{"id":347792,"date":"2024-10-20T09:17:09","date_gmt":"2024-10-20T07:17:09","guid":{"rendered":"https:\/\/climatescience.press\/?p=347792"},"modified":"2024-10-20T09:17:11","modified_gmt":"2024-10-20T07:17:11","slug":"monarch-butterflies-a-new-mystery-unfolds","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=347792","title":{"rendered":"Monarch Butterflies: a New Mystery Unfolds"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" width=\"723\" height=\"501\" data-attachment-id=\"347802\" data-permalink=\"https:\/\/climatescience.press\/?attachment_id=347802\" data-orig-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?fit=1600%2C1110&amp;ssl=1\" data-orig-size=\"1600,1110\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"0monarch-butterfly-flowers-bush\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?fit=723%2C501&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=723%2C501&#038;ssl=1\" alt=\"\" class=\"wp-image-347802\" srcset=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=1024%2C710&amp;ssl=1 1024w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=300%2C208&amp;ssl=1 300w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=768%2C533&amp;ssl=1 768w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=1536%2C1066&amp;ssl=1 1536w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?resize=1200%2C833&amp;ssl=1 1200w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?w=1600&amp;ssl=1 1600w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?w=1446&amp;ssl=1 1446w\" sizes=\"auto, (max-width: 723px) 100vw, 723px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">From <a href=\"https:\/\/wattsupwiththat.com\/2024\/10\/18\/monarch-butterflies-a-new-mystery-unfolds\/\">Watts Up With That?<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Guest Essay by <a href=\"https:\/\/wattsupwiththat.com\/author\/kiphansen2\/\">Kip Hansen<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The marvelous mysterious Monarch Butterfly is at it again:&nbsp; baffling lepidopterists \u2014 a branch of&nbsp;<a href=\"https:\/\/en.wikipedia.org\/wiki\/Entomology\">entomology<\/a>&nbsp;concerning the scientific study of moths and the two superfamilies of&nbsp;<a href=\"https:\/\/en.wikipedia.org\/wiki\/Butterfly\">butterflies<\/a>&nbsp;\u2014 with questions they can\u2019t answer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-e487823c-9155-427d-8fd2-e9e7707dd4df\">The observational evidence is this:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-740ce635-e632-48fc-ac65-755870cdbb33\"><strong><em>It is clear that&nbsp;<\/em>[Monarch]<em>&nbsp;winter colonies in Mexico are declining, yet some recent studies suggest that summer breeding populations are relatively stable and similar to historical abundances.<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-01d8dd5b-3e68-4a5d-aa73-93c786c47e84\">Here they are speaking of the Eastern United States Monarch population \u2014 the Monarch population that migrates from as far north as Canada every fall south to the mountains of central Mexico.&nbsp; If your are not already familiar with the mysterious nature of this phenomenon, read my&nbsp;<strong><a href=\"https:\/\/wattsupwiththat.com\/2019\/02\/14\/the-marvelous-and-mysterious-monarch\/\" target=\"_blank\" rel=\"noreferrer noopener\">primer on the Monarch Migration<\/a><\/strong>&nbsp;or any of&nbsp;<a href=\"https:\/\/wattsupwiththat.com\/?s=%22by+Kip+Hansen%22++Monarchs\" target=\"_blank\" rel=\"noreferrer noopener\">my earlier Monarch essays here<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-d27706c7-9447-4a10-afcb-584954c58339\">There exists a modern scientific controversy about the monarchs and their migration \u2013 such a big hullabaloo that I have named it&nbsp;<a href=\"https:\/\/wattsupwiththat.com\/?s=%22by+Kip+Hansen%22++The+Monarch+Wars\" target=\"_blank\" rel=\"noreferrer noopener\">The Monarch Wars<\/a>. &nbsp;&nbsp;The basis of the Monarch Wars is:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-72dda19d-d1ec-4831-b08b-befbff44f750\">1)&nbsp; Some governmental agencies, scientists and activist groups want to declare the Monarch Butterfly, or one of its two Northern Hemisphere populations, as an&nbsp;<a href=\"https:\/\/www.epa.gov\/laws-regulations\/summary-endangered-species-act\" target=\"_blank\" rel=\"noreferrer noopener\">Endangered Species<\/a>.