Breeding biology of Red-tailed Tropicbirds Phaethon rubricauda and response to predator control on O'Ahu, Hawai'I

Published source details VanderWerf E.A. & Young L.C. (2014) Breeding biology of Red-tailed Tropicbirds Phaethon rubricauda and response to predator control on O'Ahu, Hawai'I. Marine Ornithology, 42, 73-76.
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Summary

Control mammalian predators on islands for seabirds

A study in 2006–2013 on O’ahu, Hawaii, USA (Vanderwerf & Young 2014) found that during a period in which feral cats Felis catus, Indian mongooses Herpestes auropunctatus and rats Rattus spp. were controlled, the productivity of red-tailed tropicbirds Phaethon rubricauda increased, but breeding success did not significantly change. Between 2006 and 2013, there were significant increases in the number of eggs laid (from 19 to 38/year), the number of eggs hatched (from 11 to 31/year) and chicks fledged (from 10 to 24/year). Hatching success and fledging success tended to be higher in 2010–2013 (77–87% of eggs hatched; 77–90% of chicks fledged) than in 2006–2009 (58–83% of eggs hatched; 53–91% of chicks fledged), but these differences were not statistically significant. The same was true for overall reproductive success (2010–2013: 60–70% vs 2006–2009: 40–63%). Tropicbird nests were monitored on cliffs and steep slopes in southeast O’ahu. Predator control involved (a) trapping mongooses, cats and rats in 2006-2013 (using a variety of traps, and not all species targeted in all years), and (b) using poison bait for mongooses and rats in 2008, 2009, 2011 and 2012.