scholarly journals No broad decline of breeding monarch butterflies in North America: implications for conservation efforts

2021 ◽  
Author(s):  
Andrew K Davis ◽  
Michael S Crossley ◽  
Matthew K Moran ◽  
Jeffrey Glassberg ◽  
William E Snyder
Keyword(s):  
North America ◽  
Habitat Restoration ◽  
Danaus Plexippus ◽  
Geographic Range ◽  
Breeding Habitat ◽  
Flagship Species ◽  
Monarch Butterflies ◽  
Breeding Populations ◽  
First Time

Many insects are in clear decline, with monarch butterflies (Danaus plexippus) drawing particular attention as a flagship species. Falling numbers of overwintering monarchs are well documented, but there has been debate regarding population trends of summer breeding populations. Here, we compile a series of long-term monarch monitoring datasets, some which are analyzed here for the first time, that reveal highly variable responses across the migratory geographic range, but no broad net decline in numbers of breeding monarchs. We also did not find evidence that sampling biased towards natural sites was masking declines at disturbed sites. Overall, our results suggest a robust resiliency in summer populations that thus far has allowed recovery from losses during the winter. Thus, monarchs may not require as much breeding habitat restoration as once thought, and focus should be on conserving the fall and spring migration.

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 Estimating the annual distribution of monarch butterflies in Canada over 16 years using citizen science data

FACETS ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 238-253
Author(s):  
D. T. Tyler Flockhart ◽  
Maxim Larrivée ◽  
Kathleen L. Prudic ◽  
D. Ryan Norris
Keyword(s):  
North America ◽  
Citizen Science ◽  
Habitat Restoration ◽  
Danaus Plexippus ◽  
The United States ◽  
Science Data ◽  
Eastern Canada ◽  
Long Distance ◽  
Monarch Butterflies ◽  
Breeding Distribution

Monarch butterflies ( Danaus plexippus, Linnaeus, 1758) are comprised of two migratory populations separated by the Rocky Mountains and are renowned for their long-distance movements among the United States, Canada, and Mexico. Both populations have declined over several decades across North America prompting all three countries to evaluate conservation efforts. Monitoring monarch distribution and abundance is a necessary aspect of ongoing management in Canada where they are a species at risk. We used presence-only data from two citizen science data sets to estimate the annual breeding distribution of monarch butterflies in Canada between 2000 and 2015. Monarch breeding distribution in Canada varied widely among years owing to natural variation, and when considering the upper 95% of the probability of occurrence, the annual mean breeding distribution in Canada was 484 943 km2 (min: 173 449 km2; max: 1 425 835 km2). The area of occurrence was approximately an order of magnitude larger in eastern Canada than in western Canada. Habitat restoration for monarch butterflies in Canada should prioritize productive habitats in southern Ontario where monarchs occur annually and, therefore, likely contribute most to the long-term viability of monarchs in eastern North America. Overall, our assessment sets the geographic context to develop successful management strategies for monarchs in Canada.

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.

scholarly journals Monarch butterflies cross the Appalachians from the west to recolonize the east coast of North America

2010 ◽  
Vol 7 (1) ◽  
pp. 43-46 ◽  
Author(s):  
Nathan G. Miller ◽  
Leonard I. Wassenaar ◽  
Keith A. Hobson ◽  
D. Ryan Norris
Keyword(s):  
North America ◽  
Direct Evidence ◽  
East Coast ◽  
Gulf Coast ◽  
Danaus Plexippus ◽  
Early Spring ◽  
Eastern United States ◽  
The West ◽  
Monarch Butterflies ◽  
The Usa

Each spring, millions of monarch butterflies ( Danaus plexippus ) migrate from overwintering sites in Mexico to recolonize eastern North America. However, few monarchs are found along the east coast of the USA until mid-summer. Brower (Brower, L. P. 1996 J. Exp. Biol. 199, 93–103.) proposed that east coast recolonization is accomplished by individuals migrating from the west over the Appalachians, but to date no evidence exists to support this hypothesis. We used hydrogen ( δ D) and carbon ( δ 13 C) stable isotope measurements to estimate natal origins of 90 monarchs sampled from 17 sites along the eastern United States coast. We found the majority of monarchs (88%) originated in the mid-west and Great Lakes regions, providing, to our knowledge, the first direct evidence that second generation monarchs born in June complete a ( trans -) longitudinal migration across the Appalachian mountains. The remaining individuals (12%) originated from parents that migrated directly from the Gulf coast during early spring. Our results provide evidence of a west to east longitudinal migration and provide additional rationale for conserving east coast populations by identifying breeding sources.

