You are here: Home
/ Publication Information
Title: A new method for ageing Marbled Murrelets and the effect on productivity estimates
Author: Long, L.L.; Ralph, C.J.; Miller, S.;
Source: Pacific Seabirds 28(2):82-91
Publication Series: Miscellaneous Publication
Description: Accurate knowledge of the number of newly-fledged juveniles offshore is critical to estimates of productivity of the threatened Marbled Murrelet (Brachyramphus marmoratus). We describe a method for collecting productivity data which allows researchers to objectively evaluate age determinations and their effect on juvenile percentages. This has the potential to reduce the effect of observer variability and the number of misidentified birds, especially late in the breeding season when adults in late pre-basic molt are very similar to juveniles. We analyzed the timing of this molt in adults, and found some variation between regions and years. Therefore, critical dates for identification of adults in late molt versus juveniles may need to be reassessed annually. During our study, productivity estimates ranged from 1% to 7% juveniles. We used two methods for assessing the effect of missed juveniles. Even after adjusting for misclassified murrelets, the resulting juvenile percentages (1% to 17%) would suggest an unstable population in our study area.
Keywords: Marbled Murrelet, Brachyrarnphus marmoratus, productivity, juvenile, molt, ageing
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication. (Please specify exactly
which publication you are requesting and your mailing address.)
XML: View XML
Long, L.L.; Ralph, C.J.; Miller, S. 2001. A new method for ageing Marbled Murrelets and the effect on productivity estimates. Pacific Seabirds 28(2):82-91
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility