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Seasonal Occurrence of Blackbird Species (Icteridae) in Wild Rice (Zizania): A Response to Rice Stage or Breeding Phenology?

  • Author(s): Scott, Thomas A.
  • Marcum, Daniel B.
  • Lee, Pey-Yi
  • Shuler, James
  • Fry, John
  • et al.
Abstract

Blackbird species (Icteridae) are considered a primary cause of yield loss prior to harvest in wild rice, which equaled about $3 million in 2007. Although rice consumption should be a null model of bird damage to yield, data from cage traps and point counts indicate that blackbird flocks arrive in wild rice fields 3 to 4 weeks before rice was available for consumption, but coincidental with the time when blackbird form post-breeding flocks. Wild rice plants appear to be attractive habitat from the time the wild rice begins heading until it is harvested (c. 6 weeks), even though wild rice is a food source only for the last 2 to 3 weeks (milk stage to harvest of mature grains). The onset of occurrence in wild rice fields appears to be a function of breeding season of red-winged blackbird and Brewer’s blackbird, specifically they arrive shortly after the time when young-of-the-year become independent of parental care (first week of July). Hence, nesting phenology is the best predictor of blackbird occurrence and their potential damage to wild rice.

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