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Conservation on Lord Howe Island
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- Category: Weeds
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I have recently returned from a 2 week trip to Lord Howe Island. Lord Howe Island is the remnant of a much larger volcanic island approximately 600km east of Port Macquarie. This was an exciting time to visit because rats have recently been eliminated from the island. Indeed the island is a success story of ecological management (at least in the last couple of decades). The majority of the island is in a 'Permanent Park Preserve' under the Lord Howe Island Act, similar to a National Park. The vegetation is quite tropical, at least to my eyes. It is very beautiful.
Migration of the Caper Whites
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Looking
out my front window in suburban Wangaratta this morning I noticed a white butterfly fluttering by, and a few in the background, and I thought gee, the Cabbage White butterflies are bad this year!. But then another pair flew by and another, all in the same south-westerly direction.
Something stirred in the back of my brain about butterfly migrations so I went out into my back yard to have a look. Sure enough there was a steady stream of butterflies coming from the northeast, but when one passed close by I could see the wings were edged with black, not like Cabbage Whites at all. I'm not very practiced at identifying butterflies, especially fluttering by, and wished for a butterfly net to capture one to get a good look at it.
Pulling out my Common & Waterhouse I was a bit overwhelmed by the number of white butterflies (not entirely white, but classified as whites). I couldn't see any colour on the butterflies fluttering by, but eventually looking at the distribution maps settled on the Caper White, which has minimal colour and a mainland-wide distribution and to the north. Common & Waterhouse notes that:
"Immense migratory flights of this species frequently occur in southern Queensland and New South Wales and sometimes extend into Victoria. Entomologists at the Australian Museum are collecting information about such flights, but it is still too early to reach conclusions about their function in the biology of the species. The larval food plants do not normally grow farther south than about the latitude of Newcastle in the east and Griffith in the south-west, but migratory flights often extend well into Victoria and sometimes to southern Victoria"
Weird that the migrations are away from food plants. Why??
I put a chair up against one fence and counted butterflies passing the wall of next-door's garage while timing 2 minutes on my phone. I counted 22 butterflies passing, mostly within a few metres of the ground, but some up to maybe 30 metres. Then I paced out the distance: 23m. That's 29 butterflies per metre per hour. This was at midday, but I had been watching the butterflies passing for about an hour. Guessing that the migration was 20km across, that's half a million butterflies in an hour. What? I had to recalculate. Yep. And the migration didn't stop till mid-afternoon. It's a lot of butterflies. It was a fine day, 19°C, partly cloudy, 80% humidity, and still, so it definitely wasn't that the butterflies were wind-blown. And there were none flying northeast.
Eventually I noticed that some were stopping to feed on my sage bush, which was in full flower. They must have been hungry, because they let me get close enough to photograph them with my phone. Not the best photos, but enough to confirm the identification as Caper White, Belenois java. Interestingly the photo on the Australian Museum website seems to also be on sage bush.
Geoff Park recorded a migration on 19 November 2015 in his excellent Natural Newstead blog, and Angair Factsheet 9 describes a migration on 29 November 2004. Here is a video of Caper White butterflies in Brisbane in November 2016. I found one reference to a Caper White migration in October at Strathbogie Ranges Nature View.
Swamp Wallaby movements on Lower Merri Creek
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- Category: Waterways
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In May 2019 after seeing Swamp Wallabies along Merri Creek and at Yarra Bend Park I published an article on this blog speculating on ground mammal refuges and movements along Merri Creek. The article was kindly featured on the Friends of Merri Creek Facebook page, and got a lot of feedback, with many people reporting their own sightings of Swamp Wallabies.
To better understand the movements of Swamp Wallabies along Merri Creek I mapped these sightings as best I could (they are in red in the map on the right from Google MyMaps). I included reports from the Victorian Biodiversity Atlas (there were only a few). I also approached Wildlife Victoria, who kindly provided details of reports to them of Swamp Wallabies in suburbs adjoining the lower Merri Creek.The Wildlife Victoria data points are purple.
I also searched through Merri Creek Management Committee's fauna sightings records; these are shown in green.
The map provides some fascinating insights.
- Predation by dogs seems to be an important factor as the areas where sightings are more common tend to be difficult for people and dogs to access. Some level of predation might not be a bad thing though.
- Shrubs are important as food plants (and shelter), although they don't need to be indigenous.
