Monarch Butterfly Habitat Loss
Sharon Stichter
Paul Cherubini
> I am a longtime member of the Nature Conservancy, but there is one
> very important conservation issue which I never see mentioned in your
> magazine. I was devastated to read in the New York Times on March 7,
> 2008, of the widespread illegal logging in Mexico which is destroying
> habitat for our beloved Monarch butterfly.
It's not accurate to say the illegal logging is "extensive" and
"devastating" in Mexico. In the overwintering areas of Mexico
there are vastly more trees available (tens of thousands of acres)
for the butterflies to use then there are butterflies available to occupy
them (butterfly colonies are mere pinpoints within these forests)
That's why there has never been a case where logging or forest fires
ever drove the monarchs away from any of the 12 separate
overwintering areas in Mexico.
I believe the overemphasis on overwintering habitat protection
is distracting the American public from appreciating the real
threat - spring and summer breeding habitat deterioration in the USA.
Unlike logging which is a temporary habitat disturbance, runaway
suburban development in the USA has been permanently deminshing
monarch breeding habitat.
In the western USA the overwintering monarch populations over
the past 15 years have declined 70% over what they were in the
60s, 70's and 80's due to development destroying spring and
summer breeding habitats plus factors no one is studying such
as the impact of non-native predators and parasites introduced
from other countries (which might be impacting other widespread
species as well such as Mourning Cloaks and Lorquin's Admirals).
Because the number of fall migrant monarchs in the West has
deminished so much, many California overwintering sites
are not occupied anymore or are only marginally occupied.
So some of the millions of dollars that was poured into
Calif. overwintering site protection in the 80's & 90's has gone
to waste because researchers wrongly assumed maintaining the
abundance and quality of overwintering sites would maintain
the abundance of the monarch butterfly population as a whole.
We need conservation organizations that have the guts
to tell the public they have to make a choice; either start
making sacrfices like buying small homes and cars and
cutting back on roadside alterations like mowing and spraying
or else be willing to accept reduced abundance of monarchs
and other wildlife.
If the eastern monarchs decline in the years ahead then the
Mexicans will be able to correctly claim it is the Americans
who are to blame. The Mexicans could come up here and make a
video documentary of all the ways we permanently destroy
monarch habitat. But the reverse is not true - the Americans
can't make a video documentary showing how logging
in Mexico has caused the butterflies to run out of good
quality forest to form their cluster sites.
Paul Cherubini
Julie Lisk
There seem to be contradictions regarding the conservation status of the
monarch butterfly in the United States and Mexico. None of the comments I
read contained any citations for the source of "facts" presented. I
checked out the website listed below in hopes of sorting out the truth.
While all of us in the U.S. could stand to "lighten our footprint" on this
lovely land, according to the infomation on www.natureserve.org, it does
not suggest that at this time that loss of breeding habitat in the U.S. is
a primary cause for alarm, however, turtles on the other hand.......
Julie Lisk
Groton, MA
http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Danaus%20plexippus
NatureServe Status
Global Status: G5
Global Status Last Reviewed: 24Nov2003
Global Status Last Changed: 24Nov2003
Rounded Global Status: G5 - Secure
Reasons:
Species is considered globally secure. However, the North American
populations do face serious threats to their obligate overwintering areas.
Note this document (EGR) is actually for the wintering sites because the
wintering population is restricted to a few dozen sites; the overwintering
habitat is limited and under developmental and agricultual pressures. Loss
of these few sites would probably eliminate the North American populations.
Nation: United States
National Status: N5B,N2N3N (10Feb2003)
Nation: Canada
National Status:N4N5B (10Feb2003)
Degree of Threat: B
Threats: Overwintering habitat coming under pressure from logging,
agricultural development and urban development.
Fragility Comments: Sensitive to alterations in air temperature and
humidity, caused by logging and development activities at wintering sites in
Mexico.