&nbsp; In 2022, the U.S. Fish and Wildlife Service \u201cdetermined that&nbsp;<a href=\"https:\/\/www.govinfo.gov\/content\/pkg\/FR-2020-12-17\/pdf\/2020-27523.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">listing the monarch under the Endangered Species Act is warranted&nbsp;<strong>but precluded<\/strong><\/a>&nbsp;<strong>at this time<\/strong>&nbsp;by higher priority listing actions.\u201d&nbsp; The IUCN&nbsp;<em>unilaterally<\/em>&nbsp;declared the Monarch Endangered and in 2022&nbsp;<a href=\"https:\/\/iucn.org\/press-release\/202207\/migratory-monarch-butterfly-now-endangered-iucn-red-list\" target=\"_blank\" rel=\"noreferrer noopener\">added it to the IUCN Red List as Endangered<\/a>.&nbsp; However, IUCN then&nbsp;<a href=\"https:\/\/texasbutterflyranch.com\/2023\/09\/30\/iucn-revises-listing-of-monarch-butterfly-from-endangered-to-vulnerable\/\">deli<\/a><a href=\"https:\/\/texasbutterflyranch.com\/2023\/09\/30\/iucn-revises-listing-of-monarch-butterfly-from-endangered-to-vulnerable\/\" target=\"_blank\" rel=\"noreferrer noopener\">s<\/a><a href=\"https:\/\/texasbutterflyranch.com\/2023\/09\/30\/iucn-revises-listing-of-monarch-butterfly-from-endangered-to-vulnerable\/\">ted monarchs in 2023<\/a>, declaring them only \u201cVulnerable\u201d.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-52d596cc-10bb-429c-bd5c-2aa7ece44f67\">2)&nbsp; Other scientists, groups and interests oppose the listing of this nearly ubiquitous species as endangered \u2013 showing evidence that it is not suffering population declines or fragmented populations.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-fae4b1d3-9e58-4f07-8c17-c88f647c50cd\">3)&nbsp; There is a third view that proposes that the Monarch Migration itself, as a phenomenon, should be declared Endangered.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-0949dd94-c596-4fff-9b14-ffe4162f88be\">The evidence is unfortunately clear \u2014 for&nbsp;<strong>all sides<\/strong>&nbsp;in the controversy.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-814c074b-ca58-430f-80fc-a744d09ff9b6\"><strong>How is this possible?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-abc44ce0-02f4-45be-8c49-4a0b822ec810\">The latest study is:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-0775523c-46a4-4a0d-9117-808180ecb6e4\"><strong><em>Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration&nbsp;<\/em><\/strong>[&nbsp;<a href=\"https:\/\/www.preprints.org\/manuscript\/202405.1630\/v1\/download\">full pre-p<\/a><a href=\"https:\/\/www.preprints.org\/manuscript\/202405.1630\/v1\/download\" target=\"_blank\" rel=\"noreferrer noopener\">r<\/a><a href=\"https:\/\/www.preprints.org\/manuscript\/202405.1630\/v1\/download\">int .pdf<\/a>&nbsp;]<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-9d61ea3e-0101-4ea4-888c-824156b6d6d1\">by Andrew K. Davis, Jordan R. Croy and William E. Snyder out of the University of Georgia in Athens, GA, USA.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-d12e17e2-08d5-4c7d-8cf3-9cb3ab21de32\">Their Abstract starts with this line:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-e3be3ac6-8e34-402e-bbc5-e99f503fc091\"><strong>\u201cThe conservation status of monarch butterflies in North America is a topic of intense scrutiny and debate.\u201d<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-fe767939-e0a4-42b3-9c44-3afc0f8c72d9\">For several years I have been calling this&nbsp;<em>The Monarch Wars<\/em>.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-f0b93f23-9a80-4b17-b285-435f21111ee9\">Let\u2019s look at the evidence once more:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-b4834cb6-47f7-47c5-af61-fb3147c8047f\">\u201cIt is clear that winter colonies in Mexico are declining\u201d<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"487\" data-attachment-id=\"347795\" data-permalink=\"https:\/\/climatescience.press\/?attachment_id=347795\" data-orig-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-483.png?fit=720%2C487&amp;ssl=1\" data-orig-size=\"720,487\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"image\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-483.png?fit=720%2C487&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-483.png?resize=720%2C487&#038;ssl=1\" alt=\"\" class=\"wp-image-347795\" srcset=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-483.png?w=720&amp;ssl=1 720w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-483.png?resize=300%2C203&amp;ssl=1 300w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\" id=\"block-980ba1fe-c97d-4e5e-b18e-42f8b3a3bb41\">Clearly&nbsp;<strong>winter colonies<\/strong>&nbsp;in Mexico are declining \u2013 in the first 20 years of the record, there were some boom years and some low years, less than 5 hectares, but the entire two decades show much larger roosting populations.