Relationship between reproductive hormones and migration distance in a polygynous songbird, the Red-winged Blackbird (Agelaius phoeniceus)

Author(s):  
Michelle A. Eshleman ◽  
Page E. Klug ◽  
Esther Morales-Vega ◽  
Björn Wissel ◽  
Timothy J. Greives
2006 ◽  
Vol 27 (7) ◽  
pp. 1312-1321 ◽  
Author(s):  
Bingquan Li ◽  
Xiaohua Fang ◽  
Haobin Luo ◽  
Eric Petersen ◽  
Young-Soo Seo ◽  
...  

2013 ◽  
Vol 158 ◽  
pp. 80-87 ◽  
Author(s):  
Christopher A. Searcy ◽  
Emilio Gabbai-Saldate ◽  
H. Bradley Shaffer

Ecology ◽  
2013 ◽  
Vol 94 (8) ◽  
pp. 1839-1847 ◽  
Author(s):  
Frank A. La Sorte ◽  
Daniel Fink ◽  
Wesley M. Hochachka ◽  
John P. DeLong ◽  
Steve Kelling

2009 ◽  
Vol 36 (6) ◽  
pp. 1194-1208 ◽  
Author(s):  
Nathalie Doswald ◽  
Stephen G. Willis ◽  
Yvonne C. Collingham ◽  
Deborah J. Pain ◽  
Rhys E. Green ◽  
...  

2013 ◽  
Vol 726-731 ◽  
pp. 1613-1618
Author(s):  
Xiao Yong Peng ◽  
Xin Zhang ◽  
Shuai Huang ◽  
Xu Sheng Chai ◽  
Lan Xia Guo ◽  
...  

For two conditions of (non-) vegetation cover in uranium tailings beach face, the concentration distribution and settlement regularity of tailing sand with diameter of 10μm at speed of 0.5, 1, 2, and 4 m/s was studied by numerical simulation method. Results shows, with the increase of wind speed and migration distance, particle concentration decreases. Compared with the non-vegetation cover condition, particles concentration in the condition of with vegetation cover is significantly higher than the condition that without vegetation cover; but along with the increase of horizontal distance, the concentration lowers than the latter gradually.


2015 ◽  
Vol 282 (1809) ◽  
pp. 20150375 ◽  
Author(s):  
Richard K. Simpson ◽  
Michele A. Johnson ◽  
Troy G. Murphy

The mechanisms underlying evolutionary changes in sexual dimorphism have long been of interest to biologists. A striking gradient in sexual dichromatism exists among songbirds in North America, including the wood-warblers (Parulidae): males are generally more colourful than females at northern latitudes, while the sexes are similarly ornamented at lower latitudes. We use phylogenetically controlled comparative analysis to test three non-mutually exclusive hypotheses for the evolution of sexual dichromatism among wood-warblers. The first two hypotheses focus on the loss of female coloration with the evolution of migration, either owing to the costs imposed by visual predators during migration, or owing to the relaxation of selection for female social signalling at higher latitudes. The third hypothesis focuses on whether sexual dichromatism evolved owing to changes in male ornamentation as the strength of sexual selection increases with breeding latitude. To test these hypotheses, we compared sexual dichromatism to three variables: the presence of migration, migration distance, and breeding latitude. We found that the presence of migration and migration distance were both positively correlated with sexual dichromatism, but models including breeding latitude alone were not strongly supported. Ancestral state reconstruction supports the hypothesis that the ancestral wood-warblers were monochromatic, with both colourful males and females. Combined, these results are consistent with the hypotheses that the evolution of migration is associated with the relaxation of selection for social signalling among females and that there are increased predatory costs along longer migratory routes for colourful females. These results suggest that loss of female ornamentation can be a driver of sexual dichromatism and that social or natural selection may be a stronger contributor to variation in dichromatism than sexual selection.


2018 ◽  
Vol 222 (1) ◽  
pp. jeb183517 ◽  
Author(s):  
Orsolya Vincze ◽  
Csongor I. Vágási ◽  
Péter László Pap ◽  
Colin Palmer ◽  
Anders Pape Møller

2020 ◽  
Vol 7 (1) ◽  
pp. 58-66
Author(s):  
Nathan Wolf ◽  
T. Scott Smeltz ◽  
Jeffrey M. Welker ◽  
Matthew C. Rogers ◽  
Craig Ely

AbstractDetermining the processes that shape the relative timing of energetically-costly events in the annual cycle of migrating birds is important to our understanding of avian phenology and ecology. We paired satellite tracking and hydrogen stable isotope analysis (δ2H) to examine the relative timing of two such events – migration and feather molting – in tundra swans from four breeding areas in Alaska, USA. Our results show a trend of increasing intra-individual variability in breast feather δ2H values with increasing migration distance, suggesting the overlap of breast feather molting and migration. However, when individual samples were pooled by breeding area, the δ2H values of breast and head feathers showed no trend with migration distance, presumably resulting from high levels of inter-individual variability in δ2H values within each breeding area. We explore potential reasons for this variability, propose potential mechanisms influencing feather δ2H values of tundra swans, and recommend further research into methods for exploring the temporal configuration of events in the annual cycle of migrating birds.


1992 ◽  
Vol 70 (10) ◽  
pp. 2021-2027 ◽  
Author(s):  
Jay B. Hestbeck ◽  
James D. Nichols ◽  
James E. Hines

Predictions of the time-allocation hypothesis were tested with several a posteriori analyses of banding data for the mallard (Anas platyrhynchos). The time-allocation hypothesis states that the critical difference between resident and migrant birds is their allocation of time to reproduction on the breeding grounds and survival on the nonbreeding grounds. Residents have higher reproduction and migrants have higher survival. Survival and recovery rates were estimated by standard band-recovery methods for banding reference areas in the central United States and central Canada. A production-rate index was computed for each reference area with data from the U.S. Fish and Wildlife Service May Breeding Population Survey and July Production Survey. An analysis of covariance was used to test for the effects of migration distance and time period (decade) on survival, recovery, and production rates. Differences in migration chronology were tested by comparing direct-recovery distributions for different populations during the fall migration. Differences in winter locations were tested by comparing distributions of direct recoveries reported during December and January. A strong positive relationship was found between survival rate and migration distance for 3 of the 4 age and sex classes. A weak negative relationship was found between recovery rate and migration distance. No relationship was found between production rate and migration distance. During the fall migration, birds from the northern breeding populations were located north of birds from the southern breeding populations. No pattern could be found in the relative locations of breeding and wintering areas. Although our finding that survival rate increased with migration distance was consistent with the time-allocation hypothesis, our results on migration chronology and location of wintering areas were not consistent with the mechanism underlying the time-allocation hypothesis. Neither this analysis nor other recent studies of life-history characteristics of migratory and resident birds supported the time-allocation hypothesis.


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