There has been a rush of laying this week and, as of Tuesday, 34 birds from around 130 study nest sites have been confirmed as incubating an egg! Daytime occupancy of nest sites has been over 25%, suggesting that lots more birds may be about to lay.
Inside Mousa's Iron Age broch (Hannah Watson)
Nests are checked every 5 days for the presence of a bird and evidence of having laid. Due to the nature of nest locations, visibility is often difficult and it is not always possible to determine if a bird is sitting on an egg or not. In this case, nests are visited and checked on up to 3 consecutive days. If a bird is present for 3 days in a row, it can be confidently assumed the bird is incubating an egg.
Study nest sites are located all over the island in areas subjected to varying levels of visitor pressure. Visitor movements are being recorded using beam counters and cameras. The beam counters have a sensor emitting an infra-red beam; each time a person walks by, the beam is broken and a count is made. Camera traps are being used alongside the counters to validate the data recorded by beam counters and check that sheep are not being counted too!
Camera and beam counter hidden within one of the dry stone walls