Accuracy and precision of dolphin group size estimates. Issue 1 (14th May 2018)
- Record Type:
- Journal Article
- Title:
- Accuracy and precision of dolphin group size estimates. Issue 1 (14th May 2018)
- Main Title:
- Accuracy and precision of dolphin group size estimates
- Authors:
- Gerrodette, Tim
Perryman, Wayne L.
Oedekoven, Cornelia S. - Abstract:
- Abstract: Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and precision of dolphin group size estimates, observer estimates were compared to counts from large‐format vertical aerial photographs. During 11 research cruises, a total of 2, 435 size estimates of 434 groups were made by 59 observers. Observer estimates were modeled as a function of the photo count in a hierarchical Bayesian framework. Accuracy varied widely among observers, and somewhat less widely among dolphin species. Most observers tended to underestimate, and the tendency increased with group size. Groups of 25, 50, 100, and 500 were underestimated by <1%, 16%, 27%, and 47%, respectively, on average. Precision of group size estimates was low, and estimates were highly variable among observers for the same group. Predicted true group size, given an observer estimate, was larger than the observer estimate for groups of more than about 25 dolphins. Predicted group size had low precision, with coefficients of variation ranging from 0.7 to 1.9. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are included in the analysis.
- Is Part Of:
- Marine mammal science. Volume 35:Issue 1(2019)
- Journal:
- Marine mammal science
- Issue:
- Volume 35:Issue 1(2019)
- Issue Display:
- Volume 35, Issue 1 (2019)
- Year:
- 2019
- Volume:
- 35
- Issue:
- 1
- Issue Sort Value:
- 2019-0035-0001-0000
- Page Start:
- 22
- Page End:
- 39
- Publication Date:
- 2018-05-14
- Subjects:
- group size estimation -- abundance estimation -- aerial photography -- Bayesian hierarchical model -- random‐effects model -- reversible jump MCMC
Marine mammals -- Congresses
Marine mammals -- Periodicals
Marine mammals, Fossil -- Periodicals
Mammifères marins -- Périodiques
599.5 - Journal URLs:
- http://apt.allenpress.com/aptonline/?request=get-archive&issn=0824-0469 ↗
http://ejournals.ebsco.com/direct.asp?JournalID=114222 ↗
http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-7692 ↗
http://www.blackwell-synergy.com/loi/mms ↗
http://www.blackwellpublishing.com/journal.asp?ref=0824-0469&site=1 ↗
http://onlinelibrary.wiley.com/ ↗ - DOI:
- 10.1111/mms.12506 ↗
- Languages:
- English
- ISSNs:
- 0824-0469
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - 5376.170000
British Library DSC - BLDSS-3PM
British Library HMNTS - ELD Digital store - Ingest File:
- 9415.xml