scholarly journals Monarchs Reared in Winter in California Are Not Large Enough to Be Migrants. Comment on James et al. First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California. Insects 2021, 12, 946

Insects ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 63 ◽  
Author(s):  
Andrew K. Davis
Keyword(s):  
North America ◽  
San Francisco ◽  
Population Study ◽  
Danaus Plexippus ◽  
Monarch Butterflies ◽  
Urban South ◽  
Winter Breeding

A recent study in this journal aimed to understand certain changes in the wintering behavior of monarch butterflies, specifically in the western subpopulation of North America [...]

Parelaphostrongylus andersoni (Nematoda: Protostrongylidae) in caribou (Rangifer tarandus) of northern and central Canada

1989 ◽  
Vol 67 (8) ◽  
pp. 1966-1975 ◽  
Author(s):  
Murray W. Lankester ◽  
P. Lynn Hauta
Keyword(s):  
North America ◽  
Northwest Territories ◽  
Rangifer Tarandus ◽  
Geographic Range ◽  
Neurologic Disease ◽  
Rangifer Tarandus Caribou ◽  
Central Canada ◽  
Size And Morphology ◽  
First Time ◽  
Improved Methods

Woodland (Rangifer tarandus caribou) and barren ground (R. t. groenlandicum) caribou are reported for the first time as hosts of Parelaphostrongylus andersoni, greatly extending the known geographic range of this muscle nematode. Up to 56% of caribou in the Beverly herd, central Northwest Territories, passed dorsal-spined first-stage larvae in their feces. Animals less than 3 years old were more frequently infected and passed greater numbers of larvae than older animals. Larval output in winter and spring did not differ. Adults of the four elaphostrongyline nematodes known to occur in caribou are distinguished by their location in the host, the size of the worms, and the size and morphology of the male copulatory structures. There is an urgent need for tested and improved methods of differentiating larvae of P. andersoni and other elaphostrongyline nematodes from those of P. tenuis that cause neurologic disease in various North American cervids. Demonstration of the occurrence of P. andersoni in Rangifer sp. in North America raises the possibility that it originated in Eurasian cervids and may still occur in the Old World.

scholarly journals Variation in wing characteristics of monarch butterflies during migration: Earlier migrants have redder and more elongated wings

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Dara A. Satterfield ◽  
Andrew K. Davis
Keyword(s):  
North America ◽  
Bird Migration ◽  
Danaus Plexippus ◽  
Flight Performance ◽  
Wing Morphology ◽  
Long Distance ◽  
Monarch Butterflies ◽  
Significant Tendency ◽  
Length Width ◽  
Ultimate Fate

AbstractThe migration of monarch butterflies (Danaus plexippus) in North America has a number of parallels with long-distance bird migration, including the fact that migratory populations of monarchs have larger and more elongated forewings than residents. These characteristics likely serve to optimize flight performance in monarchs, as they also do with birds. A question that has rarely been addressed thus far in birds or monarchs is if and how wing characteristics vary within a migration season. Individuals with superior flight performance should migrate quickly, and/or with minimal stopovers, and these individuals should be at the forefront of the migratory cohort. Conversely, individuals with poor flight performance and/or low endurance would be more likely to fall behind, and these would comprise the latest migrants. Here we examined how the wing morphology of migrating monarchs varies to determine if wing characteristics of early migrants differ from late migrants. We measured forewing area, elongation (length/width), and redness, which has been shown to predict flight endurance in monarchs. Based on a collection of 75 monarchs made one entire season (fall 2010), results showed that the earliest migrants (n = 20) in this cohort had significantly redder and more elongated forewings than the latest migrants (n = 17). There was also a non-significant tendency for early migrants to have larger forewing areas. These results suggest that the pace of migration in monarchs is at least partly dependent on the properties of their wings. Moreover, these data also raise a number of questions about the ultimate fate of monarchs that fall behind

scholarly journals Employing Very High Frequency (VHF) Radio Telemetry to Recreate Monarch Butterfly Flight Paths

