scholarly journals Demography of Bell's Vireos in Missouri Grassland-Shrub Habitats

The Auk ◽  
2000 ◽  
Vol 117 (4) ◽  
pp. 925-935 ◽  
Author(s):  
Joel M. Budnik ◽  
Mark R. Ryan ◽  
Frank R. Thompson III
Keyword(s):  
Nest Predation ◽  
Molothrus Ater ◽  
Nesting Success ◽  
Growth Potential ◽  
Population Declines ◽  
Annual Survival ◽  
Rate Of Increase ◽  
Study Population ◽  
Breeding Seasons ◽  
Seasonal Fecundity

Abstract Numbers of Bell's Vireos (Vireo bellii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80 territories per 10 ha at the first site and increased from 1.11 to 1.33 at the second site during the study. Mean nesting success was 31 ± SE of 0.03% overall and ranged from 13 to 42% among years and study areas; 57% of the pairs fledged at least one young. Low annual production was a function of high rates of nest predation (41% of all nests observed, accounting for 44 to 78% of daily nest mortality annually) and nest parasitism by Brown-headed Cowbirds (Molothrus ater; 29% of nests observed, 17 to 37% of daily nest mortality annually). Mean seasonal fecundity was 1.60 young fledged per pair per year (range 1.00 to 1.79). Annual survival of adults was 61 ± 0.04% and was higher than previously reported. We used our estimates of seasonal fecundity and annual survival of adults to determine the finite rate of increase (λ) for our study population. Our study areas seemingly comprised sink habitats (λ = 0.85). Thus, the vireos on our study areas likely were limited by low reproductive success. Population declines also may be caused by habitat loss, which highlights the need for investigation of historical and current rates of loss of grassland-shrub habitat.

scholarly journals Anti-parasite treatment removes negative effects of environmental pollutants on reproduction in an Arctic seabird

2006 ◽  
Vol 273 (1605) ◽  
pp. 3117-3122 ◽  
Author(s):  
Jan O Bustnes ◽  
Kjell E Erikstad ◽  
Sveinn A Hanssen ◽  
Torkild Tveraa ◽  
Ivar Folstad ◽  
...  
Keyword(s):  
Polychlorinated Biphenyl ◽  
Environmental Pollutants ◽  
Natural Populations ◽  
Nesting Success ◽  
Return Rate ◽  
Negative Effects ◽  
Anthropogenic Pollutants ◽  
Study Population ◽  
Breeding Seasons ◽  
Reproductive Consequences

Recent studies have shown that the detrimental effects of anthropogenic pollutants may be worse if organisms are exposed to natural stress. In this study, we examined whether negative effects of organochlorines (OCs) could be influenced by parasites. In two breeding seasons, we administered an anti-helminthic drug to groups of breeding glaucous gulls ( Larus hyperboreus ), whereas control groups were placebo treated. In all birds, blood residues of the most important OCs in the study population (hexachlorobenzene, oxychlordane, p , p ′-dichlorodiphenyldichloroethylene and polychlorinated biphenyl), were measured. The relationships between OCs and fitness components (i.e. nesting success and return rate between breeding seasons) were then compared between the birds receiving anti-parasite treatment and the controls. Among untreated males, higher blood residues of OCs were associated with lowered nesting success, while in males receiving anti-parasite treatment, there was no detrimental effect of OCs on fitness. Return rate was not affected by treatment or OCs. Our findings suggest that parasites may be an important factor in triggering reproductive effects of such pollutants, and that relatively low levels of OCs may have serious reproductive consequences in natural populations when stress from other sources is high.

scholarly journals Reproduction of the Atlantic Forest endemic star-throated antwren, Rhopias gularis (Aves: Thamnophilidae)

2016 ◽  
Vol 77 (2) ◽  
pp. 356-360 ◽  
Author(s):  
D. F. Perrella ◽  
C. H. Biagolini Junior ◽  
L. Ribeiro-Silva ◽  
P. V. Q. Zima ◽  
M. R. Francisco
Keyword(s):  
Atlantic Forest ◽  
Nest Predation ◽  
Nesting Success ◽  
Southeastern Brazil ◽  
Breeding Phenology ◽  
Nestling Provisioning ◽  
Comprehensive Information ◽  
Males And Females ◽  
Breeding Seasons ◽  
Small Clutch

