Capture and handling of saddlebacks during pre-nesting does not affect timing of egg-laying or reproductive success
|Title||Capture and handling of saddlebacks during pre-nesting does not affect timing of egg-laying or reproductive success|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||Jamieson, IG, Grant, JL, Beaven, BM|
|Type of Article||paper|
|Keywords||egg-laying, mist-netting, Petroica australis rakiura, Philesturnus carunculatus carunculatus, South Island saddleback, Stewart Island robins, Ulva Island|
We examine whether mist-netting and handling of birds (including taking blood samples) during the pre-nesting period caused egg-laying to be delayed in a threatened species, South Island saddleback (tïeke) Philesturnus carunculatus carunculatus. We used data on egg-laying dates of first clutches for 12 pairs in 2002-03 and 22 pairs in 2003- 04, of which 3 (2002-03) and 7 (2003-04) pairs had been caught and handled. There was a significant delay in the peak laying period of first clutches in 2003-04, which was associated with more birds being caught and handled. However, pairs that were handled showed typical laying dates of first clutches for both experienced and inexperienced pairs, and there was no significant correlation between the date when a pair was caught and the date of laying its first clutch. There were also no significant differences between handled and non-handled pairs in the number of chicks raised or fledged. Like saddlebacks, Stewart Island robins Petroica australis rakiura monitored at the same site showed a two-week delay in the average laying dates of first clutches in 2003-04. The five inexperienced robin pairs in 2002-03 laid their first clutches earlier in 2003-04, but all three experienced pairs laid later. Weather data indicated it was substantially colder before the nesting period in 2003 compared to 2002, suggesting that colder weather conditions plus a greater number of inexperienced pairs caused a delay in peak egg laying in both species in 2003-04 relative to 2002-03. We conclude that mist-netting, banding and bleeding – standard technique used in present-day research of threatened avian species – did not have any measured short-term effects on nesting behaviour or breeding success of South Island saddlebacks.