&nbsp; The most recent decade has had very low roosting numbers.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-4e4230f9-3ce3-40a2-b421-52363f7d8204\">And&nbsp;<strong>Summer Populations?<\/strong><\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"610\" data-attachment-id=\"347797\" data-permalink=\"https:\/\/climatescience.press\/?attachment_id=347797\" data-orig-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-485.png?fit=720%2C610&amp;ssl=1\" data-orig-size=\"720,610\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"image\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-485.png?fit=720%2C610&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-485.png?resize=720%2C610&#038;ssl=1\" alt=\"\" class=\"wp-image-347797\" srcset=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-485.png?w=720&amp;ssl=1 720w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-485.png?resize=300%2C254&amp;ssl=1 300w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\" id=\"block-c6ddf135-2608-4b13-970c-4f35265a5ded\">The above image, from&nbsp;<em>Crossley et al. (2022)<\/em>&nbsp;&nbsp;published in&nbsp;<em><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/full\/10.1111\/gcb.16282\" target=\"_blank\" rel=\"noreferrer noopener\">Global Change Biology<\/a>&nbsp;<\/em>&nbsp;clearly shows that the summer population of&nbsp;<em>Danaus plexippus,&nbsp;<\/em>the Monarch Butterfly, seen as the vertical orange line, has&nbsp;<strong>not shown radical declines<\/strong>&nbsp;over the last two decades, but, if anything, &nbsp;shows a&nbsp;<strong>slight increase&nbsp;<\/strong>of about 0.7% per year. Not a big increase, but certainly not a sharp, dangerous or worrying decline.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-0e709bef-e9de-47fd-85a6-996b6fa3d1a2\">[Note:&nbsp; The Mexico overwintering population graph covers three more years than the summer Population study.&nbsp; Those three years were boom years for the overwintering population.]<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-4535a817-b13a-4ecb-a46f-526c0acec2e6\">The most recent study, Davis et al. (2024) is about the sizes of Monarch roosts that they form during their migration south, when they stop for the night.&nbsp;&nbsp; Davis et al. say:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-21f5d9aa-2c1c-44c6-8a70-9ae54cce5458\"><em>\u201cObservations of far fewer overwintering monarch butterflies, alongside apparent rebounds during the summer breeding season, have led to heated debate whether monarchs are truly endangered. We used ~2600 citizen scientist observations of monarch \u201croosts\u201d \u2013 mass aggregations of fall-migrating monarchs \u2013 to assess whether they are struggling to reach Mexico.\u201d<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-3f5234b2-c08c-4735-8f95-aa6cad78c802\">And this is an important and interesting question.&nbsp;&nbsp;<em>Are there plenty of monarchs in the summer which then fail to reach the overwintering grounds in Mexico, and if so, for what reasons?<\/em>&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-0fda711f-c04b-4772-bf60-b631e90c5fc3\">Their plain language summary:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-562bde3f-a869-435b-8abd-20c5e17746d5\"><em>\u201cPositive effects of a warming and greening flyway were overwhelmed by unexplained declines in roost size of up to 80%, increasing all along the path of their arduous southern migration.\u201d<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-63d1a0f6-3cf8-4d21-822d-4644c5764a3e\">They find that \u201c<em>a warming and greening flyway\u201d&nbsp;<\/em>\u2014 and feel free to label this CO2-enhanced atmosphere and maybe climate change \u2014 had&nbsp;<strong>positive effects<\/strong>&nbsp;on the annual migration.&nbsp; Yet there remained \u201c<em>unexplained declines in&nbsp;<\/em>[in during-migration]&nbsp;<em>roost size of up to 80%\u201d,&nbsp;<\/em>declines which increased along the southern route.