Abstract The Thamnophilidae are one of the most speciose Neotropical bird families, yet aspects of their natural history remain poorly documented. Here we provide information on breeding phenology, the length of incubation and nestling periods, parental care, and nesting success of the Star-throated Antwren, Rhopias gularis, an Atlantic Forest endemic. The data are discussed in light of life history theories. We found 27 active nests during two breeding seasons (2013/2014 and 2014/2015) at Carlos Botelho State Park in southeastern Brazil. Nesting activities were observed from September to January. Incubation and nestling periods lasted 16.8 ± 0.6 and 11.0 ± 0.86 days, respectively, as with most other antbirds. Males and females shared equally in incubation and nestling provisioning. The small clutch size of two eggs is that most commonly found in tropical birds and is hypothesized to have evolved due to increased nest predation rates. However, our data was not consistent with this hypothesis as the nest survival probability was high (57%). This is one of only a handful of studies that provide comprehensive information on the breeding biology of a Thamnophilid species in undisturbed habitat.

scholarly journals A multiscale assessment of Red-tailed Hawk reproductive success relative to urban density and habitat type

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Justin H White ◽  
Jessi L Brown ◽  
Zachary E Ormsby
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Habitat Type ◽  
Nesting Success ◽  
Arid Environments ◽  
Hatch Date ◽  
Urban Density ◽  
Landscape Characteristics ◽  
Suburban Areas ◽  
Breeding Seasons

Abstract Despite the unique threats to wildlife in urban areas, many raptors have established successfully reproducing urban populations. To identify variations in raptor breeding ecology within an urban area, we compared metrics of Red-tailed Hawk reproductive attempts to landscape characteristics in Reno and Sparks, NV, USA during the 2015 and 2016 breeding seasons. We used the Apparent Nesting Success and logistic exposure methods to measure nesting success of the Red-tailed Hawks. We used generalized linear models to relate nesting success and fledge rate to habitat type, productivity to hatch date (Julian day) and hatch date to urban density. Nesting success was 86% and 83% for the respective years. Nesting success increased in grassland-agricultural and shrub habitats and decreased in riparian habitat within the urban landscape. Productivity was 2.23 and 2.03 per nest for the breeding seasons. Fledge rates were 72% and 77%, respectively, and decreased in riparian areas. Nestlings hatched earlier with increased urban density and earliest in suburban areas, following a negative quadratic curve. Nesting success and productivity for this population were high relative to others in North America. Productivity increased in habitats where ground prey was more accessible. We suggest that suburban areas, if not frequently disturbed, provide sufficient resources to sustain Red-tailed Hawks over extended periods. As urban expansion continues in arid environments globally, we stress that researchers monitor reproductive output across the urban predator guild to elucidate patterns in population dynamics and adaptation.

scholarly journals Influence of Temperature on Age-Stage, Two-Sex Life Tables for a Minnesota-Acclimated Population of the Brown Marmorated Stink Bug (Halyomorpha halys)

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 108 ◽  
Author(s):  
Byju N. Govindan ◽  
William D. Hutchison
Keyword(s):  
Population Growth ◽  
Life Table ◽  
Growth Potential ◽  
Intrinsic Rate Of Increase ◽  
Halyomorpha Halys ◽  
Brown Marmorated Stink Bug ◽  
Stink Bug ◽  
Current Limit ◽  
Rate Of Increase ◽  
Survival And Reproduction

