Sunday, 3 March 2013

Random Rodent Rudiments

Hello Rice Survivors,

Hopefully we can soon also call ourselves 'Rat Survivors'.

wow, what an interesting 'Rice Survivors meet IRRI Experts' session with Alex Stuart last Wednesday.
I am still overwhelmed by the amount of information we heard about rats in rice fields and am blogging here to process what I heard, learned and  to share with you as for sure I don't remember every detail.

So,  for those of us who went to the filed with Alex and the 3 live caged rat specimens, let's bring on the collective memory technique and share what we heard between us as well as with the survivors who could not come along.
If you missed Wednesdays session, yes, you read correctly, we actually didn't just go out there looking for rats or evidence of their existence, we also took three live rats with us on the bus, to the field. Don't worry animal rights protesters, we took good care of the three rodents and Alex even covered their cage with weedy grass cuttings to prevent dehydration and heat stroke of our precious pests.

Now about the random rodent rudiments, here is what I learned and remember:

  • Rats gestation periods are three weeks only (as a reference gestation periods of humans 266 days, kangaroos 42 days, cows ~285 days and elephants 616 days)
  • Female rats can be pregnant with one litter (Do you call it a litter for rodents?) while still feeding the previous litter
  • The average rat litter  is around ten pinkies (baby rats, named after their furless skin colour), sometimes up to 16 but not all will survive
  • Within one rice crop season they can reproduce up to three times (varying with season length based on difference between the earliest and latest planted crops within the one habitat of the rat population). Hence the famous quote 'one rat removed now is worth 30 rats later'
  • Ideally the number of rat generations generated in one season is minimised by synchronised planting/sowing, however, as we know this is not always realistic on a broad scale due to labour and equipment constraints
  • Uncontrolled rats can be accounted for 40% of crop loss in rice
  • Rats don't just eat rice, it's one of their favourite meals but they also eat other things like snails (yay!)
  • Before booting stage of the rice, rats already eat rice plants although the base of the stems are not as nutritious as the grains
  • Just before booting stage of the rice some complicated pathway triggers of a hormone release in the rats that initiates mating behaviour because soon there is going to be plenty of food around (grain filled heads)
  • If you can't see the rat or it's hollows in the ground themselves, the best indication that they are in your crop are chewed off plants laying on the ground
  • Here is a picture of one that shows the typical 'rat angle chew symptom'
  • Rats love weedy surroundings of rice crops, high grasses and shrubs to hide and build nests in. This includes the piles of grass cuttings around our fields from when the slasher went along and moved. It's important to remove those prime nesting spots
  • Rats will 'tavel' up to 200 m for food, hence not all the rats feasting on our rice crops actually live in our plots. It is likely that they travel from surrounding crops, nesting habitats in the empty blocks and weeds behind our crops
So those are the random rodent rudiments I remember. Please comment on anything I forgot.
In addition we also learned that our four survivor plots are at high risk of rat damage very soon, due to the large variation in age between the plots. Future techs, it sounds like you're the first to be experiencing the rodents. Double Trouble Makers, with the two varieties at two quite different stages, well, sounds like rat reproduction trouble is coming twice your way...

The good news is, Alex also told us what we can do now, to minimise the rat damage. We will outline our options and send around a survey so you can vote on your preferred method how to tackle the rats.
So look out for the survey and make sure you vote so that the future of your crop is in your hands and not the gnawing teeth of a rat. 

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