Assessing Integration of Black Cockatoos Using Behavioral Change Point Analysis

Establishing integration of an individual bird into a wild flock is particularly important in species that are highly gregarious and are reliant on the flock to increase their likelihood of survivorship. When individuals, rehabilitated and reintroduced to wild flocks, are tracked through satellite or global positioning system (GPS) telemetry, it is of further significance to establish integration to assess rehabilitation success and whether the individual can serve as a marker of the flock. To date, for black cockatoos (Calyptorhynchus spp.) this has been achieved through visual observations, which requires field-based observations that may not be possible because of inaccessible terrain, or may be untenable because the tagged individual can move quickly or is cryptic within a given land cover type. To establish whether an individual had joined a flock, we proposed the use of behavioral change point analysis. Our analyses showed that for GPS data of 6 individuals of the 3 black cockatoo species endemic to Western Australia we could demonstrate behavioral differences in their movement paths that were either individual or flocked (integrated) behavior. We undertook field observations to validate integration into wild flocks. We characterized flocked behavior as a constant, repeated pattern at variable levels of velocity. Individual behavior manifested in 2 different forms: resident and exploratory behavior. The analysis showed that all birds had integrated into a wild flock within a month of release. Behavioral change point analysis is a useful method to characterize movement behavior in black cockatoos and to confirm their membership within a flock. Furthermore, confirmation of flock membership makes it possible to use the data from 1 tagged bird to indicate movement behavior at the flock level.