Temperature is a critical single factor influencing insect population dynamics, and is foundational for improving our understanding of the phenology of invasive species adapting to new agroecosystems or in the process of range expansion. An age-stage, two-sex life table was therefore developed to analyze fundamental demographic features such as development, survival, and reproduction of a Minnesota-acclimated population of the invasive brown marmorated stink bug (Halyomorpha halys), in the north central USA. All salient life history parameters were estimated to better understand the population growth potential of H. halys at the current limit of its northern range in North America. We examined the effect of selected constant temperatures on immature development and survival (15–39 °C), adult reproduction and longevity (17–36 °C) of H. halys in the laboratory. The Minnesota population developed faster and survived at higher rates relative to a population that had previously established in Pennsylvania, USA. Mean generation time for the Minnesota population was minimized at 30 °C, while survival and fecundity were maximized at 27 and 23 °C, respectively. Given these findings, we assessed the effect of temperature on the intrinsic rate of increase ( r m ), the life table parameter that integrates the effects of temperature on development, survival, and reproduction. A Ratkowsky model predicted r m was maximized (0.0899) at 27.5 °C. We discuss the implications of our findings for understanding population growth rates for H. halys in the context of a warming climate, and potential to emerge as a serious crop pest in the Midwest U.S. region.

Annual Productivity and Its Measurement in a Multi-Brooded Passerine, the Eastern Bluebird

The Auk ◽  
1979 ◽  
Vol 96 (3) ◽  
pp. 562-572
Author(s):  
Benedict C. Pinkowski
Keyword(s):  
Success Rate ◽  
Age Groups ◽  
Nesting Success ◽  
Egg Laying ◽  
Success Rates ◽  
Sialia Sialis ◽  
Eastern Bluebird ◽  
Annual Productivity ◽  
Eastern Bluebirds ◽  
Breeding Seasons

Abstract Breeding and demographic parameters are examined for 434 Eastern Bluebirds (Sialia sialis) attempting 324 nests in southeastern Michigan during 1968-1977. Nesting birds spent an average of 10.4 weeks (63.9% of a 16.2-week season) in the study area. Only 154 (35.5%) of the nesting birds remained for entire breeding seasons; these season-long residents averaged 2.14 nests/season and had a higher success rate (68.4%) and presumably greater productivity (5.6 young · pair−1 · season −1) than other birds because site fidelity depends on nesting success. Although two seasonal peaks for egg-laying were observed, only 75 of 357 birds (21.0%) successfully raised two broods. Evidence is presented to suggest that birds observed for only part of a season initiated nests at the same rate while in and not in the study area, so that an average annual productivity value of 5.0 young · pair−1 · season −1 is calculated for all nesting birds from the observed success rate (57.1%) and mean length of stay in the area. Estimated average productivity of yearlings (4.3 young · pair−1 · season −1) was lower than that of adults (5.7 young · pair−1 · season −1) although nesting success rates were similar in the two age groups.

Australian fur seals at Seal Rocks, Victoria: pup abundance by mark - recapture estimation shows continued increase

2000 ◽  
Vol 27 (6) ◽  
pp. 629 ◽  
Author(s):  
P. D. Shaughnessy ◽  
S. K. Troy ◽  
R. Kirkwood ◽  
A. O. Nicholls
Keyword(s):  
Confidence Intervals ◽  
Arithmetic Mean ◽  
Rapid Rate ◽  
Exponential Rate ◽  
Guard Hair ◽  
Mark Recapture ◽  
Fur Seals ◽  
Fur Seal ◽  
Rate Of Increase ◽  
Breeding Seasons

The abundance of Australian fur seal pups was determined at Seal Rocks, Westernport, Victoria in late December 1997 using a mark–recapture procedure with repeated recapture sessions. Pups (n = 1291) were marked by clipping the black guard hair on the head to reveal lighter underfur. Recaptures from the whole colony were made on eight occasions 1–3 days later. In the recapture sessions, a mean of 32% of sighted pups had been marked. Estimates of pup numbers over the eight recapture sessions were calculated using the Petersen estimate and then combined by taking their arithmetic mean. The combined estimate was 4024 (95% confidence range 3908–4141). In 1991–92, a similar procedure led to an estimate of pup numbers of 2817 (95% confidence range 2703–2930). For both breeding seasons, estimates of pup numbers from each recapture session were also combined assuming a joint hypergeometric distribution; there was little difference in the results from the two procedures, although the confidence intervals for the hypergeometric mean were smaller than those for the arithmetic mean. From 1991–92 to 1997–98, pup numbers increased by 43%, at an exponential rate of 0.059 (95% confidence range 0.0526–0.0664), equivalent to 6.1% per annum (5.4–6.9%). This is greater than the rate of increase of pups at the colony between 1968–69 and 1991–92, which was 0.023 (95% confidence range 0.0198–0.0268), equivalent to 2.4% per annum (2.0–2.7%). Because of the rapid rate of increase of the Australian fur seal colony at Seal Rocks and the importance of the locality for tourism, we recommend that the abundance of pups there be determined every 3–5 years using a mark–recapture technique.

