Foraging opportunities for Herring Gulls from Texel throughout the annual cycle

Species: Herring gull

An important breeding colony for ongoing research is found on the Wadden Island, Texel.  (53°00’N, 04°43’E).  Approximately 5000 pairs of Herring Gulls breed in that area. The breeding ecology in this colony has been studied since 2006. In 2013 we started tracking herring gulls with UvA-BiTS GPS loggers. This study is running in parallel to a lesser black-backed gull tracking study in the same colony.

 

 

 

Current tracking work, together with the collection of prey items in the colony, will help us identify their primary foraging areas and resources during the breeding season, as well as their movement patterns throughout the non-breeding season. Tracking data from 2013 confirmed information derived from colour-ring resightings, that herring gulls from Texel spend a large proportion of their time along wave breakers (breakwaters or groynes) along the coast of Noord-Holland. On these breakwaters they feed predominantly on Blue Mussels Mytilus edulis. Current plans to re-enforce the coastline by covering many of these breakwaters with sand will significantly change this foraging habitat.

FASD with logger (photo Jan Zorgdrager)

The consequences for Herring Gulls breeding on Texel are unclear and a main focus of our current research. Colour-rings and tracking data show that individual birds utilising these (150 or so) breakwaters are often highly site-faithful: most birds use a small subset of the available breakwaters. The effect of destroying part of this foraging area will therefore be different for different individuals. Persistent dominance hierarchies, established at individual breakwaters, are the likely force steering the distribution of individual gulls rather than food supplies and differences in food quality between breakwaters. These and future tracking studies will focus on the changes imposed on the main foraging area, as well as on winter foraging areas that might explain why the overwinter survival of this species is compromised.

 

In 2015 the following birds can be followed on this website ( GPS tag number and colour ring code are provided):

  • 1600 FASD
  • 6006 MARZ
  • 6011 FASH
  • 6015 MANK
  • 6016 MAMH
  • 6017 MASL
  • 6073 FAJP
  • 6077 MAUF
  • 6080 MANM
  • 6202 MAVV
  • 6205 JUDY
  • 6206 SUUS
  • 6208 MAVX
  • 6212 MAWA
  • 6214 MAWB
  • 6216 FAWR

 

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Near real-time tracking data (last 3 days of data available per individual bird)
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Contact Persons:

Kees Camphuysen, NIOZ kees.camphuysen@nioz.nl

Judy Shamoun-Baranes, IBED-UvA shamoun@uva.nl

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