Stable isotopes (δD and δ 13 C) are geographic indicators of natal origins of monarch butterflies in eastern North America

Oecologia ◽  
1999 ◽  
Vol 120 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Keith A. Hobson ◽  
Leonard I. Wassenaar ◽  
Orley R. Taylor
Keyword(s):  
Stable Isotopes ◽  
North America ◽  
Eastern North America ◽  
Monarch Butterflies

scholarly journals Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131087 ◽  
Author(s):  
D. T. Tyler Flockhart ◽  
Leonard I. Wassenaar ◽  
Tara G. Martin ◽  
Keith A. Hobson ◽  
Michael B. Wunder ◽  
...  
Keyword(s):  
North America ◽  
Danaus Plexippus ◽  
Late Summer ◽  
Breeding Habitat ◽  
Eastern North America ◽  
Distribution Models ◽  
Monarch Butterflies ◽  
Breeding Distribution ◽  
Breeding Grounds ◽  
Isotope Measurements

Insect migration may involve movements over multiple breeding generations at continental scales, resulting in formidable challenges to their conservation and management. Using distribution models generated from citizen scientist occurrence data and stable-carbon and -hydrogen isotope measurements, we tracked multi-generational colonization of the breeding grounds of monarch butterflies ( Danaus plexippus ) in eastern North America. We found that monarch breeding occurrence was best modelled with geographical and climatic variables resulting in an annual breeding distribution of greater than 12 million km 2 that encompassed 99% occurrence probability. Combining occurrence models with stable isotope measurements to estimate natal origin, we show that butterflies which overwintered in Mexico came from a wide breeding distribution, including southern portions of the range. There was a clear northward progression of monarchs over successive generations from May until August when reproductive butterflies began to change direction and moved south. Fifth-generation individuals breeding in Texas in the late summer/autumn tended to originate from northern breeding areas rather than regions further south. Although the Midwest was the most productive area during the breeding season, monarchs that re-colonized the Midwest were produced largely in Texas, suggesting that conserving breeding habitat in the Midwest alone is insufficient to ensure long-term persistence of the monarch butterfly population in eastern North America.

scholarly journals Wing Color of Monarch Butterflies (Danaus plexippus) in Eastern North America across Life Stages: Migrants Are “Redder” than Breeding and Overwintering Stages

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Andrew K. Davis
Keyword(s):  
North America ◽  
Southeastern United States ◽  
Danaus Plexippus ◽  
Color Difference ◽  
Color Variation ◽  
Eastern North America ◽  
Life Stages ◽  
Monarch Butterflies ◽  
Bright Orange ◽  
The Many

Monarch butterflies are famous among insects for their unique migration in eastern North America to overwinter sites in Mexico and their bright orange wing color, which has an aposematic function. While capturing migrating monarchs in northeast Georgia, USA, I noticed that many appeared to have unusually deep orange wings. I initiated the current study to compare wing hues (obtained using image analysis of scanned wings) of migrants (captured in 2005 and 2008) to samples of breeding and overwintering monarchs. Consistent with initial observations, migrants had significantly lower orange hues (reflecting deeper, redder orange colors) than breeding and overwintering monarchs. There was also a difference in hue between sexes and a relationship with wing size, such that larger monarchs had deeper, redder hues. The reasons for the color difference of migrants are not apparent, but one possibility is that the longer-lived migrant generation has denser scalation to allow for scale loss over their lifespan. Alternatively, this effect could be confined to the subpopulation of monarchs in the Southeastern United States, which may not be well represented at the Mexican overwintering sites. In any case, this discovery highlights the many questions emerging on the significance of wing color variation in this species.

