive parameters and nest types (White Terns), the two monsoon seasons and nest reuse. We postulate reasons for observed differences in the measured parameters between the two species

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaf 213). Also available via World Wide Web.

Conservation efforts to increase duck production have led the United States Fish and Wildlife Service to restore grasslands with multi-species (3-5) mixtures of cool season vegetation often termed dense nesting cover (DNC). The effectiveness of DNC to increase duck production has been variable, and maintenance of the cover type is expensive. In an effort to decrease the costs of maintaining DNC and support a more diverse community of wildlife, restoration of multi-species (16-32) plantings of native plants has been explored. Understanding the mechanisms of nest site selection for nesting ducks within these plantings is important in estimating the efficiency of this cover at providing duck nesting habitat and determining appropriate management techniques. I investigated the vegetation characteristics between the 2 aforementioned cover types in the prairie pothole region of North Dakota, USA to see if native plantings provide the same vegetative structure to nesting hens as DNC. I also determined the nest density and nest success of upland nesting waterfowl in the cover types to determine if restored native plantings are providing the same nesting opportunity as DNC. Within each cover type I identified vegetation characteristics at nest sites of the 5 most common nesting species and compared them to random locations and within species to identify species specific factors in nest site selection. I located 3,524 nests (1,313 in restored-native vegetation and 2,211 in DNC) of 8 species in 2010-11. Native plantings had an average of 6.17 (SE = 1.61) nests/ha while DNC had an average of 6.71 (0.96) nests/ha. Nest densities were not different between cover types for the 5 most common nesting species. In 2010, nest success differed between cover types with restored-native plantings having 48.36% (SE = 2.4) and DNC having 42.43% (2.1) success. In 2011, restored-native planting success dropped considerably to 13.92% (1.7) while DNC success was similar to 2010 at 37.10% (1.7) The variability in nest success appeared to be impacted by late season success, as native plantings had similar success early in the nesting season, but much lower success later in the nesting season in both years. Vegetation data indicated no structural difference between cover types in 2010; however, a difference was detected during the late sampling period in 2011, with native plantings having shorter vegetation at random locations than DNC during this sampling period. In general ducks selected nest sites with greater leaf litter and denser, taller cover compared to random sites, however, vegetation density and height selection varied among species. Gadwall and mallards selected the tallest, densest vegetation, with northern pintail, blue-winged teal, and northern shovelers selecting vegetation of intermediate height and density. My results indicate native plantings are able to support similar densities of nests, but have great variability in nest success from year to year. In years with low nest success, native plantings may create an ecological sink as hens were not able to identify low quality patches and nested in similar densities despite lower success.

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No description available.

Grassland bird species are declining more quickly than any other avian group within North America, possibly due in part to declines in nesting success. In 2009-2010, I monitored nests of five songbird species in southwestern Saskatchewan. Two 300-m² plots were located in each of 12 pastures, three of which were ungrazed controls. The remaining pastures had stocking rates ranging from 0.23 – 0.83 AUM/ha, which were grazed for 2-3 or >15 years. Stocking rate affected nest site selection by three species, suggesting that some pastures have a greater availability of nest sites than others. Logistic exposure nesting success models suggested a nonlinear effect of stocking rate on nesting success of Sprague’s Pipit in 2009. The nesting success of two species was negatively correlated with grazing duration in 2009 and 2010, respectively. To encompass the different habitat needs of each species, I suggest maintaining rangeland landscapes with a range of grazing treatments.

Since the 1970s, artificially stabilized hydrology, increased presence of Common Carp (Cyprinus carpio), and invasion by a highly competitive cattail hybrid (Typha x glauca) have changed the nesting ecology of Western Grebes at Delta Marsh, Manitoba. To evaluate the impact of stressors within Delta Marsh on Western Grebes, I repeated surveys originally conducted by Nuechterlein (1975) on the nesting ecology of Western Grebes at Delta Marsh, and compared 2009/2010 breeding success and nesting ecology data with 1973/1974 data. Reductions in breeding success during 2009 and 2010 were primarily due to increases in rates of nesting losses from wave action. Nests destroyed by spawning Common Carp, and depredations by River Otters (Lontra canadensis) further contributed to nesting losses. Reestablishing stands of emergent bulrush around nesting islands and reducing the abundance of carp within the marsh might help return Western Grebe breeding success to rates recorded in the 1970s

Grassland bird species are declining more quickly than any other avian group within North America, possibly due in part to declines in nesting success. In 2009-2010, I monitored nests of five songbird species in southwestern Saskatchewan. Two 300-m² plots were located in each of 12 pastures, three of which were ungrazed controls. The remaining pastures had stocking rates ranging from 0.23 – 0.83 AUM/ha, which were grazed for 2-3 or >15 years. Stocking rate affected nest site selection by three species, suggesting that some pastures have a greater availability of nest sites than others. Logistic exposure nesting success models suggested a nonlinear effect of stocking rate on nesting success of Sprague’s Pipit in 2009. The nesting success of two species was negatively correlated with grazing duration in 2009 and 2010, respectively. To encompass the different habitat needs of each species, I suggest maintaining rangeland landscapes with a range of grazing treatments.

Since the 1970s, artificially stabilized hydrology, increased presence of Common Carp (Cyprinus carpio), and invasion by a highly competitive cattail hybrid (Typha x glauca) have changed the nesting ecology of Western Grebes at Delta Marsh, Manitoba. To evaluate the impact of stressors within Delta Marsh on Western Grebes, I repeated surveys originally conducted by Nuechterlein (1975) on the nesting ecology of Western Grebes at Delta Marsh, and compared 2009/2010 breeding success and nesting ecology data with 1973/1974 data. Reductions in breeding success during 2009 and 2010 were primarily due to increases in rates of nesting losses from wave action. Nests destroyed by spawning Common Carp, and depredations by River Otters (Lontra canadensis) further contributed to nesting losses. Reestablishing stands of emergent bulrush around nesting islands and reducing the abundance of carp within the marsh might help return Western Grebe breeding success to rates recorded in the 1970s

Thesis (M.S.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references (leaves 92-96). Also available on the World Wide Web.