The effect of seed dispersion on the foraging success of dominant and subordinate dark eyed juncos junco hyemalis
Animal Behaviour 35(6): 1883-1890
ISSN/ISBN: 0003-3472 DOI: 10.1016/s0003-3472(87)80081-7
Laboratory experiments were conducted to determine the effect of seed dispersion on the rate of seed consumption by dark-eyed juncos, Junco hyemalis, feeding in dyads and in triads. In the dyad experiments, dominants consumed significantly more seeds than subordinates when seeds were clumped in a patch of 0.09 m2, but subordinates obtained as many seeds as dominants when food was dispersed in a larger 1.44-m2 patch. In the triad experiments, there was a significant difference in seed consumption between dominants, intermediates and subordinates when food was dispersed in patches of 0.09 m2 and 1.44 m2, but there was no significant difference between ranks when it was dispersed in a larger 2.88 m2 patch. Dominants had significantly more agonistic interactions with intermediates than with subordinates. This was not related to differences in distances maintained between birds. Dispersion of seeds in the environment can have a marked effect on whether dominants realize an immediate foraging advantage over subordinates.