Larus argentatus - Herring Gull
This is one of the four Leiden roof-breeding Herring Gulls that were color marked. It was ringed on June 4, 2007, as an adult, on roof of the Gorlaeus Building, about 1 km from here. The March 5, 2010 observation is the first reported sighting of this animal after marking. This gull was regularly seen foraging between March 5 and April 1, 2010. After several months of absence it showed up again on August 6, 2010. On August 23, K.NAT and its partner fed a full-grown fledgeling. After more than a month of absence, 'K.NAT' reappeared on the same spot on October 8, 11, 12, 13 and November 1, 11 (with 1 CY begging for food), 17, 22 (with partner) and 24. After the snow disappeared, G[K.NAT] reappeared on December 14, 2010, with its partner, catching worms. Again on December 15, K.NAT and partner were seen eating worms, likewise daily between January 3rd, and 6th, and on January 13, 16, 21, 26-28, and February 2-4, and 7-9, 11, 14, 18, 21, 25, and March 15, 21 (with begging 2nd CY bird) and 22, 2011 with its partner, each day eating worms. On March 24, K-NAT and partner were 'harrassed' again by a begging 2nc CY Herring Gull. Maybe this is a still-demanding young of last season? On March 25 it was present with partner, eating worms. On March 29, it was seen drinking water on the rooftop. Subsequently, K.NAT was seen giving up food for a begging 2nd CY Herring Gull (!), probably last year's young. On March 30, it was seen with partner searching for worms again. K.NAT and partner wwere also present on April 1, 2011. On April 4, K.NAT and partner were seen drinking fresh water on the rooftop of the 'Valk' building. On April 5 and April 15, it was seen with partner catching worms again. Again a 2nd CY Herring gull was begging for food. No food transfer was seen. On April 18, K.NAT was seen drinking water at the rooftop of the VALK building. On April 19, K.NAT was seen drinking at the rooftop. Upon hearing them calling at 17.00 hrs, I noted K.NAT being stalked on the ground by a the 2nd CY Herring Gull, the latter begging for food (low posture with bill slightly raised). Interestingly, K.NAT's partner aggressively chased-off another 2nd CY Herring gull, and returned after about 60 seconds to land near K.NAT and the begging 2nd CY Herring Gull. K.NAT walked to the water and took a swim followed by the begging young. After about a minute all gulls (3 pairs of adults and the 2nd CY) flew and disappeared. April 20, K.NAT and partner seen at the rooftop, no sign of the 2nd CY Gull. April 21, at 8.30 K.NAT, partner and 2nc CY were seen standing on the chimney of the VALK building for about 5 minutes. The young gull was begging for food mainly with K.NAT. An adult Lesser Black-backed Gull was chased-off from the roof top by partner. On April 26, K.NAT and partner were seen at the roof top of the Valk building.