Difference between NZ and Nth American Monarchs

This topic contains 2 replies, has 3 voices, and was last updated by  Jacqui 1 year, 6 months ago.

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  • #52696

    splayford
    Participant

    Canadian and Nth American Monarchs travel 3000 Miles to Mexico and live over the winter before mating and dying. Why do Monarchs in NZ have such a short life in comparison?

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  • #52699

    Jacqui
    Moderator

    Hello S Playford

    With the onset of winter monarchs go into diapause. This means that although they’re sexually mature, they won’t breed until the weather warms/day length gets longer.

    It never gets cold enough in New Zealand for the monarchs to need to travel far – there are overwintering sites in Timaru, Oamaru, Christchurch and others further north (I won’t rattle them off here, as I might miss one…) Sometimes diapause occurs in March or April – in some parts of NZ it’s June… and then it can get warm enough for them to return to breeding in September.

    So it’s not a matter of having a shorter lifespan – it’s just that it’s not necessary. They don’t need to travel the long distance to find the perfect overwintering climate/location – and the winter isn’t long enough.

    #52697

    Terry
    Participant

    The answer is climate and migration triggers. The Monarch danaus plexippus are basically the same wherever they occur on the planet. I was given a couple of old tatty mated female monarchs back in the late 1990s from the old London Butterfly House. Origin; Tropical Asia. However the offspring adapted quickly to conditions in a cooler environment. My butterfly house in the UK is not heated properly in the winter and only enough to keep hard frosts at bay but the Autumn Butterflies still acted as they would in North America and the cooler autumn weather prompted them to stop breeding and seek places to roost together (obviously they couldn’t migrate being captive). They chose my lemon tree and would only awaken on warmer days during the winter and fly down to drink nectar before roosting again for the cold nights (as low as 0c). In the spring the longer days and higher temperatures triggered pairing and breeding again so behaviour was different to living in constant tropical weather and shows the triggers are built in to the DNA of this species thus proving why it is so adaptive and widespread worldwide.
    Don’t forget also that autumn generation Monarchs in New Zealand live longer because they are not as active and spend most of the time roosting except in warmer spots where some will keep breeding. Breeding uses more energy and in the summer months the monarchs are basically busier with longer day lengths and shorter nights.

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