Observations of the territorial behavior of the Prothonotary Warbler: male within- and between-season relocations, polyterritoriality, and the role of extraterritorial explorations

Abstract

From 1983 to 1987, a natural riverine population, without the use of artificial nest boxes, of Prothonotary Warblers ( Protonotaria citrea ) was studied along a 10.5 km section of the North Fork of Salt Creek, located in Monroe County, Indiana, USA. During the study, 101 territorial males were captured and marked, and their subsequent movements documented. Of these, 31 (31%) returned to the study area in at least one subsequent year, and these resulted in 21 cases of males returning to the territory of the previous year and 13 observations of males returning to a different territory from that of the previous year. Eleven males were observed to relocate their territories within-season. Nine of these were individuals unable to attract a female to the initial site, with this pattern being statistically significant. Two cases of polyterritorial polygyny were observed, representing the first documentation of this behavior in the Prothonotary Warbler. No evidence was found suggesting the presence of a population of “floaters”: nonterritorial males unable to find suitable nesting territories. By mid-May of the 1984 to 1986 seasons, all territorial males had been captured and marked with all subsequent observations each year being of known individuals. In addition, during all years of the study, apparently suitable Prothonotary Warbler habitat along the stream was unoccupied by territorial males. Long distance homing to the breeding territory by a male, captured and released 47 km from the initial site is reported. Male extraterritorial exploration forays were observed, with detailed observations being made of eight individuals observed wandering a large distance from their respective territories. Some males were observed more than once, resulting in 11 observations of exploration. The results of this study suggests that male exploring behavior in the Prothonotary Warbler plays a role in a general dispersal mechanism in this species.

Keywords

• extraterritorial exploration
• polyterritorial polygyny
• prothonotary warbler
• territory relocation