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Tjelden på taket

Summary of the breeding in 2005


The male is alert and still incubating, while the female is taking care of the only chick. Snapshot from the webcam 29 May 2005, 21:45.
Despite being weeks since it first flew off the roof, the juvenile bird returns together with its father during the evening. We suppose they spend the night on the roof. This picture was taken 22 July 2005, 21:00.

The webcamera was mounted 11 May 2005. The nest was on top of the science building in Bergen, western Norway. The building is about 25 meters high, and the roof is covered with gravel, mosses and lichens. Three eggs were present when the camera was activated, and the adult birds did already incubate the eggs. The camera itself did apparently not disturb the Oystercatchers, since they continued incubation just minutes after we left the roof that day.

During the early morning on 29 May the first chick hatched. It was heavy rain at the time, and the little one kept close to the still incubating adults. Despite warming the eggs for 35 more hours, the two other eggs did not hatch. The adults left the nest, and took the chick to another part of the roof. Some days later we uninstalled the webcam, and collected the eggs. When opening them we found that one egg was not fertilized, and the other had a dead embryo inside. The dead egg was about four days from hatching (based on the size of the embryo).

When embryos die before hatching there may be several reasons causing it. Problems during the hatching process may be caused by inbreeding or poor quality sperm from the male. Another possibility is that the adults did not synchronize the incubation. Shorebirds have to start the development of all eggs at the same time. This means that they should not incubate (only keep the egg ďaliveĒ) before all eggs are laid. If they donít they might abandon the nest before all chicks hatch. We suppose the latter explanation may be the most plausible here. There were no unfortunate disturbances in the hatching period.

08 June 2005: The chick has grown a lot and seems to be very fit. 25 June 2005: The chick is now full-grown, and was last seen on the roof yesterday. 22 July 2005: The juvenile bird is still using the roof together with its father. They spend the nights here.