Distance sampling techniques compared for a New Zealand endemic passerine (Philesturnus carunculatus rufusater)

Phillip Cassey, JL Craig, BH McArdle, RK Barraclough

Research output: Contribution to journalArticle

15 Citations (Scopus)


The effectiveness of line- and point-transect distance sampling methods was compared for estimating the density of a conspicuous endemic passerine, the North Island saddleback Philesturnus carunculatus rufusater, in two forest habitats on Tiritiri Matangi Island, Hauraki Gulf, New Zealand. The reference population abundance in each habitat was calculated through an intensive capture, colour-banding, and resighting effort. Line transects consistently produced unbiased estimates of density for both sites at two time periods (morning and afternoon), and proved to be the most efficient of the distance sampling methods tested. Point-transect methods proved to be biased in this instance, consistently producing overestimates of density for this species, and were unreliable as indices of the small differences in density between habitats. Transect counts conducted from established walking tracks underestimated both density and the variance of estimated density. We conclude that in situations requiring estimates of absolute density for North Island saddleback, a series of randomly positioned line transects will accurately represent the density of individuals. Furthermore, this study highlights the need to pilot distance survey techniques on the species of interest to detect possible violation of the assumptions underlying these methods. We question the widespread use of point-transect counts for censusing avian species without such preliminary investigation, and recommend further comparisons of distance sampling methods in New Zealand with reference populations where opportunity provides.
Original languageEnglish
Pages (from-to)223-231
Number of pages9
JournalNew Zealand Journal of Ecology
Publication statusPublished - 1 Jan 2007


  • Tiritiri Matangi Island
  • mist netting
  • saddleback
  • density estimation


Dive into the research topics of 'Distance sampling techniques compared for a New Zealand endemic passerine (Philesturnus carunculatus rufusater)'. Together they form a unique fingerprint.

Cite this