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-4d0b0445-bfd8-450c-bda1-d20dd7d29db3\">To this author\u2019s dismay, they conclude:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-5406b088-8658-48ba-9602-9049122b00e0\"><em>\u201cThis suggests that to save monarchs, we should focus on avoiding well-meaning efforts such as planting non-native milkweeds that foster parasites, sicken monarchs, and disrupt migration.\u201d<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-955bdbc0-f82a-4dad-9a58-78be52532b77\">I do not think that that conclusion is warranted or supported based on the evidence of the study.&nbsp; It is a valid hypothesis \u2013 a possible explanation \u2013 but certainly not strongly supported.&nbsp; Like all hypotheses, it is a guess, based on some data.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-0d2fd001-0b95-40d2-b14a-956934f71ee9\">They are correct when they say&nbsp;<em>\u201cThis suggests that climate change might generally be benefiting monarch migration by creating milder flight conditions and enhancing nectar availability along the flyway (but see 24).\u201d<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-9453e94a-61bb-477d-9fa3-76797c82ae6d\">Ah, yes, there is a&nbsp;<em>but.&nbsp;&nbsp;<a href=\"https:\/\/journals.biologists.com\/jeb\/article\/226\/21\/jeb245296\/334654\" target=\"_blank\" rel=\"noreferrer noopener\">You can read the but here<\/a>.&nbsp;<\/em>It is a complex calculation of \u201cenergy expenditure\u201d that might be found true of migrating monarch butterflies under warmer temperatures, not of real &nbsp;butterflies actually migrating, of course.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-19f02ca9-041d-4ce0-b7b0-46b5825a08a7\">The reasoning of Davis et al. goes like this:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-1df52806-54d1-4fd5-a535-4cd0cb6287ac\">\u201c<em>That is, while roost sizes were declining throughout the flyway, these declines grew increasingly severe further along the migration route. This latitudinal gradient in roost size declines would be consistent with increasing mortality during migration and\/or monarchs increasingly abandoning migration as they move south. This apparent disruption of migration might be the missing puzzle piece that explains relatively stable summer populations in the Midwest and declining overwintering populations in Mexico<\/em>.\u201d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-af25ccc3-4ba1-40b1-8387-b0582b434fd7\">Alas, Davis et al., despite being a very well done investigation, &nbsp;offers no definitive or actionable findings.&nbsp;&nbsp;<em>\u201cThen what is driving the clear, dramatic declines in roost size seen in these data? We can only speculate,\u2026\u201d.<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-4ebaba9e-7a74-46ae-88c4-9a644cad3034\">And speculate they do. While none of the speculations are new, they include:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-c0a01f46-35cc-467f-a118-8daece96c16d\">1) Prevalence of the monarch parasite&nbsp;<em>Ophryocystis elektroscirrha&nbsp;<\/em>(\u201cOE\u201d) which has increased over the last decade, some say \u201cten-fold\u201d.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-b766b0bc-46fa-43f2-a33d-68678c1bf76a\">2) The widespread planting of non-native milkweeds such as&nbsp;<em>Asclepias curassavica<\/em>&nbsp;and&nbsp;<em>Calotropis gigantea<\/em>&nbsp;by homeowners and even land managers. Some feel that this leads to more parasitisation. There have been some studies that suggested that monarch caterpillars feeding on these species might suffer stunting or weakening. &nbsp;&nbsp;Or that the longer growing season for these species might lure the monarchs to remain north later into the Fall.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-015742be-266b-4097-a53a-8f387e12dcff\">3) The raising and releasing thousands of captive-reared monarchs each year.&nbsp; Some studies have implied that captive bred monarchs are weaker or have reduced navigational ability.&nbsp; There are worries that interbreeding of captive and wild monarchs will harm the species as a whole.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-680787a8-bd16-448c-b8aa-03067e6f98dc\">4)&nbsp; Finally, year-round resident populations of monarchs appear to be increasingly common and growing along the western and southern edges of the species range.