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Richmond Birdwing Conservation Network
Bring back the Birdwing Butterfly
A project of Wildlife Queensland
| This website is no longer the official website of the Richmond Birdwing Conservation Network. It was developed for the Richmond Birddwing Recovery Network. The author has continued to maintain it in recognition of the efforts of the many volunteers involved in the project and in the collection of the wild and planted vines and butterfly sightings. |
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Threats
to the Richmond Birdwings survival |
Until
the late 1880s the Richmond Birdwing Butterfly was common in and around Brisbane. Since then,
increasing population, demand for farmland
and the resultant clearing, and general ignorance and complacency,
has seen the range of the butterlfy reduced to two distinct
populations, one on the Sunshine Coast and one stretching
from the Gold Coast and its hinterland to the more northern
parts of Northen New South Wales. Brisbane and its environs
no longer has a stable and viable Richmond Birdwing
The threats to the Richmond Birdwing Butterfly are both natural
and man made.
It is unfortunate in some respects that the Richmond Birdwing
and people enjoy the same environment.
Fragmentation of
habitat
In earlier years the need for more and more farming land for dairying
and in later years, small crops such as pineapples and other tropical
fruits, led to the destruction of a significant amount of Richmond
Birdwing habitat.
In more recent years, the rapid rise in the need for residential
land, much of which was on former farm land, has continued
the degredation of birdwing habitat. With the rise in residential
colonization, ignorance has led to further degredation. A
misconceived perception that vines and trees do not belong
together and that any vine is bad, has led to many landholders
removing all vines growing on their properties, resulting
in the subsequent destruction of much birdwing habitat. In
any of our subtropical rainforests, vines form more than 50%
of the forest canopy.
Education is slowly reversing this trend. The Double Helix
Club, an initiative of CSIRO, the Richmond Birdwing Recovery
Network and Richmond Birdwing Conservation Network, have been
instrumental in reducing the decline in habitat, but still
more has to be done. Community based workshops, information
booths and the establishment of community nurseries in which
larval host vines are propagated, are some of the mechanisms
being used to encourage people to grow vines in their gardens,
life-style blocks, and in habitat from which old growth vines
have either been removed or have died. |
In-breeding Depression
Habitat destruction and drought are two of the prime causes
leading to another threat to the butterflies survival - in-breeding
depression. To understand this, one has to look at the
biology and behaviour of the butterfly.
Richmond Birdwing Butterflies are not normally migratory.
To maintain strong and viable populations, there must be plenty
of opportunity for females to mate with non-related males.
The female Richmond Birdwing butterfly is known to fly up
to 30 kilometres from where she pupated in order to lay her
eggs on suitable vines. Strong populations of birdwing butterflies
ensure that there is enough genetic diversity in subsequent
generations to ensure the species continues. Brother sister
matings result in infertile eggs and the potential loss of
a generation of butterflies.
Fragmentation has resulted in the isolation of many populations
of butterflies. While an isolated population may initially
be strong and viable, lengthy drought events, as there has
been between the 1990s and 2008, has seen these populations
dwindle in many cases to extinction. To bring the butterfly
back to these areas, habitat corridors with large and numerous
vines have to established, linking existing strong populations
with former with the areas where the butterflies are now extinct.
This process can be hastened by the development of captive
rearing programs and the release of genetically strong butteflies
into areas facing extinction.
Many of the areas from which the butterfly has been extinct
for some decades may never see the butterfly again. This is
due to other threats such as complete loss of habitat and
climate change. Given limited resources, target areas should
be those with the greatest potential for recovery.
Click here for more information on
in-breeding depression.
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Dutchmans
Pipe Vine
In the 1900s, the nursery industry, ignorant of many of the
environmenal issues, released onto the unsuspecting public,
the vine Aristolochia elegans. This vine is commonly
known as the Dutchan's pipe vine. Why? The flowers were showier,
larger and more colourful than the native Arisolochias and
Paristolochias of the local area, just what gardeners were
looking for.
At the time and unbeknown to the nursery industry,
these South American vines became devastating to the Richmond
Birdwing larvae, causing 100% mortality in any birdwing larvae
which hatched from eggs laid on these vines. Death occurred
within the first 3 instars from poisoning. Furthermnore, the
female Richmond Birdwing Butterflies seemed to be attracted
to, and prefer to lay their eggs on these dangerous vines
than on the native host vines, Pararistolochia praevenosa
and P. laheyana.
This vine is no longer sold in nurseries, but many of these weedy
vines have already found their way into the sub-tropical rainforests
of SE Queensland and Northern NSW from seed from vines planted
in gardens and continue to devastate the viability of the
Richmond Birdwing populations. The Dutchman's Pipe is also poisonous to many other animals including sheep and cattle.
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Drought
Drought is an event that has affected the climate of Eastern
Australia for centuries. Two major impacts on the Richmond
Birdwing Butterfly brought about by drought are the scarcity
of soft leaves for newly hatched caterpillars and the drying
our of pupa due to low humidity levels, causing the death
of many of the pupa. Prolonged drought from 1998 to 2009 has
had very serious impact on the Birdwing populations and distributions.
The egg laying female butterflies look for the soft leaves
on the P. praevenosa vines on which to lay their
eggs. These leaves are mainly found in the upper levels of
the canopy on the mature vines. In times of drought, the vine
may not produce new leaves. The older tougher leaves are not
edible to a newly hatched larva.
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Climate
Change
Climate Change has implications for the number of life cycle
generations per year, survival of sensitive immature stages,
ability of adult butterflies to find sufficient nectar, and
the production of seed capsules for the food plant vine.
If forced to move south to find suitable climate, the butterfly
must find sufficient vines on which to reproduce.
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For more information:
Life cycle of the Richmond Birdwing
Butterfly
Slideshow on in-breeding depression
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