Featured Research

from universities, journals, and other organizations

Habitat loss on breeding grounds cause of monarch decline, study finds

Date:
June 4, 2014
Source:
University of Guelph
Summary:
Habitat loss on breeding grounds in the United States -- not on wintering grounds in Mexico -- is the main cause of recent and projected population declines of migratory monarch butterflies in eastern North America, according to new research. Milkweed is the only group of plants that monarch caterpillars feed upon before they develop into butterflies. Industrial farming contributed to a 21-per-cent decline in milkweed plants between 1995 and 2013, and much of this loss occurred in the central breeding region.

Monarch butterfly on swamp milkweed wildflower (stock image). Changes in milkweed abundance can affect everything from larval competition for food to egg-laying in adults.
Credit: Mark Herreid / Fotolia

Habitat loss on breeding grounds in the United States -- not on wintering grounds in Mexico -- is the main cause of recent and projected population declines of migratory monarch butterflies in eastern North America, according to new research from the University of Guelph.

The groundbreaking study was published in the Journal of Animal Ecology.

"Our work provides the first evidence that monarch butterfly numbers in eastern North America are most sensitive to changes in the availability of milkweed on breeding grounds, particularly in the Corn Belt region of the United States," said Ryan Norris, a professor in Guelph's Department of Integrative Biology.

He conducted the study with lead author and current Guelph post-doc Tyler Flockhart, as well as scientists from the Commonwealth Scientific and Industrial Research Organisation (Australia's national science agency).

These results contradict the long-held belief that monarch butterflies are most vulnerable to disturbances on wintering grounds in Mexico. They also confirm suspicions that recent declines have actually been driven by breeding events.

During the winter months, monarch butterflies congregate in a small area at high densities in Mexico. Scientists thought factors on those wintering grounds, such as climate change or deforestation, were the greatest threat to the population.

That led to multiple Mexican presidential decrees to protect butterfly overwintering habitats and efforts to curb illegal deforestation.

"The protection of overwintering habitat has no doubt gone a long way towards conserving monarchs that breed throughout eastern North America. However, our results provide evidence that there is now another imminent threat," said Flockhart.

Milkweed is the only group of plants that monarch caterpillars feed upon before they develop into butterflies. Industrial farming contributed to a 21-per-cent decline in milkweed plants between 1995 and 2013, and much of this loss occurred in the central breeding region, the study said.

More than 70 per cent of milkweed in this region is located in agricultural-intensive landscapes where genetically modified crops are increasing, as opposed to 16 per cent in conservation lands and 10 per cent in public areas such as roadways, the study said.

Changes in milkweed abundance can affect everything from larval competition for food to egg-laying in adults.

"The rapid loss of milkweed projected for this region, attributable to land cover changes and shifts in agricultural practices, is a very large concern," said Flockhart. Left unchecked, milkweed loss will cause the monarch population to decline by at least another 14 per cent, the study said.

The researchers developed a model to predict effects of habitat loss on both breeding and wintering grounds and the effects of climate change. They aimed to explain the observed population decline and make predictions for the next 100 years.

Their results connect an increase in genetically modified, herbicide-resistant crops and the current population decline of monarch butterflies in eastern North America.

"Reducing the negative effects of milkweed loss in the breeding grounds should be the top conservation priority to slow or halt future population declines of the monarch in North America," Flockhart said.

Norris added:"Planting milkweed in the south and central United States would provide the largest immediate benefit."

Earlier pioneering studies from Norris's research lab have tracked year-round migration patterns of this iconic species using chemical markers and have looked at how monarchs migrate to their Mexican wintering grounds.


Story Source:

The above story is based on materials provided by University of Guelph. Note: Materials may be edited for content and length.


Cite This Page:

University of Guelph. "Habitat loss on breeding grounds cause of monarch decline, study finds." ScienceDaily. ScienceDaily, 4 June 2014. <www.sciencedaily.com/releases/2014/06/140604203056.htm>.
University of Guelph. (2014, June 4). Habitat loss on breeding grounds cause of monarch decline, study finds. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140604203056.htm
University of Guelph. "Habitat loss on breeding grounds cause of monarch decline, study finds." ScienceDaily. www.sciencedaily.com/releases/2014/06/140604203056.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Newsy (July 30, 2014) The Peace Corps is one of several U.S.-based organizations to pull workers out of West Africa because of the Ebola outbreak. Video provided by Newsy
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins