Report from 6 to 7 July 2022

The first returning Greenshank is confirmation that fall migration has begun.

Many juvenile Common Terns have now fledged, and all in all, while the fledgling rate may not have been as high as we had hoped, it was still satisfactory, especially considering all the perils the chicks must face. As it turns out, another problem emerged: several nests were abandoned after all the eggs were laid and incubation was almost over; this meant that many of the eggs that were laid never hatched. Predators had nothing to do with it: the eggs simply remained where they were without the adults caring for them. We wondered about the possible motive. One hypothesis is that the drought has reduced water flow in local rivers to the point that fish are scarce, and the terns simply could not find enough food to feed any hatchlings. Another hypothesis has to do with fertility: as the hatching date approached, the adults may have sensed that their eggs were infertile and abandoned them. This would also explain the unusual phenomenon of extra eggs being laid in some nests that already had a full clutch of three eggs, yet saw additional eggs being laid besides or even on top of them. Once the terns leave, we will try to collect some of these unhatched eggs, and perhaps will will then know whether or not they were sterile.
The flight pattern of the Common Terns is fast and unpredictable. After hours of fruitless efforts, I am quite pleased with this photograph.