Low prevalence of the parasite Ophryocystis elektroscirrha at the range edge of the eastern North American monarch (Danaus plexippus) butterfly population

Author(s):  
Felipe Dargent ◽  
Sydney M Gilmour ◽  
Emma A Brown ◽  
Rees Kassen ◽  
Heather M Kharouba

Every year monarch butterflies (Danaus plexippus Linnaeus, 1758) from the eastern North American population migrate from Mexico to Southern Canada in the spring. This northward migration has been shown to reduce monarch infection with the host-specific parasite Ophryocystis elektroscirrha (OE) (McLaughlin and Myers, 1970); yet, the prevalence of OE at their range limits, and the mechanism(s) responsible, is unknown. We assessed OE infection levels of monarchs at the northern edge of the eastern population distribution around Ottawa, Canada, and found extremely low levels of infection (~1% with upper confidence intervals close to 3%). Low OE infection levels are likely due to low densities of monarchs in this region and/or migratory escape effects, where migrating individuals leave behind areas with high density of conspecifics and high potential for parasite accumulation and transmission. Future work should aim to disentangle the relative contribution of these two mechanisms for governing the decrease in parasitism at the range limits of migratory populations.

2018 ◽  
Vol 151 (1) ◽  
pp. 49-57 ◽  
Author(s):  
D.T. Tyler Flockhart ◽  
John H. Acorn ◽  
Keith A. Hobson ◽  
D. Ryan Norris

AbstractMonarch butterflies (Danaus plexippus (Linnaeus) (Lepidoptera: Nymphalidae)) in eastern North America migrate each year from overwintering areas in Mexico to cover a large breeding distribution across the United States of America and southern Canada. In 2012, monarch butterflies migrated well beyond their usual range, resulting in an extended breeding distribution compared to typical years. We used stable isotope (δ2H, δ13C) measurements in wing chitin to determine the area of natal origin of these butterflies. Most monarch butterflies collected in May, June, and July from Manitoba and Alberta, Canada had natal origins in the North American Midwest. Monarch butterflies collected in Alberta and Saskatchewan, Canada in August and September had local natal origins indicating successful recruitment of offspring from colonising individuals. However, it is unknown whether these offspring migrated successfully to overwintering areas. Our work highlights the ability of monarch butterflies to colonise distant breeding areas and demonstrates how stable isotopes can be used to understand the dynamics of range-edge populations.


2011 ◽  
Vol 57 (14) ◽  
pp. E1924
Author(s):  
Ana Laynez Carnicero ◽  
Michael A. Gaglia ◽  
Kohei Wakabayashi ◽  
Rafael Romaguera ◽  
Gabriel Maluenda ◽  
...  

2020 ◽  
Author(s):  
Alana A. E. Wilcox ◽  
Amy E. M. Newman ◽  
Nigel E. Raine ◽  
D. Ryan Norris

AbstractEastern North American migratory monarch butterflies (Danaus plexippus) have faced sharp declines over the last two decades. Although captive rearing has been used as an important tool for engaging the public and supplementing conservation efforts, a recent study that tested monarchs in a flight simulator suggested that captive-reared monarchs lose their capacity to orient southward during fall migration to their Mexican overwintering sites. We raised offspring of wild-caught monarchs on swamp milkweed (Asclepias incarnata) and, after eclosion, individuals were either tested in a flight simulator or radio-tracked in the wild using array of over 100 automated telemetry towers. While only 33% (7/39) of monarchs tested in the flight simulator showed strong southeast to southwest orientation, 97% (28/29) of the radio-tracked individuals were detected by automated towers south or southeast of the release site, up to 200 km away. Our results suggest that, though captive rearing of monarch butterflies may cause temporary disorientation, proper orientation is likely re-established after exposure to natural skylight cues.


2007 ◽  
Vol 17 (9-10) ◽  
pp. 869
Author(s):  
C. Feener ◽  
P. Kang ◽  
E. Estrella ◽  
B. Darras ◽  
A. Amato ◽  
...  