Other Considerations: Elimination of Mexican sites would mean virtual
extinction of eastern North American populations. Nearly all western
individuals have been thought to winter in California, but some of these
also go to Mexico. This species has become a significant ecotourism resource
locally in Mexico.
Neil Jones
----- Original Message -----
From: "Julie Lisk" <jal...@charter.net>
To: <mon...@saber.net>; "MassLep" <Mas...@googlegroups.com>
Sent: Sunday, March 16, 2008 5:03 PM
Subject: [MassLep] Re: Monarch Butterfly Habitat Loss
>
> Greetings All,
>
> There seem to be contradictions regarding the conservation status of the
> monarch butterfly in the United States and Mexico. None of the comments I
> read contained any citations for the source of "facts" presented. I
> checked out the website listed below in hopes of sorting out the truth.
> While all of us in the U.S. could stand to "lighten our footprint" on this
> lovely land, according to the infomation on www.natureserve.org, it does
> not suggest that at this time that loss of breeding habitat in the U.S.
is
> a primary cause for alarm, however, turtles on the other hand.......
>
> Julie Lisk
> Groton, MA
>
Both factors are important., but what you must realise is that the monarch
colonies in Mexico
are the really vulnerable link. There is a smallis hand vital area there
that the whole migration
east of the Rockies depends on. Loose those roosts and you loose the
migration as it currently is.
If anyone wants to know more about the dangers caused by the thining of the
forests in Mexico
I'd suggest as a start this paper.
JB ANDERSON, LP BROWER - Ecological entomology, 1996.
This is the abstract.
1. At their high-altitude overwintering sites in Mexico, monarch butterflies
frequently are subjected to sub-zero°C temperatures during December-March.
Although monarchs have moderate supercooling ability, two ecological factors
strongly influence their capacity to resist freezing : wetting and exposure
to the clear night sky.
2. As shown in Fig. 2, 50% of a population of butterflies with water on
their body surfaces freeze at warmer sub-zero temperatures (-4.2°C) compared
to butterflies with no water on their bodies (-7.7°C). 100% mortality
occurs, respectively, at -7.7°C and -15°C.
3. Comparative measurements of rainfall within a large overwintering colony
in Mexico indicated that the intact canopy acts as an umbrella that reduces
butterfly wetting during winter storms.
4. Variable experimental exposure of butterflies to the clear night sky
indicated that openings in the forest canopy increases radiational cooling
and causes monarch body temperatures to drop as much as 4°C below ambient
air temperature. Monarchs under dense cover had body temperatures
approximately the same as the ambient air temperature, but more exposed
individuals had body temperatures below ambient in direct proportion to the
degree of exposure. Consequently, forest thinning increases the probability
that the butterflies will freeze to death.
5. Whereas both wetting and exposure are increased by disturbance of the
forest canopy, the interaction of these two factors exacerbates freezing
mortality during winter storms : 50% of dry and unexposed butterflies froze
at -8°C, whereas wetted and fully exposed butterflies froze at only -0.5°C
. 6. Butterflies inside and on the bottom of the fir bough clusters are
better protected from wetting than those on the outside. This supports the
hypothesis that the structure of the butterfly clusters has evolved through
individual selection to avoid wetting.
7. The data strongly reinforce previous evidence that forest thinning
should be totally prevented within and adjacent to the overwintering sites
in order to minimize both wetting and exposure of the butterflies that
synergistically increase winter mortality at the overwintering sites in
Mexico.
Paul Cherubini
> Threats: Overwintering habitat coming under pressure from logging,
> agricultural development and urban development.
Julie, unfortunately the "facts" presented by www.natureserve.org
do not tell the whole story.