&nbsp; Vague worries about interbreeding of non-migrating monarchs and migrating monarchs and thus genetic dilution are included.&nbsp; This is the \u201cmonarchs increasingly abandoning migration as they move south\u201d hypothesis. Another possibility is that more-and-more monarchs migrate to the South, find it perfectly suitable, and settle down there for the winters.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-1f6bff76-8b1e-4bb8-aba2-4a0cfff9994d\">All, as in every single one, of the monarch butterflies found in northern regions, &nbsp;where winters are freezing and below, are the offspring of monarchs that have migrated north from overwintering somewhere warmer in the south.&nbsp; Thus, stable or even growing summer populations in the north seems inconsistent with very small numbers of monarchs overwintering in Mexico. Yet it is the case.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-5f37339a-7f17-4f09-ab36-ffd7f5133191\"><strong>West Coast Monarchs<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"block-e09d104d-6527-43a5-a746-ffca031d2273\">A similar, but more profound, situation was found with the West Coast monarch population in the winters of 2020-2021 and into the next year, 2021-2022:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" width=\"720\" height=\"434\" data-attachment-id=\"347799\" data-permalink=\"https:\/\/climatescience.press\/?attachment_id=347799\" data-orig-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-487.png?fit=720%2C434&amp;ssl=1\" data-orig-size=\"720,434\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"image\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-487.png?fit=720%2C434&amp;ssl=1\" src=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-487.png?resize=720%2C434&#038;ssl=1\" alt=\"\" class=\"wp-image-347799\" srcset=\"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-487.png?w=720&amp;ssl=1 720w, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/image-487.png?resize=300%2C181&amp;ssl=1 300w\" sizes=\"auto, (max-width: 720px) 100vw, 720px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\" id=\"block-9cef023c-6c34-4c6d-a825-083df57967cc\">You see, that recovery is simply biologically impossible.&nbsp; Thus a mangled version of the Sherlock Holmes quote can be applied: \u201cWhen you have eliminated the impossible, whatever remains, however improbable, must be the truth\u201d.&nbsp; For that recovery, which is a physical fact, we must eliminate the impossible and doing that requires that&nbsp;<strong>the monarchs were overwintering somewhere&nbsp;<\/strong>\u2013 just not where they were expected and thus uncounted.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is one of the speculative explanations for the mystery of the Eastern Population as well \u2013 the monarchs may be overwintering in Mexico after all, just not at the usual or known locations where they are expected, thus failing to be counted.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><u>Bottom Lines:<\/u><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1)&nbsp; We simply don\u2019t know how or why this situation is occurring:&nbsp; far fewer Monarchs overwintering in Mexico yet stable or even growing population in the summer in the north.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2)&nbsp; There are four or five good speculative answers, but none of them stand out or have stronger evidence.&nbsp; It is more probable that the situation is a&nbsp;<em>combination<\/em>&nbsp;of one or more of the suggested explanations; or the dreaded&nbsp;<em>something else<\/em>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">3)&nbsp; One thing is fairly certain now:&nbsp; the slight warming seen in continental North America over the last 20 years, of maybe 1.5 degrees F, commonly called climate change, is not the cause but rather more likely a mitigating factor benefiting the monarchs.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong># # # # #<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><u>Author\u2019s Comment:<\/u><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In my part of the United States, I saw very few monarchs this last summer.