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Sixteen years of monthly bird monitoring at the western end of Lake Rotoiti, Rotorua, and implications of one-off surveys

Bycroft, Christopher1, Shaw, William2

1Wildland Consultants Ltd, P.O. Box 7137, Te Ngae, Rotorua (

2Wildland Consultants Ltd, P.O. Box 7137, Te Ngae, Rotorua (

Many avifauna assessments are undertaken as one-off surveys, or repeat surveys at similar times of the year.  Results are presented of 16 years of monthly bird counts (adults, and juveniles in three size classes) on the same part of Lake Rotoiti.  In 2005 a bird monitoring programme was initiated to monitor the effects of a diversion wall structure in Lake Rotoiti.  Monitoring was established prior to wall construction and was funded by Bay of Plenty Regional Council until autumn 2017 and has been continued in a private capacity since then.  Lake Rotoiti is outstanding water bird habitat and the western end being monitored contains representative populations of key water bird species in the Rotorua Lakes complex.  These lakes support the largest national populations of two endemic species:  weiwea/New Zealand dabchick (Poliocephalus rufopectus) and pāpango/New Zealand scaup (Aythya novaeseelandiae).  Some species at Rotoiti show marked seasonal patterns throughout the year.  Higher numbers of adult pāpango/scaup are present between July and January, with numbers declining from late summer.  There is also some evidence that population of pāpango may be slowly declining at the site, although the population does vary between years.  Similar information will be presented for other water birds, and the time of year young have been recorded.  Breeding season information is potentially useful for the timing of lakeshore developments.