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GregH
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Joined: 17 Feb 2009, 08:20
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Location: Chapel Hill, Brisbane Qld

I've been aked to write a 1000 word piece on rice birds for the International Rice Research Institute. I've done so but won't claim I'm an expert on Java sparrows and my rice growing colleages might see me as a trator to the cause but the following is what I've written and I would welcome any feedback before I submit it.

Greg
Rice is life for billions of people around the globe but before people came to dominate the Asian landscape many organisms had evolved to exploit this nutritious group of swamp grasses. Today we call these organisms pests and diseases as they compete with us for the shrinking resources brought about by our own inability to contain our numbers. One particular group that farmers target hard are granivorous birds and while some less specialized birds like sparrows are faring well in this fight, many of the grass-finches (Estrillidadae), once considered pests, are rapidly declining. Advice on reducing the impact of birds is available from IRRI and government agencies but precious little information exits on preserving the avian diversity of cultivated rice ecosystems when the opportunity cost might just be the farmer’s next meal. Advocated bird control measures range from the passive and active scaring (utilizing visual and sonic cues) to active trapping and brutal extermination methods like stamping on the netted birds as is promoted in Sabbah.

The most specialized rice eater of all the granivorous birds is the Java sparrow or rice bird, known scientifically as Padda oryzivora which literally translates as “rice eater of the field”. In the Philippines this bird is also known as maya costa. The Java sparrow is the largest of the Estrillidad finches and its huge red beak is uniquely adapted to dehull even mature rice a trick that is beyond most other finches but that does set it up to be an unwelcome competitor for cultivated rice crops. Before the advent of rice cultivation the habitat of these birds was probably restricted to the junction (ecotone)between swamps dominated by wild rice species in Java and Bali and surrounding savannah-woodland but as rice cultivation spread so did the Java sparrow.

This partnership or commensalism between humans and the Java sparrow worked well for it until human populations grew to the point where it’s favoured habitat the ecotone between the rice paddy where it fed and the trees and structures where it nested started to be filled in with more cultivation. Now Java sparrows have the unfortunate distinction of now being under threat of extinction in their home range within Indonesia but are considered feral pests where they have established populations on Christmas Island, Hawaii, Fiji and in the Philippines. Within their home islands these birds have been relentlessly hunted not just because they are considered rice pests but because of their desirability as caged birds. Ironically Java sparrows are one of the easiest species to breed in captivity however economic circumstances and poor regulatory control continue work against captive breeding in Indonesia and favor the movement of the remaining wild birds from the fields to a life of barren captivity. The closely related Timor Sparrow (P. fuscata) is even more threatened by these processes and the genetic integrity of the few captive populations held outside the Indonesia archipelago is threatened by hybridization with the Java sparrow by careless avicultural practices.

With few exceptions Estrillidad finches, commonly referred to as grass finches, are all adapted to eat grass seeds although some species supplement the diet of hatchlings with insects during the breeding season. Reproductive success in Estrillidad finches is tied tightly to that of the grasses they feed upon. In rice and other grasses all the protein that will ever be stored by the grain is translocated to it in the first week after pollination while the endosperm is liquid. This protein rich milk is what sustains most nestlings in the wild but to have a continuous supply requires a diversified landscape containing a mosaic of genotypes in different stages of growth. Modern agricultural practices seek to shorten the generation time and synchronize grain-filling not just within a plant or a single crop but across the landscape.

For millennia the landscape across Asia was a mixture of rice paddies, primary and secondary forest, isolated villages and urban centers. This suited many granivorous birds and the lack of temporal and spatial continuity between crops isolated them and so contained outbreaks of plant diseases and pests. After World War II modern agricultural techniques were introduced, productivity went up and the barriers that separated rice paddies started to disappear, creating the present agroecological landscape. These changes have not only have shrunk the food supply for the specialized granivorous birds but have reduced the available nesting sites since none actually nest in rice but need close access to it and other seeding grasses in order to raise their young. Weeds constitute an alternative seed sources within a rice crop and in fact for many Estrillidads, particularly the munias (Lonchura sp), barnyard grasses (Echinochloa sp.) are actually favored over rice but no farmer wants to waste space, water, fertilizer, insect control measures etc. to grow food for birds when it could be used to grow more food for his/her family or for trade.

As human populations have increased the number of commensal species that exploit the anthropogenic landscape have decreased and the winners outcompete their rivals. One particularly well adapted winner is the Eurasian tree sparrow. The protein requirements of nestling sparrows is not dependant on immature milk-seed but comes from insects which in a well functioning paddy are found in abundance. Most Estrillidads nest in trees or shrubs but a few like Padda sp. are cavity nesters utilizing natural tree hollows and rock crevices and in developed landscapes these natural spaces are replaced by roof cavities and other spaces within buildings. This habit places them in direct competition from the worst of its avian competitors, the Eurasian Tree Sparrow. Increasing affluence too can have a direct effect as building are repaired and construction standards are introduced which reduce the available nesting opportunities for cavity nesting birds.

So what hope is there for the Java sparrow? Firstly it may be endangered in its home range but it is secure where it has established feral populations and also in captivity. Diminishing nesting opportunities can be overcome through the placement of artificial nesting boxes as was demonstrated during the restoration of the Prambanan Temple in Java. Increasing affluence in Indonesia has brought about not just a larger population that wants to keep birds but a more educated population that wants to preserve them in their native habitat and this should drive the political will to enforce regulatory controls on trade in endangered species. Ecotourism and bird watching bring millions of dollars of foreign revenue to Indonesia each year and for tourists to go to Java without being able to sight a Java sparrow would surely taint this with deliberate environmental vandalism and economic mismanagement. The future of the Java sparrow and every species lies with the collective responsibility of humanity to control it’s own population and impact so that the Earth remains as a diverse, healthy and resilient place for all it’s inhabitants.
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Diane
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:clap: I think it reads really well :clap:
I can see why you might have to duck for cover from your rice growing colleagues :lol:
Diane
The difference between Genius and Stupidity is, Genius has it’s limits
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Myzomela
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Joined: 24 Jan 2011, 18:44
Location: Melbourne Vic

Well written Greg!

I'd love to be a fly on the wall when your agri-colleagues read it!! ;)
Research; evaluate;observe;act
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finchbreeder
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Joined: 27 Jun 2009, 20:00
Location: Midwest of West. Aust. Coast
Location: Midwest of West.Aust.Coast

Great article. :thumbup: Now if you can just inspire people with it so they leave remnant areas for the birds. :think: And start considering it a duty to provide artificial nest sites. :clap: And an honour for those nest sites to be used. :angel:
LML
LML
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MadHatter
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Location: Ferntree Gully, VIC

Top work mate! :thumbup:
I feel bad for nit-picking, but I will anyway. :) You consitently mis-spelled "Estrildid" as "Estrildad" (also in the context of "Estrildidae")
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gomer
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Location: Victoria Australia

Quite enjoyable read.Well done :thumbup:
Keeper of Australian Grass Finches
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GregH
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Joined: 17 Feb 2009, 08:20
Location: Brisbane
Location: Chapel Hill, Brisbane Qld

Good call. I actually believe you're right since the suffix "idae" should denote a subfamily taxon but I so often see it written as "Estrillidad finches" that I started to believe my 30year old taxonmy training was out of date. I will gladly change it.
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