thumbnail

Abundance and productivity of marbled murrelets (Brachyramphus marmoratus) off central California during the 2017 breeding season

Data Series 1093

By:
https://doi.org/10.3133/ds1093

Links

Abstract

Marbled murrelets (Brachyramphus marmoratus) have been listed as “Endangered” by the State of California and “Threatened” by the U.S. Fish and Wildlife Service since 1992 in California, Oregon, and Washington. Information regarding marbled murrelet abundance, distribution, population trends, and habitat associations is critical for risk assessment, effective management and evaluation of conservation efficacy, and ultimately to meet Federal- and State-mandated recovery efforts for this species. During June–August 2017, the U.S. Geological Survey Western Ecological Research Center continued previously established, long-term (1999–2016), at-sea surveys to estimate abundance and productivity of marbled murrelets in U.S. Fish and Wildlife Service Conservation Zone 6 (central California—San Francisco Bay to Monterey Bay). Using conventional distance sampling methods, we estimated marbled murrelet abundance using 189 detections of 321 individuals observed on nine unique surveys. The abundance estimated for the entire study area using all surveys in 2017 was 530 birds (95-percent confidence interval, 384–732 birds). Estimated abundance from 2017 is comparable to most prior years of study, except for 2008 and 2015, which had anomalously low abundances. We estimated productivity (calculated as the hatch-year [HY] to after-hatch-year [AHY] ratio) in 2017 using three detections of three individuals observed in six surveys. After date-correcting HY and AHY counts to account for birds expected to be absent from the water while inland at nests, the date-corrected juvenile ratio was 0.022 ± 0.014 standard error. We created a synthesized database of all marbled murrelet survey data from 1999 to 2017 to allow scientists and managers to evaluate established survey methods and assess trends in abundance and productivity estimates. Future modifications of survey design could help reduce variance in abundance estimation.

Suggested Citation

Felis, J.J., Adams, J., and Kelsey, E.C.., 2018, Abundance and productivity of marbled murrelets (Brachyramphus marmoratus) off central California during the 2017 breeding season: U.S. Geological Survey Data Series 1093, 12 p., https://doi.org/10.3133/ds1093.

ISSN: 2327-638X (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • Marbled Murrelet Abundance and Productivity Results
  • Discussion
  • Summary
  • Acknowledgments
  • References Cited

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Abundance and productivity of marbled murrelets (Brachyramphus marmoratus) off central California during the 2017 breeding season
Series title:
Data Series
Series number:
1093
DOI:
10.3133/ds1093
Year Published:
2018
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Western Ecological Research Center
Description:
Report: iv, 12 p.; Data release
Country:
United States
State:
California
Online Only (Y/N):
Y