Fluttering shearwaters on Mana Island in the 2017/18 season


There is some really interesting information about fluttering shearwater activity on Mana Island, in this extract from a report for FOMI by Helen Gummer …

Background

Fluttering shearwaters were reintroduced to Mana Island via a series of translocations between 2006 and 2008 in a project funded by Friends of Mana Island and assisted by the Department of Conservation. A total of 211 chicks fledged from two nearby colony sites (South Point and the Northern Colony) on Mana Island, following transfer from Long Island. The arrival of the first immigrant fluttering shearwater to Mana Island, lured in by sound, coincided with the 2008 translocation.

Post-release monitoring was funded by FOMI to assess the project’s outcome. A contractor (with volunteer assistance) was employed to undertake this work annually between 2010 and 2016. In 2017 FOMI volunteers and ranger Chris Bell took over the monitoring. The data collected was passed on to Helen Gummer to process for this report.

Conclusion

There were 69 adult fluttering shearwaters identified in the 2017/18 season on Mana Island. Notable captures and finds include:

  • Four new unbanded immigrants (bringing the total number of immigrants of unknown age and origin visiting Mana Island to seven birds).
  • Another first-time adult recovery of a 2007 translocated chick (increasing the known survival of the 2007 cohort of 91 translocated chicks to 46%).
  • Five more first-time captures of Mana-raised fluttering shearwater chicks as adults. There have now been 11 Mana-raised chicks recaptured as adults from 2015 onwards: three of the seven chicks (43%) banded in the 2011/12 season, five of the 14 chicks (36%) banded in the 2012/13 season, and three of the 13 chicks (23%) banded in the 2013/14 season.
  • Two new pairings at the Northern Colony site nesting in artificial fairy prion burrows. There are now six breeding fluttering shearwater burrows at this site.
  • 25 chicks banded at South Point and six at the Northern Colony. One chick belonging to a new pairing is likely to have been too light to survive post-fledging. This brings the total number of Mana-raised chicks fledging from the island since 2011 to 118.

The sudden influx of four more immigrants is likely to be due to the increased seabird activity on Mana Island. and the attractiveness of this to passing birds. However, it is possible that some or all these birds may be chicks that fledged without bands from unknown burrows on Mana Isalnd, particularly at the Northern Colony where some previously caught adults were unaccounted for over several years but have recently been found breeding in artificial burrows.

A first-time adult recapture of one of the 2007 translocated birds (at over 10.5 years old) shows that it can take more than 10 years to recapture fluttering shearwaters from the time they fledged.

A total of 69 fluttering shearwaters transferred to Mana Island in 2006−2008 are now reported to have survived, with 60 birds recaptured as adults on Mana Island, and nine birds found on Matiu/Somes Island.

This 33% survival rate of all three translocated chick cohorts combined so far exceeds that found for translocation projects involving any other seabird species in New Zealand, except for the Chatham Island taiko. The 28% return rate of birds to Mana Island is over double the overall return rate of 12% last reported for fluttering shearwaters translocated to Maud Island.

This year’s breeding season seems to be back on track (25 chicks banded) after a bad season last year when only 14 chicks survived to fledge following some severe flooding events in spring 2016. We should see an influx of 2014/15 Mana-raised birds next year, and probably more 2013/14 Mana-raised birds.