2019 ◽  
Vol 48 (3) ◽  
pp. 675-684 ◽  
Author(s):  
Andrew Myers ◽  
Christie A Bahlai ◽  
Douglas A Landis

AbstractAs agricultural practices intensify, species once common in agricultural landscapes are declining in abundance. One such species is the monarch butterfly (Danaus plexippus L.), whose eastern North American population has decreased approximately 80% during the past 20 yr. One hypothesis explaining the monarch’s decline is reduced breeding habitat via loss of common milkweed (Asclepias syriaca L.) from agricultural landscapes in the north central United States due to the adoption of herbicide-tolerant row crops. Current efforts to enhance monarch breeding habitat primarily involve restoring milkweed in perennial grasslands. However, prior surveys found fewer monarch eggs on common milkweed in grassland versus crop habitats, indicating potential preference for oviposition in row crop habitats, or alternatively, greater egg loss to predation in grasslands. We tested these alternative mechanisms by measuring oviposition and egg predation on potted A. syriaca host plants. Our study revealed that habitat context influences both monarch oviposition preference and egg predation rates and that these patterns vary by year. We found higher monarch egg predation rates during the first 24 h after exposure and that much of the predation occurs at night. Overall, we documented up to 90% egg mortality over 72 h in perennial grasslands, while predation rates in corn were lower (10–30% mortality) and more consistent between years. These findings demonstrate that weekly monarch egg surveys are too infrequent to distinguish oviposition habitat preferences from losses due to egg predation and suggest that monarch restoration efforts need to provide both attractive and safe habitats for monarch reproduction.


The Auk ◽  
2002 ◽  
Vol 119 (3) ◽  
pp. 676-684 ◽  
Author(s):  
Michel Robert ◽  
Réjean Benoit ◽  
Jean-Pierre L. Savard

Abstract Little is known of the eastern North American population of Barrow's Goldeneyes (Bucephala islandica), which was recently listed as “of special concern” in Canada. In 1998 and 1999, we marked 18 adult males wintering along the St. Lawrence River, Québec, with satellite transmitters to document their breeding, molting, and wintering distribution and phenology, and to describe timing and routes of their spring, molt, and fall migrations. Thirteen males moved inland from the St. Lawrence River to breed; the spring migration averaged 5.9 days, and birds arrived on breeding areas on average 9 May. All breeding areas were inland, on the north shore of the St. Lawrence River estuary and gulf. Breeding areas averaged 64.8 km from the St. Lawrence corridor. Males stayed on their respective breeding area a mean of 34.5 days, and left on average 11 June. Twelve males were tracked to their molting areas, one of which stayed on its wintering area until 5 June and flew directly to its molting area. Their molt migration averaged 18.6 days, and the mean arrival date on molting areas was 30 June. All molting areas were located north and averaged 986 km from breeding areas. Four males molted in Hudson Bay, four in Ungava Bay, two in northern Labrador, one on Baffin Island, and one inland, near the Québec–Labrador border. The mean length of stay on the molting areas was 105.3 days, and the mean date of departure from molting areas was 4 October. All goldeneyes for which the radio still functioned during fall migration returned to winter in the St. Lawrence River estuary, on average 6 November. Our results refute the idea that the main breeding area of the eastern North American population of Barrow's Goldeneyes is located in northern Québec and Labrador and rather indicate that it is in the boreal forest just north of the St. Lawrence River estuary and gulf. They also indicate that Barrow's Goldeneye males undertake a genuine molt migration, and highlight the importance of molting areas because birds stayed there approximately four months each year.


2017 ◽  
Vol 131 (2) ◽  
pp. 133-140
Author(s):  
Emily J. Herdman ◽  
Karen E. Hodges

in Canada, Nuttall’s Cottontails (Sylvilagus nuttallii nuttallii) occur in southcentral British Columbia (BC), where they are federally listed as a species of special Concern due to their presumed small populations and limited distribution in fragmented habitats. Their habitat use and movement patterns are poorly known at this northern edge of their distribution. We used livetrapping, radio-collaring, and fecal pellet surveys to examine Nuttall’s Cottontails’ use of remaining patches of native habitat as well as use of human-impacted areas. Cottontails were present in low densities and only about half of presumably suitable patches of native sagebrush-steppe were occupied. Cottontails were more likely to occur in shrubby habitat, but at a fine scale cottontails used areas that had a lower density of shrubs and finer substrates. movement patterns differed significantly between areas of varying habitat quality, with longer movements in natural habitat. one radio-collared male cottontail used anthropogenic habitats adjacent to native habitat; this use corresponds with landowner reports. However, it is not clear whether Nuttall’s Cottontails are able to use anthropogenically-impacted areas to maintain populations or in areas where such habitats are not near native habitats. our results suggest that these animals are rare and occur primarily in remnant patches of shrub-steppe within BC.


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