scholarly journals Long-term trends and drought: spatiotemporal variation in juvenile sex ratios of North American ducks

2021 ◽  
Author(s):  
Sage Ellis ◽  
Madeleine Lohman ◽  
James Sedinger ◽  
Perry Williams ◽  
Thomas Riecke
Keyword(s):  
United States ◽  
North American ◽  
Sex Ratios ◽  
Survival Rates ◽  
The United States ◽  
Avian Communities ◽  
Eastern United States ◽  
Bird Populations ◽  
Long Term Trends

Sex ratios affect population dynamics and individual fitness, and changing sex ratios can be indicative of shifts in sex-specific survival at different life stages. While climate- and landscape-change alter sex ratios of wild bird populations, long-term, landscape scale assessments of sex ratios are rare. Further, little work has been done to understand changes in sex ratios in avian communities. In this manuscript, we analyse long-term (1961-2015) data on five species of ducks across five broad climatic regions of the United States to estimate the effects of drought and long-term trends on the proportion of juvenile females captured at banding. As waterfowl have a 1:1 sex ratio at hatch, we interpret changes in sex ratios of captured juveniles as changes in sex-specific survival rates during early life. Seven of twelve species-region pairs exhibited evidence for long-term trends in the proportion of juvenile females at banding. The proportion of juvenile females at banding increased for duck populations in the western United States and typically declined for duck populations in the eastern United States. We only observed evidence for an effect of drought in two of the twelve species-region pairs, where the proportion of females declined during drought. As changes to North American landscapes and climate continue and intensify, we expect continued changes in sex-specific juvenile survival rates. More broadly, we encourage further research examining the mechanisms underlying long-term trends in juvenile sex ratios in avian communities.

scholarly journals American Engineering Doctoral Enrollments

2015 ◽  
pp. 23-24
Author(s):  
Richard Skinner
Keyword(s):  
Higher Education ◽  
United States ◽  
International Education ◽  
Doctoral Programs ◽  
The United States ◽  
American Higher Education ◽  
Long Term Trends

International education has deep historical roots and has spurred relationships that persist for decades. In the case of the United States and the field of engineering, American dependence since the mid-1960s on other countries' students – especially Indian ones – for enrollments and graduates of engineering doctoral programs has been, is and will likely continue to be significant. But long-term trends portend a time when the appeal of American higher education may be less than has been the case.

Long-term trends in cancer mortality in the United States, 1930-1998

Cancer ◽  
2003 ◽  
Vol 97 (S12) ◽  
pp. 3133-3275 ◽  
Author(s):  
Phyllis A. Wingo ◽  
Cheryll J. Cardinez ◽  
Sarah H. Landis ◽  
Robert T. Greenlee ◽  
Lynn A. G. Ries ◽  
...  
Keyword(s):  
United States ◽  
Cancer Mortality ◽  
The United States ◽  
Long Term Trends

Are We Investing Enough

1954 ◽  
Vol 23 ◽  
pp. 142-168
Author(s):  
A. K. Cairncross
Keyword(s):  
United States ◽  
The United States ◽  
Life Assurance ◽  
The Future ◽  
Interesting Discussion ◽  
Long Term Trends

Mr. President and gentlemen, I should like to express my pleasure at being back in the Faculty Hall, where I was privileged to listen to your interesting discussion last year on “The Growth of Pension Rights”. I am glad to find that the number of occasions on which economists and actuaries are not only on speaking terms but able to take counsel of one another is increasing, for I am sure that there are many problems, of which the future of pensions is only one, that can only be satisfactorily resolved through our joint efforts and deliberations. This conviction rests partly on my experience as a member of the Phillips Committee, which was heavily dependent both on the actuaries who served on it and on the members of the profession who, in one way or another, helped it along; but it is a conviction that is just as forcibly brought home to me when I look across the Atlantic to the inquiry that has been in progress since 1950 into the long-term trends in savings and investment in the United States—an inquiry carried out by economists but sponsored and largely financed by the Life Assurance Association of America.

Long-Term Trends in Intra-Financial Sector Lending in the United States (1950–2012)

2016 ◽  
Vol 42 (4) ◽  
pp. 611-629 ◽  
Author(s):  
Juan Antonio Montecino ◽  
Gerald Epstein ◽  
Iren Levina
Keyword(s):  
United States ◽  
Financial Sector ◽  
The United States ◽  
Long Term Trends
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