- Swamp Wallabies are clearly moving up and down Merri Creek, but despite the dangers, they also appear to be moving east-west through adjacent suburbs, often coming to grief.
- Creek Management could enhance or destroy the refuges used by Swamp Wallabies.
Like an English country garden
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- Category: Parks Victoria
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Visiting the Killawarra section of the Warby-Ovens National Park I finally understood what the explorers meant by saying the forest was like an English Garden.
Buffel Grass changing the ecology of the West MacDonnell Ranges
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- Category: Weeds
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I recently returned from walking the Larapinta Track west from Alice Springs in the Tjoritja West MacDonnell National Park. One issue stood out above all others in terms of the ecological management of the park. Buffel Grass.
Buffel Grass was originally introduced into the NT inadvertently by the Afghan cameleers - it had been used to stuff the camel saddles (or at least this is what the guides on the walk told me). Subsequently, graziers in the north introduced several other Buffel Grass species. Buffel Grasses are ideally suited to spreading in the dry parts of Australia. They are deep rooted, resprout after fire, seed prolifically, germinate quickly, the seed has comb-like appendages which means in blows in the wind and can easily hitch a ride on a passing animal, and they are competitive with many of the sparser native grasses.
Unsurprisingly Buffel Grass grows better along the sandy creeklines than the driest slopes of the ranges. Indeed it grows so well in these locations that it creates an almost continuous cover, excluding native grasses, and building up a heavy fuel load of dry dead leaves around the base of each plant. This means, much more than any indigenous grass, that Buffel Grass creates more intense fires, and leads the fires along watercourses. There was plenty of evidence of this that I saw on the walk from the fires that burnt roughly half the park in January 2019. And distressingly, the creek beds are where almost all of the hollow-bearing trees are, and many of the oldest trees in the burnt areas were burnt to almost nothing but a pile of white ash.
Do we have a Prickly Pear problem on Merri Creek?
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- Category: Weeds
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I used not to think so, but I'm starting to think we do have a problem.
Most people are familiar with the edible prickly pear, which has large paddle-shaped "leaves" (they are actually flattened stems) with small prickles. Many don't realise that there are lots of prickly pear species. Some species have enormous (5cm long) needle sharp prickles, and some have lots of very fine prickles (glochids) that break off if the plant is disturbed and blow around, and if you get them on your skin they can cause nasty sores. If you breathe them in... well... Just dont. Serious injuries can occur through contact with prickly pear.
In Australia twenty-seven species of prickly pear and similar cacti (the "Opuntiod" weeds) are recognised as Weeds of National Significance, and are some of Australia's worst weeds.
I have started mapping prickly pear species on Merri Creek. This has been helped enormously by going to the Opuntioid Weeds Workshop held on 14 May, and learning to recognise the species. Along with other participants in the workshop I was given two fantastic resources - a field identification guide for opuntioid weeds, and a management guide for Opuntioid weeds.
I have to say I have been shocked by the number of species of prickly pear present along Merri Creek, and I have only surveyed from the Yarra River as far upstream as North Coburg. I know there is worse in Fawkner and Reservoir. So far I have found 6 species in 30 occurrences.
Zero budget for weeds & reveg at Yarra Bend Park
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- Category: Parks Victoria
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On today's walk through Yarra Bend Park (Managed by Parks Victoria) I got hot under the collar. Once again Parks Vic is busy cutting down indigenous trees in picnic areas because they might drop a branch on unwary picnickers. Couldn't possibly direct people away from sitting under such trees... At a number of places managers do this by creating a mulched bed under such trees instead of providing inviting mowed grass. But it can also be done by fencing. And... wait a minute... why do people come to the picnic areas? Isn't it to be in nature?
They were also cutting trees in the wider park. One I saw seemed to have been a Red Gum, 11 metres from the nearest path, otherwise in the middle of nowhere. Nearby Elms, full of rot holes, above the car park servicing another picnic area were untouched. And to add to my indignation, they were dumping the cut branches and trunk segments in the nearest bit of bush. Not carefully arranging them to make habitat, just piling them on the edge. Right on top, in come cases, of planted Bursarias.
This led me to a long conversation with a Parks Vic staffer who, when I asked how much budget Parks Vic had provided for Yarra Bend Park to do ecological work told me they received zero. ZERO!
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