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I am fascinated by the evidence about monarchs and the growing realization that so much of it driven by a \u201cSave the Monarchs\u201d bias.&nbsp; As in almost all fields of science, the desires of researchers lead directly to their findings.&nbsp; Those looking for disasters will find them, as has been the case with the monarchs.&nbsp; But those researchers are stymied by other evidence \u2013 stable summer populations.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In science, the evidence should lead to a proper framing of the situation, which, if it is deemed undesirable, then the evidence should suggest solutions that will correct or mitigate the discovered causes of the undesired situation.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Jumping the gun with solutions to problems for which the causes are only suspected lead us on a merry chase and often make the original problem even worse.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For monarchs, I still favor planting native milkweeds in your gardens (private and public), discouraging mowing of highways verges and the edges and space between corn fields, and, of course, admission that we still don\u2019t understand what is going on with the monarchs which should lead to more and better research.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Thanks for reading.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong># # # # #<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The marvelous mysterious Monarch Butterfly is at it again:  baffling lepidopterists \u2014 a branch of entomology concerning the scientific study of moths and the two superfamilies of butterflies \u2014 with questions they can\u2019t answer.<\/p>\n","protected":false},"author":121246920,"featured_media":347802,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1],"tags":[691820144,691831018,691831019],"class_list":["post-347792","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-mexico","tag-monarch-butterfly","tag-winter-colonies","fallback-thumbnail"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/10\/0monarch-butterfly-flowers-bush.webp?fit=1600%2C1110&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-1sty","jetpack-related-posts":[{"id":287302,"url":"https:\/\/climatescience.press\/?p=287302","url_meta":{"origin":347792,"position":0},"title":"Catching-up on Monarch Butterflies","author":"uwe.roland.gross","date":"11\/09\/2023","format":false,"excerpt":"The large and brilliantly-colored monarch butterfly is among the most easily recognizable of the butterfly species that call North America home. They have two sets of wings and a wingspan of three to four inches (7 to 10 centimeters). Their wings are a deep orange with black borders and veins,\u2026","rel":"","context":"In \"California\"","block_context":{"text":"California","link":"https:\/\/climatescience.press\/?tag=california"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/image-262.png?fit=1200%2C843&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/image-262.png?fit=1200%2C843&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/image-262.png?fit=1200%2C843&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/image-262.png?fit=1200%2C843&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/11\/image-262.png?fit=1200%2C843&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":365912,"url":"https:\/\/climatescience.press\/?p=365912","url_meta":{"origin":347792,"position":1},"title":"The Devastating Ecological Carnage Wrought by Wind Turbines","author":"uwe.roland.gross","date":"02\/12\/2025","format":false,"excerpt":"Evidence continues to grow that onshore wind turbines are causing heavy ecological carnage, with increasing concern focused on the removal of a vast tonnage of insect life. For obvious political, Net Zero reasons, insect decimation is not a well-funded research area, but work in Germany in 2016 put the loss\u2026","rel":"","context":"In \"Alarmism\"","block_context":{"text":"Alarmism","link":"https:\/\/climatescience.press\/?tag=alarmism"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0GettyImages-1166332945.webp?fit=1200%2C800&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0GettyImages-1166332945.webp?fit=1200%2C800&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0GettyImages-1166332945.webp?fit=1200%2C800&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/02\/0GettyImages-1166332945.webp?fit=1200%2C800&ssl=1&resize=700%2C400 