Reproductive success of rose-ringed parakeets Psittacula krameri in a captive UK population.

Background: Rose-ringed parakeets Psittacula krameri (Scop.) have recently become established in several European countries, with potential for significant negative economic and ecological impacts. However, in northern Europe the potential for reproductive output is largely unknown. In 2005 the authors established a captive outdoor colony in north-east England and examined breeding success over 2 years.
Results: In 2006 (19 pairs, 15 clutches) the average first clutch size was 3.6 (+/-0.3) eggs. Six clutches were infertile, and overall the colony produced 1.4 (+/-0.5) fertile eggs per pair. Eleven pairs produced a second clutch following removal of the first; seven were infertile, and overall productivity was 0.7 (+/-0.4) fertile eggs per pair. Unsuccessful pairs were rearranged or replaced. In 2007, overall productivity was 2.5 (+/-0.4) and 1.8 (+/-0.4) fertile eggs per pair for the first and second attempts respectively. For pairs that remained unchanged through 2006-2007, productivity was consistent between years and breeding attempts.
Conclusion: Where food and nest sites were not limiting, clutch sizes in north-east England were similar to those in the native range, and consistent between first and second attempts. This has implications for the future expansion and management of the species.
((c) Crown Copyright 2009. Reproduced with permission of Her Majesty's Stationery Office.)