Example: The overwintering habitats in Mexico are not under
pressure from urban development because the region is a rural
farm area where the human population is growing slowly (most
young people migrate to the big cities to find employment). So
are no housing subdivisions or shopping centers being built up on
mountainsides. Examples:
A panoramic view of 3 overwintering colony areas to the north of
Zitacuaro, Michoacan:
http://i85.photobucket.com/albums/k75/4af/zitapan.jpg
A landscape view of the Herrada colony area:
http://i85.photobucket.com/albums/k75/4af/herrada-1.jpg
A landscape view of the Chincua colony area:
http://i85.photobucket.com/albums/k75/4af/chinfirea.jpg
The overwintering habitats in Mexico are also not under alot
of pressure from agricultural development because it's too cold
to grow crops at the altitude where the butterflies overwinter
(10,200 - 10,800 feet). In one case, on a warm south slope,
crops are grown in the summer months up to the edge of
where the butterflies overwinter:
http://i5.photobucket.com/albums/y189/mastertech/9005.jpg
But in winter these open fields provide the butterflies with
water and nectar so one could argue they are beneficial to
the butterflies:
http://i5.photobucket.com/albums/y189/mastertech/elrmea.jpg
http://i85.photobucket.com/albums/k75/4af/elrosnecb.jpg
Illegal logging pressures on the butterflies have been minimal
because the logging has almost always occurred well away
from butterfly cluster areas. In the few exceptions when the
logging was in or near a cluster area the butterflies relocated
their colony to the thousands of acres of available
adjacent forest, just as they have done in the past when
forest fires have burnt out of couple cluster areas.
Paul Cherubini
pavu...@aol.com
Elimination of Mexican sites would mean virtual extinction of eastern North American populations.
>>
I challenge the statement with this: IF all the Mexican sanctuaries were to suddenly be cut down to the stump, the Monarchs would move elsewhere. At first, there would likely be considable mortality, and the migration would dwindle to alarming levels. But the species could eventually adapt to new (probably less-optimum) sites. We don't even know for sure if there are other overwintering sites. Perhaps they'd move further south or select sites further north. Many have theorized that there may yet be unknown sites in Cuba or other parts of Central America.
Should there be no alternate sites in Central America, the east coast migration may even then not be doomed. We know that Monarchs can overwinter as far north as Virginia Beach during mild winters and apparently do so during most winters along the Carolina Coast. According to my daughter, they hang around her college campus in Sarasota all winter but are not seen there at other times of year. Supposedly Florida is a genetic "sink" in that they don't have that impetus to migrate back north, but perhaps they DO move out of Florida in some numbers.
I'd take ALL sides with caution. Always question. Many people disagree with Paul Cherubini but at least he's published considerable photos to show that the situation is not as bad as claimed. Paul does cite sources. Do I believe him? I can't say yes or no because I've never been down to the Mexican Monarch sites. Regardless, I want to hear all sides of the issue, all voices.
Say, isn't it time to start with local observations?
Harry Pavulaan
-----Original Message-----
From: Julie Lisk <jal...@charter.net>
To: mon...@saber.net; MassLep <Mas...@googlegroups.com>
Sent: Sun, 16 Mar 2008 1:03 pm
Subject: [MassLep] Re: Monarch Butterfly Habitat Loss
Planning your summer road trip? Check out AOL Travel Guides.
Tom Murray
Thanks for posting this well thought out and fact based assessment of a worst case scenario for the monarchs in Mexico. Hopefully it'll never get that bad, and we won't have to see how well these monarchs can adapt.
I agree we should take ALL sides with caution, always question, and keep it civil.
Unfortunately Julie isn't getting your posting. She unsubscribed to Maslep after receiving this email:
"Julie;
>
> I think most of the points Paul Cherubini (and many others) have made
> demonstrate some very valid issues regarding the total Monarch situation.
> As
> for "credible scientific literature" on this subject, I haven't seen any
> from you either. At least Paul has been to the overwintering sites in
> Mexico.
>
> But, more to the point, the Mass Leps List is NOT a forum for personal
> attacks or muck-racking so, I for one, would be happy NOT, to here from
> you
> again.
>
> Don Adams
>
> CC: Andrew Birch - List Moderator"
Tom Murray
Groton, Ma.