Nest Hollow CompetitionNest Hollow Competition

Nest Hollow Competition

Green Parrots compete for nest hollows with introduced Crimson Rosellas, European Starlings and Honey Bees. Crimson Rosellas are known to aggressively expel Green Parrots from their territory (Hicks and Preece 1991). While it was understood that Crimson Rosellas on Norfolk Island nest from September-November, during which months Green Parrots rarely nest, some variation in this pattern has been observed in recent times. The incidence of Crimson Rosellas using Green Parrot hollows has also decreased significantly from 1993 to 1997, probably due to regular culling of Crimson Rosellas in NINP since 1990.

Green Parrots will use a nest site that has been used by Crimson Rosellas. Prior Red Parrot nesting activity at specific hollows did not significantly affect Green Parrot breeding success at those hollows (as measured by the number of Green Parrot chicks produced in each breeding attempt (R. Ward pers.comm.).

European Starlings use tree hollows from August to November (Hermes et al. 1986) thus there is no direct competition with Green Parrots for nest sites. However, the starling’s nesting material can render a nest site unattractive to Green Parrots. If the hollow is not cleared of this material, a nesting opportunity may be lost. There have been numerous examples of nesting material attributed to European Starlings being found in hollows previously used by Green Parrots. (D. Greenwood and R. Ward, pers. obs.)

In the 1992-93 breeding season, bees occupied seven wild nest sites and bee control was considered a priority (Greenwood 1993). In 1995, feral bees caused one fatality and two injuries to captive Green Parrots (Yorkston 1995). Bees occupied one nest site from 1992 to 1996 (unpubl. data) and another site for one month in 1994. There are no records of feral bees at wild nest sites or within the aviaries since 1995. Feral bees are systematically removed from near nest sites within NINP.