2x, 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\"BBC\"","block_context":{"text":"BBC","link":"https:\/\/climatescience.press\/?tag=bbc"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/06\/0stupidity-sign-72d4e5c19709f038.jpg?fit=1200%2C1066&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/06\/0stupidity-sign-72d4e5c19709f038.jpg?fit=1200%2C1066&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/06\/0stupidity-sign-72d4e5c19709f038.jpg?fit=1200%2C1066&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/06\/0stupidity-sign-72d4e5c19709f038.jpg?fit=1200%2C1066&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/06\/0stupidity-sign-72d4e5c19709f038.jpg?fit=1200%2C1066&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":360523,"url":"https:\/\/climatescience.press\/?p=360523","url_meta":{"origin":347792,"position":3},"title":"Modern Scientific Controversies: The War on Food: Part 1","author":"uwe.roland.gross","date":"01\/05\/2025","format":false,"excerpt":"This is a new entry to a series-of-many which have discussed ongoing scientific controversies, a specific type of which are often referred to in the science press and elsewhere as \u201cWars\u201d \u2013 for instance \u00a0The Monarch Wars, The Meat Wars, The Obesity Epidemic, The Salt Wars, The War in Sugar\u2026","rel":"","context":"In \"British Medical Journal (BMJ)\"","block_context":{"text":"British Medical Journal (BMJ)","link":"https:\/\/climatescience.press\/?tag=british-medical-journal-bmj"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/01\/0d4331017934843.562c108350ee7.jpg?fit=1200%2C800&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/01\/0d4331017934843.562c108350ee7.jpg?fit=1200%2C800&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/01\/0d4331017934843.562c108350ee7.jpg?fit=1200%2C800&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/01\/0d4331017934843.562c108350ee7.jpg?fit=1200%2C800&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/01\/0d4331017934843.562c108350ee7.jpg?fit=1200%2C800&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":256545,"url":"https:\/\/climatescience.press\/?p=256545","url_meta":{"origin":347792,"position":4},"title":"Attenborough expects King Charles to continue his activism","author":"uwe.roland.gross","date":"05\/08\/2023","format":false,"excerpt":"Now that Charles is King, it seems the new euphemisms for\u00a0WEF-style totalitarian climate change activism\u00a0is a defence of \u201cenvironmental issues,\u201d \u201cprotecting the natural world,\u201d and \u201cbacking conservation.\u201d","rel":"","context":"In \"Climate change\"","block_context":{"text":"Climate change","link":"https:\/\/climatescience.press\/?tag=climate-change"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/05\/0BBC-Attenborough-interview-screenshot-at-338_5-May-2023.jpg?fit=717%2C405&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/05\/0BBC-Attenborough-interview-screenshot-at-338_5-May-2023.jpg?fit=717%2C405&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/05\/0BBC-Attenborough-interview-screenshot-at-338_5-May-2023.jpg?fit=717%2C405&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/05\/0BBC-Attenborough-interview-screenshot-at-338_5-May-2023.jpg?fit=717%2C405&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":301367,"url":"https:\/\/climatescience.press\/?p=301367","url_meta":{"origin":347792,"position":5},"title":"Weaponizing \u2018The Science\u2019","author":"uwe.roland.gross","date":"02\/11\/2024","format":false,"excerpt":"If a thing, an idea, an opinion, or a consensus is\u00a0contemporary\u00a0is just means it\u00a0\u201cexists now\u201d.\u00a0 The fact that it could or does \u201cexist now\u201d means that it could have been different in the past and might be different in the future.\u00a0","rel":"","context":"In \"consensus\"","block_context":{"text":"consensus","link":"https:\/\/climatescience.press\/?tag=consensus"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/02\/0spaceforce_1280p.jpg?fit=1200%2C676&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/02\/0spaceforce_1280p.jpg?fit=1200%2C676&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2024\/02\/0spaceforce_1280p.jpg?fit=1200%2C676&ssl=1&resize=525%2C300 1.5x, 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