Tuesday, September 18, 2018

Monarch Watch Speaks Out About Raising Monarchs at Home

The discussion regarding raising monarchs in the home continues, with Monarch Watch weighing in today about their position on the practice. Dr. Orley "Chip" Taylor, founder of Monarch Watch, and one of the most knowledgeable people on the planet in regard to monarchs, felt compelled to release this statement, which should be of comfort to those who choose to raise monarchs:

Date: Tue, 18 Sep 2018 16:51:02
From: "Taylor Jr, Orley R"
Subject: Rethinking captive rearing

Greetings: I wasn't going to comment publicly on the captive rearing issue. However, since some of you rear monarchs, and Emma Pelton has chosen to post the Xerces [Society] position on our Monarch Watch discussion list, I feel compelled to articulate our position at Monarch Watch along with the reasoning we use to justify our position. For those of you that don't know, the position adopted by Xerces and MJV [Monarch Joint Venture] has created quite a stir on various Facebook sites and more than one Blog.

Our position at Monarch Watch is that we neither encourage or discourage rearing. As I will try to make clear, this is a low priority issue. Further, the concerns are exaggerated and unsupported by data. 

Facts, Observations, Questions, Tagging and Priorities

Monarch numbers have been declining since the mid 2000s coincident with the adoption of herbicide tolerant crop lines that facilitated the use of glyphosate that all but eliminated milkweed from these row crops.

Habitat loss has been invoked, and supported by data, as the most likely cause of the decline. The alternative hypothesis that the decline is due to an increase in mortality during the migration is unsupported by data.

Habitat loss continues. Estimates are that we are losing 1 million acres of grassland each year and are likely losing at least another million acres due to development and other forms of land conversion.

There is no credible data suggesting that we are restoring habitat for monarchs and pollinators at a rate that matches these losses. In other words, monarchs are losing habitat as we argue about the merits of one detail or another.

Cerro Pelón monarch sanctuary in the state of Mexico, in Central Mexico
February 20, 2018
If my predictions come true, the overwintering population in Mexico will be approximately 5 hectares - maybe more. That translates to at least 60 million monarchs. This will be the largest population since 2008 and may be the last big population for another decade and maybe ever due to changing spring conditions in Texas and higher temperature in May and early June. If you remember the conditions during 2012, those are in our future and it's those conditions that were the precursor to the low monarch return in the spring of 2013 and the alarmingly low population (.67 hectares) that winter.

Monarch larval monitoring and other studies show that 98% of all eggs and larvae succumb to predators or other conditions. 


Most of those advocating the reduction and even the cessation of all rearing are not engaged in monarch rearing. Those doing the rearing are being told that what they are doing will have negative consequences for the population. These admonitions are supported by strongly worded opinions and references to conditions that do not apply to the average person rearing monarchs, e.g. the argument about inbreeding and genetic declines. 

While there are lots of data that show that LONG TERM cultures of various species often lose fitness, this argument DOES NOT apply to those who simply collect eggs and caterpillars in their gardens or along roadsides or even those who breed monarchs for 1-2 generations. In fact, it's not even clear that it applies to monarchs. 

How many breeders maintain long term inbreed cultures? We don't know. 
How often do breeders refresh their stocks? We don't know but have been told that "refreshing" stocks is common, mostly from northern states. 
How many breeders rear more than two of three generations per year? We don't know. 

 What does any of that have to do with those who harvest monarch eggs and larvae in their gardens and natural areas for rearing and release? Zero. While many are dismayed by commercial releases of monarchs, it's not prohibited. These "do not rear" directives will not impact commercial releases but they have raised concerns by many lay persons who enjoy rearing monarchs.

Under magnification, Oe spores can be seen as tiny football-
shaped particles among the larger monarch scales that
cover a monarch's body.

The fact that 98% of the monarch immatures are consumed by predators and parasites inspires people to engage in "monarch rescue," that is, harvesting monarch eggs and larvae and rearing them both indoors and outdoors to "save" them from their usual fate. So, is it really a bad thing to do this? What are the risks? 

Yes, the spread of O.e. (Ophryocystis elektroscirrha) could be a risk but that is easy to avoid if the foliage is sanitized before being fed to the larvae. Monarchs to be released could also be checked for O.e. spores and some people do that. Interestingly, we have found that, if you collect all the 5th instar larvae and rear them through indoors, you can suppress the tachinid fly population.

As to whether monarchs should be reared with the goal of increasing the population, the reality is that such efforts are likely to have little or no impact on the overall population. To have a real impact on population growth, monarchs would have to be released in the RIGHT places at the RIGHT times early in the season rather than during the migration.