60-Day Aging Requirement Does Not Ensure Safety of Surface-Mold-Ripened Soft Cheeses Manufactured from Raw or Pasteurized Milk When Listeria monocytogenes Is Introduced as a Postprocessing Contaminant

2008 ◽  
Vol 71 (8) ◽  
pp. 1563-1571 ◽  
Author(s):  
DENNIS J. D'AMICO ◽  
MARC J. DRUART ◽  
CATHERINE W. DONNELLY
Keyword(s):  
Listeria Monocytogenes ◽  
Control Strategies ◽  
Raw Milk ◽  
Growth Potential ◽  
Initial Population ◽  
Population Declines ◽  
Pasteurized Milk ◽  
Holding Period ◽  
High Level ◽  
Similar Growth

Because of renewed interest in specialty cheeses, artisan and farmstead producers are manufacturing surface-mold-ripened soft cheeses from raw milk, using the 60-day holding standard (21 CFR 133.182) to achieve safety. This study compared the growth potential of Listeria monocytogenes on cheeses manufactured from raw or pasteurized milk and held for >60 days at 4°C. Final cheeses were within federal standards of identity for soft ripened cheese, with low moisture targets to facilitate the holding period. Wheels were surface inoculated with a five-strain cocktail of L. monocytogenes at approximately 0.2 CFU/cm2 (low level) or 2 CFU/cm2 (high level), ripened, wrapped, and held at 4°C. Listeria populations began to increase by day 28 for all treatments after initial population declines. From the low initial inoculation level, populations in raw and pasteurized milk cheese reached maximums of 2.96 ± 2.79 and 2.33 ± 2.10 log CFU/g, respectively, after 60 days of holding. Similar growth was observed in cheese inoculated at high levels, where populations reached 4.55 ± 4.33 and 5.29 ± 5.11 log CFU/g for raw and pasteurized milk cheeses, respectively. No significant differences (P < 0.05) were observed in pH development, growth rate, or population levels between cheeses made from the different milk types. Independent of the milk type, cheeses held for 60 days supported growth from very low initial levels of L. monocytogenes introduced as a postprocess contaminant. The safety of cheeses of this type must be achieved through control strategies other than aging, and thus revision of current federal regulations is warranted.

scholarly journals Defending against disparate marine turtle nest predators: nesting success benefits from eradicating invasive feral swine and caging nests from raccoons

Oryx ◽  
2014 ◽  
Vol 50 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Richard M. Engeman ◽  
David Addison ◽  
J.C. Griffin
Keyword(s):  
Nest Predation ◽  
Sus Scrofa ◽  
Nesting Success ◽  
Marine Turtle ◽  
Financial Cost ◽  
Feral Swine ◽  
Predator Species ◽  
Marine Turtles ◽  
Nest Protection ◽  
Nesting Season

AbstractNest predation can threaten marine turtle nesting success, and having to address dissimilar predator species complicates nest protection efforts. On Florida's Keewaydin Island predation by raccoons Procyon lotor and invasive feral swine Sus scrofa are disparate, significant threats to marine turtle nests. Using 6 years of nesting data (mostly for loggerhead marine turtles Caretta caretta) we examined the impacts of swine predation on nests and the benefits of swine eradication, caging nests to protect them from raccoon predation, and the effects of nest caging on swine predation. Nest predation by swine began in mid nesting season 2007, after which swine quickly annihilated all remaining marine turtle nests. During 2005–2010 raccoon predation rates for caged nests (0.7–20.4%) were significantly lower than for uncaged nests (5.6–68.8%) in every year except 2009, when little raccoon predation occurred. The proportions of eggs lost from raccoon-predated nests did not differ between caged and uncaged nests. Caging did not prevent destruction by swine but median survival time for caged nests was 11.5 days longer than for uncaged nests, indicating that caged eggs in nests have a greater chance of hatching before being predated by swine. The financial cost of the eradication of swine greatly outweighed the value of hatchlings lost to swine predation in 2007.

