Density-dependent population growth in a reintroduced population of North Island saddlebacks

  • Published source details Armstrong D.P, Davidson R.S., Perrott J.K., Roygard J. & Buchanan L. (2005) Density-dependent population growth in a reintroduced population of North Island saddlebacks. Journal of Animal Ecology, 74, 160-170.


Saddlebacks Philesturnus carunculatus have become extinct from much of their range in New Zealand due to predation by introduced mammals such as rats Rattus spp. This study investigates the success of reintroducing a population to an island in a lake.


Between 1989 and 1990, brown rats R. norvegicus were eradicated from Mokoia Island, Lake Rotorua, North Island, New Zealand. In April 1992, 36 saddlebacks were released on the island.

The number of birds on the island was then monitored from 1992 until 1997.



The population increased from the 36 birds released to 217 birds in September 1996. The population fell following the attempted eradication of mice but recovered to 200 by September 1997. Reproductive output declined over time as the population grew, and was best explained by density-dependence. The sex ratio was not significantly different from 50:50.

Note: If using or referring to this published study, please read and quote the original paper.


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