How many monarchs are reared and released by amateurs relative to the total monarchs in the migration - 40,000 or maybe 60,000? 

We don't know.

Where and when are these monarchs released? Does it make a difference?

I don't have time to elaborate, but the tagging data, as well as the seasonal dynamics, show that the impact associated with the when and where of releases varies greatly across the continent. In short, the outcomes of a thousand monarchs released at three widely (MN, ME, FL) different locations on the same day during the migration are likely to be very different. There are seasonal differences in outcomes as well. 

What happens if O.e. infested adult monarchs are released into the population?

The dangers of O.e. are reasonably clear and infested monarchs should NOT be released at any time. Most of the heavily infested monarchs have a reduced fitness and a low probability of getting to Mexico, let alone returning in the spring. Given that scenario, it's likely that most of the O.e. spores that persist in the population through the winter have been acquired by healthy monarchs through horizontal transfer - that is, the proximity of healthy monarchs to those infested with spores while clustered during the winter or even through contact at roosts through the fall migration. The clear message in these directives is that rearing needs to be conducted in a way that eliminates the release of O.e. infested butterflies.         

Do tagged monarchs have a reduced chance of making it to Mexico?

Tagging may or may not have an impact on whether monarchs get to Mexico. There has never been a fair test. If tagged and wild monarchs of the same age, sex and size distributions were released at the same date and same place, we could determine whether tagging impacted the ability to get to Mexico. (Assuming also that the monarchs were tagged according to our instructions).

Tropical milkweed
Asclepias curassavica
What we do know is that lots of reared and tagged monarchs make it to Mexico some having fed on non-native milkweeds such as Calotropis procera and C. gigantea (both species of giant milkweed) and the much maligned Asclepias curassavica (tropical milkweed).

Irrespective of the potential impact of tagging, the data from reared monarchs is quite valuable. Like the data from wild tagged monarchs, it tells us a great deal about the migration - the timing, the pace and the probability of reaching Mexico based on sex, geographic origins and date of tagging.

Further, the recovery of reared monarchs can be used as a control for isotope studies.

Given the habitat losses due to agricultural practices and the continuing loss of habitat, what should our priorities be if our goal is to sustain the monarch migration?

Habitat restoration has to be the number 1 priority. The "All hands on Deck" analysis indicated that we need to re-establish at least 1 BILLION milkweed stems mostly in the Upper Midwest to return the monarch numbers to an average of close to 6 hectares at the overwintering sites. That figure is based on an extinction analysis - that is, the probability of losing the migration due to a series of catastrophic events such as the winter storm of 2002 and 2004. That analysis was conservative in that the projections could only be made using past data and inferences based on those conditions. 

Unfortunately, conditions are changing and if the projections based on climate models come true, and that seems likely, the need to restore habitat is even greater than estimated. 

We have work to do and we need all hands on deck and that means that we need everyone who can to pitch in in any way they can. 

We need people to pass on their enthusiasm for monarchs and their concern for maintaining the migration.         

Should rearing be conducted with the goal of increasing the wild population?

Again, to be clear, at Monarch Watch we neither encourage nor discourage monarch rearing. Looking a the monarch population holistically - and from the standpoint of the year-to-year dynamics of a population that is governed largely by both temperatures, and other weather-related phenomena, as well as habitat limitations, rearing is a minor issue. 


Orley R. "Chip" Taylor [chip@ku.edu]
Founder and Director of Monarch Watch; Professor Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS.
Trained as an insect ecologist, Chip Taylor has published papers on species assemblages, hybridization, reproductive biology, population dynamics and plant demographics and pollination. Starting in 1974, Chip Taylor established research sites and directed students studying Neotropical African honey bees (killer bees) in French Guiana, Venezuela, and Mexico.

In 1992, Taylor founded Monarch Watch, an outreach program focused on education, research and conservation relative to monarch butterflies. Since then, Monarch Watch has enlisted the help of volunteers to tag monarchs during the fall migration. This program has produced many new insights into the dynamics of the monarch migration. 

In 2005 Monarch Watch created the Monarch Waystation program, in recognition that habitats for monarchs are declining at a rate of 6,000 acres a day in the United States. The goal of this program is to inspire the public, schools and others to create habitats for monarch butterflies and to assist Monarch Watch in educating the public about the decline in resources for monarchs, pollinators and all wildlife that share the same habitats.

***I have formatted the information provided by Monarch Watch to make it easier to read and have provided some emphasis to some words and phrases. The text provided here is accurate, and is what Monarch Watch issued, with no other changes.


Unknown said...

Excellent information! As Manager of a learning center at a major garden center in the upper midwest, I will do my best to share Dr. Taylor's message. Thank you for posting this!

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