Abstract
Through body size, social interaction, and foraging behavior, we investigated the dominance
rank and interference competition among 6 bird species foraging at a park feeding site in Kaohsiung
City, Taiwan. Social interactions and foraging behaviors of these birds were recorded in June
to September 2009. David’s scores were calculated from an interspecific interaction matrix, and
the score roughly increased with the body size of birds, but some exceptions were noted. Concerning
foraging behavior, feral pigeons (Columba livia) and Spotted-necked Doves (Streptopelia chinensis)
took over the food area once they appeared even though Tree Sparrows (Passer montanus)
usually arrived first. A linear regression model indicated that the number of Tree Sparrows outside
the food area was positively correlated with the number of feral pigeons and Spotted-necked Doves
inside the food area. Feral pigeons and Spotted-necked Doves moved away as the food was gradually
consumed, and smaller species accordingly increased their foraging in the food area. Nevertheless,
the Tree Sparrow was also suppressed by other medium-sized birds, like the White-vented
Myna (Acridotheres javanicus) and Chinese Bulbul (Pycnonotus sinensis), and they eventually occupied
the food area in large numbers at a later stage. This study revealed that body size did matter
and the Tree Sparrow was clearly the least dominant species among the 6. However, a discrepancy
between the dominance status and interference competition in foraging was apparent. In addition
to David’s score, we suggest incorporating body size, group size, and interference competition to
reach a more-comprehensive dominance hierarchy in bird communities.