Thursday, April 29, 2010

Birds and weeds

Hungry birds destroy ripening grain all over the world, yet few researchers study on them. Farmers in Senegal told AfricaRice researchers that their two major rice pests were birds and weeds.

 Farmers have insights about birds. In a farmer survey by AfricaRice near Saint Louis, Senegal farmers said that birds did lower yields, especially when the fields were weedy. The weeds mature before the rice does, and birds like to eat weed seeds, the farmers said. The birds only eat rice once the weeds are gone. Farmers said that “if I manage my weeds I have less bird attack”.

The farmers were right. In 2008 AfricaRice weed scientist Dr. Jonne Rodenburg joined the team and validated what the farmers said in experiments on-station with four treatments:

  1. No control of either weeds or birds
  2. Only bird control (plots were covered with nets)
  3. Only weed control (hand weeded every ten days) and
  4. Full control of birds and weeds.

They did the experiment with early and late maturing rice varieties. The weed-free fields discouraged birds. Weedy fields, on the other hand, attracted birds. The birds fed on weed seeds, found shelter in the weeds, and perched on the weeds to eat the rice. Weed-free, early maturing varieties suffered little from bird attacks. If the rice matures late, it is ripe when the weeds seeds are all gone, and the birds then turn to the rice grains.

Managing birds. Pest management scientists tend to ignore birds, and ornithologists tend not to think of birds as pests. Therefore, far too little research is done on birds as pests. This research, although in an early stage, suggests that farmers have several options to manage birds.

  • Keep fields weed free
  • Plant early maturing rice
  • Experiment with different planting times.

The AfricaRice team measured bird damage in the Senegal River Valley, based on their annual farmer surveys. They estimated average bird damage at 11.2% of the potential rice yield in 2003-2007, which translates into an average annual economic loss of 4 billion FCFA (about $9 million).

Some governments and farmers use large quantities of non-selective poisons to kill birds. This needlessly kills non birds that do not eat grain, besides damaging the environment and human health. Alternatives to these harmful pesticides are urgently needed. Research like this is a step in the right direction.

The team conducting this research includes Dr. Jonne Rodenburg (AfricaRice Weed Scientist), Dr. Matty Demont (AfricaRice Agricultural Economist), Yann de Mey (K.U. Leuven MSc Student) and Abdoulaye Sow (AfricaRice Research Assistant).