Designing a Monarch habitat?

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  • #14403

    Jacqui
    Keymaster

    Then this report from California will be of interest to you.

    https://www.monarch.org.nz/2010/08/15/monarch-habitat/stevensandfrey/

    ;

    To add to this, according to Paul Cherubini in California, the authors claim "moisture regimes act as a strong bottom-up driver of monarch abundance pattern via resource availability in western USA" and that years with above normal Jan-Sept rainfall produce higher subsequent numbers of monarchs at the overwintering sites.

    However, the worst drought in California history occurred between 1987- late 1991 and monarch numbers peaked during the dryest period of that drought (peaked in 1989, 1990 and 1991). Then ironically the monarch population crashed in mid-late summer of 1992 despite abundant rains during the preceding wintering and spring.

    And this year, we are not seeing a major boom in monarch

    abundance despite above the normal rainfall last winter and spring and relative cool to average temperatures this past spring and summer.

    It’s interesting – wish someone would do some research on why our Monarch population crashed last year. HOPEFULLY things will rectify themselves this summer… ROLL ON SUMMER.

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  • #25043

    Anonymous

    Hi,

    To help clarify a few points from above. In the discussion part of the above link, there is this quote;

      In terms of monarch breeding habitat, drought reduces milkweed germination, survivorship, growth, and seed production. Bell showed that supplemental water provided to milkweed (A. eriocarpa) in a seasonally dry western habitat resulted in longer growing seasons for the plants, which enhanced the survival and development rates of monarch larvae that fed on them. This suggests that increased moisture availability translates into higher host plant availability, which in turn yields larger wintering monarch populations. Water availability can also cause changes in plant properties, such as latex concentration, that can affect larval performance. Milkweed plants with low water availability often have more viscous latex which can make leaf eating more difficult for larvae, which may lead to declines in larval survival.

    .

    This makes sense as poor plant health will lead to poor larval health (just like us eating poor quality food).

    As for our ‘crash’ last year, this in my opiniion is mainly because of the warm late winter (which got things going for a early spring), then the temps dropped & the rain started. This will knock-back the plants & insects as the environment becomes too hostile. Hence, the Monarchs had a very poor start to the spring & never really caught up to ‘normal’.

    Presently the weather is following a similar pattern as last year, so the spring may not be so great. This will be bad news for Insects if it happens. Time will tell.

    Robert.

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