Factors Affecting Clutch Size in the Teiid Lizards Cnemidophorus tigris gracilis and C. t. septentrionalis

1992 ◽  
Vol 26 (4) ◽  
pp. 443 ◽  
Author(s):  
Harry L. Taylor ◽  
Christopher R. Cooley ◽  
Rose Ann Aguilar ◽  
Carmeliza J. Obana
Keyword(s):  
Clutch Size ◽  
Factors Affecting

Factors affecting egg viability and incubation time in prairie dabbling ducks

1993 ◽  
Vol 71 (6) ◽  
pp. 1146-1152 ◽  
Author(s):  
Todd W. Arnold
Keyword(s):  
Clutch Size ◽  
Incubation Time ◽  
Egg Size ◽  
Hatching Success ◽  
Size Variation ◽  
Negative Effects ◽  
Factors Affecting ◽  
Ambient Temperatures ◽  
Weak Support ◽  
Anas Clypeata

I determined hatching success for 328 dabbling duck (Anas spp.) eggs that were experimentally subjected to varying lengths of preincubation delay and then artificially incubated. Hatchability declined as unincubated eggs were exposed to longer preincubation delays. This effect was more pronounced at higher ambient temperatures and later in the nesting season, but did not vary with egg size or among duck species. These results are largely consistent with observed patterns of clutch-size variation among prairie-nesting waterfowl. Clutch size may be smaller later in the year and at lower latitudes owing to the negative effects of date and temperature on the ability of eggs to withstand preincubation delay. The timing of embryo mortality was bimodal, with peaks occurring during early development (<6 d) and just before hatching (>22 d); however, only early mortality was affected by preincubation delay. Eggs lost up to 2.6% of their initial mass as water vapor during preincubation delay, but the amount of water loss did not affect hatching success. Eggs subjected to preincubation delay required about 1 additional day to hatch. Incubation time was related to egg size in northern shovelers (Anas clypeata) and in all species combined, but not in blue-winged teal (Anas discors) or mallards (Anasplatyrhynchos). These data provide only weak support for the hypothesis that large eggs are costly because they take longer to hatch.

Factors affecting the reproductive success of common tern (Sterna hirundo) colonies on the lower Great Lakes during the summer of 1972

1976 ◽  
Vol 54 (11) ◽  
pp. 1850-1862 ◽  
Author(s):  
Ralph D. Morris ◽  
Rodger A. Hunter ◽  
James F. McElman
Keyword(s):  
Reproductive Success ◽  
Great Lakes ◽  
Clutch Size ◽  
Relative Proportion ◽  
Common Tern ◽  
Sterna Hirundo ◽  
Success Rates ◽  
Factors Affecting ◽  
Fledging Success ◽  
Egg Failure

The breeding biology of five common tern (Sterna hirundo) colonies in the lower Great Lakes was studied between May and August 1972. Frequent visits were made to each colony and data collected on nests within large artificially enclosed areas. The objective was to identify factors that influence the reproductive success of common tern colonies on the Great Lakes. Hatching success was significantly dependent on clutch size and time of clutch initiation, whereas fledging success was independent of clutch size. The most common category of egg failure was disappearance from the nest. One colony (Port Colborne) realized a significantly higher hatching and fledging success than the others, among which there were no significant differences in prehatch or posthatch success rates. Factors that contributed to differences in reproductive success are presented and their relative contributions to the reproductive success of the tern colonies are discussed. The factors include the relative proportion of three-egg clutches, incubation time as a measure of 'parent attentiveness,' numerical size of the colony, predation, competition for nesting sites by gulls, food availability, flooding, and toxic chemicals. We conclude that no single factor can be readily correlated with reproductive success and suggest that caution should be exercised when considering the relationships between reproductive success and factors influencing it.

Factors Affecting Clutch Size in Arctic Passerines

1972 ◽  
Vol 42 (3) ◽  
pp. 317-364 ◽  
Author(s):  
David J. T. Hussell
Keyword(s):  
Clutch Size ◽  
Factors Affecting

Factors affecting clutch Size and Duckling Survival in the Common GoldeneyeBucephala clangula

1998 ◽  
Vol 4 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Markku Milonoff ◽  
Hannu Pöysä ◽  
Pentti Runko
Keyword(s):  
Clutch Size ◽  
Factors Affecting ◽  
Duckling Survival ◽  
The Common

Potential Factors Affecting Nest Initiation Date, Clutch Size and Nest Success in the Plumage Dimorphic Reddish Egret

Waterbirds ◽  
2012 ◽  
Vol 35 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Zachary Holderby ◽  
William Simper ◽  
Brock Geary ◽  
M. Clay Green
Keyword(s):  
Clutch Size ◽  
Nest Success ◽  
Factors Affecting ◽  
Potential Factors ◽  
Nest Initiation

scholarly journals Clutch Size in the Eastern Kingbird: Factors Affecting Nestling Survival

The Auk ◽  
1983 ◽  
Vol 100 (2) ◽  
pp. 326-334 ◽  
Author(s):  
Michael T. Murphy
Keyword(s):  
Clutch Size ◽  
Brood Size ◽  
Weather Conditions ◽  
Ambient Air ◽  
Factors Affecting ◽  
Temperature And Precipitation ◽  
Trade Offs ◽  
Nestling Survival ◽  
Eastern Kingbird ◽  
Induced Changes

Abstract Observational and experimental procedures were used to evaluate the potential importance of brood size and weather on the evolution of clutch size in the Eastern Kingbird. Modal clutch size was three eggs, yet broods of four were most productive. Nestling size varied inversely with brood size, so that "nestling quality" was lower in broods of four than in broods of three. Asymptotic weight of nestlings in broods of three was directly and significantly correlated with ambient air temperature, followed by hatch order. Because larger broods were being fed during a period of relatively cool and wet weather, the effects of brood size were probably confounded by weather-induced changes in food availability, suggesting that the ability to produce surviving young successfully from large broods is dependent upon weather conditions during the nestling period. These observations match patterns seen in other aerial foragers and indicate that unpredictable changes in temperature and precipitation dramatically affect the ability of the adults to feed young. A high variance in fledging success from the largest broods is indicated and probably selects for a reduced number of offspring in the Eastern Kingbird. Trade-offs in reproductive effort and parental survival do not appear to be required to explain patterns of clutch size in the Eastern Kingbird or, probably, other aerial foragers.

Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

1977 ◽  
Vol 35 ◽  
pp. 214-217
Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly
Keyword(s):  
Image Analysis ◽  
Image Quality ◽  
Exposure Time ◽  
Image Contrast ◽  
Automated Image Analysis ◽  
Practical Application ◽  
Factors Affecting ◽  
High Image Quality ◽  
Qualitative Evidence ◽  
Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

Factors affecting microstructural scale in liquid crystalline polymers

1990 ◽  
Vol 48 (4) ◽  
pp. 220-221
Author(s):  
Christine M. Dannels ◽  
Christopher Viney
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Factors Affecting ◽  
Crystalline Polymers ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Lower Viscosity ◽  
Fine Microstructure ◽  
Planar Orientation ◽  
Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

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