Variation in Cardiac Glycoside Content of Monarch Butterflies from Natural Populations in Eastern North America

Science ◽  
1972 ◽  
Vol 177 (4047) ◽  
pp. 426-429 ◽  
Author(s):  
L. P. Brower ◽  
P. B. McEvoy ◽  
K. L. Williamson ◽  
M. A. Flannery
Keyword(s):  
North America ◽  
Cardiac Glycoside ◽  
Natural Populations ◽  
Eastern North America ◽  
Monarch Butterflies

Patterns of parasitism in monarch butterflies during the breeding season in eastern North America

2017 ◽  
Vol 43 (1) ◽  
pp. 28-36 ◽  
Author(s):  
D. T. TYLER FLOCKHART ◽  
ANJULI DABYDEEN ◽  
DARA A. SATTERFIELD ◽  
KEITH A. HOBSON ◽  
LEONARD I. WASSENAAR ◽  
...  
Keyword(s):  
North America ◽  
Breeding Season ◽  
Eastern North America ◽  
Monarch Butterflies

scholarly journals A Review of Published and Unpublished Findings from 20 Long-term Monitoring Studies of Eastern Monarch Butterflies: the Population was Never in Danger, Despite Recent Winter Colony Declines

2020 ◽  
Author(s):  
Andrew Davis
Keyword(s):  
North America ◽  
Grey Literature ◽  
Agricultural Practices ◽  
The United States ◽  
Distinct Pattern ◽  
Eastern North America ◽  
Monarch Butterflies ◽  
Isotopic Signatures ◽  
Long Term Studies

There are a large number of wildlife and insect species that are in trouble on this planet, and most believe that monarch butterflies in eastern North America are too, because of the well-publicized declines of their winter colonies in central Mexico in the last 25 years. A small number of studies over the last decade have cast doubt on this claim by showing declines are not evident at other stages of the annual cycle. To determine how extensive this pattern is, I conducted an exhaustive review of peer-reviewed and grey literature on (eastern) monarch population censuses and studies, conducted across all seasons, and extracted data from these sources to evaluate how monarch abundance has or has not changed over time. I identified 20 collections of data that included butterfly club reports, compilations of citizen-science observations, migration roost censuses, long-term studies of isotopic signatures, and even museum records. These datasets range in duration from 15 years to over 100 years, and I endeavored to also update each with information from the most current years. I also re-examined the winter colony data after incorporating historical records of colony measurements dating back to 1976. This represents the most complete and up-to-date synthesis of information regarding this population. When I examined the long-term trajectory within each dataset a distinct pattern emerged. Modest declines are evident within the winter colonies (over the full 45 year dataset), and, within three censuses conducted during the spring recolonization. Meanwhile, 16 completely separate monitoring studies conducted during the summer and fall (and from varying locations) revealed either no trend at all or in fact an increase in abundance. While each of these long-term studies has inherent limitations, the fact that all 16 sources of data show the same pattern is undeniable. Moreover, this evidence is consistent with recently-conducted genetic work that shows a lack of decline. Collectively, these results indicate that despite diminishing winter colonies and spring migrations, monarchs in eastern North America are capable of rebounding fully each year, implying that milkweed is not limiting within their collective range. Moreover, there is no indication from these data that the summer population was ever truly diminished by changing agricultural practices in the Midwest that reduced milkweed in crop fields within that region. It is possible that the larger population is not as dependent on Midwestern agricultural milkweed as once thought, and/or that monarchs are adapting to increasingly human-altered landscapes. These results are timely and should bear on the upcoming USFWS decision on whether the monarch requires federal protection in the United States. Importantly, they argue that despite losses of many insects globally, the eastern North American monarch population is not in the same situation.

The Identification and Study of Indian Shell Middens in Eastern North America: 1643–1861

1986 ◽  
Vol 6 (3) ◽  
pp. 227-243 ◽  
Author(s):  
Andrew L. Christenson
Keyword(s):  
Nineteenth Century ◽  
Civil War ◽  
North America ◽  
East Coast ◽  
Eastern North America ◽  
Shell Midden ◽  
Shell Middens ◽  
Work Done

Although the interest in shell middens in North America is often traced to reports of the discoveries in Danish kjoekkenmoeddings in the mid-nineteenth century, extensive shell midden studies were already occurring on the East Coast by that time. This article reviews selected examples of this early work done by geologists and naturalists, which served as a foundation for shell midden studies by archaeologists after the Civil War.

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