scholarly journals Fitness of Races 0 and 1 of Phytophthora parasitica var. nicotianae

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1220-1228 ◽  
Author(s):  
M. J. Sullivan ◽  
T. A. Melton ◽  
H. D. Shew
Keyword(s):  
Partial Resistance ◽  
Minor Effect ◽  
Population Declines ◽  
Phytophthora Parasitica ◽  
Growing Seasons ◽  
Incubation Periods ◽  
Race 1 ◽  
Study Population ◽  
Overwintering Survival ◽  
Pathogen Populations

Deployment of tobacco (Nicotiana tabacum) varieties with complete resistance to race 0 of Phytophthora parasitica var. nicotianae has led to a rapid increase in the field populations of race 1 in North Carolina. In a field study, population levels of race 1 decreased relative to race 0 when cultivars with partial resistance to both races were planted, suggesting that race 1 isolates were less fit than race 0 isolates. Experiments were conducted to quantify differences in aggressiveness and survivability of the two races. Tobacco varieties with low, moderate, or high levels of partial resistance were inoculated with 60 pathogen isolates, and symptom development was monitored for 3 weeks. Race 0 isolates were more aggressive than race 1 isolates on cultivars with moderate or high levels of partial resistance; incubation periods were shorter and root rot severity was greater with race 0 isolates. Isolates of race 1, however, caused greater stunting of plants with moderate and high levels of partial resistance than race 0 isolates. Field microplots were infested with either a single race or an equal mixture of each race. Soil samples were collected at the end of two growing seasons and again the following spring. Pathogen populations declined from 40 to 80% during winter months, but population declines for race 0 were lower than for race 1 in each treatment over each winter. Race shifts from race 1 to race 0 that were observed in the presence of cultivars with partial resistance appear to be primarily the result of differences in aggressiveness of the races, with a possible minor effect of enhanced overwintering survival of race 0 compared with race 1.

scholarly journals Increased songbird nest depredation due to invasive Aleppo pine (Pinus halepensis) encroachment in Mediterranean shrubland

2019 ◽  
Author(s):  
Asaf Ben-David ◽  
Hila Shamoon ◽  
Ido Izhaki ◽  
Roni Efronny ◽  
Roi Maor ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
Nest Predation ◽  
Pinus Halepensis ◽  
Indirect Evidence ◽  
Nesting Success ◽  
Aleppo Pine ◽  
Occurrence Rate ◽  
Mediterranean Shrublands ◽  
Mediterranean Shrubland ◽  
Nest Depredation

Abstract Background In recent decates, a decrease of passerine densities was documented in Mediterenean shrublands. At the same time, a widspread encroachment of Aleppo pines (Pinus halepensis) to Mediterranean shrubland occurred. Such changes in vegetation structure may effect passerine predator assemblage and densities, and in turn impact passerine densities. Depredation during the nesting season is an important factor to influence passerine population size. Understanding the effects of changes in vegetation structure (pine encroachment) on passerine nesting success is the main objective of this study. We do so by assesing the effects of Aleppo pine encroachment on Sardinian warbler (Sylvia melanocephala) nest depredation in Mediterranean shrublands. Methods We examined direct and indirect predation pressures throught a gradients of pine density, using four methods: (1) placing dummy nests; (2) acoustic monitoring of mobbing events; (3) direct observations on nest predation using cameras; and (4) observation of Eurasian jay (Garrulus glandarius) behaviour as indirect evidence of predation risk. Results We found that Aleppo pine encroachment to Mediterranean shrublands increased nest predation by Eurasian jays. Nest predation was highest in with median encroaching pine. These areas are suitable for warblers, but had high occurrence rate of Eurasian jays. Conclusions Invasive pines directly increase activity of avian predators in shrubland habitats which impacted shrubland songbird nesting success. These findings are supported by multiple methodologies, illustrating different predation pressures along a gradient of pine densities in natural shrublands. Management of Aleppo pine seedlings and removal of unwanted trees in natural shrubland might mitigate arrival and expansion of native-invasive predators and decrease the predation pressure on passerine nests.

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