Friday, 30 January 2015

January Wildlife Report

The Blue Swarms of Summer


Above: Blue Blubber swarm off Surfers Paradise. Photo by Grahame Long.
Below: Blue Tiger, Ferny Hills.

South-east Queensland has had a wet, warm and humid start to 2015, receiving twice the average amount of monthly rainfall for this time of year. A well-nourished landscape is currently allowing our wildlife to flourish; a casual walk in a National Park, suburban reserve or even your own garden will reveal huge numbers of insects, birds, reptiles and frogs.

Australia offers a harsh environment for our wildlife to live in, so when conditions become as favourable as they are right now, some species seize the opportunity in a very noticeable way. Earlier this month, I had several people contact me on one particular weekend to enquire about the huge numbers of butterflies they were seeing in Brisbane's suburbs. The species I believe they were referring to - and that I saw myself - is the Blue Tiger (Tirumala hamata). This is a tropical species that visits South-east Queensland each summer and is regarded by the Queensland Museum as uncommon in a normal year. Excessively wet and warm summers foster abundant vegetation growth however, and during these times, Blue Tigers undergo a population explosion like the one we are witnessing now. Found throughout South-east Asia, tropical Australia and also on the Great Barrier Reef islands, this butterfly is a brave traveler that will merrily head out into the wide blue yonder in order to colonise distant shores. By having a large population explosion before doing so, the species can withstand the inevitable losses incurred by unsuccessful forays, as there are enough butterflies left on the mainland to ensure continued survival. This wandering habit is why the Blue Tiger is often found beach-washed or seen flying out into coastal waters.

Speaking of coastal waters, it's not just creatures of the land that are in a 'boom' phase right now. Huge swarms of Blue Blubber (Catostylus mosaicus) jellyfish are congregating along our coastlines at present, making life difficult for recreational users of the water. Thick floating rafts of these jellyfish have been seen off Surfers Paradise, Redcliffe and North Stradbroke Island, but most estuaries and beaches are home to large numbers as well. These creatures feed on the plankton blooms that result from increased rain water flowing out of our rivers, and they gather en masse for an orgy of feasting and breeding. Though the sight of such large and vivid jellyfish swarms may cause alarm, this species has only a mild, itching sting if encountered by swimmers. They pose more of an inconvenience to boaters, surfers, jet-skiers and even commercial ships because the density of their rafts at the surface of the water can interfere with the safe operation of such watercraft. Many jellyfish species - including the Blue Blubber - find the warm oceanic conditions created by climate change to be extremely favourable, so we had best get used to them!

13 comments:

  1. thanks for explaining the blue blubbers! had no idea!

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    1. No worries Theresa, glad you find the phenomenon as interesting as I do! :)

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  2. Wow! That's quite a swarm of Blue Blubbers. I have never seen anything like it!
    I do see a number of the Blue Tiger butterflies every summer though.

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    1. I would be almost nervous to see a jellyfish swarm like that - I've always found them unsettling for some reason!

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  3. What an amazing sight of those Blue Blubber. I imagine getting caught in a raft of them might result in a bit more that an itch though! They kind of look like curdled blue cake mixture.....

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    1. Haha! Yes, I wouldn't be game to swim through those, no matter what sweet treats they resemble! :)

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  4. What an incredible phenomena - I really appreciate your explanations Christian :D)

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    1. Thanks Susan, that's really lovely of you to say.

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  5. Loved learning about the blue tiger butterflies. I am glad to hear they are seen in swarms in wet summers....and that perhaps the pesticides and herbicides are not as much of a problem there in Australia. We are seeing such a butterfly decline (along with the bees!)

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    1. Thanks Marie, glad you enjoyed the write-up! That's such a shame about your butterfly situation in North America. It's not something being seen here for the most part, though a few species with particular host plant requirements have declined with the plants themselves.

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  6. love to see butterflies....glad you have lots of them.

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  7. love to see butterflies....glad you have lots of them.

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