Onset and duration of gray seal (Halichoerus grypus) molt in the Wadden Sea, and the role of environmental conditions
Surveys of gray seals (Halichoerus grypus) during the molt period, when they are abundant on land, can be used to monitor changes in population size, but accurate interpretation of results requires an understanding of the molt process and how it may vary between years. This study investigates variability in onset (start date) and duration of visible molt by gray seals in the Wadden Sea, and the influence of environmental conditions on the onset. Molt was monitored in nine captive seals and observed molt phases were applied to wild seals over seven annual molt periods between 2004 and 2010, monitored using aerial photography. The onset of visible molt varied significantly between years, for example it differed 28 d between 2008 and 2009. Model selection by AIC retained one environmental variable that correlated with molt onset; however, its effect was inconsistent within the molt season and did not explain some of the apparent observed annual variation. Hence, the main causes of interannual variability in the onset of molt remain unclear and warrant further study. Researchers should account for annual variability in the onset of molt when interpreting survey results based on molt counts.
Main Authors: | Schop, Jessica, Aarts, Geert, Kirkwood, Roger, Cremer, Jenny S.M., Brasseur, Sophie M.J.M. |
---|---|
Format: | Article/Letter to editor biblioteca |
Language: | English |
Subjects: | Annual life cycle, Dutch Wadden Sea, Gray seals, Halichoerus grypus, Haul-out, North Sea, Peak molt, Phocid seals, Population monitoring, |
Online Access: | https://research.wur.nl/en/publications/onset-and-duration-of-gray-seal-halichoerus-grypus-molt-in-the-wa |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Similar Items
-
Seals in motion : how movements drive population development of harbour seals and grey seals in the North Sea
by: Brasseur, Sophie Marie Jacqueline Michelle -
Voedselecologie van de gewone en grijze zeehond in de Nederlandse kustwateren; I onderzoek naar de voedselecologie van de gewone zeehond; II literatuurstudie naar het dieet van de grijze zeehond
by: Brasseur, S.M.J.M., et al. -
Seal monitoring and evaluation for the Luchterduinen offshore wind farm: 2. Tconstruction - 2014 report
by: Kirkwood, R.J., et al. -
Interactions between grey seal (Halichoerus grypus), Atlantic salmon (Salmo salar), and harvest controls on the salmon fishery in the Gulf of Bothnia
by: Jounela, P., et al. -
Investigation of the ability of gray seals to differentiate composite audio signals
by: Litvinov, Yu. V., et al.
Published: (2019)