EFFECTS OF FIRE ON A FIELD SPARROW POPULATION

The effects of fire on a field sparrow [Spizella pusilla] population were documented on a 23.6 ha study area composed of grassland, shrub-grassland and shrub-woodland. The breeding ecology of this species was studied before and after a prescribed burn (conducted in late April) of the grassland and shrub-grassland. The completeness of the burn varied depending on the density of grass litter. Although territory establishment and maintenance appeared unaffected by the fire, burn resulted in an increased frequency of use of the shrub-grassland and a reduction in usage of the grassland compared with the previous year. The fire did not interfere with pair-bonding or mate fidelity. Although potential nest cover was severely reduced by the fire, females continued nesting in the burned region. Rates of nest desertion and cowbird parasitism were lower after the burn. The potential effects of fire on nesting outcome and food availability are discussed. Timing and frequency of burns will largely determine their effects on field sparrow populations.