| | Equipment at nest | Confirmed hatched | Likely hatched | Confirmed failed | Likely failed | Total nests | % Successb |
|---|
All nests | No equipment | 98 | 28 | 53 | 11 | 190 | 66.3 |
With iButtons | 17 | 7 | 4 | 0 | 28 | 85.7 |
With iButton + camera | 5 | 0 | 3 | 1a | 9 | 55.6 |
Original nests | No equipment | 90 | 16 | 23 | 9 | 138 | 76.8 |
With iButtons | 14 | 5 | 0 | 0 | 19 | 100 |
With iButton + camera | 5 | 0 | 0 | 1a | 6 | 83.3 |
- aThe camera was removed from the nest site before a definitive status could be determined, though all signs point to nest failure
- bHatching success (%) was determined by equipment class using the following formula: (Confirmed hatched + Likely hatched)/Total nests × 100
- The impact of cameras and iButtons on the hatching success of all Common Tern nests in the focal colony at Poplar Island based upon colony survey data. We differentiated between original and re-nesting attempts based upon the date at which a large number of individuals were documented arriving at the colony following the collapse of a nearby colony. We considered a nest to have likely hatched if eggs were no longer found in the nest within 19‒31 days after the clutch initiation date, unless (1) sign of failure was present (i.e., sign of predation, nest wash out, non-pipping related holes, etc.) in which case it was considered confirmed failed, or (2) a chick was captured or observed in which case it was considered confirmed hatched. Eggs gone from the nest prior to 19 days or remaining after 31 days of clutch initiation were considered likely to have failed