2020 ◽  
Vol 49 (2) ◽  
pp. 312-323 ◽  
Author(s):  
Kelsey E Fisher ◽  
James S Adelman ◽  
Steven P Bradbury
Keyword(s):  
High Frequency ◽  
Radio Telemetry ◽  
Danaus Plexippus ◽  
Movement Patterns ◽  
Agricultural Landscapes ◽  
Breeding Habitat ◽  
Stationary Points ◽  
Very High Frequency ◽  
Monarch Butterflies ◽  
Very High

Abstract The overwintering population of eastern North American monarch butterflies (Danaus plexippus) has declined significantly. Loss of milkweed (Asclepias sp.), the monarch’s obligate host plant in the Midwest United States, is considered to be a major cause of the decline. Restoring breeding habitat is an actionable step towards population recovery. Monarch butterflies are highly vagile; therefore, the spatial arrangement of milkweed in the landscape influences movement patterns, habitat utilization, and reproductive output. Empirical studies of female movement patterns within and between habitat patches in representative agricultural landscapes support recommendations for habitat restoration. To track monarch movement at distances beyond human visual range, we employed very high frequency radio telemetry with handheld antennae to collect movement bearings on a biologically relevant time scale. Attachment of 220–300 mg transmitters did not significantly affect behavior and flight capability. Thirteen radio-tagged monarchs were released in a restored prairie, and locations were estimated every minute for up to 39 min by simultaneous triangulation from four operators. Monarchs that left the prairie were tracked and relocated at distances up to 250 m. Assuming straight flights between locations, the majority of steps within the prairie were below 50 m. Steps associated with exiting the prairie exceeded 50 m with high directionality. Because butterflies do not fly in straight lines between stationary points, we also illustrate how occurrence models can use location data obtained through radio telemetry to estimate movement within a prairie and over multiple land cover types.

An Ecological Field Lab for Tracking Monarch Butterflies & Their Parasites

2010 ◽  
Vol 72 (6) ◽  
pp. 339-344 ◽  
Author(s):  
Carrie N. Wells
Keyword(s):  
Citizen Science ◽  
Scientific Method ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Biological Research ◽  
Research Projects ◽  
Ecological Data ◽  
Monarch Butterflies

The inclusion of nonscientists in biological research projects has become a useful mechanism for capturing long-term ecological data while exposing students firsthand to science and the scientific method. I have combined several existing citizen-science-based research efforts focused on Danaus plexippus, the monarch butterfly, into a comprehensive yet simple ecological lab activity that is appropriate for all ages and biological backgrounds.

scholarly journals Growth and Survival of Two Western Milkweed Species: Effects of Container Volume and Fertilizer Rate

2017 ◽  
Vol 27 (4) ◽  
pp. 482-489
Author(s):  
Nikki Hanson ◽  
Amy L. Ross-Davis ◽  
Anthony S. Davis
Keyword(s):  
Habitat Restoration ◽  
Danaus Plexippus ◽  
Monarch Butterfly ◽  
Fertilizer Application ◽  
Application Rate ◽  
Breeding Habitat ◽  
High Rate ◽  
Fertilizer Rate ◽  
Growth And Survival ◽  
Fertilizer Application Rate

Diminishing milkweed (Asclepias sp.) populations are contributing to the conspicuous decline of the iconic monarch butterfly (Danaus plexippus). This research sought to improve milkweed propagation success, a core component of summer habitat restoration projects. Specifically, this research assessed the effects of container volume and fertilizer application rate on growth and first year field survival of two species of milkweed common to western North America, namely showy milkweed (A. speciosa) and narrowleaf milkweed (A. fascicularis). Generally, larger roots and shoots developed when plants were given the high rate of fertilizer (6.5 g·L−1) and when reared in the largest containers (2600 mL). For narrowleaf milkweed, nearly all plants developed a firm plug (i.e., one in which the root system remained intact when removed from the container) after 22 weeks. Most narrowleaf milkweed plants flowered 15 weeks after sowing when grown in the largest container with either the low (2.7 g·L−1) or high fertilizer rate or the midsized container (444 mL) with a high rate of fertilizer. For showy milkweed, a firm plug developed for nearly all individuals by the end of the growing season only when given the high fertilizer rate. None of the showy milkweed plants developed an inflorescence by 15 weeks. Results of this research improve our understanding of milkweed propagation and will aid in the efforts to restore the monarch butterfly’s summer breeding habitat by providing propagation protocols across a range of stocktypes.

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