G'day Mark
The Speckled Warbler, with a few other species (Hooded Robin, Southern
Whiteface, Diamond Firetail, Crested Bellbird) seem to be disappearing from
Victorian woodlands. I don't know why. Maybe others on birding-aus can offer
suggestions. Most of the species we are losing spend a lot of time foraging on
the ground but other species with similar habits are still common (Fairy-wrens,
scrubwrens, thornbills, Red-browed Finch).
I remember hearing Crested Bellbirds in several sections of the Chiltern Forest
(never actually saw one) up until January 1990. They are now extinct in the
forest yet it looks just as suitable for them now as then.
I watched Attenborough's State of the Planet series and he talked about 5
reasons for extinction. One that might be applying here is habitat
fragmentation and how some species seem incapable of travelling even small
distances between islands of suitable habitat. Maybe to a Speckled Warbler
there are little islands of suitable vegetation in what appears (to humans) as
reasonably healthy woodland. I'm thinking in the order of 10s of square meters
here. If the population goes extinct in one island it might be imposible for it
to be repopulated from other islands. I can see flaws in this - how did each
island get its population in the first place - but it's my best guess.
Contributions welcome...
Steve
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Steve Clark
Hamilton, Victoria, 3300
HTTP://www.ansonic.com.au/clarks/sw_birds.htm
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