UNO Least Tern update

I have been following the Least Tern colony on the roof of Milneburg Hall since early June, visiting every 3-4 days typically.  It is easily visible from a portion of an adjacent building, providing the unusual opportunity to look down in leisure from an air-conditioned room at the nesting birds nearby.

The number of incubating terns peaked at 25 on June 18.  It fell to 15, and rose back to 17 yesterday.

Each time I visit, most of the previous nest sites (which I map each time) are still attended by incubating birds, a few are newly abandoned (I suspect predated), and there are always a few birds incubating in new locations.  I am not sure whether these represent newly laid eggs- I would guess so, but I am not sure that birds never move their eggs short distances.  Three hatched young have been present, but were not visible yesterday- possibly predated.

Yesterday I watched during a heavy rainstorm, while the birds sat on their eggs.  The roof was about 60% flooded, not enough to immerse eggs entirely, but enough to put three of the nests in standing water at least for a short time.  A number of tern nests seemed to be on local high spots, that stayed dry while largely or wholly surrounded by rain puddles.  

The incubating  terns frequently flush from the roof as a group, at intervals of only 5 minutes or so, which seems a lot to me.  Sometimes raptors are evident in the sky (Cooper's Hawk, Miss. Kites), but otherwise there is no obvious reason for the alarm.  They usually re-settle within a few minutes or so.

Good birding,

Peter

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