Summary of anthropogenic drivers

Main Questions:

(1)    What is the expected effect of climate change on monarch wintering and breeding habitats, and patterns of annual migration?
(2)     How will changes in land use and agricultural practices affect monarchs at different stages of their annual life cycle?
(3)    What are the expected changes in nectar availability and how will this influence monarch migration?
(4)    What is the contribution of the butterfly breeding industry (i.e., captive-bred monarchs sold for release to the wild) on monarch distributions, abundance and disease?

Data resources:

(2) Overwintering data (eastern): habitat use/conversion in Mexico from Eduardo?

(2) Overwintering data (western): habitat use/conversion in CA from Dennis?

(2) Land use/change data availability--base layers? EPA NLCD

-changing farming practices

-conversion from agriculture to surburban, urban

(2) County-level data on 23 crops from USDA

(2 and 3) Pesticide usage in US?

(2) Bt spraying – are there records for that?  Gypsy moths- LR to ask Sandy Liebhold

(2) Herbicide/pesticide spraying data  -industry records? (i.e., RoundUp)

(3) Maps of nectar sources (National Phenology Network)

(4) USDA permits issued for commercial release of butterflies

Data Gaps:

*Note for monarch monitoring programs: Can observers record fresh vs non-fresh in some of the monitoring programs? This could be very informative

#s of artificial releases from butterfly breeders

Milkweed map data

Result highlights:

Ideas/discussion -

Scales at which we can examine anthropogenic effects:

3 spatial scales: site, region, global population

3 annual stages: breeding, migrating, overwintering

 Habitat change in wintering sites:  Need to ask Eduardo and Lincoln what they are doing with this now, and possibly take this up at a future meeting

* Can we look at changes in the western US wintering sites?

 Urban/residential land use:  Note that land conversion to residential neighborhoods could either help or hurt monarchs – people gardening with milkweed could provide monarchs with resources – versus building subdivisions on field/pastures could convert milkweed habitat to lawns and golf courses

*are the low years being pushed up by climate and the high years pushed down by habitat loss (host plant decline)? The up-down trend is population dynamics. So, population trend is wedge-shaped.

Planned manscripts w/authors:

(1) Butterfly breeding industry and butterfly releases: We could write an opinion piece on this using anecdotal  observations and some ballpark calculations (i.e., # permits issued by USDA, # breeders registered with IBBA); possible issues to mention are effects on disease spread, effects on spatial distribution of monarchs (esp. at times/places when normally rare), and effects on scientific analysis (i.e., cardenolide fingerprints, population genetic studies)